FUNDAMENTAL OF MECHANICAL ENGINEERING 3300015 PRACTICAL MANNUAL

BHAGWAN MAHAVEER ENGINEERING COLLEGE

MECHANICAL DEPARTMENT

INDEX SR.NO.

PRACTICAL

PAGE NO

1

Introduction of basic mechanical engineering

1

2

To study about power transmission and safety.

7

3

To study about welding and gas cutting brazing and soldering process.

15

4

To prepare a welding joint

24

5

To study about various machining process and prepare simple turning job

31

6

To study about various types of Mounting and Accessories of Boilers.

40

7

Study the effects of variation of the load on the fuel consumption of Petrol I.C. engine and fault & remedies for I.C. engine.

44

8

Study the effects of variation of the load on the fuel consumption of Diesel I.C. engine and fault and remedies for I.C. engine.

47

9

To demonstrate a water turbine.

50

10

To perform a test on Air Compressors

56

11

Performance test on the pump and suggest fault and remedies for it. 1. To determine the efficiency of the pump. 2. To draw the operating characteristic of the pump for different flow rates and find the optimum condition.

12

To Study various type of material handling equipments.

61

65

EXPERIMENT NO:-1

AIM: - INTRODUCTION OF BASIC MECHANICAL ENGINEERING  Use of mechanical engineering:-

 Mechanical engineering is an important field of engineering. Mechanics means machine’s detailed knowledge.

 Every person needs machine to make his life easy and fast. Mechanical engineering is used every day in our life.  IN DAY TO DAY LIFE

 A man is incomplete without a machine in today’s life with the use of machine in day to day life, every work becomes easier & faster.

 For example: - Phone, Printer, laptop, cars, bikes, brakes, screws, nuts, spring etc.  The given examples are used in day to day life and a part of mechanical engineering.  INTERDECIPLINERY USE: Mechanical engineering is also use in other engineering branches like civil, electrical, computer etc. mechanics is used in every branches.  Civil engineering means the engineering of building & construction. The machines & parts used in construction of a building.  Automobile engineering means engineering of vehicles. It is little bit related to mechanical engineering.  Electrical engineering is the field in which mechanical engineering is used. E.g. Shafts, belt, bearing, etc. and they are made from mechanical engineering concepts and mechanical equipments.  So, mechanical engineering is very important in other fields too.  So, these are the daily and disciplinary use of mechanical engineering.  ITEMS IN GENERAL USE: We all have general mechanical parts or machines around us. With the use of these items are many parts in machines which are really important to work the machines and they are as follows  Bolts, Nuts, Washers, Bearing, Bushes, Belts, Springs, Reverse, Couplings, Brakes, Screws, Rivets, Oil seals, Gears, Pulley, Shafts, etc. BEARING:

Bearing provides support to the shaft or journal of the machines transmitting power. By proper support of suitable bearing proper to shaft, its alignment can be maintained

FUNDAMENTALS OF MECHANICAL ENGINEERING

and bending of shaft can be prevented. Thus bearing plays an important role in power transmission.  TYPES OF BEARINGS: SLIDING CONTACT BEARINGS:(1) Guide Bearings (2) Bush Bearings (3) Journal Bearings (4) Thrust Bearings  ROLLER CONTACT BEARINGS (1) Ball Bearings (2) Cylindrical roller Bearings (3) Tape roller Bearings (4) Needle roller Bearings BELTS:



 (1) (2) (3) (4) (5) (6) (7)

In industries, generally flat belt, V-belt and rope are used to transmit power and circular velocity from one shaft to another shaft. When the distance between two shafts is not more than 10 meter and power to be transmitted is of moderate nature; flat belt is used for power transmission whereas when distance between two shafts is more than 5 meters and huge power transmission is required, rope drive is used. The belt and the rope drive are used to transmit the power from one shaft to another by means of pulley which rotates at the same speed or different speeds depending upon diameter of pulleys. TYPES OF FLAT BELT DRIVE:Open belt drive Cross belt drive Quarter-turn belt drive Belt drive with idler pulley Compound belt drive Cone pulley drive Fast & loose pulley drive

GEAR:

 (1) (2) (3) (4)

Gear drive transmits power without slipping. It is therefore called positive drive and used where more power is to be transmitted. It can transmit more power than belt drive system. TYPES OF GEARS:Spur gear Helical gear Worm & worm wheel Rack and pinion BHAGWAN MAHAVIR POLYTECHNIC

1

FUNDAMENTALS OF MECHANICAL ENGINEERING

(5) (6) (7) 

Internal gear Spiral gear Hypoid gear Gear drive provides constant velocity ratio but useful only at shorter distances between two shafts.

 TYPES OF GEAR TRAIN: (1) (2) (3)

Based on arrangement of gears, gear train are of following types Simple gear train Compound gear train Epicycle gear train

COUPLING:

Coupling is used to connect electric motor and water pump, electric motor and generator etc.

 TYPES OF COUPLINGS: Rigid Coupling (1) Slip & muff coupling (2) Clamp & compression coupling (3) Flange coupling  Flexible Coupling (1) Bush & pin type flange coupling (2) Universal coupling (3) Oldham coupling SCREW: Screw is a common & known part in engineering. These are types of screws:  Cap screwCap screw are used for connecting two parts together by passing through a hole in one and screwing into a tapered hole in the other. There are various types of cap screws.  Machine screwsThey are generally similar to screws in all respects but are generally smaller in diameter. They are primarily used for light duty work.  Set screwsThey are similar to screws, but it is threaded particularly throughout its length. They are used for holding two machines parts. Nut: 

Nuts are generally in the form of hexagonal or square prisms. Besides there, other forms are used in particular requirement. There are many types of nut. BHAGWAN MAHAVIR POLYTECHNIC

2

FUNDAMENTALS OF MECHANICAL ENGINEERING

(1) (2) (3) (4) (5) (6) (7)

Hexagonal nut Square nut Ring nut Cap nut Cylindrical or capstan nut Dome nut Wing nut or thumb nut

RIVETS:  (1) (2) (3) (4)

Rivets are permanent fasteners used for joining two or more permanent joint. TYPES OF RIVETS:Cup head or snap head Pan head Conical head Countersunk head

members to form a

BOLTS:

 (1) (2) (3) (4) (5) (6) (7) (8)  (1) (2) (3) (4)

A bolt comprises of two parts shank and head. The cylindrical portion of the bolt known as the shank. The shape of the head depends upon the purpose for which the bolt is required. To completely specify a bolt is necessary to mention eight features. Shape or form of the thread Pitch Shape of the head Outline of the body, barrel or stem Size or diameter Direction of threads Length Material as steel or brass etc Some of the most commonly used bolts are described here under Square- headed bolt Cylindrical or cheese-headed bolt Cup-headed or round-headed bolt T-headed bolt  So, this is the detailed information of items in general use in mechanical engineering.

BHAGWAN MAHAVIR POLYTECHNIC

3

FUNDAMENTALS OF MECHANICAL ENGINEERING

PIPES AND PIPE FITTING: Pipes can be specified by (1) Material (2) Inside thickness (3) Wall thickness (4) Length (5) Surface treatment  Types of pipes 1) Cast iron solid pipe. 2) Cast iron span pipe. 3) Mild steel pipe. 4) Asbestoses-Cement Pipe. 5) Ceramics pipe. 6) R.C.C. Pipe. 7) Copper Pipe. 8) Stainless steel Pipe. 9) Lead Pipe. 10) Plastic Pipe. 11) Teflon Pipe. 12) PVC lined cast iron Pipe. 13) Rubber Pipe. PIPE FITTING:

1. 2. 3. 4. 5. 6.

Fitting are used for joining two or more sections of pipe for required length for changing the diameter or direction of flow of line, or for controlling the flow in the line. Coupling 7. Nipple Elbow 8. Union Bend Tee Plug Cap

HAND & POWER TOOLS:

These are many tools which can be used manually and with electricity. Hand tools are used by us and they are as below.  VICES: The vice is the most common tool for holding work.  HAMMERS: Hammer is used to strike a job or a tool. They are made of forged steel of various sizes and shapes to suit various purposes.

BHAGWAN MAHAVIR POLYTECHNIC

4

FUNDAMENTALS OF MECHANICAL ENGINEERING



Hammers are classified according to the shape of the peen, as ball peen, and straight peen hammers.

 CHISSELS: Chisels are used for cutting & chipping away pieces of metal and are made of carbon steel usually rectangular, hexagonal, or octagonal cross-section.  FILING-cross filing and draw filing  HACKSAW- power hacksaw  SAWING- sawing of tubes  SCRAPING.

BHAGWAN MAHAVIR POLYTECHNIC

5

FUNDAMENTALS OF MECHANICAL ENGINEERING

EXPERIMENT NO:-2

AIM: - TO STUDY ABOUT POWER TRANSMISSION AND SAFETY. INTRODUCTION:-

To operate machines, velocity, & power of various mechanical machines, electric motors and I.C. engines are being transmitted. Velocity & power are transmitted from one shaft of the machine to another shaft of the machine. For this purpose belt, rope & chain drives are used. Positive drives such as gears and clutch are also used. Selection of appropriate drive is dependent on the distance of power transmission of mechanical power for getting required velocity and torque. And for these power transmission drives are essential. INPORTANCE OF POWER TRANSMISSION:-

As we know, electric motors are used in industries to run the machine. Velocity &power of electric motors are transmitted to operate various machine tools such as lathe, shaping m/c, drilling m/c etc. So power transmission is very important to run such m/c tools in the industries. Apart from this industrial important, power transmission is also important in other field. Gates of dam are being opened & closed by transmitting power of electric motor. In scooter, car, truck velocity &power of IC engine is being transmission to road wheel through power transmission system. Similarly power of I.C. engine is being remitted through appropriate power transmission system to run road roller, bulldozer, cairns etc. Even in tailoring m/c & sugarcane juice m/c power transmission is used. In this way, power transmission is important every right from house hold application to industrial vehicles heavy earthmoving m/c, ship, submarines etc. METHOD OF POWER TRANSMISSION:Different method of power transmission is 1. Belt & rope drive. 2. Chain drive. 3. Gear drive. 4. Came drive. 5. Roller drive. APPLICATION OF POWER TRANSMISSION:Various application of power transmission is listed as below:BHAGWAN MAHAVIR POLYTECHNIC

6

FUNDAMENTALS OF MECHANICAL ENGINEERING

A). to operate tools machine in industries. B). to transmit power of electric motors to water pump 7 compressors. C). to operate heavy earthmoving machine such as duper, excavator etc. D). to operate cranes & elevators. E). to transmit velocity and power of I.C. engines. F). to transmit power and velocity from one shaft of the machine to another shaft. G). to operate tailoring machine and sugarcane and juice machine. H). to operate mixture, grinder, washing machine, etc. TYPES OF FLAT BELT DRIVE:Different types of flat belt drives are:1. Open belt drive. 2. Cross belt drive. 3. Quarter turn belt drive. 4. Belt drive with idler pulley. 5. Compound belt drive. 6. Coe pulley drive. 7. Fast and loose pulley drive. 1. OPEN BELT DRIVE:Fig:-1 illustrates open belt drive. When two shafts are running in the same direction and parallel to each other then this drive is used. Driver pulley A pulls belt from lower and pushes it from upper side. Due to this, lower side of the belt remains in more tension compared to upper side of the belt. Therefore lower side of the belt is called tight side and upper side is called slack side. 2. CROSS BELT DRIVE:Figure indicates cross belt drive. This drive is also called twist belt drive. This drive is used two parallel shafts are ruing in opposite direction. POWER TRANSMISSION BY GEARS AND CHAINS:Gear drive transmits power without power without slipping. It is therefore called positive drive and used where more power is to be transmitted. It can be transmit more power than belt drive system. Parallel and interacting shafts are connected with help of different.

BHAGWAN MAHAVIR POLYTECHNIC

7

FUNDAMENTALS OF MECHANICAL ENGINEERING

TYPES OF GEARS AS MENTIONED BELOW:1. SPUR GEAR. 2. BEVEL GEAR. 3. RACK AND PINION. 4. SPIRAL GEAR. 5. HELICAL GEAR WORM AND WHEEL. 6. INTERNAL GEAR. 7. HIPOID GEAR. Belt and rope drive can not provide constant velocity ratio due to slip in the drive system. Gear rive provides constant velocity ratio but useful only at shorter distances between two shafts. Due to this chain drive is used to transmit power at larger distances. Keeping the velocity ratio constant chain made out of steel and sprocket is used in chain drive system. Teeth of sprocket engage with space between two links of the chain. Due to this engagement chain and sprocket both rotate simultaneously. By meshing two or more gear wheels power can be transmitted from one shaft to another. Such system is called gear train. TYPES OF GEAR TRAIN:Based on arrangement of gears, gear trains are of following types. 1. 2. 3. 4.

Simple gear train. Compound gear train. Reverted gear train. Epicyclical gear train.

1. SIMPLE GEAR TRAIN:These types of gear train are used to transmit power and motion where distance between driver and follower shaft is large fig shows simple gear train. This drive is made up by assembling intermediate gears between driver and follower. In this drive only one gear is mounted on intermediate shaft.

BHAGWAN MAHAVIR POLYTECHNIC

8

FUNDAMENTALS OF MECHANICAL ENGINEERING

2. COMPOUND GEAR TRAIN:These types of gear train are used to increase or decrease the velocity ratio of the gear train. In simple gear train, drive is made up by putting gears between driver and follower. By this arrangement velocity ratio of the gear train is not getting changed. Fig illustrates compound gear train arrangement. As seen from the fig that driver and drive shafts are having one gear train each mounted on it with integral gears mounted on intermediate shafts.

3. REVERTED GEAR TRAIN:This gear train is shown in fig gear 1 is driver gear and gear 3 is driven gear. Both these gears are on the same axes and rotating in the same direction. Such arrangement is called reverted gear train.

4. EPICYCLIC GEAR TRAIN:In epicyclic gear train two shafts are having relative motion as shown in Fig are of gear A is stationary whereas gear B rotates around gear a. Thus there exists relative motion between axes 01 and 02. The important point to note here is that expect this gear train axes of all the gear trains explained above remain stationary.

BHAGWAN MAHAVIR POLYTECHNIC

9

FUNDAMENTALS OF MECHANICAL ENGINEERING

ROLE OF COUPING AND JONRAL BEARING IN POWER TRANSMISSION:1. COUPLING:Coupling is used to connect electric motor and water pump, electric motor and generator etc. This machines connected by coupling rotates in the same direction, Such connection can be kept in use for longer duration. To shocks of driving rubber bushing are provide around the bolts of the coupling. 2. TYPES OF BEARINGS:(A) RIGID COPULING:1. SLIP AND MUF COUPLING. 2. CLAMP AND COMPRESSON COUPLING. 3. FLANGE COUPLING. (B)FLEXIBLE COUPLING:1. BUSH AND PIN TYPE FLANGE COUPLING. 2. UNIVERSAL COUPLING. 3. OLDHAM COUPLING. 3. TYPES OF BEARINGS:(A) SLIDING CONTACT BEARINGS:1. GUIDE BEARINGS. 2. BUSH BEARINGS. 3. JOURNAL BEARINGS. 4. THRUST BEARINGS. (B) ROLLING CONTACT BEARINGS:1. BALL BEARINGS. 2. CYLINDRICAL ROLLER BEARINGS. 3. TAPER ROLLER BEARINGS. 4. NIDDLE ROLLER BEARINDS. Fig shows ball and roller bearings. In bearings some power is lost where as there is no power loss in coupling. Bearings are with stand axial load and lateral thrust to maintain balance of the shaft. CAUSE OF ACCIDENTS AND THEIR REMEDIES:DEFINITION OF ACCIDENT:Accidents are injury to a person due to his or other faults. Such injuries are moderate, serious or even causing death. Accident can happen to a person while working in the industry or even in other conditions. Apart from this situations, causing damage, moderate or serious to factory building machinery etc are also termed as accidents.

BHAGWAN MAHAVIR POLYTECHNIC

10

FUNDAMENTALS OF MECHANICAL ENGINEERING

1. CAUSE OF ACCIDENTS:1. Defective machinery. 2. No guard on machine drive or defective guard. 3. No guard on cutting tool. 4. Defective electric wiring. 5. Improper or insufficient space for working. 6. Unnecessary during working. 7. Carelessness during working. 8. Less concern for safety by workers 9. Noise pollution in the industries. 2. REMEDIES TO AVOID ACCIDENTS:1. Proper housekeeping of plant. 2. Use of defect for machinery. 3. Appropriate uniform. 4. Proper space for working. 5. Cooperation by workers for safety.

VELOCITY RATIO The ratio between the velocities of driver and driven is known as velocity ratio. Simple Belt Drive Let N1 be the rotational speed of the driving pulley, N2 be the rotational speed of the driven pulley, d1 be the diameter of the driving pulley, d2 be the diameter of the driven pulley, and t be the thickness of the belt, as shown in Figure.

BHAGWAN MAHAVIR POLYTECHNIC

11

FUNDAMENTALS OF MECHANICAL ENGINEERING

Neglecting any slip between the belt and the pulleys and also considering the belt to be inelastic, we can state that speed of belt on the driving pulley is equal to speed of belt on the driven pulley:

or

Ordinary Gear Trains Gear trains consist of two or more gears for the purpose of transmitting motion from one axis to another. Ordinary gear trains have axes, relative to the frame, for all gears comprising the train. Figure shows a simple ordinary train in which there is only one gear for each axis. In Figure a compound ordinary train is seen to be one in which two or more gears may rotate about a single axis.

BHAGWAN MAHAVIR POLYTECHNIC

12

FUNDAMENTALS OF MECHANICAL ENGINEERING

Ordinary gear trains Velocity Ratio We know that the velocity ratio of a pair of gears is the inverse proportion of the diameters of their pitch circle, and the diameter of the pitch circle equals to the number of teeth divided by the diametric pitch. Also, we know that it is necessary for the to mating gears to have the same diametric pitch so that to satisfy the condition of correct meshing. Thus, we infer that the velocity ratio of a pair of gears is the inverse ratio of their number of teeth. For the ordinary gear trains,

These equations can be combined to give the velocity ratio of the first gear in the train to the last gear:

BHAGWAN MAHAVIR POLYTECHNIC

13

FUNDAMENTALS OF MECHANICAL ENGINEERING

Experiment No: 3 AIM: - To study about welding and gas cutting brazing and soldering process. Introduction:Metal joining is one of the most important basic processes in industries. Welding is the prime metal joining process. Welding can produce very strong and permanent joint. Many awkward and odd shape components are welded together to look like single piece design. You might have seen a small repair shop near your residential area or at some other place doing repairing of broken metallic parts like preparing small windows grills and preparing small garden zulla etc. Welding is extensive used in many field with plenty of advantages which we will see in due course in this practical. Welding:Welding can be define as process of joining – similar the application of heat with or without the application of pressure and filler metal in such a way that the result is a composition and characteristic as the two parts to be joined together. The part produce as result of welding process that is produce of welding process is called “welding”. 1) General condition for welding: For getting good strong and sound joints it is desirable that the surface of parts to be welded should be clean and free from foreign materials. Depending upon the shape and surface condition of the parts. Any oxide produce during the operation also interfere with welding of many metals. These oxides if not removed many get entrapped in the weld making the joint weak. 2) Flux in welding: Fluxes are added to the weld joint during welding process. Fluxes react with harmful oxide and produce slags which are more fluid and having lower melting points. Fluxes can be applied as day powder or as past or coated the welding roads depending on the welding process.

Types of Welding:A. Arc welding B. Gas welding

Arc welding Arc welding is a type of welding that uses a welding power supply to create an electric arc between an electrode and the base material to melt the metals at the welding point. They can use either direct (DC) or alternating (AC) current, and consumable or nonconsumable electrodes. The welding region is usually protected by some type of shielding gas, vapor, or slag. Arc welding processes may be manual, semi-automatic, or fully automated. First developed in the early part of the 20th century, arc welding became commercially important in shipbuilding during the Second World War. Today it remains an important process for the fabrication of steel structures and vehicles. There are a variety of different welding arc processes and cutting processes which vary in their ultraviolet and visible light output. The following pages summarize the principal BHAGWAN MAHAVIR POLYTECHNIC

14

FUNDAMENTALS OF MECHANICAL ENGINEERING

techniques and the standard nomenclature used by the American Welding Society (AWS). Although arc currents vary from approximately 50 amperes up to nearly 1,000 amperes for different processes, there is no one process that covers this entire range of currents. For instance Gas Tungsten Arc Welding (GTAW) on soft metals such as aluminum may use only 50 amperes; however, a very high-powered plasma cutting (PAC) torch may exceed 1,000 amperes. Arc welding requires a large current, generally of a relatively low voltage after the arc has been struck. The arc is struck between an electrode and the work piece -- the base metal. The electrode may have either a largely non-consumable metallic tip or it may be a consumable rod of carbon or a consumable metal rod or wire. In some processes, a separate wire or rod – a welding rod (a rod of filler material that is not an electrode and should not be confused with rod-shaped electrodes used in shielded metal arc welding) may be used to supply filler metal. Welding does not necessarily require the addition of filler metal from a consumable electrode or welding rod. Fusion of two metal surfaces can be produced with only the high temperature of the arc. Some welding process may employ automatic wire feed systems and be totally automated. In other semi-automatic operations, the welder must advance arc along the work piece, but the wire is fed automatically.  Equipments used in arc welding. 1. AC or DC machine 2. Electrode 3. Electrode holder 4. Cable, cable connector 5. Cable lug 6. Chipping Hammer 7. Erath clamp 8. Wire brush 9. Safety goggles and head screen 10. Hand gloves, apron  Different arc welding method. 1. Carbon arc welding 2. Metal arc welding 3. Metal inert gas welding (MIG) 4. Tungsten inert gas welding (TIG) 5. Atomic hydrogen arc welding. 6. Plasma arc welding 7. Submerged arc welding 8. Electro slag welding.  Advantages and disadvantages of arc welding. Gas welding Oxy-fuel welding (commonly called oxyacetylene welding, oxy welding, or gas welding in the U.S.) and oxy-fuel cutting are processes that use fuel gases and oxygen to weld and cut metals, respectively. French engineers Edmond Fouché and Charles Picard became the first to develop oxygen-acetylene welding in 1903.Pure oxygen, instead of air (20% oxygen/80% nitrogen), is used to increase the flame temperature to allow localized melting of the work piece material (e.g. steel) in a room environment. A common propane/air flame burns at BHAGWAN MAHAVIR POLYTECHNIC

15

FUNDAMENTALS OF MECHANICAL ENGINEERING

about 3,630 °F (2,000 °C), a propane/oxygen flame burns at about 4,530 °F (2,500 °C), and an acetylene/oxygen flame burns at about 6,330 °F (3,500 °C). Oxy-fuel is one of the oldest welding processes. Still used in industry, in recent decades it has been less widely utilized in industrial applications as other specifically devised technologies have been adopted. It is still widely used for welding pipes and tubes, as well as repair work. It is also frequently well-suited, and favored, for fabricating some types of metal-based artwork. In oxy-fuel welding, a welding torch is used to weld metals. Welding metal results when two pieces are heated to a temperature that produces a shared pool of molten metal. The molten pool is generally supplied with additional metal called filler. Filler material depends upon the metals to be welded.  Equipments used in gas welding. 1. Welding torch or blow pipe. 2. Pressure regulator. 3. Hose and hose fitting. 4. Gas cylinder. 5. Gas bottle 6. Goggles 7. Hand gloves and apron 8. Welding rod and wire brush 9. Spark lighter. 10. Flux.  Method of gas welding. 1. Clean the work piece edge. 2. Preparation of edge. 3. Setting up or alignment of edge. 4. Setting up cylinder outlet gas pressure connected with blow pipe as per requirements 5. Preparation of flame. 6. Take welding. 7. To perform welding operation. 8. Remove the slag. 9. Post welding operation. 10. Inspection and testing of welding.  Advantages and disadvantages of gas welding.  Safety Precaution during metal joining process. Gas Cutting.  Working Setup for gas cutting operation: An oxygas cutting outfit usually consists of a cylinder of acetylene gas, a cylinder of oxygen, two regulators, two lengths of hose with fittings, and a cutting torch with tips. An oxygas cutting outfit also is referred to as a cutting rig as shown in fig 4.1.

BHAGWAN MAHAVIR POLYTECHNIC

16

FUNDAMENTALS OF MECHANICAL ENGINEERING

In addition to the basic equipment mentioned above, numerous types of auxiliary equipment are used in oxygas cutting. An important item is the spark igniter that is used to light the torch (fig. 4-2, view A). Another item you use is an apparatus wrench. It is similar in design to the one shown in figure 4-2, view B. The apparatus wrench is sometimes called a gang wrench because it fits all the connections on the cutting rig. Note that the wrench shown has a raised opening in the handle that serves as an acetylene tank key.

BHAGWAN MAHAVIR POLYTECHNIC

17

FUNDAMENTALS OF MECHANICAL ENGINEERING

Other common accessories include tip cleaners, cylinder trucks, clamps, and holding jigs. Personal safety apparel, such as goggles, hand shields, gloves, leather aprons, sleeves, and leggings, are essential and should be worn as required for the job at hand. Oxygas cutting equipment can be stationary or portable. A portable oxygas outfit, such as the one shown in figure 4-1, is an advantage when it is necessary to move the equipment from one job to another. To conduct your cutting requirements, you must be able to set up the cutting equipment and make the required adjustments needed to perform the cutting operation. For this reason it is important you understand the purpose and function of the basic pieces of equipment that make up the cutting outfit. But, before discussing the equipment, let’s look at the gases most often used in cutting acetylene, gas, and oxygen.  Accessories for gas cutting: 1) Oxygen gas cylinder painted in black color containing about 7 cubic meter of oxygen at 15 MPa pressure & 20 ̊C Temperature. 2) Oxygen pressure regulator. 3) Acetylene pressure regulator 4) Oxygen gas hose in red color 5) Acetylene gas hose in blue color 6) Welding torch with set of nozzles and gas lighter. 7) Filler roads and fixtures. 8) Set of appropriate spanner and key.

BHAGWAN MAHAVIR POLYTECHNIC

18

FUNDAMENTALS OF MECHANICAL ENGINEERING

Safety check list for gas cutting operation:1. Is the area well ventilated? 2. Have you tested all connections for leaks? 3. Are all combustibles away from work area or protected from sparks? 4. If in use, have you checked properly the functioning of the flashback arrestors and or check valves? 5. Have you purged the gas hoses and regulators of residual gas? BRAZING: Brazing is a process which differs from braze welding in one very important way: In brazing, the filler metal is drawn into the joint by capillary attraction, rather than deposited in the joint in somewhat the same fashion as in oxy-acetylene fusion welding. While the majority of industrial brazing operations do not involve the oxy- acetylene fusion welding, in one field – the fabrication and installation of copper-tube piping systems – the oxy-acetylene torch is frequently employed. We shall cover this application shortly. First, let’s take a general look at brazing, an extremely important process in metal fabrication. By American Welding Society definition, brazing is a welding process in which the filler metal has a melting point higher than 8000F (4250C) but lower than that of the metal of metals being joined, and in which the filler metal is drawn into the joint by capillary attraction. To put it in very simple terms, it is the ability of a liquid to rise into a narrow gap or passage against the force of gravity. The process known as soldering is generally similar to brazing except that the filler metals used melt at temperatures below 4270C (8000F). In actual practice, most brazing alloys melt at temperatures well above 4270C, most solders at temperatures well below 4270C. Many of the brazing alloys based on silver (all of which melt above 6000C) were formerly termed” silver solders”. Avoid that term, and its relative,” silver soldering”. Even the term ”silver brazing” is sometimes misleading, since some brazing applications for which silver alloys are generally used can also be handled with alloys which contain no silver. Brazing is a liquid phase process, whereby molten filler metal (the braze) is drawn into the gap between closely adjacent surfaces by capillary attraction. In general, the melting point of the filler metal is above 450°C, but always below that of the parent material. To achieve a perfect joint, the filler and parent materials should be metallurgical compatible and the design of the joint should incorporate a gap into which the braze filler metal will be drawn. There are many ways of brazing, and they all include the method of applying heat 1. Dip brazing 2. Furnace brazing 3. Induction brazing 4. Infrared brazing 5. Resistance brazing 6. Torch brazing The processes can be carried out under vacuum, inert gas or by using fluxes. BHAGWAN MAHAVIR POLYTECHNIC

19

FUNDAMENTALS OF MECHANICAL ENGINEERING

Brazing: Methods  Furnace Brazing: This process is accomplished by placing cleaned parts in a furnace. The parts should be selfjigging and assembled, with filler materials preplaced near or in the joint. The preplaced brazing filler material may be in the form of wire, foil, fillings, slugs, powder, paste, tape, and so on. The furnaces are usually heated by electrical resistance. Automatic temperature controllers are required so that they can be programmed for the brazing temperatures and cooling. Flux is employed except when an atmosphere is specifically introduced in the furnace to perform this function. Flux should not be used where post brazed cleaning is made difficult by the complexity of the design of the brazed parts. cleaning is made difficult by the complexity of the design of the brazed parts. Furnace brazing is often done without the use of flux by the use of special atmospheres (hydrogen and other special gases – helium and argon) in the brazing furnace.  Resistance Brazing: The heat is obtained from the resistance to the flow of an electrical current through the parts being brazed. The parts become a part of the electrical circuit through electrodes made of copper alloys or carbon-graphite. Alternating current is normally applied. The parts to be brazed are held between the two electrodes while the correct pressure and electrical current applied. The pressure is maintained until the filler metal has solidified. Resistance brazing is normally used for low-volume production where heating is localized at the area to be brazed. It is also limited to applications where the brazing filler metal is preplaced.  Torch Brazing: It is done by heating the parts to be brazed with the flame of a gas torch or torches. The temperature and the amount of heat required determine the gas used.Torch brazing is very useful on assemblies that involve heating sections of different mass. Manual torch brazing is particularly useful for Manual torch brazing is particularly useful for repair work. The neutral or reduced flame is normally used. The brazing filler metal may be preplaced in or it may be face-fed manually. Torch brazing is used when the part to be brazed is too large, is an unusual shape, or cannot be heated by the other methods. Filler Metals: Aluminium-silicon, copper, copper-zinc, copped-phosphorus, nickel-gold, heat-resisting materials, magnesium, and silver. Filler metals are available in many forms; the most common is the wire and rod. They are also available in thin sheet, powder, paste, or as a clad surface of the part to be brazed. Base metal and the compatible filler metal: Base metal and the compatible filler metal: Base Metal Aluminium Nickel-Copper alloys Copper Steel and cast iron Stainless steel

Filler Metal Aluminium and Silicon Copper Copper and phosphorus Copper and zinc Gold and silver BHAGWAN MAHAVIR POLYTECHNIC

20

FUNDAMENTALS OF MECHANICAL ENGINEERING

Fluxes: The flux is chosen according to the material to be brazed and the temperature range. Flux in powder form is usually used for furnace brazing. Paste flux is usually used for torch brazing. Placement of the flux affects the quality of the brazed joint. Functions:  Remove oxides from the surface chemically  Avoid oxidation during preheat  Helps to decrease the surface tension of the molten filler metal so that it can flow and spread over the surface easily  Reduce the cooling time Uses: Three major industries using brazing are the electrical industry, the utensil-manufacturing industry and the maintenance and repair industry. Soldering: Introduction Soldering is a group of processes that produce coalescence of material by heating them to the soldering temperature and by using a filler metal having liquidus not exceeding 450ºC and below the solidus of the base metals. The filler metal is distributed between closely fitted flying surfaces of the work pieces. Solder is a filler metal used in soldering that has liquidus not exceeding 450ºC. It is normally nonferrous alloy.There are at least eight popular soldering methods in wide use: There are at least eight popular soldering methods in wide use:  Dip soldering  Furnace soldering  Induction soldering  Infrared soldering  Iron soldering  Resistance soldering  Torch soldering  Wave soldering etc. Soldering Methods 

Furnace Soldering:

It is a soldering process in which the parts to be joined are placed in a furnace and heated to the soldering temperature. In furnace soldering the parts must be assembled and fixed in their proper position. The solder must be preplaced in the joint. 

Resistance Soldering:

It is soldering process that uses heat from the resistance to the electric current flow in a circuit of which the work pieces are a part. This is a very common method of manufacturing electrical machinery involving soldered joints. The solder is applied manually and also used for soldering copper plumbing fittings.

BHAGWAN MAHAVIR POLYTECHNIC

21

FUNDAMENTALS OF MECHANICAL ENGINEERING



Torch Soldering:

It is very similar to torch brazing except that lower temperatures are involved and air is used rather than oxygen. The solder is manually applied. Torch soldering is widely used in the plumbing trade for soldering copper tubing to copper fittings  Soldering flux: The flux helps to remove oxide, but the flux must be designed so that it can be removed after the joints in soldered. It should be fluid at a lower temp than the liquidus of the solder It should have a lower specific gravity than the solder so that the solder will displace it in the joint. Flux should be applied to the base metal to protect it from oxidation.

Solder: Solders are classified according to whether or not they contain lead. The most common general-purpose solder is the 50% lead- 50% tin composition. Solder procedure: The joint must be properly cleaned. It must be free of all oil, grease, dirt, oxides, and so on. It must be free of all oil, grease, dirt, oxides, and so on. Cleaning can be accomplished by brushing, filling, machining, sanding, and by the use of chemicals. Heat is applied to the joint by many different mechanisms and then the space is filled with solder.

BHAGWAN MAHAVIR POLYTECHNIC

22

FUNDAMENTALS OF MECHANICAL ENGINEERING

EXPERIMENT - 4 AIM: To prepare a welding joint INTRODUCTION Welding is one the most widely used methods of permanently joining Structural Shapes used throughout the world. Generally engineers, supervisors and technicians are charged with joint design and selection. Welders, however; need to be familiar with the most commonly used joint shapes, their names, and the type of welds applied to them. Since there is a wide and varied list of possible joints to fabricate structural shapes, this lesson will discuss only the most common joints used in Arc Welding. When two pieces of structural steel are to be connected by welding, the way they are prepared for welding and placed together is known as the Weld Joint. EDGE PREPARATION Preparation or edge shaping may be applied to each piece (joint member) in the same way, or combinations of the joint preparations may be used. The edge preparation for welding these joints depends on the strength requirements and other design considerations. The Welder needs to be aware of the most common edge preparations as shown below:

JOINT ARRANGEMENTS AND WELDS

BHAGWAN MAHAVIR POLYTECHNIC

23

FUNDAMENTALS OF MECHANICAL ENGINEERING

The edge preparations are arranged to make the weld joint. The pieces to be welded may be connected or a gap between the pieces to ensure penetration may be used. On most joints the gap is at the bottom of the joint and is referred to as the root of the joint. The term root opening or open root is used to describe this condition. For example; Open root V groove, or V groove with an open root. When the joint design allows, a backing strip or insert may be used for easier welding. Some joints may have a backing weld, or back weld applied. A back weld is applied after the groove is filled. A backing weld is applied before the groove is filled. See examples below:

THE FIVE BASIC JOINTS There are five basic joints in common use for assembling metal. 1. BUTT JOINTS 2. T JOINTS 3. LAP JOINTS 4. CORNER JOINTS 5. EDGE JOINTS 1. BUTT JOINTS A butt joint is formed when the pieces to be welded are laid side by side and it is one of the most widely used types of joint.

BHAGWAN MAHAVIR POLYTECHNIC

24

FUNDAMENTALS OF MECHANICAL ENGINEERING

The names in the examples above are from the type of weld applied to the joint. Often the type of weld is used to fully describe the joint. For example; this joint is a single bevel butt joint.The V groove and bevel grooves are easier to prepare and are used more than the J or U groves.KEY POINT: If two imaginary lines are drawn parallel to the horizontal line in the above symbols they show the joint shape, this is true for most of the symbols. This can be helpful to remember since symbols on a blueprint do not show the actual joint shape or edge preparation.

2. T JOINTS A T joint is formed when one piece of metal to be welded is placed vertically on another piece lying horizontally, to form the shape of an inverted T.

KEY POINT: The T shape resembles an overhead position T joint.

BHAGWAN MAHAVIR POLYTECHNIC

25

FUNDAMENTALS OF MECHANICAL ENGINEERING

The vertical member is usually placed at 90 deg to the horizontal member. One of the most widely used types of weld applied to a T joint is the fillet weld. When a single pass or multiple passes are made against the joint, the weld resembles a Triangle when viewed from the side.

KEY POINT: Pronounce the T in fillet FILL-ET; not as FILL-AY a fish

The T joint and fillet weld are the most frequently used joint and type of weld. In the same way the edges of the butt joint may be prepared for welding, the tee joint’s vertical piece may be prepared using a Bevel, or J shape. The preparation allows the Welder to penetrate into the root of the joint. See examples below:

3. LAP JOINTS A Lap joint is formed when one piece to be welded is laid down and another piece is overlapped to form an edge for fillet welding or an area to allow plug or slot welding.

BHAGWAN MAHAVIR POLYTECHNIC

26

FUNDAMENTALS OF MECHANICAL ENGINEERING

Lap joints are often used when plug or slot welding thinner sections.

A plug weld is made by welding holes evenly spaced across the length of one or both sides of the joint. A slot weld is similar except slots are made instead of holes.

Other welds may be applied to laps such as projection, or seam welding. See examples below:

LAP JOINTS

4. CORNER JOINTS A corner joint is formed by placing one piece to be welded on the other so that a corner is formed. The corner may be Flush; Half Open; or Fully Open.

An edge preparation may be applied to one, or both of the pieces of the joint for penetration and strength.

BHAGWAN MAHAVIR POLYTECHNIC

27

FUNDAMENTALS OF MECHANICAL ENGINEERING

KEY POINT: The weld applied to the inside of many of the above is a fillet weld.

5. EDGE JOINT An Edge joint is formed when the two edges of the pieces to be welded come together. This joint may be formed as a result of another structural shape and is not as widely used as some of the other joints. See examples below.

BHAGWAN MAHAVIR POLYTECHNIC

28

FUNDAMENTALS OF MECHANICAL ENGINEERING

SUMMARY

Welders need to know the basic joint shapes and the type of welds most commonly applied to them. The five basic joints are: Butt; T; Lap: Corner; and Edge. The edge preparation may be: Square edge; Bevel edge; Double Bevel edge; Chamfer edge; J groove edge; and Double J groove edge. J and U grooves are more labor intensive to prepare and may not be seen as often in production. Butt joints may be open root, have a backing, or be welded both sides. The weld applied to a T joint is a called a Fillet weld. Fillet welds are the most commonly used welds. Corner joints may be: Flush; Half open; or Full open. Corner joints may be simple or have edge preparation to increase penetration. Lap joints are more likely to be used when welding thinner sections, or when plug and slot welding is called for. Edge joints are usually seen as a result of an overall joint configuration. The Welding symbols used are for illustration, and will be discussed fully in another lesson

BHAGWAN MAHAVIR POLYTECHNIC

29

FUNDAMENTALS OF MECHANICAL ENGINEERING

Experiment- 5 AIM: To study about various machining process and prepare simple turning job Introduction to Milling Milling is an important process of manufacturing technology and basically it refers to the removal of metal from the work piece using a tool which has several cutting points and is rotating about its axis. Thus each cutting point removes a little bit of the metal but since there are multiple such points and the tool is rotating at a fast speed, the overall removal is quite brisk. The main advantage of the milling machine is that it can be used to perform literally any operation with a great degree of accuracy and hence it is an indispensable machine for any workshop worth its salt. Milling machines come in a wide variety such as universal, horizontal, vertical, drum type to name a few. Each of these have their own unique features and used for various operations. We won’t go in these details in this article but will try to see what sort of milling methods can be deployed using these machines as follows.

Milling operates on the principle of rotary motion. A milling cutter is spun about an axis while a workpiece is advanced through it in such a way that the blades of the cutter are able to shave chips of material with each pass. Milling processes are designed such that the cutter makes many individual cuts on the material in a single run; this may be accomplished by using a cutter with many teeth, spinning the cutter at high speed, or advancing the material

BHAGWAN MAHAVIR POLYTECHNIC

30

FUNDAMENTALS OF MECHANICAL ENGINEERING

through the cutter slowly. Most often it is some combination of the three.The speed at which the piece advances through the cutter is calledfeed rate, or just feed; it is most often measured in length of material per full revolution of the cutter. As material passes through the cutting area of a milling machine, the blades of the cutter take swarfs of material at regular intervals. This non-continuous cutting operation means that no surface cut by a milling machine will ever be completely smooth; at a very close level (microscopic for very fine feed rates), it will always contain regular ridges. These ridges are known as revolution marks, because rather than being caused by the individual teeth of the cutter, they are caused by irregularities present in the cutter and milling machine; these irregularities amount to the cutter being at effectively different heights above the workpiece at each point in its rotation. The height and occurrence of these ridges can be calculated from the diameter of the cutter and the feed. These revolution ridges create the roughness associated with surface finish.

Methods of Milling Given below are few of the most commonly used milling methods in the manufacturing industry. This list is certainly not exhaustive but only indicative of the wide variety of uses that a milling machine can be put to in the industry. Single piece milling – this method is used for milling a single job work which is held on the milling machine. It is important to note that the piece has to be worked in a single machine cycle for it to be classified under this category of milling methods. String milling is quite similar to single piece milling but the only difference being that instead of a single piece there are several parts which is simultaneously fixed and are worked upon. Index milling refers to a special kind of milling operation wherein the machine is set to perform identical operations on a work piece. Each of these identical operations is performed one after the other by indexing the work piece into a new position. A very good example of such a process is the gear cutting operation wherein the gear grooves are cut in succession one after the other. Copy milling technique refers to where a design or cut is difficult to make by itself, hence it is first made in the form of a master template which is turn is used to guide the tool path. Hence basically the template acts as an original from which the other parts are copied just like you would photocopy a document from an original paper in the Xerox machine. Gang milling refers to the situation when a gang or group of cutters is used to simultaneously work on the work piece in order to produce the desired shape

BHAGWAN MAHAVIR POLYTECHNIC

31

FUNDAMENTALS OF MECHANICAL ENGINEERING

Reciprocal milling refers to the process wherein the time taken to load and upload the job work from the fixture on the milling table is minimized by utilizing two fixtures which are ready at the same time for milling one after the other. There are several other types of milling methods apart from these and each of these methods have their own unique features. The reader is advised to refer to any good textbook of Production Technology in case he/she is interested to gain advanced knowledge about this area of manufacturing technology Introduction to drilling Drilling machines or drill presses are one of the most common machines found in the machine shop. A drill press is a machine thatturns and advances a rotary tool into a workpiece. The drill press is used primarily for drilling holes, but when used with the proper tooling, it can be used for a number of machining operations. The most common machining operations performed on a drill press are drilling, reaming, tapping, counterboring, countersinking, and spotfacing. There are many different types or configurations of drilling machines, but most drilling machines will fall into four broad categories: upright sensitive, upright, radial, and special purpose.

Under normal usage, swarf is carried up and away from the tip of the drill bit by the fluting of the drill bit. The cutting edges produce more chips which continue the movement of the chips outwards from the hole. This is successful until the chips pack too tightly, either because of

BHAGWAN MAHAVIR POLYTECHNIC

32

FUNDAMENTALS OF MECHANICAL ENGINEERING

deeper than normal holes or insufficient backing off (removing the drill slightly or totally from the hole while drilling). Cutting fluid is sometimes used to ease this problem and to prolong the tool's life by cooling and lubricating the tip and chip flow. Coolant may be introduced via holes through the drill shank, which is common when using a gun drill. When cutting aluminum in particular, cutting fluid helps ensure a smooth and accurate hole while preventing the metal from grabbing the drill bit in the process of drilling the hole. When cutting brass, another soft metal that can grab the drill bit and causes "chatter" the cutting edges of the drill bit, which normally form an acute angle, a face of approx. 1-2 millimeters can be ground on the cutting edge to create an obtuse angle of 91 to 93 degrees. This prevents "chatter" where the drill tears rather than cuts the metal. However, the drill is pushing the metal away. This creates high friction and very hot swarf. For heavy feeds and comparatively deep holes oil-hole drills can be used, with a lubricant pumped to the drill head through a small hole in the bit and flowing out along the fluting. A conventional drill press arrangement can be used in oil-hole drilling, but it is more commonly seen in automatic drilling machinery in which it is the workpiece that rotates rather than the drill bit. Upright sensitive drill press The upright sensitive drill press (Figure 1) is a light-duty type of drilling machine that normally incorporates a belt drive spindle head. This machine is generally used for moderateto-light duty work. The upright sensitive drill press gets its name due to the fact that the machine can only be hand fed. Hand feeding the tool into the workpiece allows the operator to "feel" the cutting action of the tool. The sensitive drill press is manufactured in a floor style or a bench style.

Radial arm drill press The radial arm drill press (Figure 3) is the hole producing work horse of the machine shop. The press is commonly refered to as a radial drill press. The radial arm drill press allows the operator to position the spindle directly over the workpiece rather than move the workpiece to the tool. The design of the radial drill press gives it a great deal of versatility, especially on parts too large to position easily. Radial drills offer power feed on the spindle, as well as an automatic mechanism to raise or lower the radial arm. The wheel head, which is located on the radial arm, can also be traversed along the arm, giving the machine added ease of use as well as versatility. Radial arm drill presses can be equipped with a trunion table or tilting table. This gives the operator the ability to drill intersecting or angular holes in one setup. SPECIAL PURPOSE DRILL MACHINES

BHAGWAN MAHAVIR POLYTECHNIC

33

FUNDAMENTALS OF MECHANICAL ENGINEERING

There are a number of types of special purpose drilling machines. The purposes of these types of drilling machines vary. Special purpose drilling machines include machines capable of drilling 20 holes at once or drilling holes as small as 0.01 of an inch. Gang Drilling Machines The gang style drilling machine or gang drill press has several work heads positioned over a single table. This type of drill press is used when successive operations are to be done. For instance, the first head may be used to spot drill. The second head may be used to tap drill. The third head may be used, along with a tapping head, to tap the hole. The fourth head may be used to chamfer. Multiple Spindle Drilling Machine The multiple spindle drilling machine is commonly refered to as a multispindle drill press. This special purpose drill press has many spindles connected to one main work head. All of the spindles are fed into the workpiece at the same time. This type of drilling machine is especially useful when you have a large number of parts with many holes located close together. Micro-Drill Press The micro drill press is an extremely accurate, high spindle speed drill press. The micro drill press is typically very small and is only capable of handling very small parts. Many micro drill presses are manufactured as bench top models. They are equipped with chucks capable of holding very small drilling tools. Turret Type Drilling Machine Turret drilling machines are equipped with several drilling heads mounted on a turret (Figure 6). Each turret head can be equipped with a different type of cutting tool. The turret allows the needed tool to be quickly indexed into position. Modern turret type drilling machines are computer-controlled so that the table can be quickly and accurately positioned. Introduction to lathe A lathe machine is used for the shaping and machining of various work pieces. There are many different types depending on the material. In manufacturing, it is important to produce work pieces according to specifications. This is where the lathe machine comes in handy. A lathe machine is used for the machining and working of hard materials. Conventionally, the lathe machine is designed for the machining of metals, but as new materials emerged, there are lathe machines that are used for these materials as well. The main function of the lathe is to remove material from a work piece through the use of cutting tools. The lathe shapes a material by holding and rotating the material as a cutting tool is advanced into it. There are a lot of shapes and forms that can be produced by the lathe machine. More importantly, these shapes come in various sizes and specifications. BHAGWAN MAHAVIR POLYTECHNIC

34

FUNDAMENTALS OF MECHANICAL ENGINEERING

At one end of the bed (almost always the left, as the operator faces the lathe) is a headstock. The headstock contains high-precision spinning bearings. Rotating within the bearings is a horizontal axle, with an axis parallel to the bed, called the spindle. Spindles are often hollow, and have exterior threads and/or an interior Morse taper on the "inboard" (i.e., facing to the right / towards the bed) by which work-holding accessories may be mounted to the spindle. Spindles may also have exterior threads and/or an interior taper at their "outboard" (i.e., facing away from the bed) end, and/or may have a hand-wheel or other accessory mechanism on their outboard end. Spindles are powered, and impart motion to the workpiece. The spindle is driven, either by foot power from a treadle and flywheel or by a belt or gear drive to a power source. In most modern lathes this power source is an integral electric motor, often either in the headstock, to the left of the headstock, or beneath the headstock, concealed in the stand.

BHAGWAN MAHAVIR POLYTECHNIC

35

FUNDAMENTALS OF MECHANICAL ENGINEERING

In addition to the spindle and its bearings, the headstock often contains parts to convert the motor speed into various spindle speeds. Various types of speed-changing mechanism achieve this, from a cone pulley or step pulley, to a cone pulley with back gear (which is essentially a low range, similar in net effect to the two-speed rear of a truck), to an entire gear train similar to that of a manual-shift auto transmission. Some motors have electronic rheostat-type speed controls, which obviates cone pulleys or gears. The counterpoint to the headstock is the tailstock, sometimes referred to as the loose head, as it can be positioned at any convenient point on the bed, by undoing a locking nut, sliding it to the required area, and then re-locking it. The tail-stock contains a barrel which does not rotate, but can slide in and out parallel to the axis of the bed, and directly in line with the headstock spindle. The barrel is hollow, and usually contains a taper to facilitate the gripping of various type of tooling. Its most common uses are to hold a hardened steel center, which is used to support long thin shafts while turning, or to hold drill bits for drilling axial holes in the work piece. Many other uses are possible. Metalworking lathes have a carriage (comprising a saddle and apron) topped with a crossslide, which is a flat piece that sits crosswise on the bed, and can be cranked at right angles to the bed. Sitting atop the cross slide is usually another slide called a compound rest, which provides 2 additional axes of motion, rotary and linear. Atop that sits a toolpost, which holds a cutting tool which removes material from the workpiece. There may or may not be a leadscrew, which moves the cross-slide along the bed. Woodturning and metal spinning lathes do not have cross-slides, but rather have banjos, which are flat pieces that sit crosswise on the bed. The position of a banjo can be adjusted by hand; no gearing is involved. Ascending vertically from the banjo is a tool-post, at the top of which is a horizontal toolrest. In woodturning, hand tools are braced against the tool rest and levered into the workpiece. In metal spinning, the further pin ascends vertically from the tool rest, and serves as a fulcrum against which tools may be levered into the workpiece.

Types of lathe machine Engine lathes. These are probably the most popular among the lathe machines. In fact, no machine shop is seen without this type of lathe. The good thing about engine lathes is that it can be used in various materials, aside from metal. Moreover, the set-up of these machines is so simple that they are easier to use. Its main components include the bed, headstock, and tailstock. These engine lathes can be adjusted to variable speeds for the accommodation of a wide scope of work. In addition, these lathes come in various sizes.

BHAGWAN MAHAVIR POLYTECHNIC

36

FUNDAMENTALS OF MECHANICAL ENGINEERING

Turret Lathes. These types of lathes are used for machining single workpieces sequentially. This means that several operations are needed to be performed on a single work piece. With the turret lathes, sequential operations can be done on the work piece, eliminating errors in work alignment. With this set-up, machining is done more efficiently. Correspondingly, time is saved because there is no need to remove and transfer the work piece to another machine anymore. Special Purpose Lathes. As the name implies, these lathes are used for special purposes such as heavy-duty production of identical parts. In addition, these lathes also perform specific functions that cannot be performed by the standard lathes. Some examples of special purpose lathes include the bench-type jewelers’ lathes, automatic lathes, crankshaft lathes, duplicating lathes, multispindle lathes, brakedrum lathes, and production lathes among others. Introduction to hacksaws The hacksaw is used to cut steel and other metals. It can also be used to cut plastics, although it is not normally used to cutwoods. It is sometimes called an adjustable hacksaw because the length of the frame can be altered to hold blades of different sizes. Blades are supplied in two lengths, 250mm and 300mm. If the adjusting screw is unscrewed, the frame can be pushed into the handle so that the smaller blades fit the hacksaw. Blades are also described by the number of teeth per inch (TPI). Blades have 14, 18, 24, 32 teeth per 25mm (inch). A blade with 14 TPI is coarse whilst a blade with 32 TPI is very fine.

Junior Hacksaw First made by Stanley. A small saw with a simple one piece bent metal frame for metal and plastics cutting. It uses cheap disposable 6 inch blades. Mini Hacksaw A handle and a support bar that uses standard length hacksaw blades. The front end of the blade is not supported and so it is useful for sliding into spaces that a standard hacksaw will not fit into.

PROCEDURE OF TURNING JOB:

BHAGWAN MAHAVIR POLYTECHNIC

37

FUNDAMENTALS OF MECHANICAL ENGINEERING

Turning may be performed upon a work piece supported in a chuck, but the majority of work piece turned on an engine lathe are turned between centers. Turning is the removal of metal from the external surface of cylindrical work piece using various types of cutter tool bits. In our case turning operation is done to bring the cylindrical work piece to 36 mm diameter. Conclusion: By doing this practical student will come to know about how to use different types of machine and different machining processes.

BHAGWAN MAHAVIR POLYTECHNIC

38

FUNDAMENTALS OF MECHANICAL ENGINEERING

Experiment No. 6

AIM: To study about various types of Mounting and Accessories of Boilers.

Introduction Boiler: It is a closed vessel in which steam is produced from water by combustion of fuel.

Classification of Boilers:

1. According to their Axis (Horizontal, Vertical or Inclined) i. If the axis of the boiler is horizontal, the boiler is called as horizontal. ii. If the axis is vertical, it is called vertical boiler. iii. If the axis is inclined it is known as inclined boiler.

2. Fire Tube and Water Tube i. In the fire tube boilers, the hot gases are inside the tubes and the water surrounds the tubes, Examples: Cochran, Lancashire and Locomotive boilers. ii. In the water tube boilers, the water is inside the tubes and hot gases surround them, Examples: Babcock and Wilcox boiler.

3. Externally Fired and Internally Fired i. The boiler is known as externally fired if the fire is outside the shell, Examples: Babcock and Wilcox boiler. ii. The furnace is located inside the boiler shell, Examples: Cochran, Lancashire boiler etc.

4. Forced Circulation and Natural Circulation i. In forced circulation type of boilers, the circulation of water is done by a forced pump.

BHAGWAN MAHAVIR POLYTECHNIC

39

FUNDAMENTALS OF MECHANICAL ENGINEERING

ii. In natural circulation type of boilers, circulation of water in the boiler takes place due to natural convention currents produced by the application of heat, Examples: Lancashire, Babcock and Wilcox boiler etc.

5. High Pressure and Low Pressure Boilers i. The boilers which produce steam at pressures of 80 bar and above are called high pressure boilers, Examples: Babcock and' Wilcox boilers. ii. The boilers which produce steam at pressure below 80 bar are called low pressure boilers, Examples: Cochran, Lancashire and Locomotive boilers.

6. Stationary and Portable i. Stationary boilers are used for power plant-steam, for central station utility power plants, for plant process steam etc. ii. Mobile boilers or portable boilers include locomotive type, and other small units for temporary use at sites (Large Ships). 7. Single Tube and Multi-tube Boilers The fire tube boilers are classified as single tube and multi-tube boilers, depending upon whether the fire tube is one or more than one.

Boiler Mountings: These are the fitting and devices which are necessary for the operation and safety of a boiler.

Boiler Accessories: These are auxiliary plants required for steam boilers for the proper operation and for the increase of their efficiency.

Types of Mountings: • Safety valves • Water level indicator • A pressure gauge • A steam stop valve • A feed check valve

BHAGWAN MAHAVIR POLYTECHNIC

40

FUNDAMENTALS OF MECHANICAL ENGINEERING

• A Fusible plug • A blow-off cock

Types of Accessories: • Feed pumps • Injector • Economiser • Air preheater • Superheater • Steam separator

Mountings: 1. SAFETY VALVES: It is use for release the excess steam when the pressure of steam inside the boiler exceeds the rated pressure.

Types of safety valve are the following: • Dead weight safety valve • Lever safety valve • Spring loaded safety valve • Gravity safety valve

2. WATER LEVEL INDICATOR: It is use to indicate the level of water in the boiler constantly.

3. PRESSURE GAUGE: It is use to measure the pressure exerted inside the vessel.

4. STEAM STOP VALVE: It is use to regulate the flow of steam from the boiler to the steam pipe.

5. FEED CHECK VALVE: It is use to control the supply the water to the boiler and to prevent the escaping of water from the

BHAGWAN MAHAVIR POLYTECHNIC

41

FUNDAMENTALS OF MECHANICAL ENGINEERING

boiler when the pump is stopped.

6. FUSIBLE PLUG: It is use to protect the boiler against damage due to overheating for low water level.

7. BLOW-OFF COCK: It is use to discharge a portion of water when the boiler is empty when necessary for cleaning, inspection, repair, mud, scale and sludge.

Accessories: 1. FEED PUMPS: It is used to deliver feed water to the boiler by the pump.

2. INJECTOR: The water is delivered to the boiler by steam pressure; The Kinetic energy of steam is used to increase the pressure and velocity of feed water.

3. ECONOMISER: It is a device in which the waste heat of flue gases is utilized for heating the feed water.

4. AIR PREHEATER: It is use to increase the temperature of air before it enters the furnace.

5. SUPERHEATER: It is use to increase the temperature of steam above it saturation point.

6. STEAM SEPARATOR: It is use to separate the water particles from the steam to the steam engine or steam turbine.

NOTE: Figure will be drawn by students

BHAGWAN MAHAVIR POLYTECHNIC

42

FUNDAMENTALS OF MECHANICAL ENGINEERING

EXPERIMENT NO:-7

AIM: Study the effects of variation of the load on the fuel consumption of Petrol I.C.engine and fault & remedies for I.C.engine, Introduction: The Students will have to conduct wide variety of engine tests to find out performance of an engine. The performance is an indication of the degree of success on the basic of the following. 1. 2. 3. 4. 5.

Power output Specific fuel consumption Thermal efficiency Exhaust smoke and other emission Energy balances

Note: 1. Accurate measurement of the fuel consumption is very important in engine testing work. 2. Load is one of the important factors for the fuel consumption so we study variation of load on the fuel consumption. EQUIPMENTS/MATERIAL/INSTRUMENTS:    

I.C. engine with rope brake dynamometer( or hydraulic dynamometer) Tachometer or digital r.p.m. meter Stop watch, measuring rule. Caliper etc. Specifications Bore(d)= ___________m Stroke(L)= _________m Speed(N)= __________r.p.m.

PROCEDURE:1. 2. 3. 4. 5. 6. 7. 8.

Check the engine and accessories for the test. Determine the value of maximum net load for given engine. Start the engine and bring, it to steady running condition. Load the engine by putting weights. Allow the engine to run at steady condition. Note down the value of the actual load. Note down the time for define quantity of fuel. Repeat step 4 to 7 for different value of brake loads.

BHAGWAN MAHAVIR POLYTECHNIC

43

FUNDAMENTALS OF MECHANICAL ENGINEERING

9. Unload the engine step by step. 10. Draw the following graph.  Break power v/s fuel consumption. MEASURMETNS:1. Circumference of brake pulley = __________m 2. Diameter of brake pulley D1=___________m 3. Diameter of rope d1=_______________m

GIVEN DATA:1. Caloric value of petrol = _______________kj/kg 2. Density of petrol =_______________ kg/𝑚3 3. Density of water =_______________ kg/𝑚3

SR NO

NET BRAKE W-S

ENGINE SPEED CONSTANT (RPM)

MEAN EFFECTIVE PRESSURE PR.(Bar)

FUEL CONSUMPTION (kg/sec)

1 2 3 4 5 6 CALCULATIONS: 1. BRAKE POWER Bp= (W-S) π DN/60,000 KW 2. FUEL CONSUMPTION (kg/sec) 𝑄𝐹𝑈𝐸𝐿∗𝐷𝐸𝑁𝑆𝐼𝑇𝑌 𝑂𝐹 𝑃𝐸𝑇𝑅𝑂𝐿

SFC =

𝐷𝑈𝑅𝐴𝑇𝐼𝑂𝑁 𝐼𝑁 𝑆𝐸𝐶∗ 106

Conclusion: By result of this test we come to know that variation of load does effect on fuel consumption. When load increases fuel consumption also increases.

BHAGWAN MAHAVIR POLYTECHNIC

44

FUNDAMENTALS OF MECHANICAL ENGINEERING

FAULT AND REMEDEIS FOR PETROL ENGINE Fault: petrol engine fails to starts. REASONS 1) Empty petrol tank 2) Stoppage of petrol supply. 3) Air in petrol line. 4) Fault in spark plug. 5) Incorrect spark timing

REMEDIES 1)Petrol tank should be filled with petrol 2) There should be proper supply of petrol. 3)Petrol line should be filled with petrol. 4)Spark plug should be faultless. 5) Spark timing should be correct.

Fault: Reduced petrol average of an engine. REASONS 1) Poor sparking 2) Lack of lubrication. 3) Improper air-fuel ratio. 4) Worn out piston rings. 5) Faulty carburetor.

REMEDIES 1)Spark plug should be faultless 2)Lubrication should be proper. 3)air-fuel ratio should be proper. 4)Change piston rings. 5)Carburetor should be faultless.

Fault: Reasons for overheating of an I.C. Engine.. REASONS 1) Less quantity of cooling water 2)Faulty water pump 3)Choked up radiator 4)Faulty thermostat valve 5)Fan belt is slipping

REMEDIES 1) Provide enough cooling water 2)Repair water pump 3) Clean radiator 4)Replace thermostat valve 5)Change fan belt

Fault:- Reasons for engine developing less power. REASONS 1)Leakage of fuel nozzle 2)Worn out piston ring 3)Use of improper fuel 4)Chocked up Air filter 5)Insufficient engine cooling

REMEDIES 1)Change fuel nozzle 2)replace piston ring 3)Use proper fuel 4)Clean Air filter 5)Provide sufficient cooling

Fault: - Reasons for increased fuel consumption of an engine. REASONS 1)Leakage of fuel nozzle 2)Make fuel from injector 3)Too much friction 4)Wrong setting of Governer 5)Over load on engine

REMEDIES 1)check fuel system 2)Replace injector 3)Provide lubrication 4)Correct setting of Governer 5)Reduce load on engine

BHAGWAN MAHAVIR POLYTECHNIC

45

FUNDAMENTALS OF MECHANICAL ENGINEERING

EXPERIMENT NO:-8

AIM: Study the effects of variation of the load on the fuel consumption of Diesel I.C.engine and fault and remedies for I.C.engine, Introduction: The Students will have to conduct wide variety of engine tests to find out performance of an engine. The performance is an indication of the degree of success on the basic of the following. 6. Power output 7. Specific fuel consumption 8. Thermal efficiency 9. Exhaust smoke and other emission 10. Energy balances Note: 3. Accurate measurement of the fuel consumption is very important in engine testing work. 4. Load is one of the important factors for the fuel consumption so we study variation of load on the fuel consumption. EQUIPMENTS/MATERIAL/INSTRUMENTS:    

I.C. engine with rope brake dynamometer( or hydraulic dynamometer) Tachometer or digital r.p.m. meter Stop watch, measuring rule. Caliper etc. Specifications Bore(d)= ___________m Stroke(L)= _________m Speed(N)= __________r.p.m.

PROCEDURE:11. Check the engine and accessories for the test. 12. Determine the value of maximum net load for given engine. 13. Start the engine and bring it to steady running condition. 14. Load the engine by putting weights. 15. Allow the engine to run at steady condition. 16. Note down the value of the actual load. 17. Note down the time for define quantity of fuel.

BHAGWAN MAHAVIR POLYTECHNIC

46

FUNDAMENTALS OF MECHANICAL ENGINEERING

18. Repeat step 4 to 7 for different value of brake loads. 19. Unload the engine step by step. 20. Draw the following graph.  Break power v/s fuel consumption. MEASURMETNS:4. Circumference of brake pulley = __________m 5. Diameter of brake pulley D1=___________m 6. Diameter of rope d1=_______________m

GIVEN DATA:4. Caloric value of diesel = _______________kj/kg 5. Density of diesel =_______________ kg/𝑚3 6. Density of water =_______________ kg/𝑚3

SR NO

NET BRAKE W-S

ENGINE SPEED CONSTANT (RPM)

MEAN EFFECTIVE PRESSURE PR.(Bar)

FUEL CONSUMPTION (kg/sec)

1 2 3 4 5 6 CALCULATIONS: 3. BRAKE POWER Bp= (W-S) π DN/60,000 KW 4. FUEL CONSUMPTION (kg/sec) 𝑄𝐹𝑈𝐸𝐿∗𝐷𝐸𝑁𝑆𝐼𝑇𝑌 𝑂𝐹 𝐷𝐼𝐸𝑆𝐸𝐿

SFC =

𝐷𝑈𝑅𝐴𝑇𝐼𝑂𝑁 𝐼𝑁 𝑆𝐸𝐶∗ 106

Conclusion: By result of this test we come to know that variation of load does effect on fuel consumption. When load increases fuel consumption also increases.

BHAGWAN MAHAVIR POLYTECHNIC

47

FUNDAMENTALS OF MECHANICAL ENGINEERING

FAULT AND REMEDEIS FOR DIESEL ENGINE Fault: Diesel engine fails to starts. REASONS 6) Empty diesel tank 7) Stoppage of diesel supply. 8) Air in diesel line. 9) Fault in spark plug. 10) Incorrect spark timing

REMEDIES 1)Diesel tank should be filled with diesel 2) There should be proper supply of diesel. 3) Diesel line should be filled with diesel. 4) Spark plug should be faultless. 5) Spark timing should be correct.

Fault: Reduced diesel average of an engine. REASONS 6) Poor sparking 7) Lack of lubrication. 8) Improper air-fuel ratio. 9) Worn out piston rings. 10) Faulty carburetor.

REMEDIES 1)Spark plug should be faultless 2) Lubrication should be proper. 3) air-fuel ratio should be proper. 4) Change piston rings. 5) Carburetor should be faultless.

Fault: Reasons for overheating of an I.C. Engine.. REASONS 1) Less quantity of cooling water 2)Faulty water pump 3)Choked up radiator 4)Faulty thermostat valve 5)Fan belt is slipping

REMEDIES 1) Provide enough cooling water 2)Repair water pump 3) Clean radiator 4)Replace thermostat valve 5)Change fan belt

Fault: - Reasons for engine developing less power. REASONS 1)Leakage of fuel nozzle 2)Worn out piston ring 3)Use of improper fuel 4)Chocked up Air filter 5)Insufficient engine cooling

REMEDIES 1)Change fuel nozzle 2)replace piston ring 3)Use proper fuel 4)Clean Air filter 5)Provide sufficient cooling

Fault: - Reasons for increased fuel consumption of an engine. REASONS 1)Leakage of fuel nozzle 2)Make fuel from injector 3)Too much friction 4)Wrong setting of Governor 5)Over load on engine

REMEDIES 1)check fuel system 2)Replace injector 3)Provide lubrication 4)Correct setting of Governor 5)Reduce load on engine

BHAGWAN MAHAVIR POLYTECHNIC

48

FUNDAMENTALS OF MECHANICAL ENGINEERING

EXPERIMENT NO: - 9 AIM:-To demonstrate a water turbine. Water turbine: Water turbine converts stored potential energy of water into the mechanical energy. Water wheels have been around for several thousand years, the concept of using water to power basic machinery like mill wheels (essentially harnessing the Earth’s gravity) being well within the grasp of ancient engineers. Turbines are the next natural technological evolution of the water wheel and, although the Romans sometimes used a form of turbine for their water wheels and agricultural uses, it wasn’t until the Industrial Revolution (circa 17501850) that the first modern turbines emerged. “Water Turbines have a row of blades fitted to the rotating shaft or a rotating plate. Flowing liquid, mostly water, when pass through the Water Turbine it strikes the blades of the turbine and makes the shaft rotate. While flowing through the Water Turbine the velocity and pressure of the liquid reduce, these result in the development of torque and rotation of the turbine shaft. There are different forms of Water Turbines in use depending on the operational requirements.” For every specific use a particular type of Hydraulic Turbine provides the optimum output. Classification of Water Turbine: (1) According to the type of flow of water : The water turbines used as prime movers in hydro electric power stations are of four types. They are    

axial flow : having flow along shaft axis inward radial flow : having flow along the radius tangential or peripheral : having flow along tangential direction mixed flow : having radial inlet axial outlet

If the runner blades of axial flow turbines are fixed, those are called propeller turbines. (2) According to the action of water on moving blades :

BHAGWAN MAHAVIR POLYTECHNIC

49

FUNDAMENTALS OF MECHANICAL ENGINEERING

 Impulse Turbines : These turbines change the direction of flow of a high velocity fluid jet. The resulting impulse spins the turbine and leaves the fluid flow with diminished kinetic energy. There is no pressure change of the fluid in the turbine rotor blades. Before reaching the turbine the fluid's Pressure head is changed to velocity head by accelerating the fluid with a nozzle. Pelton wheels and de Laval turbines use this process exclusively. Impulse turbines do not require a pressure casement around the runner since the fluid jet is prepared by a nozzle prior to reaching turbine. Newton's second law describes the transfer of energy for impulse turbines.  Reaction Turbines : These turbines develop torque by reacting to the fluid's pressure or weight. The pressure of the fluid changes as it passes through the turbine rotor blades. A pressure casement is needed to contain the working fluid as it acts on the turbine stage(s) or the turbine must be fully immersed in the fluid flow (wind turbines). The casing contains and directs the working fluid and, for water turbines, maintains the suction imparted by the draft tube. Francis turbines and most steam turbine use this concept. (3) According to the Head and quantity of water available The water turbines can be classified in two type, which are high head - low flow and low to medium head and high to medium discharge turbines. (4) According to the name of the originator : Water turbines are of 3 types namely Pelton Wheel,Francis tubine and Kaplan turbine. Pelton Wheel Turbine: The Pelton Turbine has a circular disk mounted on the rotating shaft or rotor. This circular disk has cup shaped blades, called as buckets, placed at equal spacing around its circumference. Nozzles are arranged around the wheel such that the water jet emerging from a nozzle is tangential to the circumference of the wheel of Pelton Turbine. According to the available water head (pressure of water) and the operating requirements the shape and number of nozzles placed around the Pelton Wheel can vary.

BHAGWAN MAHAVIR POLYTECHNIC

50

FUNDAMENTALS OF MECHANICAL ENGINEERING

Working Principle of Pelton Turbine The high speed water jets emerging from the nozzles strike the buckets at splitters, placed at the middle of a bucket, from where jets are divided into two equal streams. These stream flow along the inner curve of the bucket and leave it in the direction opposite to that of incoming jet. The high speed water jets running the Pelton Wheel Turbine are obtained by expanding the high pressure water through nozzles to the atmospheric pressure. The high pressure water can be obtained from any water body situated at some height or streams of water flowing down the hills. The change in momentum (direction as well as speed) of water stream produces an impulse on the blades of the wheel of Pelton Turbine. This impulse generates the torque and rotation in the shaft of Pelton Turbine. To obtain the optimum output from the Pelton Turbine the impulse received by the blades should be maximum. For that, change in momentum of the water stream should be maximum possible. That is obtained when the water stream is deflected in the direction opposite to which it strikes the buckets and with the same speed relative to the buckets.

Francis Turbine: In Francis Turbine water flow is radial into the turbine and exits the Turbine axially. Water pressure decreases as it passes through the turbine imparting reaction on the turbine blades making the turbine rotate. Francis Turbine is the first hydraulic turbine with radial inflow. It was designed by American scientist James Francis. Francis Turbine is a reaction turbine. Reaction Turbines have some primary features which differentiate them from Impulse Turbines. The major part of pressure drop occurs in the turbine itself, unlike the impulse turbine where complete pressure drop takes place up to the entry point and the turbine passage is completely filled by the water flow during the operation. Francis Turbine has a circular plate fixed to the rotating shaft perpendicular to its surface and passing through its center. This circular plate has curved channels on it; the plate with channels is collectively called as runner. The runner is encircled by a ring of stationary channels called as guide vanes. Guide vanes are housed in a spiral casing called as volute. The exit of the Francis turbine is at the center of the runner plate. There is a draft tube attached to the central exit of the runner. The design parameters such as, radius of the runner, curvature of channel, angle of vanes and the size of the turbine as whole depend on the available head and type of application altogether.

BHAGWAN MAHAVIR POLYTECHNIC

51

FUNDAMENTALS OF MECHANICAL ENGINEERING

Working of Francis Turbine Francis Turbines are generally installed with their axis vertical. Water with high head (pressure) enters the turbine through the spiral casing surrounding the guide vanes. The water looses a part of its pressure in the volute (spiral casing) to maintain its speed. Then water passes through guide vanes where it is directed to strike the blades on the runner at optimum angles. As the water flows through the runner its pressure and angular momentum reduces. This reduction imparts reaction on the runner and power is transferred to the turbine shaft. If the turbine is operating at the design conditions the water leaves the runner in axial direction. Water exits the turbine through the draft tube, which acts as a diffuser and reduces the exit velocity of the flow to recover maximum energy from the flowing water. Kaplan turbine: Kaplan Turbine is designed for low water head applications. Kaplan Turbine has propeller like blades but works just reverse. Instead of displacing the water axially using shaft power and creating axial thrust, the axial force of water acts on the blades of Kaplan Turbine and generating shaft power. Most of the turbines developed earlier were suitable for large heads of water. With increasing demand of power need was felt to harness power from sources of low head water, such as, rivers flowing at low heights. For such low head applications Viktor Kaplan designed a turbine similar to the propellers of ships. Its working is just reverse to that of propellers. The Kaplan Turbine is also called as Propeller Turbine. To generate substantial amount of power from small heads of water using Kaplan Turbine it is necessary to have large flow rates through the turbine. Kaplan Turbine is designed to accommodate the required large flow rates. Except the alignment of the blades the construction of the Kaplan Turbine is very much similar to that of the Francis Turbine. The overall path of flow of water through the Kaplan Turbine is from radial at the entrance to

BHAGWAN MAHAVIR POLYTECHNIC

52

FUNDAMENTALS OF MECHANICAL ENGINEERING

axial at the exit. Similar to the Francis Turbine, Kaplan Turbine also has a ring of fixed guide vanes at the inlet to the turbine.

Unlike the Francis Turbine which has guide vanes at the periphery of the turbine rotor (called as runner in the case of Francis Turbine), there is a passage between the guide vanes and the rotor of the Kaplan Turbine. The shape of the passage is such that the flow which enters the passage in the radial direction is forced to flow in axial direction. The rotor of the Kaplan Turbine is similar to the propeller of a ship. The rotor blades are attached to the central shaft of the turbine. The blades are connected to the shaft with moveable joints such that the blades can be swiveled according to the flow rate and water head available.The blades of the Kaplan Turbine are not planer as any other axial flow turbine; instead they are designed with twist along the length so as to allow swirling flow at entry and axial flow at exit. Working of the Kaplan Turbine: The working head of water is low so large flow rates are allowed in the Kaplan Turbine. The water enters the turbine through the guide vanes which are aligned such as to give the flow a suitable degree of swirl determined according to the rotor of the turbine. The flow from guide vanes pass through the curved passage which forces the radial flow to axial direction with the initial swirl imparted by the inlet guide vanes which is now in the form of free vortex. The axial flow of water with a component of swirl applies force on the blades of the rotor and loses its momentum, both linear and angular, producing torque and rotation (their product is power) in the shaft. The scheme for production of hydroelectricity by Kaplan Turbine is same as that for Francis Turbine. Application of water turbine: 1. Large-Scale Electric Power Generation A water turbine is an essential component of a hydroelectric plant. Hydroelectric power plants are equipped with one or more water turbines that convert the kinetic energy of flowing water into mechanical energy. This mechanical energy is then fed through an electricity generator that converts it to electrical energy. BHAGWAN MAHAVIR POLYTECHNIC

53

FUNDAMENTALS OF MECHANICAL ENGINEERING

2. Micro-Hydropower Generation Micro-turbines (also called small hydroelectric turbines) are similar to large water turbines in structure and function. A micro-turbine works when a moving bed (or stream) of water turns the blades of the turbine, which in turn spins a shaft that is connected to an electricity generator. Electricity is produced when the generator converts the mechanical energy of water into electrical energy. Micro-turbines are used to produce electricity on a small scale. They commonly serve villages and small communities. 3. Irrigation & Drinking Purposes Water turbines are used to irrigate lands and crops. According to "Simplified Irrigation Design," there are two types of water turbines used for irrigation: horizontal centrifugal pump and vertical turbine pump. Irrigation lands use these water turbines for the control and supply of water. Horizontal centrifugal pumps impel water from lakes, shallow wells and other water reservoirs. Vertical turbine pumps are used for pipeline plumbing, drainage plumbing, plant and municipal water supply, petrochemical applications, high-pressure pumping and flood control. A vertical turbine pump is commonly used whenever a liquid has to be pumped out from an underground water table, underground storage systems or open bodies of water (lakes, rivers, ponds, oceans and tanks).

BHAGWAN MAHAVIR POLYTECHNIC

54

FUNDAMENTALS OF MECHANICAL ENGINEERING

EXPERIMENT NO: - 10

AIM: To perform a test on Air Compressors

1 Introduction The compressed air system is not only an energy intensive utility but also one of the least energy efficient. Over a period of time, both performance of compressors and compressed air sys-tem reduces drastically. The causes are many such as poor maintenance, wear and tear etc. All these lead to additional compressors installations leading to more inefficiency. A periodic performance assessment is essential to minimize the cost of compressed air.

2 Purpose of the Performance Test To find out: •

Actual Free Air Delivery (FAD) of the compressor

•

Isothermal power required

•

Volumetric efficiency

•

Specific power requirement

The actual performance of the plant is to be compared with design / standard values for assessing the plant energy efficiency.

3 Performance Terms and Definitions

BHAGWAN MAHAVIR POLYTECHNIC

55

FUNDAMENTALS OF MECHANICAL ENGINEERING

 Measurement of Free Air Delivery (FAD) by Nozzle method

Principle: If specially shaped nozzle discharge air to the atmosphere from a receiver getting its supply from a compressor, sonic flow conditions sets in at the nozzle throat for a particular ratio of upstream pressure (receiver) to the downstream pressure (atmospheric) i.e. Mach number equals one. When the pressure in the receiver is kept constant for a reasonable interval of time, the air-flow output of the compressor is equal to that of the nozzle and can be calculated from the known characteristic of the nozzle.  Arrangement of test equipment The arrangement of test equipment and measuring device shall confirm to Figure 8.1.

 Nozzle Sizes The following sizes of nozzles are recommended for the range of capacities indicated below: Flow Nozzle: Flow nozzle with profile as desired in IS 10431:1994 and dimensions

Capacity (m3/hr)

Nozzle size (mm) 6

3

–9

10

9

– 30

16

27

– 90

22

60

– 170

33

130

– 375

50

300

– 450

80

750

– 2000

125

1800

– 5500

165

3500

– 10000

 8.4.4 Measurements and duration of the test.

BHAGWAN MAHAVIR POLYTECHNIC

56

FUNDAMENTALS OF MECHANICAL ENGINEERING

The compressor is started with the air from the receiver discharging to the atmosphere through the flow nozzle. It should be ensured that the pressure drop through the throttle valve should be equal to or twice the pressure beyond the throttle. After the system is stabilized the following measurements are carried out: •

Receiver pressure

•

Pressure and temperature before the nozzle

•

Pressure drop across the nozzle

•

Speed of the compressor

•

kW, kWh and amps drawn by the compressor

The above readings are taken for the 40%, 60%, 100% and 110% of discharge pressure values.

Measuring instruments required for test      

Thermometers or Thermocouple Pressure gauges or Manometers Differential pressure gauges or Manometers Standard Nozzle Psychrometer Tachometer/stroboscope



Electrical demand analyser

Calculation Procedure for Nozzle Method

BHAGWAN MAHAVIR POLYTECHNIC

57

FUNDAMENTALS OF MECHANICAL ENGINEERING

k = Flow coefficient – as per IS d = Nozzle diameter M T1 = Absolute inlet temperature °K P1 = Absolute inlet pressure kg/cm2 P3 = Absolute Pressure before nozzle kg/cm2 T3 = Absolute temperature before nozzle °K Ra = Gas constant for air 287.1 J/kg k P3–P4 = Differential pressure across the nozzle kg/cm2

BHAGWAN MAHAVIR POLYTECHNIC

58

FUNDAMENTALS OF MECHANICAL ENGINEERING

Isothermal Efficiency = Isothermal power/Input power

Isothermal power (kW) = P1 x Qf x loger / 36.7 P1 = Absolute intake pressure kg/ cm2 Qf = Free air delivered m3/hr. r = Pressure ratio P2/P1

III. Specific power consumption at rated discharge pressure = Power consumption, kW/ Free Air Delivered, m3/hr IV. Volumetric efficiency = Free air delivered m3/min x 100 / Compressor displacement, m3/min

Compressor Displacement =π x D2 x L x S x χ x n / 4

D = Cylinder bore, meter L = Cylinder stroke, meter S = Compressor speed rpm Χ = 1 for single acting and 2 for double acting cylinders n = No. of cylinders

Conclusion: By doing this practical we come to know the testing process of Air compressor and also the factor affecting on performance of an Air Compressor.

BHAGWAN MAHAVIR POLYTECHNIC

59

FUNDAMENTALS OF MECHANICAL ENGINEERING

EXPERIMENT NO:-11

AIM: - Performance test on the pump and suggest fault and remedies for it. 1. To determine the efficiency of the pump. 2. To draw the operating characteristic of the pump for different flow rates and find the optimum condition. APPARATUS: - Working model of centrifugal pump OBJECTIVES:1. To know about function of pump & different parts of it. 2. To calculate power consumption, Output power of pump, Pump efficiency. INTRODUCTION Transport of fluid through closed conduit is a common feature in all chemical industries. It may be necessary to move a liquid against gravity force i.e. into a pressure vessel, or pump it out from a vessel under vacuum as in the case of evaporators. In all these cases, there will be additional loss of energy due to friction as the liquid flows through conduits, fittings and valves. To ensure fluid movement, energy has to be supplied to fluid from an external source. The centrifugal pumps are the most widely used in chemical industries. They are simple to operate, give an uniform flow rate, occupy small floor space and have low maintenance cost and can be used either with a motor or turbine drive. EXPERIMENTAL SET UP: Water from a storage tank is pumped by a centrifugal pump, driven by a motor. The flow rate of water is measured by using measuring tank. A watt meter connected to the motor of the pump measures the energy input to the pump. A pressure gauge and a vacuum gauge connected across the pump measures the theoretical head developed by the pump. PRECAUTIONS: 1) Initially measuring tank must be empty. 2) Priming must be done before starting pump. PROCEDURE: 1) Check the valves of the experiment al setyp. 2) Fill the storage tank with liquid. Switch on the pump and by operating the valve on the delivery line adjust the flow rate. 3) Note down the initial level of the liquid in the tank at the time zero (i.e. at the time of starting the stop watch).

BHAGWAN MAHAVIR POLYTECHNIC

60

FUNDAMENTALS OF MECHANICAL ENGINEERING

4) When steady conditions are reached note the readings of the pressure gauge, vacuum gauge, final liquid level and time. Also note the energy input for this time from energy meter reading. 5) Take watt meter reading under no flow conditions for the same time. 6) Repeat the following for different positions of delivery line valve. OBSERVATION TABLE:Sr No

Initial level of liquid h₁ (cm)

Final level of liquid h₂ (cm)

Diff. Time level Δh= t h₂- h₁ (sec) (cm)

N (rpm)

Pressure gauge reading p₁ (kg/cm2)

Vacuum gauge Reading P₂ (mmhg)

Initial Energy Meter Reading(E₀) watt

Final Energy Meter Reading (E) watt

1 2 3 4 5 6

SAMPLE CALCULATIONS: 1. Capacity of the pump or Volumetric flow rate Q= [(Δh) × C/S area of the tank] / Time = ________ m3 /s. C/S Area of measuring tank: 0.4 × 0.4 = 0.16m2 2. hp = p1 / ρ g = ________ mwc & hv = p2 / ρ g = ________ mwc. Where p = intensity of pressure in N/m2 ρ = Density of water = 1000 kg/m3 g = Gravitational force = 9.81 m/s2 hp= Pressure gauge reading hv= Vacume gauge reading 760 mm of Hg = 1.01×105 N/m2 3. Total head developed (H) in mwc H= Pressure gauge Reading (mwc) + Vacuum gauge reading (mwc) hv = ________ mwc 4. Power Output (po)= (ρ×g×Q×H)/ 1000= _________ kw

BHAGWAN MAHAVIR POLYTECHNIC

61

FUNDAMENTALS OF MECHANICAL ENGINEERING

Q= Flow rate in m3/Sec ρ= Density in kg/m3 H= Head in mwc 5. Power input in t second (Pi) = (E- Eo)×(3600/t) = ___________ kw 6. Efficiency ἠ = (Po/Pi) ×100= _________% [NOTE : CONCLUSION WILL BE WRITTEN BY STUDENT] Fault and Remedies of Centrifugal pump: 1. Pump Fails to start Pumping

Causes 1. Delivery head too high 2. Speed is too low 3. Damaged pump impeller or dust in it 4. Leakage in suction joints 5. 6. 7. 8.

Remedies 1. Reduce delivery head 2. Operate pump at appropriate speed 3. Clean the impeller or if required replace it 4. Check the packing of suction joints and replace them if required 5. Stop the pump and fill the sump 6. Clean them 7. Run it in right direction 8. Ensure proper priming

No water in the pump Dust in foot valve and strainer Pump running in reverse direction Improper priming of pump 2. Pump stop after starting

Causes Remedies 1. Electricity supply failure 1. Check supply of electricity 2. Air leakage in suction pipe 2. Tighten up joints of suction pipe 3. Higher pump lift 3. Reduce pump lift 4. Cavitations( mixing of air) in the water 4. Fit the foot valve deeper in the water, being sucked make suction side leak proof increase the velocity of water entering the pump 5. Slugging in water seal of pipe 5. Back wash the pipes 6. High vibration of pump at working 6. Check alignment 3.

Pump overload

Causes 1. Higher suction and delivery heads 2. Higher delivery pressure 3. Delivery valve not opened fully 4. Higher speed of prime mover 5. Dust, sand etc. coming with water

Remedies 1.keep both the heads as rated 2.Increase the size of delivery pipe 3.Ensure full opening of delivery valve 4. Run the pump at rated speed only 5. Replace strainer

BHAGWAN MAHAVIR POLYTECHNIC

62

FUNDAMENTALS OF MECHANICAL ENGINEERING

4. Noisy Pump Operation Causes Remedies 1. Worn out bearings 1. Replace them 2. Worn out moving parts 2. Replace them 3. Improper shaft alignment 3. Make it proper 4. Dust in suction pipe and foot valve 4. Clean them 5. Air leakage in suction pipe 5. Tighten up joints and packings 6. High or low suction head 6. Keep suction head as rated 7. Lead pump speed 7. Run pump at rated speed 8. Suction valve not opened fully 8. Open the valve fully 9. Insufficient lubrication 9. Make it sufficient 10. Dust in impeller 10. Clean the impeller 11. Air leakage in suction pipe and stuffing 11. Tighten up joints and packings box 12. Wrong pump selected 12. Make appropriate pump selection 13. Pump running in reverse direction 13. Run the pump in right direction 14. Improper pump alignment 14. Make proper pump alignment 5. Pump has very low efficiency Causes 1. Improper pump alignment 2. Air leakage in suction pipe 3. Discharged pressure too high 4. Improper pump alignment 5. Insufficient lubrication 6. Dust in impeller 7. Insufficient suction head 8. Low capacity of pump

Remedies 1. Make proper pump alignment 2. Tighten up joints and packings 3. Reduce the discharged pressure 4. Make proper pump alignment 5. Make it sufficient 6. Clean the impeller 7. Select proper suction head 8. Select the pump with appropriate capacity

BHAGWAN MAHAVIR POLYTECHNIC

63

FUNDAMENTALS OF MECHANICAL ENGINEERING

EXPERIMENT NO:-12 AIM:-To Study various type of material handling equipments. 1) Introduction:Material handling is backbone of type of industries. It is basic requirement at any industry. Without material handling industrial activity comes stand still. Lots of materials are transport in industry ranging from nuts, bolts, raw material, semi-finished material and finished goods. Raw material transports from storage place to the point of use. During the process raw material will further travel from one machine to another machine in shop. It can even transfer to one shop to another depending on process. The transporting any material from one place to another place is known as material handling. Material handling is even grooving subject to research and development is continuously going to design more efficient material handling equipment for verities of application speed and ease of handling overall economy main factor based on which newer material equipment are being designed and developed. In mass production industries continuous supply for all size and weight of material is necessary. Here mechanized material handling system can ensure this a suitable material handling system with appropriate equipment can ensure this. 2) Types of material handling equipment:1) Hoisting equipment. 2) Conveying equipment. 3) Surface and over head equipment. 3) Classification of material handling equipment:Material handling equipment is classified based on direction of material handling. Equipment direction.

handling

in

horizontal Equipment handling in Vertical direction.

1) Hand lorry. 1) Crane. 2) Power truck. 2) Hoist. 3) Motor trolley. 3) Lift/elevator. 4) Belt conveyor. 4) Screw jack. 5) Chain conveyor. 5) Simple chain pulley. 6) Screw conveyor. 6) Differential Pulley. 7) Apron conveyor. 8) Winch. 9) Tractor. 10) Motor lorry. 4) Housing equipments:1) Jack 2)hand operated portable hoist 3)pulleys 4) power operated portable hoist 5) winches 6)power operated traveling trolley 7) crane trolley 8) motorized rail tractors. 5) Types of cranes:1) Stationary crane 2) Rotary crane

BHAGWAN MAHAVIR POLYTECHNIC

64

FUNDAMENTALS OF MECHANICAL ENGINEERING

3) Locomotive crane 4) Jib crane 5) Gantry crane 6) Bridge over head crane 7) Track mounted crane 8) Crawler mounted crane Cranes are generally used to handle heavy weights articles, packages, crates etc. It is having overhead moment and widely used in industries building of almost all kind. Among many varieties overhead crane is widely used in heavy & basic industries such as foundries. Steel mill compressors, pressure vessels manufacturing units, heavy machine building industry etc .Where overhead bridge crane cannot be installed due to space limitation. Jib crane can be used. Gantry crane is mounted on platform with rail and wheel arrangement. Due to this it can be operated with much ease. 6) Elevators:Elevators are used to transport material as well as livestock and humans from one floor to another .It facilitate faster and easier movements of materials. Fast and easiest movements of materials. Following are different type of elevators 1) Cage elevators. 2) Portable air operated elevator. 3) Manually operated stacker.

7) Belt conveyor:Belt conveyor is the most popular and widely used conveyor in many industrial applications. It is an endless belt mounted on drive roller and take up device keep the belt in tension on rollers, materials are loaded on the belt through a hopper . Impact roller is provided to with stand impact force on belt while loading material on it. Advantages of belt conveyor:1) 2) 3) 4) 5)

Suitable for long distance Simple maintenance Less power consumption High load caring capacity Suitable for application requiring continuous transfer of materials

BHAGWAN MAHAVIR POLYTECHNIC

65

FUNDAMENTALS OF MECHANICAL ENGINEERING

Disadvantages of belt conveyor:1) 2) 3) 4) 5) 6)

Costly equipment set up. Limited installation is possible. Limit on belt with. Must be keep straight between two end rollers. Limit on liner speed of the belt. It requires guide rollers. Application of belt conveyors:1) For transfer coal in power plants 2) Used to transport minerals in the mines 3) For transfer of ironers, minerals, sand etc, in cement industries

9) Surface and over head equipments:Following are the commonly used in this category: 1) 2) 3) 4)

Industrial truck Land lift truck Fork lift truck Plate from track

10) Criteria & selection and factors affections selection of material handling equipments.      

Types of magnitude of load. Types of materials to be handled. Quantity of materials to be transported in unit time. Distance of travel. Type of industry and production system. General environment condition.

Technical supports:      

Factory building and plant lay out Production system and machinery in the shops Lower power consumption Flexibility in materials movements paths Scope for modification in the design Speed of materials movements Load bearing capacity of the handling equipments

Economic factors: Primarily expanses of the equipments.

BHAGWAN MAHAVIR POLYTECHNIC

66

FUNDAMENTALS OF MECHANICAL ENGINEERING

   

Repair & maintenance cost of equipments. Frequency of use of the equipments of use of the equipments. Capital cost and &salvage value. Depreciation cost.

11) Factors affecting selection of cranes:        

Types of materials to be handled. Distance of travel. Path movements. Type of the industry. Capital of the conveyor. Lay out of the factory. Types of process. Power consumption of the conveyor.

12) Factors affecting selection of cranes:       

Structure of the building. Area of movement. Atmosphere where crane is to be used. Height of movement. Weight movement. Indoor/outdoor usage. Direction of movement.

BHAGWAN MAHAVIR POLYTECHNIC

67