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Everything posted by saurabhjain

  1. saurabhjain


    We welcome comments on each picture of engines...
  2. Topping-cycle systems produce electricity first, then recover the excess thermal energy for heating or cooling applications. By contrast, bottoming-cycle systems, also known as “waste heat to power,” are a process whereby waste heat from an existing process is used to produce electricity.
  3. Smart hello to every one... As off late I got busy in some personal projects, this year we are back and look forward to make the community live, quick, vibrant and responsive. I recommend few points to give it a great push... Make sure to login every day on the website mechanical-engg.com Time to showcase your skills, start your blog, give response to others, appreciate the starters. Do not put ads or promote others links, website.... we are making it a clean community..once banned you will miss the long term opportunities. Ask researchers, professors, to write their learning and teachings We will be starting quizzes very soon...we will even invite professors who are willing to make some interesting/challenging quiz for us We look forward to start job section soon - will need help from community members to give us information of various openings in your company.. help us to reach your HR. Help us to reach and connect each and every single mechanical engineering professional. I am listing down the following ways Facebook - Connect with me directly on this profile https://www.facebook.com/mechanical.engineering.website and add all your friends in the following group https://www.facebook.com/groups/4mechanicalengineers/ Whatsapp - we will be forming whatsaopp groups.. https://mechanical-engg.com/whatsapp-group/ These groups will be just to send you the updates on phone .. do not join more then one group as same information will be shared on each group...
  4. couple of points your site.. this is site of all members - this is a community... read how every one is writing here on this link When you write the answer .. you are demonstrating your knowledge...
  5. try to write answer....open your text books... study and write in your own words
  6. From the album: Gears

    Construction: It is made up of following components: 1. Counter shaft or Lay Shaft: This shaft is in direct contact with the clutch and the main shaft. Keeping in mind according to the gear ratio, the speed of the counter shaft may be less that the speed of the engine. The gear ratio can be defined as the ratio of the teeth of driven gear to the teeth of the driver gear. 2. Main shaft: This shaft operates the speed of the vehicle. The power is made available to the main shaft through the gears from the counter shaft. This is done in accordance with the gear ratio. 3. Dog clutch: Dog clutch is special feature of constant mesh gearbox. It is used for the coupling of any two shafts. This is done by interference. Using a dog clutch, various gears can be locked to the output and input shafts. 4. Gears: The main work of the gears is the transmission of power between the shafts. If the gear ratio is more than one, the main shaft will work at a speed that is slower than the counter shaft, and vice versa. The arrangement of both reverse, as well as forward gears, is present.
  7. Quiz author has to click button .. "Allow playing" .. this is because ..he has added 7 questions and the quiz is not ready -- may be he is adding 3 more questions... once he click on allow playing.... the quiz be open for every one .... And I can see - he has added quiz but nit added any questions......
  8. From the album: Engineering images 10

    In plasma-arc welding (PAW), developed in the 1960s, a concentrated plasma arc is created and directed towards the weld area. The produced arc is stable and reaches temperatures around 33,000°C. Plasma is an ionized hot gas composed of nearly equal numbers of electrons and ions. The plasma is started between the tungsten electrode and the orifice by a low-current pilot arc. What creates plasma-arc welding unlike other processes is that the plasma arc is concentrated because it is forced through a relatively small orifice Plasma Arc Welding Torch Operating currents generally are below 100 A, but they can be superior for special applications. While a filler metal is used, it is fed into the arc, as is made in GTAW. Arc and weld-zone shielding is supplied by means of an outer-shielding ring and the use of gases like the following argon, helium, or mixtures.
  9. Type of chips Continuous chips Discontinuous chips Built up Chips
  10. In an automobile, the engineproduces power and this power is carry to the wheels by use of power train. The first element of this train isclutch. The main function of the clutch is to engage and disengages the engine to the wheel when the driver need or when shifting the gears. Basically clutch may be classified as follow. Types of Clutches: These may classified as follow: According to the method of transmitting torque: 1. Positive clutch (Dog clutch): In the positive clutch, grooves are cut either into the driving member or into the driven member and some extracted parts are situated into both driving and driven member. When the driver releases clutch pedal then these extracted parts insert into grooves and both driving and driven shaft revolve together. When he push the clutch pedal these extracted parts come out from grooves and the engine shaft revolve itself without revolving transmission shaft. 2. Friction clutch: In this types of clutches, friction force is used to engage and disengage the clutch. A friction plate is inserted between the driving member and the driven member of clutch. When the driver releases the clutch pedal, the driven member and driving member of clutch, comes in contact with each other. A friction force works between these two parts. So when the driving member revolves, it makes revolve the driven member of clutch and the clutch is in engage position. This type of clutch is subdivided into four types according to the design of the clutch. A.) Cone clutch: It is a friction type of clutch. As the name, this type of clutch consist a cone mounted on the driven member and the shape of the sides of the flywheel is also shaped as the conical. The surfaces of contact are lined with the friction lining. The cone can be engage and disengage form flywheel by the clutch pedal. B.) Single plate clutch: In the single plate clutch a flywheel is fixed to the engine shaft and a pressure plate is attached to the gear box shaft. This pressure plate is free to move on the spindle of the shaft. A friction plate is situated between the flywheel and pressure plate. Some springs are inserted into compressed position between these plates. When the clutch pedal releases then the pressure plate exerts a force on the friction plate due to spring action. So clutch is in engage position. When the driver pushes the clutch pedal it due to mechanism it serves as the disengagement of clutch. C.) Multi-plate clutch: Multi-plate clutch is same as the single plate clutch but there is two or more clutch plates are inserted between the flywheel and pressure plate. This clutch is compact then single plate clutch for same transmission of torque. D.) Diaphragm clutch: This clutch is similar to the single plate clutch except diaphragm spring is used instead of coil springs for exert pressure on the pressure plate . In the coil springs, one big problem occur that these springs do not distribute the spring force uniformly. To eliminate this problem, diaphragm springs are used into clutches. This clutch is known as diaphragm clutch. 3. Hydraulic clutch: This clutch uses hydraulic fluid to transmit the torque. According to their design, this clutch is subdivided into two types. A.) Fluid coupling: It is a hydraulic unit that replaces a clutch in a semi or fully automatic clutch. In this type of clutch there is no mechanical connection between driving member and driven member. A pump impeller is blotted on a driving member and a turbine runner is bolted on the driven member. Both the above unit is enclosed into single housing filled with a liquid. This liquid serve as the torque transmitter form the impeller to the turbine. When the driving member starts rotating then the impeller also rotates and through the liquid outward by centrifugal action. This liquid then enters the turbine runner and exerts a force on the runner blade. This make the runner as well as the driven member rotate. The liquid from the runner then flows back into the pump impeller, thus complete the circuit. It is not possible to disconnect to the driving member to the driven member when the engine is running. So the fluid coupling is not suitable for ordinary gear box. It is used with automatic or semi-automatic gear box. B.) Hydraulic torque converter: Hydraulic torque converter is same as the electric transformer. The main purpose of the torque converter is to engage the driving member to driven member and increase the torque of driven member. In the torque converter, an impeller is bolted on the driving member, a turbine is bolted on the driven member and a stationary guide vanes are placed between these two members. This all parts are enclosed into single housing which filled with hydraulic liquid. The impeller rotates with the driven member and it through the liquid outward by centrifugal action. This liquid flowing from the impeller to turbine runner exerts a torque on the stationary guide vanes which change the direction of liquid, thereby making possible the transformation of torque and speed. The difference of torque between impeller and turbine depends upon these stationary guide vanes. The hydraulic torque converter is serve the function of clutch as well as the automatic gear box. According to the method of engaging force: 1. Spring types clutch: In this types of clutches, helical or diaphragm springs are used to exert a pressure force on the pressure plate to engage the clutch. These springs are situated between pressure plate and the cover. These springs are inserted into compact position into the clutch. So when it is free to move between these two members, it tends to expand. So it exert a pressure force on the pressure plate thus it brings the clutch in engage position. 2. Centrifugal clutch: As the name in the centrifugal clutch, centrifugal force is used to engage the clutch. This type of clutch does not require any clutch pedal for operating the clutch. The clutch is operated automatically depending upon engine speed. It consist a weight pivoted on the fix member of clutch. When the engine speed increase the weight fly of due to the centrifugal force, operating the bell crank lever, which press the pressure plate. This makes the clutch engage. 3. Semi-centrifugal clutch: One big problem occur in centrifugal clutch is that they work sufficient enough at higher speeds but at lower speed they don’t do their work sufficiently. So the need of another type of clutch occurs, which can work at higher speed as well as at lower speed. This type of clutch is known as semi-centrifugal clutch. This type of clutch uses centrifugal force as well as spring force for keeping it in engaged position. The springs are designed to transmit the torque at normal speed, while the centrifugal force assists in torque transmission at higher speeds. 4. Electro-magnetic clutch: In the electromagnetic clutch electro-magnate is used to exert a pressure force on pressure plate to make the clutch engage. In this type of clutch, the driving plate or the driven plate is attached to the electric coil. When the electricity is provide into these coils then the plate work as the magnate and it attract another plate. So both plates join when the electricity provides and the clutch is in engage position. When the driver cut the electricity, this attraction force disappear, and the clutch is in disengage position. According to the method of control: 1. Manual clutch: In this type, clutch is operate manually by the driven when he need or when shifting the gear. This type of clutch uses some mechanical, hydraulical or electrical mechanism to operate the clutch. All friction clutches are include in it. 2. Automatic clutch: This type of clutch used in modern vehicle. This clutch has self operated mechanism which control the clutch when the vehicle need. Centrifugal clutch, hydraulic torque converter and fluid coupling includes in it. This type of clutch is always used with the automatic transmission box.
  11. Selection of material is an important aspect for manufacturing industries . The quality of product is highly depends upon its material properties. These properties are used to distinguish materials from each other. For Example: A harder material is used to make tools.A ductile material is used to draw wires. So the knowledge of mechanical properties of material is desirable for any mechanical student or for any person belongs to mechanical industries. This post brings top 18 mechanical properties. Mechanical properties of material: There are mainly two types of materials. First one is metal and other one is non metals. Metals are classified into two types : Ferrous metals and Non-ferrous metals. Ferrous metals mainly consist iron with comparatively small addition of other materials. It includes iron and its alloy such as cast iron, steel, HSS etc. Ferrous metals are widely used in mechanical industries for its various advantages. Nonferrous metals contain little or no iron. It includes aluminum, magnesium, copper, zinc etc. Most Mechanical properties are associated with metals. These are #1. Strength: The ability of material to withstand load without failure is known as strength. If a material can bear more load, it means it has more strength. Strength of any material mainly depends on type of loading and deformation before fracture. According to loading types, strength can be classified into three types. a. Tensile strength: b. Compressive strength: 3. Shear strength: According to the deformation before fracture, strength can be classified into three types. a. Elastic strength: b. Yield strength: c. Ultimate strength: #2. Homogeneity: If a material has same properties throughout its geometry, known as homogeneous material and the property is known as homogeneity. It is an ideal situation but practically no material is homogeneous. #3. Isotropy: A material which has same elastic properties along its all loading direction known as isotropic material. #4. Anisotropy: A material which exhibits different elastic properties in different loading direction known as an-isotropic material. #5. Elasticity: If a material regain its original dimension after removal of load, it is known as elastic material and the property by virtue of which it regains its original shape is known as elasticity. Every material possess some elasticity. It is measure as the ratio of stress to strain under elastic limit. #6. Plasticity: The ability of material to undergo some degree of permanent deformation without failure after removal of load is known as plasticity. This property is used for shaping material by metal working. It is mainly depends on temperature and elastic strength of material. #7. Ductility: Ductility is a property by virtue of which metal can be drawn into wires. It can also define as a property which permits permanent deformation before fracture under tensile loading. The amount of permanent deformation (measure in percentage elongation) decides either the material is ductile or not. Percentage elongation = (Final Gauge Length – Original Gauge Length )*100/ Original Gauge Length If the percentage elongation is greater than 5% in a gauge length 50 mm, the material is ductile and if it less than 5% it is not. #8. Brittleness: Brittleness is a property by virtue of which, a material will fail under loading without significant change in dimension. Glass and cast iron are well known brittle materials. #9. Stiffness: The ability of material to resist elastic deformation or deflection during loading, known as stiffness. A material which offers small change in dimension during loading is more stiffer. For example steel is stiffer than aluminum. #10. Hardness: The property of a material to resist penetration is known as hardness. It is an ability to resist scratching, abrasion or cutting. It is also define as an ability to resist fracture under point loading. #11. Toughness: Toughness is defined as an ability to withstand with plastic or elastic deformation without failure. It is defined as the amount of energy absorbed before actual fracture. #12. Malleability: A property by virtue of which a metal can flatten into thin sheets, known as malleability. It is also define as a property which permits plastic deformation under compression loading. #13. Machinability: A property by virtue of which a material can be cut easily. #14. Damping: The ability of metal to dissipate the energy of vibration or cyclic stress is called damping. Cast iron has good damping property, that’s why most of machines body made by cast iron. #15. Creep: The slow and progressive change in dimension of a material under influence of its safe working stress for long time is known as creep. Creep is mainly depend on time and temperature. The maximum amount of stress under which a material withstand during infinite time is known as creep strength. #16. Resilience: The amount of energy absorb under elastic limit during loading is called resilience. The maximum amount of the energy absorb under elastic limit is called proof resilience. #17. Fatigue Strength: The failure of a work piece under cyclic load or repeated load below its ultimate limit is known as fatigue. The maximum amount of cyclic load which a work piece can bear for infinite number of cycle is called fatigue strength. Fatigue strength is also depend on work piece shape, geometry, surface finish etc. #18. Embrittlement: The loss of ductility of a metal caused by physical or chemical changes, which make it brittle, is called embrittlement.
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  13. From the album: Engineering images 10

    Overhead valve, also commonly called pushrod, engines are a simplified V-style design. These are built to be compact and resistant to oil contamination and are often used in small displacement racing.In consumer automotive, however, the pushrod engine has largely been replaced by the SOHC and DOHC designs....
  14. Extrusion is a metal forming process in which metal or work piece is forced to flow through a die to reduce its cross section or convert it into desire shape. This process is extensively used in pipes and steel rods manufacturing. The force used to extrude the work piece is compressive in nature. This process is similar to drawing process except drawing process uses tensile stress to extend the metal work piece. The compressive force allows large deformation compare to drawing in single pass. The most common material extruded are plastic and aluminum. Extrusion Process: Working Principle: Extrusion is a simple compressive metal forming process. In this process, piston or plunger is used to apply compressive force at work piece. These process can be summarized as follow. First billet or ingot (metal work piece of standard size) is produced. This billet is heated in hot extrusion or remains at room temperature and placed into a extrusion press (Extrusion press is like a piston cylinder device in which metal is placed in cylinder and pushed by a piston. The upper portion of cylinder is fitted with die). Now a compressive force is applied to this part by a plunger fitted into the press which pushes the billet towards die. The die is small opening of required cross section. This high compressive force allow the work metal to flow through die and convert into desire shape. Now the extruded part remove from press and is heat treated for better mechanical properties. This is basic working of extrusion process. Types of Extrusion: Extrusion process can be classified into following types. According to the direction of flow of metal Direct Extrusion: In this type of extrusion process, metal is forced to flow in the direction of feed of punch. The punch moves toward die during extrusion. This process required higher force due to higher friction between billet and container. Indirect Extrusion: In this process, metal is flow toward opposite direction of plunger movement. The die is fitted at opposite side of punch movement. In this process, the metal is allowed to flow through annular space between punch and container. Hydrostatic Extrusion: This process uses fluid to apply pressure on billet. In this process, the friction is eliminated because the billet is neither contact with cylinder wall or plunger. There is a fluid between the billet and plunger. The plunger applies force on fluid which further applied on billet. Normally vegetable oils are used as fluid.This process accomplished by leakage problem and uncontrolled speed of extrusion. According to the working temperature Hot Extrusion: If the extrusion process takes place above recrystallization temperature which is about 50-60% of its melting temperature, the process is known as hot extrusion. Advantages: Low force required compare to cold working. Easy to work in hot form. The product is free from stain hardening. Disadvantages: Low surface finish due to scale formation on extruded part. Increase die wear. High maintenance required. Cold Extrusion: If the extrusion process takes place below crystallization temperature or room temperature, the process is known as cold extrusion. Aluminum cans, cylinder, collapsible tubes etc. are example of this process. Advantages: High mechanical properties. High surface finish No oxidation at metal surface. Disadvantages: High force required. Product is accomplished with strain hardening. Application: Extrusion is widely used in production of tubes and hollow pipes. Aluminum extrusion is used in structure work in many industries. This process is used to produce frames, doors, window etc. in automotive industries. Extrusion is widely used to produce plastic objects. Advantages and Disadvantages: Advantages: High extrusion ratio (It is the ratio of billet cross section area to extruded part cross section area). It can easily create complex cross section. This working can be done with both brittle and ductile materials. High mechanical properties can achieved by cold extrusion. Disadvantages: High initial or setup cost. High compressive force required.
  15. Types of Nozzle in IC Engine : Pintle Nozzle, Single Hole Nozzle, Multihole Nozzle, Pintaux Nozzle Nozzle is that part of an injector through which the liquid fuel is sprayed into the combustion chamber. It is used in Diesel engine in which fuel is drawn separately through injector at end of compression stroke and air is drawn into cylinder in suction stroke. The nozzle used in IC engine should follow following functions. It should automizate fuel. This is a very important function since it is the first phase in obtaining proper mixing of the fuel and air in the combustion chamber. Distribute the fuel in require area within the combustion chamber. To prevent fuel from impinging directly on the walls of combustion chamber or piston. This is necessary because fuel striking the walls decomposes and produces carbon deposits. This causes smoky exhaust as well as increase in fuel consumption. To mix the fuel with air in case of non-turbulent type of combustion chamber. Types of Nozzle in IC Engine: The design of nozzle must be such that the liquid fuel forced through the nozzle will broke up into fine droplets, or atomize, as it passes into the combustion chamber. This is the first phase in obtaining proper mixing of the fuel and air in the combustion chamber. Various types of nozzles are used in IC engines. These types are as follow. The Pintle Nozzle: In this type of nozzle the stem of nozzle valve is extended to from a pin or Pintle which protrudes through the mouth of the nozzle. The size and shape of the Pintle can be varied according to the requirement. It provides a spray operating at low injection pressures of 8-10MPa. The spray cone angle is generally 60 degree. The main advantage of this nozzle is that it avoids weak injection and dribbling. It prevents the carbon deposition on the nozzle hole. The Single Hole Nozzle: In this type of nozzle at the center of the body there is a single hole which is closed by the nozzle valve. The size of the hole is usually of the order of 0.2 mm. Injection pressure is of order of 8-10MPa and spray cone angle is about 15 degree. One of the major disadvantages of this nozzle is that they tends to drible. Besides, their spray angle it too narrow to facilitate good mixing unless higher velocities are used. The Multi Hole Nozzle: This nozzle consists of a number of holes bored in the tip of the nozzle. The number of holes varies from 4 to 18 and the size from 35 to 200 micro meters. The hole angle may be from 20 degree upwards. These nozzles operate at high injection pressure of the order of 18 MPa. Their advantage lies in the ability to distribute the fuel properly even with lower air motion available in open combustion chambers. Pintaux Nozzle: This type of nozzle is a type of Pintle nozzle which has an auxiliary hole drilled in the nozzle body. It injects a small amount of fuel through this additional hole which is called pilot injection in upstream direction slightly before the main injection. The needle valve does not lift fully at low speeds and most of the fuel is injected through the auxiliary hole. The main advantage of this nozzle is better cold starting performance. A major drawback of this nozzle is that its injection characteristics are poorer than the multihole nozzle.
  16. They both are the metal forming processes. When plastic deformation of metal is carried out at temperature above the recrystallization temperature the process, the process is known as hot working. If this deformation is done below the recrystallization temperature the process is known as cold working. There are many other differences between these processes which are described as below. Difference between Hot Working and Cold Working: S.No. Cold working Hot working 1 It is done at a temperature below the recrystallization temperature. Hot working is done at a temperature above recrystallization temperature. 2. It is done below recrystallization temperature so it is accomplished by strain hardening. Hardening due to plastic deformation is completely eliminated. 3. Cold working decreases mechanical properties of metal like elongation, reduction of area and impact values. It increases mechanical properties. 4. Crystallization does not take place. Crystallization takes place. 5. Material is not uniform after this working. Material is uniform thought. 6. There is more risk of cracks. There is less risk of cracks. 7. Cold working increases ultimate tensile strength, yield point hardness and fatigue strength but decreases resistance to corrosion. In hot working, ultimate tensile strength, yield point, corrosion resistance are unaffected. 8. Internal and residual stresses are produced. Internal and residual stresses are not produced. 9. Cold working required more energy for plastic deformation. It requires less energy for plastic deformation because at higher temperature metal become more ductile and soft. 10. More stress is required. Less stress required. 11. It does not require pickling because no oxidation of metal takes place. Heavy oxidation occurs during hot working so pickling is required to remove oxide. 12. Embrittlement does not occur in cold working due to no reaction with oxygen at lower temperature. There is chance of embrittlement by oxygen in hot working hence metal working is done at inert atmosphere for reactive metals.
  17. Tires are the principal product of the rubber industry, accounting for about three fourths of total tonnage. Other important products include footwear, hose, conveyor belts, seals, shock-absorbing components, foamed rubber products, and sports equipment Tires Pneumatic tires are critical components of the vehicles on which they are used. They are used on automobiles, trucks, buses, farm tractors, earth-moving equipment, military vehicles, bicycles, motorcycles, and aircraft. Tires support the weight of the vehicle and the passengers and cargo on board; they transmit the motor torque to propel the vehicle (except on aircraft); and they absorb vibrations and shock to provide a comfortable ride. Tire Construction and Production Sequence A tire is an assembly of many parts, whose manufacture is unexpectedly complex. A passenger car tire consists of about 50 individual pieces; a large earthmover tire may have as many as 175. To begin with, there are three basic tire constructions steps 1. Diagonal ply 2. Belted bias 3. Radial ply In all three cases, the internal structure of the tire, known as the carcass, consists of multiple layers of rubber-coated cords, called plies. The cords are strands of various materials such as nylon, polyester, fiberglass, and steel, which provide inextensibility to reinforce the rubber in the carcass. The diagonal ply tire has the cords running diagonally, but in perpendicular directions in adjacent layers. A typical diagonal ply tire may have four plies. The belted bias tire is constructed of diagonal plies with opposite bias but adds several more layers around the outside periphery of the carcass. These belts increase the stiffness of the tire in the tread area and limit its diametric expansion during inflation. The cords in the belt also run diagonally, as indicated in the sketch. A radial tire has plies running radially rather than diagonally; it also uses belts around the periphery for support. A steel-belted radial is a tire in which the circumferential belts have cords made of steel. The radial construction provides a more flexible sidewall, which tends to reduce stress on the belts and treads as they continually deform on contact with the flat road surface during rotation. This effect is accompanied by greater tread life, improved cornering and driving stability and a better ride at high speeds. In each construction, the carcass is covered by solid rubber that reaches a maximum thickness in the tread area. The carcass is also lined on the inside with a rubber coating. For tires with inner tubes, the inner liner is a thin coating applied to the innermost ply during its fabrication. For tubeless tires, the inner liner must have low permeability because it holds the air pressure; it is generally a laminated rubber. Tire production can be summarized in three steps 1. Preforming of components 2. Building the carcass and adding rubber strips to form the sidewalls and treads 3. Molding and curing the components into one integral piece. Preforming of Components The carcass consists of a number of separate components, most of which are rubber or reinforced rubber. These, as well as the sidewall and tread rubber, are produced by continuous processes and then pre-cut to size and shape for subsequent assembly. The components and the preforming processes to fabricate them are: 1. Bead coil: Continuous steel wire is rubber-coated, cut, coiled, and the ends joined. 2. Plies: Continuous fabric (textile, nylon, fiber glass and steel) is rubber coated in a calendering process and pre-cut to size and shape. 3. Inner lining: For tube tires, the inner liner is calendered onto the innermost ply. For tubeless tires, the liner is calendered as a two-layered laminate. 4. Belts: Continuous fabric is rubber coated (similar to plies), but cut at different angles for better reinforcement; then made into a multi-ply belt. 5. Tread: Extruded as continuous strip; then cut and pre assembled to belts. 6. Sidewall: Extruded as continuous strip; then cut to size and shape. Building the Carcass The carcass is traditionally assembled using a machine known as a building drum, whose main element is a cylindrical arbor that rotates. Pre-cut strips that form the carcass are built up around this arbor in a step-by-step procedure. The layered plies that form the cross section of the tire are anchored on opposite sides of the rimby two bead coils. The bead coils consist of multiple strands of high-strength steel wire. Their function is to provide a rigid support when the finished tire is mounted on the wheel rim. Other components are combined with the plies and bead coils. These include various wrappings and filler pieces to give the tire the proper strength, heat resistance, air retention, and fitting to the wheel rim. After these parts are placed around the arbor and the proper numbers of plies have been added, the belts are applied. This is followed by the outside rubber that will become the sidewall and tread. At this point in the process, the treads are rubber strips of uniform cross section—the tread design is added later in molding. The building drum is collapsible, so that the unfinished tire can be removed when finished. The form of the tire at this stage is roughly tubular. Molding and Curing Tire molds are usually two-piece construction (split molds) and contain the tread pattern to be impressed on the tire. The mold is bolted into a press, one half attached to the upper platen and the bottom half fastened to the lower platen (the base). The uncured tire is placed over an expandable diaphragm and inserted between the mold halves. The press is then closed and the diaphragm expanded, so that the soft rubber is pressed against the cavity of the mold. This causes the tread pattern to be imparted to the rubber. At the same time, the rubber is heated, both from the outside by the mold and from the inside by the diaphragm. Circulating hot water or steam under pressure is used to heat the diaphragm. The duration of this curing step depends on the thickness of the tire wall. A typical passenger tire can be cured in about 15 minutes. Bicycle tires cure in about 4 minutes, whereas tires for large earth-moving equipment take several hours to cure. After curing is completed, the tire is cooled and removed from the press.
  18. A cam is a mechanical member used to impart desired motion or displacement to a follower by direct contact. It is widely used inautomobile industries to direct opening and closing of inlet and exhaust valves at desire time. Cams are either in rotary or reciprocating or oscillating motion. The driver member in cam follower mechanism is called cam and driven member is called follower. Cam mechanism belong to higher pair mechanism because the cam and follower makes point contact. When we study about cam follower mechanism, some common terminology like prime circle, base circle, pressure angle etc. are used to describe a cam. These are as follow. Cam Terminology and Displacement Diagram: Terminology: Base Circle: Base circle is the smallest circle that can be drawn tangentially to the cam profile. Trace Point: A trace point is a theoretical point on the follower. It’s motion describing the movement of the follower. For example a knife edge follower, the trace point is at the knife edge. Pitch Curve: It is the curve drawn by the trace point assuming that the cam is fixed and the trace point of the follower rotates around the cam. Pressure Angle: It represents the steepness of the cam profile. The angle between the direction of the follower movement and the normal to the pitch curve at any point is called pressure angle. Pitch Point: A pitch point correspond to the point of maximum pressure angle. Its Pitch Circle: A circle drawn with its center at the cam center and pass through the pitch point is known as the pitch circle. Prime Circle: The prime circle is the smallest circle that can be drawn from the center of cam and it is tangential to the pitch curve. Displacement Diagram: Angle of Ascent: It is the angle through which the cam turns during the time the follower rises. Angle of Dwell: Angle of dwell is the angle through which the cam turns while the follower remains stationary at the highest or the lowest point. Angle of Descent: Angle of descent is the angle through which the cam turns while follower returns to the initial position. Angle of Action: This is the total angle moved by the cam during the time between the beginning of rise and the end of return of the follower.
  19. Casting and forging are both industrial processes of metal forming and shaping. Different process used in different conditions. The main difference between casting and forging is that the metal is compulsory to heat and convert into liquid stage in casting but in forging metal is converted into desire shape by applying pressure with or without applying heat. If the metal is preheated into forging it does not convert into liquid stage. But before differentiate this both terms; you have to know about what is casting and what is forging What is casting? Casting is a process in which metal is heated until molten stage and pour this liquid metal into a mold or cavity where it is allow solidifying. This process converts the metal into desire shape. It is useful to make complex structure. Most of the industrial structures parts are like lathe machine bed, milling machine bed make big base of other machinery part, IC engine components etc. are made by this process. Advantages of Casting This process can form very large structure which is impossible to form by other process. It can make any complex and unsymmetrical structure. The structure formed by this process has high compressive strength. It can attain wide range of properties. This process can attain high accuracy. What is forging? On the other hand forging is the process of converting metal into desire shape by applying pressure and with or without heat. When the metal is heated before applying pressure the process is called hot forging. In forging metal is heated before below critical temperature or below molten stage. Rolling, pressing, Wire drawing etc. is various types of forging. All sheets, small component, wire etc are formed by this process. Advantages of Forging: It produces tougher product compare to other. The product made by forging has high impact or tensile strength. Tabular form of Difference between Forging vs Casting S. No. Casting Forging 1. The metal is heated until it converts into molten stage. The metal is heated below recrystallization temperature. 2. The product produce by it have high compressive strength compare to forging. It has low compressive strength. 3. It has low fatigue strength. It has high fatigue strength. 4. Imperfection or directional defecates does not improve in casting. Directional defect are refined in forging. 5. It is less reliable or has low strength. It is high reliable. 6. It is costly sometime and has high lead time. It has low lead time and cheap compare to casting. 7. The product has low tensile strength. This produces high tensile strength. 8. It required a secondary finishing operation. It does not require a secondary operation.
  20. These are two main types of welding. The term MIG is stand for Metal inert Gas welding and TIG is stand for Tungsten Inert Gas welding. These are widely use for joining a verity of shapes and material. MIG WELDING TIG WELDING 1. This welding is known as metal inert gas welding. 1. This is known as tungsten inert gas welding. 2. Metal rod is used as electrode and work piece used as another electrode. 2. Tungsten rod is used as electrode. 3. It is gas shielded metal arc welding. 3. It is gas shielded tungsten arc welding. 4. Continuous feed electrode wire is used which are fast feeding. 4. Welding rods are used which are slow feeding. 5. The welding area is flooded with a gas which will not combine with the metal. 5. Gas is used to protect the welded area form atmosphere. 6. MIG can weld materials such as mild steel, stainless steel and aluminum. A range of material thicknesses can be welded from thin gauge sheet metal right up to heavier structural plates. 6. TIG weld things like kitchen sinks and tool boxes. Pipe welding and other heavier tasks can also be performed, you just need to have a unit that is capable of putting out the amount of power that you need. 7. MIG requires consumable metallic electrode. 7. It used non consumable tungsten electrode 8. Electrode is feeded continuously from a wire reel. 8. It does not require electrode feed. 9. DC with reverse polarity is used. 9. It can use both A.C and D.C. 10. Filler metal is compulsory used. 10. Filler metal may or may not be used. 11. It can weld up to 40 mm thick metal sheet. 11. Metal thickness is limited about 5 mm. 12. MIG is comparatively faster than TIG. 12. TIG is a slow welding process.
  21. A boiler may be defined as a closed vessel in which steam is produced from water by combustion of fuel. Boiler is used in many industries such as in steam power generation, in sugar industries, in textile industries for sizing and bleaching etc. and in many other chemical industries. Earlier it was mainly used in power generation in steam engine. Boiler is also known as steam generator. The primary requirement of boilers is the water, which must be contained safely and the steam must be safely delivered in desired condition. In a boiler, many parts and fittings of mounted, which are mounted on the boiler for its proper and safe functioning. These are as follow 1. Water level indicator 2. Pressure gauge 3. Safety valves 4. Stop valve 5. Blow of cock 6. Feed check valve 7. Fusible plug Types of boilers: Boiler may be classified in following types. According to the axis of boiler 1. Horizontal boiler: If the axis of boiler is horizontal, it is known as horizontal boiler. Example Babcock and Wilcox boiler 2. Vertical boiler: If the axis of boiler is vertical, it is known as vertical boiler. The main advantages of vertical boiler that it is easy to maintain. Example : Cochran boiler 3. Inclined boiler: If the axis of boiler is inclined, it is known as inclined boiler. According to fire of boiler: 1. Externally fire boiler: If the furnace is outside of the boiler shell, it is known as externally fired boiler. Example Babcock and Wilcox boiler 2. Internally fire boiler: If the furnace is inside the shell, it is known as internally fired boiler. Example Lancashire boiler According to pressure of boiler: 1. High Pressure boiler: If the boiler pressure is above 80 MPa, the boiler is known as high pressure boiler. Example Benson boiler 2. Low pressure boiler: If the boiler pressure is below 80 MPa, the boiler is known as low pressure boiler. Example Cochran boiler According to Circulation of water 1. Forced circulation boiler: If the circulation of water is done by a feed pump, the boiler is known as forced circulation boiler. Example Velox boiler 2. Natural circulation boiler: If the circulation of water is done by natural convection, this is known as natural circulation boiler. Example Lancashire boiler According to circulation of gases: 1. Fire tube boiler 2. Water tube boiler 1. Fire tube boiler: In this types of boiler water flow surrounding the tubes and the hot flue gases flow through the tubes. The heat passes form the tube to surrounding water which is used to heat the surrounding flowing water and convert it into steam. Example Lancashire boiler 2. Water tube boiler: In this boiler, water flow through the tubes which are surrounded by hot flue gases. These flue gases used to heat the water and convert it into steam. Example Lamont Boiler
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