Mechanical Engineering - Training Report 283755

INDUSTRIAL TRAINING REPORT

CENTRAL INSTITUTE OF HAND TOOLS, MAQSUDAN,JALANDHAR

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Introduction The aim is to provide technology services and trained manpower to engineering industry in general and the hand tools industries in particular to achieve global standards. • CIHT is an autonomous organization. • CIHT is a National Institute. • CIHT was established in 1983 with assistance from UNDP, Government of India and Government of Punjab. •

CIHT is aspiring for latest technology to be a leader in region.

Organizational Profile Hand Tools Industry consists of organized, small scale and cottage sector. About 80 % of small scale and cottage sector is located in and around Jalandhar in Punjab, Nagaur in Rajasthan and Purulia in West Bengal. The Hand Tools Industries are playing a vital role in economic development and earning valuable foreign exchange for the country. With a view to provide technology services to engineering industry in general and the hand tools industries in particular, the Government of India has set up Central Institute of Hand Tools as a National Institute in Jalandhar, in the state of Punjab as an autonomous organization with the assistance of U.N.D.P and Govt. of Punjab. The management of the institute rests with the Governing Council appointed by the Govt. of India , with Development Commissioner, small scale industries as ex-officio chairman of the institute. The Principal Director is the Chief Executive Officer of the Institute. Other include the Govt. officials and the industrialists from the industry.

CIHT can offer services to local as well as industries in Developing Countries. 2

Consultancy • Design & Manufacture of various toolings, jigs, fixtures and gauges used in hand tool and other Engineering industry. • Induction Hardening processes applicable to various hand tools i.e Pipe Wrenches, Pliers, all type of hammers and other engineering items. • Forging of various hand tools i.e. Spanners, Wrenches, Pliers, Claw Hammers, Pipe Wrenches and other commercial forgings. • Chemical and Physical testing of ferrous material and calibration of gauges. • Certificate Courses and Short Term Courses in Tool & Die Making. • Establishment of Tool Rooms & Production Shops as per product mix. • Selection of Machine Tools ( New & Modern) apart from existing infrastructure. • Training Personnel in available fields of testing and quality control. • Similar Testing Laboratories / Standards rooms can be developed in those countries.

Tool Room Services The Tool Room is equipped with following indigenous as well as imported machinery: • CNC Wire Cut Machine • CNC Machining Centre (VMC-800) HMT • CNC Turning CL 2050 Make Batliboi • CNC Vertical Machining Centre, DAEWOO • CNC Turner Lathe Machine • CNC Trainer Milling Machine • 3D Co-ordinate Measuring Machine • Injection Moulding Machine • Spark Erosion Machine • Lathe HMT NH-22/1500 3

• Lathe HMT NH-26/3000 • Vertical Milling Machine (HMT) - 2 Nos. • Universal Milling Machine (HMT) - 2 Nos. • Cylindrical Grinding Machine • Horizontal Surface Grinding Machine • Tool & Cutter Grinder • Copy Milling Machine • Shaper Machine - 2 Nos. • Band Saw • Power Hacksaw The Tool Room is providing assistance to the industries by way of making: • Forging Dies • Trimming Dies • Blanking Dies • Broaches • Gauges

Heat Treatment Shop The Heat Treatment Shop is equipped with the following indigenous as well as imported machinery/equipment to undertake training and heat treatment of various Hand Tools and other engineering industries. • Induction Heater (High Frequency), 60 KW • Induction Heater (High Frequency), 20 KW • Salt Bath Furnace (Neutral) • Electric Tempering Furnace - 3 Nos. • High Speed Steel Electrode Type Salt Bath Furnace • Hydraulic Straightening Press • Gas Carburizing Furnace The department is also providing assistance by way of doing quality Heat Treatment on: • Blanking Dies • Trimming Dies • Hand Tools • Gears for Automobiles etc. •

Mild Steel 4

Forge Shop The Forge Shop is equipped with the following hammers and presses to provide technical training and common facilities services to the industries: • Forging Press, Capacity 600 Ton (Imported) • Belt Drop Hammer, Capacity - 2 Ton • Belt Drop Hammer, Capacity - 1 Ton • Power Press, Capacity 120 Ton (Italy) • Power Press, Capacity 100 Ton • Power Press, Capacity 50 Ton • Power Press, Capacity 200 Ton • Billet Shearing Machine, Capacity 100 MM • Oil Fired Furnaces - 2 Nos. • Induction Heater 125 KW This department is providing common facility services by way of forging following Hand Tools: • Claw Hammer • Open End Spanner • Brick Blaster • Masson Hammer • Pipe Wrench • Bearing Puller • Ring Spanner • Pipe Fittings

TESTING AND QUALITY CONTROL This department is providing assistance to the industry by way of testing various materials i.e. chemical composition, physical properties etc. The section is also carrying out the inspection of various screw gauges and measuring instruments. Testing & Quality Control Section has the following main equipments: • Equipment for chemical testing for iron, steel brass and bronze etc. • Salt spray test apparatus • Bursting Strength Testing Machine • Dead Weight Pressure Gauge Tester 5

• Metallurgical Micro-scope for Testing Micro Structure • Ultrasonic Flaw Detector • Proving rings for calibration of Universal Testing Machines • Universal Testing Machine • Torque Testing Equipment and Hand Load Testing Fixture • Vickers / Rockwell Hardness Tester • Tool Makers Micro-scope • PVC Insulation Testing Equipment • Monometer Thickness Gauge • B.N.F. Jet Test Apparatus • Multi Product Calibrator • Profile Projector • Slip Gauge Comparator • Screw Thread Measuring Machine • Spectrometer for Analysis of Metals This section is providing assistance to the industry by way of testing various materials i.e.: • Chemical Composition • Physical Properties etc. • Inspection of various screw gauges and measuring instrument.

CNC MACHINES(Computer Numeric Control) CNC LATHE:

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CNC lathes are rapidly replacing the older production lathes (multispindle, etc.) due to their ease of setting and operation. They are designed to use modern carbide tooling and fully use modern processes. The part may be designed and the toolpaths and the toolpaths programmed by the CAD/CAM process, and the resulting file ed to the machine, and once set and trialled the machine will continue to turn out parts under the occasional supervision of an operator. The machine is controlled electronically via a computer menu style interface, the program may be modified and displayed at the machine, along with a simulated view of the process. The setter/operator needs a high level of skill to perform the process, however the knowledge base is broader compared to the older production machines where intimate knowledge of each machine was considered essential. These machines are often set and operated by the same person, where the operator will supervise a small number of machines (cell).

Electric discharge machining: 7

Electric discharge machining (EDM), sometimes colloquially also referred to as spark machining, spark eroding, burning, die sinking or wire erosion, is a manufacturing process whereby a desired shape is obtained using electrical discharges (sparks). Material is removed from the workpiece by a series of rapidly recurring current discharges between two electrodes, separated by a dielectric liquid and subject to an electric voltage. One of the electrodes is called the tool-electrode, or simply the ‘tool’ or ‘electrode’, while the other is called the workpiece-electrode, or ‘workpiece’. When the distance between the two electrodes is reduced, the intensity of the electric field in the volume between the electrodes becomes greater than the strength of the dielectric (at least in some point(s)), which breaks, allowing current to flow between the two electrodes. This phenomenon is the same as the breakdown of a capacitor (condenser) (see also breakdown voltage). As a result, material is removed from both the electrodes. Once the current flow stops (or it is stopped - depending on the type of generator), new liquid dielectric is usually conveyed into the inter-electrode volume enabling the solid particles (debris) to be carried away and the insulating proprieties of the dielectric to be restored. Adding new liquid dielectric in the inter-electrode volume is commonly referred to as flushing. Also, after a current flow, a difference of potential between the two electrodes is restored to what it was before the breakdown, so that a new liquid dielectric breakdown can occur. 8

Generalities: Electrical discharge machining is a machining method primarily used for hard metals or those that would be very difficult to machine with traditional techniques. EDM typically works with materials that are electrically conductive, although methods for machining insulating ceramics with EDM have also been proposed. EDM can cut intricate contours or cavities in prehardened steel without the need for heat treatment to soften and re-harden them. This method can be used with any other metal or metal alloy such as titanium, hastelloy, kovar, and inconel. Also, applications of this process to shape polycrystalline diamond tools have been reported. EDM is often included in the ‘non-traditional’ or ‘non-conventional’ group of machining methods together with processes such as electrochemical machining (ECM), water jet cutting (WJ, AWJ), laser cutting and opposite to the ‘conventional’ group (turning, milling, grinding, drilling and any other process whose material removal mechanism is essentially based on mechanical forces).

Applications: Prototype production The EDM process is most widely used by the mould-making tool and die industries, but is becoming a common method of making prototype and production parts, especially in the aerospace, automobile and electronics industries in which production quantities are relatively low. In Sinker EDM, a graphite, copper tungsten or pure copper electrode is machined into the desired (negative) shape and fed into the workpiece on the end of a vertical ram. Coinage die making For the creation of dies for producing jewelry and badges by the coinage (stamping) process, the positive master may be made from sterling silver, since (with appropriate machine settings) the master is significantly eroded and is used only once. The resultant negative die is then hardened and used in a drop hammer to produce stamped flats from cutout sheet blanks of bronze, silver, or low proof gold alloy. For badges these flats may be further shaped to a curved surface by another die. This type of EDM is usually performed submerged in an oil-based dielectric. The finished object may be further refined by hard (glass) or soft (paint) enameling and/or electroplated with pure gold or nickel. Softer materials such as silver may be hand engraved as a refinement.

Advantages and disadvantages: Some of the advantages of EDM include machining of: 9

• Complex shapes that would otherwise be difficult to produce with conventional cutting tools • Extremely hard material to very close tolerances • Very small work pieces where conventional cutting tools may damage the part from excess cutting tool pressure. • There is no direct between tool and work piece. Therefore delicate sections and weak materials can be machined without any distortion. Some of the disadvantages of EDM include: • The slow rate of material removal. • The additional time and cost used for creating electrodes for ram/sinker EDM. • Reproducing sharp corners on the workpiece is difficult due to electrode wear. • Specific power consumption is very high

WIRE EDM:

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In wire electrical discharge machining (WEDM), also known as wire-cut EDM and wire cutting, a thin single-strand metal wire, usually brass, is fed through the workpiece, submerged in a tank of dielectric fluid, typically deionized water.[20] Wire-cut EDM is typically used to cut plates as thick as 300mm and to make punches, tools, and dies from hard metals that are difficult to machine with other methods. The wire, which is constantly fed from a spool, is held between upper and lower diamond guides. The guides, usually CNC-controlled, move in the x–y plane. On most machines, the upper guide can also move independently in the z–u–v axis, giving rise to the ability to cut tapered and transitioning shapes (circle on the bottom square at the top for example). The upper guide can control axis movements in x–y–u–v–i–j–k–l–. This allows the wire-cut EDM to be programmed to cut very intricate and delicate shapes. The upper and lower diamond guides are usually accurate to 0.004 mm, and can have a cutting path or kerf as small as 0.12 mm using Ø 0.1 mm wire, though the average cutting kerf that achieves the best economic cost and machining time is 0.335 mm using Ø 0.25 brass wire. The reason that the cutting width is greater than the width of the wire is because sparking occurs 11

from the sides of the wire to the work piece, causing erosion. This "overcut" is necessary, for many applications it is adequately predictable and therefore can be compensated for (for instance in micro-EDM this is not often the case). Spools of wire are long—an 8 kg spool of 0.25 mm wire is just over 19 kilometers in length. Wire diameter can be as small as 20 micrometres and the geometry precision is not far from +/- 1 micrometre. The wire-cut process uses water as its dielectric fluid, controlling its resistivity and other electrical properties with filters and de-ionizer units. The water flushes the cut debris away from the cutting zone. Flushing is an important factor in determining the maximum feed rate for a given material thickness. Along with tighter tolerances, multiaxis EDM wire-cutting machining center have added features such as multiheads for cutting two parts at the same time, controls for preventing wire breakage, automatic self-threading features in case of wire breakage, and programmable machining strategies to optimize the operation. Wire-cutting EDM is commonly used when low residual stresses are desired, because it does not require high cutting forces for removal of material. If the energy/power per pulse is relatively low (as in finishing operations), little change in the mechanical properties of a material is expected due to these low residual stresses, although material that hasn't been stress-relieved can distort in the machining process. The workpiece may undergo a significant thermal cycle, its severity depending on the technological parameters used. Such thermal cycles may cause formation of a recast layer on the part and residual tensile stresses on the workpiece.

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FORGING PROCESS:

Forging is one of the oldest known metalworking processes.[1] Traditionally, forging was performed by a smith using hammer and anvil, and though the use of water power in the production and working of iron dates to the 12th century, the hammer and anvil are not obsolete. The smithy or forge has evolved over centuries to become a facility with engineered processes, production equipment, tooling, raw materials and products to meet the demands of modern industry. In modern times, industrial forging is done either with presses or with hammers powered by compressed air, electricity, hydraulics or steam. These hammers may have reciprocating weights in the thousands of pounds. Smaller power hammers, 500 lb (230 kg) or less reciprocating weight, and hydraulic presses are common in art smithies as well. Some steam hammers remain in use, but they became obsolete with the availability of the other, more convenient, power sources. 13

Advantages and disadvantages: Forging can produce a piece that is stronger than an equivalent cast or machined part. As the metal is shaped during the forging process, its internal grain deforms to follow the general shape of the part. As a result, the grain is continuous throughout the part, giving rise to a piece with improved strength characteristics. Some metals may be forged cold, however iron and steel are almost always hot forged. Hot forging prevents the work hardening that would result from cold forming, which would increase the difficulty of performing secondary machining operations on the piece. Also, while work hardening may be desirable in some circumstances, other methods of hardening the piece, such as heat treating, are generally more economical and more controllable. Alloys that are amenable to precipitation hardening, such as most aluminium alloys and titanium, can be hot forged, followed by hardening. Production forging involves significant capital expenditure for machinery, tooling, facilities and personnel. In the case of hot forging, a high temperature furnace (sometimes referred to as the forge) will be required to heat ingots or billets. Owing to the massiveness of large forging hammers and presses and the parts they can produce, as well as the dangers inherent in working with hot metal, a special building is frequently required to house the operation. In the case of drop forging operations, provisions must be made to absorb the shock and vibration generated by the hammer. Most forging operations will require the use of metal-forming dies, which must be precisely machined and carefully heat treated to correctly shape the workpiece, as well as to withstand the tremendous forces involved.

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Processes:

A cross-section of a forged connecting rod that has been etched to show the grain flow. There are many different kinds of forging processes available, however they can be grouped into three main classes: Drawn out: length increases, cross-section decreases Upset: Length decreases, cross-section increases Squeezed in closed compression dies: produces multidirectional flow Common forging processes include: roll forging, swaging, cogging, open-die forging, impression-die forging, press forging, automatic hot forging and upsetting.[1] 15

Temperature: Hot working and Cold working

All of the following forging processes can be performed at various temperatures, however they are generally classified by whether the metal temperature is above or below the recrystallization temperature. If the temperature is above the material's recrystallization temperature it is deemed hot forging; if the temperature is below the material's recrystallization temperature but above 3/10ths of the recrystallization temperature (on an absolute scale) it is deemed warm forging; if below 3/10ths of the recrystallization temperature (usually room temperature) then it is deemed cold forging. The main advantage of hot forging is that as the metal is deformed work hardening effects are negated by the recrystallization process. Cold forging typically results in work hardening of the piece.

Drop forging: There are two types of drop forging: open-die drop forging and closed-die drop forging. As the names imply, the difference is in the shape of the die, with the former not fully enclosing the workpiece, while the latter does. The similarity between the two is that a hammer is raised up and then dropped onto the workpiece to deform it according to the shape of the die.

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Open-die drop forging: Open-die forging is also known as smith forging. In open-die forging, a hammer strikes and deforms the workpiece, which is placed on a stationary anvil. Open-die forging gets its name from the fact that the dies (the surfaces that are in with the workpiece) do not enclose the workpiece, allowing it to flow except where ed by the dies. Therefore the operator needs to orient and position the workpiece to get the desired shape. The dies are usually flat in shape, but some have a specially shaped surface for specialized operations. For example, a die may have a round, concave, or convex surface or be a tool to form holes or be a cut-off tool. Open-die forging lends itself to short runs and is appropriate for art smithing and custom work. In some cases, open-die forging may be employed to roughshape ingots to prepare them for subsequent operations. Open-die forging may also orient the grain to increase strength in the required direction. Cogging is successive deformation of a bar along its length using an open-die drop forge. It is commonly used to work a piece of raw material to the proper thickness. Once the proper thickness is achieved the proper width is achieved via edging. Edging is the process of concentrating material using an concave shaped open die. The process is called edging, because it is usually carried out on the ends of the workpiece. Fullering is a similar process that thins out sections of the 17

forging using a convex shaped die. These processes prepare the workpieces for further forging processes.

Edging

Fullering

Impression-die drop forging: Impression-die forging is also called closed-die forging. In impression-die work metal is placed in a die resembling a mold, which is attached to the anvil. Usually the hammer die is shaped as well. The hammer is then dropped on the workpiece, causing the metal to flow and fill the die cavities. The hammer is generally in with the workpiece on the scale of milliseconds. Depending on the size and complexity of the part the hammer may be dropped multiple times in quick succession. Excess metal is squeezed out of the die cavities, forming what is referred to as flash. The flash cools more rapidly than the rest of the material; this cool metal is stronger than the metal in the die so it helps prevent more flash from forming. This also forces the metal to completely fill the die cavity. After forging the flash is removed. In commercial impression-die forging the workpiece is usually moved through a series of cavities in a die to get from an ingot to the final form. The first impression is used to distribute the metal into the rough shape in accordance to the needs of later cavities; this impression is called an edging, fullering, or bending impression. The following cavities are called blocking cavities, in which the piece is working into a shape that more closely resembles the final product. These stages usually impart the workpiece with generous bends and 18

large fillets. The final shape is forged in a final or finisher impression cavity. If there is only a short run of parts to be done it may be more economical for the die to lack a final impression cavity and instead machine the final features.[2] Impression-die forging has been further improved in recent years through increased automation which includes induction heating, mechanical feeding, positioning and manipulation, and the direct heat treatment of parts after forging. One variation of impression-die forging is called flashless forging, or true closed-die forging. In this type of forging the die cavities are completely closed, which keeps the workpiece from forming flash. The major advantage to this process is that less metal is lost to flash. Flash can for 20 to 45% of the starting material. The disadvantages of this process include additional cost due to a more complex die design and the need for better lubrication and workpiece placement. There are other variations of part formation that integrate impression-die forging. One method incorporates casting a forging preform from liquid metal. The casting is removed after it has solidified, but while still hot. It is then finished in a single cavity die. The flash is trimmed, then the part is quench hardened. Another variation follows the same process as outlined above, except the preform is produced by the spraying deposition of metal droplet into shaped collectors (similar to the Osprey process). Closed-die forging has a high initial cost due to the creation of dies and required design work to make working die cavities. However, it has low recurring costs for each part, thus forgings become more economical with more volume. This is one of the major reasons closed-die forgings are often used in the automotive and tool industry. Another reason forgings are common in these industrial sectors is because forgings generally have about a 20 percent higher strength-to-weight ratio compared to cast or machined parts of the same material.

Design of impression-die forgings and tooling Forging dies are usually made of high-alloy or tool steel. Dies must be impact resistant, wear resistant, maintain strength at high temperatures, and have the ability to withstand cycles of rapid heating and cooling. In order to produce a better, more economical die the following rules should be followed:

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 The dies should part along a single, flat plane if at all possible. If not the parting plan should follow the contour of the part.  The parting surface should be a plane through the center of the forging and not near an upper or lower edge.  Adequate draft should be provided; a good guideline is at least 3° for aluminum and 5° to 7° for steel  Generous fillets and radii should be used  Ribs should be low and wide  The various sections should be balanced to avoid extreme difference in metal flow  Full advantage should be taken of fiber flow lines  Dimensional tolerances should not be closer than necessary 1. 2. The dimensional tolerances of a steel part produced using the impression-die forging method are outlined in the table below. It should be noted that the dimensions across the paring plane are affected by the closure of the dies, and are therefore dependent die wear and the thickness of the final flash. Dimensions that are completely contained within a single die segment or half can be maintained at a significantly greater level of accuracy. Dimensional tolerances for impression-die forgings Mass [kg (lb)] Minus tolerance [mm (in)] Plus tolerance [mm (in)] 0.45 (1)

0.15 (0.006)

0.48 (0.018)

0.91 (2)

0.20 (0.008)

0.61 (0.024)

2.27 (5)

0.25 (0.010)

0.76 (0.030)

4.54 (10)

0.28 (0.011)

0.84 (0.033)

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9.07 (20)

0.33 (0.013)

0.99 (0.039)

22.68 (50)

0.48 (0.019)

1.45 (0.057)

45.36 (100)

0.74 (0.029)

2.21 (0.087)

A lubricant is always used when forging to reduce friction and wear. It is also used to as a thermal barrier to restrict heat transfer from the workpiece to the die. Finally, the lubricant acts as a parting compound to prevent the part from sticking in one of the dies.

Press forging: Press forging works slowly by applying continuous pressure or force, which differs from the near-instantaneous impact of drop-hammer forging. The amount of time the dies are in with the workpiece is measured in seconds (as compared to the milliseconds of drop-hammer forges). The press forging operation can be done either cold or hot.

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The main advantage of press forging, as compared to drop-hammer forging, is its ability to deform the complete workpiece. Drop-hammer forging usually only deforms the surfaces of the workpiece in with the hammer and anvil; the interior of the workpiece will stay relatively undeformed. Another advantage to the process includes the knowledge of the new parts strain rate. We specifically know what kind of strain can be put on the part, because the compression rate of the press forging operation is controlled. There are a few disadvantages to this process, most stemming from the workpiece being in with the dies for such an extended period of time. The operation is a time consuming process due to the amount of steps and how long each of them take. The workpiece will cool faster because the dies are in with workpiece; the dies facilitate drastically more heat transfer than the surrounding atmosphere. As the workpiece cools it becomes stronger and less ductile, which may induce cracking if deformation continues. Therefore heated dies are usually used to reduce heat loss, promote surface flow, and enable the production of finer details and closer tolerances. The workpiece may also need 22

to be reheated. When done in high productivity, press forging is more economical than hammer forging. The operation also creates closer tolerances. In hammer forging a lot of the work is absorbed by the machinery, when in press forging, the greater percentage of work is used in the work piece. Another advantage is that the operation can be used to create any size part because there is no limit to the size of the press forging machine. New press forging techniques have been able to create a higher degree of mechanical and orientation integrity. By the constraint of oxidation to the outer most layers of the part material, reduced levels of microcracking take place in the finished part. Press forging can be used to perform all types of forging, including open-die and impression-die forging. Impression-die press forging usually requires less draft than drop forging and has better dimensional accuracy. Also, press forgings can often be done in one closing of the dies, allowing for easy automation.

Upset forging: Upset forging increases the diameter of the workpiece by compressing its length.[11] Based on number of pieces produced this is the most widely used forging process.[11] A few examples of common parts produced using the upset forging process are engine valves, couplings, bolts, screws, and other fasteners. Upset forging is usually done in special high speed machines called crank presses, but upsetting can also be done in a vertical crank press or a hydraulic press. The machines are usually set up to work in the horizontal plane, to facilitate the quick exchange of workpieces from one station to the next. The initial workpiece is usually wire or rod, but some machines can accept bars up to 25 cm (9.8 in) in diameter and a capacity of over 1000 tons. The standard upsetting machine employs split dies that contain multiple cavities. The dies open enough to allow the workpiece to move from one cavity to the next; the dies then close and the heading tool, or ram, then moves longitudinally against the bar, upsetting it into the cavity. If all of the cavities are utilized on every cycle then a finished part will be produced with every cycle, which is why this process is ideal for mass production.

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The following three rules must be followed when deg parts to be upset forged: The length of uned metal that can be upset in one blow without injurious buckling should be limited to three times the diameter of the bar. Lengths of stock greater than three times the diameter may be upset successfully provided that the diameter of the upset is not more than 1.5 times the diameter of the stock. In an upset requiring stock length greater than three times the diameter of the stock, and where the diameter of the cavity is not more than 1.5 times the diameter of the stock, the length of uned metal beyond the face of the die must not exceed the diameter of the bar.

Automatic hot forging: The automatic hot forging process involves feeding mill-length steel bars (typically 7 m (23 ft) long) into one end of the machine at room temperature and hot forged products emerge from the other end. This all occurs very quickly; small parts can be made at a rate of 180 parts per minute (ppm) and larger can be made at a rate of 90 ppm. The parts can be solid or hollow, round or symmetrical, up to 6 kg (13 lb), and up to 18 cm (7.1 in) in diameter. The main advantages to this process are its high output rate and ability to accept low cost materials. Little labor is required to operate the machinery. There is no flash produced so material savings are between 20 and 30% over conventional forging. The final product is a consistent 1,050 °C (1,920 °F) so air cooling will result in a part that is still easily machinable (the advantage being the lack of annealing required after forging). Tolerances are usually ±0.3 mm (0.012 in), surfaces are clean, and draft angles are 0.5 to 1°. Tool life is nearly double that of conventional forging because times are on the order of 6/100 of a second. The downside to the process is it only feasible on smaller symmetric parts and cost; the initial investment can be over $10 million, so large quantities are required to justify this process. The process starts by heating up the bar to 1,200 to 1,300 °C (2,192 to 2,372 °F) in less than 60 seconds using high power induction coils. It is then descaled with rollers, sheared into blanks, and transferred several successive forming stages, during which it is upset, preformed, final forged, and pierced 24

(if necessary). This process can also be couple with high speed cold forming operations. Generally, the cold forming operation will do the finishing stage so that the advantages of cold-working can be obtained, while maintaining the high speed of automatic hot forging. Examples of parts made by this process are: wheel hub unit bearings, transmission gears, tapered roller bearing races, stainless steel coupling flanges, and neck rings for LP gas cylinders. Manual transmission gears are an example of automatic hot forging used in conjunction with cold working.

Roll forging: Roll forging is a process where round or flat bar stock is reduced in thickness and increased in length. Roll forging is performed using two cylindrical or semi-cylindrical rolls, each containing one or more shaped grooves. A heated bar is inserted into the rolls and when it hits a stop the rolls rotate and the bar is progressively shaped as it is rolled out of the machine. The work piece is then transferred to the next set of grooves or turned around and reinserted into the same grooves. This continues until the desired shape and size is achieved. The advantage of this process is there is no flash and it imparts a favorable grain structure into the workpiece. Examples of products produced using this method include axles, tapered levers and leaf springs.

Net-shape and near-net-shape forging: This process is also known as precision forging. This process was developed to minimize cost and waste associated with post forging operations. Therefore, the final product from a precision forging needs little to no final machining. Cost savings are gained from the use of less material, and thus less scrap, the overall decrease in energy used, and the reduction or elimination of machining. Precision forging also requires less of a draft, 1° to 0°. The downside of this process is its cost, therefore it is only implemented if significant cost reduction can be achieved.

Cost implications: 25

To achieve a low cost net shape forging for demanding applications that are subject to a high degree of scrutiny, i.e. non-destructive testing by way of a diepenetrant inspection technique, it is crucial that basic forging process disciplines are implemented. If the basic disciplines are not met, there is a high probability that subsequent material removal operations will be necessary to remove material defects found at non-destructive testing inspection. Hence low cost parts will not be achievable.

Example disciplines are: die-lubricant management (Use of uncontaminated and homogeneous mixtures, amount and placement of lubricant). Tight control of die temperatures and surface finish / friction.

Induction forging: Unlike the above processes, induction forging is based on the type of heating style used. Many of the above processes can be used in conjunction with this heating method.

Equipment

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Hydraulic drop-hammer

(a) Material flow of a conventionally forged disc; (b) Material flow of an impactor forged disc. The most common type of forging equipment is the hammer and anvil. Principles behind the hammer and anvil are still used today in drop-hammer 27

equipment. The principle behind the machine is very simple—raise the hammer and then drop it or propel it into the workpiece, which rests on the anvil. The main variations between drop-hammers are in the way the hammer is powered; the most common being air and steam hammers. Drop-hammers usually operate in a vertical position. The main reason for this is excess energy (energy that isn't used to deform the workpiece) that isn't released as heat or sound needs to be transmitted to the foundation. Moreover, a large machine base is needed to absorb the impacts. To overcome some of the shortcomings of the drop-hammer, the counterblow machine or impactor is used. In a counterblow machine both the hammer and anvil move and the workpiece is held between them. Here excess energy becomes recoil. This allows the machine to work horizontally and consist of a smaller base. Other advantages include less noise, heat and vibration. It also produces a distinctly different flow pattern. Both of these machines can be used for open die or closed die forging. A forging press, often just called a press, is used for press forging. There are two main types: mechanical and hydraulic presses. Mechanical presses function by using cams, cranks and/or toggles to produce a preset (a predetermined force at a certain location in the stroke) and reproducible stroke. Due to the nature of this type of system, different forces are available at different stroke positions. Mechanical presses are faster than their hydraulic counterparts (up to 50 strokes per minute). Their capacities range from 3 to 160 MN (300 to 18,000 short tons-force). Hydraulic presses use fluid pressure and a piston to generate force. The advantages of a hydraulic press over a mechanical press are its flexibility and greater capacity. The disadvantages include a slower, larger, and costlier machine to operate. The roll forging, upsetting, and automatic hot forging processes all use specialized machinery. Scrap:Scrap is the material which is formed after forging as shown in fig.. In case of impression die forging flashes are produced and these flashes are removed by punching or mechanical press. And these removed material referred to as a scrap. We can melt this scrap for forming ingots by continuous casting process. And we can avoid the wastage of material. 28

Dies: Dies is used in forging as shown in fig. Die material is made very hard which can’t be deforming easily. So we can make dies of different shapes according to product which we want to manufacture. The shape of die is made in process of forging wise. i.e, 1. 2. 3. 4. 5.

Fullering Edging] Bending Blocking Finishing

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Heat treatment: 30

Heat treatment is a method used to alter the physical, and sometimes chemical properties of a material. The most common application is metallurgical. Heat treatments are also used in the manufacture of many other materials, such as glass. Heat treatment involves the use of heating or chilling, normally to extreme temperatures, to achieve a desired result such as hardening or softening of a material. Heat treatment techniques include annealing, case hardening, precipitation strengthening, tempering and quenching. It is noteworthy that while the term heat treatment applies only to processes where the heating and cooling are done for the specific purpose of altering properties intentionally, heating and cooling often occur incidentally during other manufacturing processes such as hot forming or welding.

Processes: Metallic materials consist of a microstructure of small crystals called "grains" or crystallites. The nature of the grains (i.e. grain size and composition) is one of the most effective factors that can determine the overall mechanical behavior of the metal. Heat treatment provides an efficient way to manipulate the properties of the metal by controlling rate of diffusion, and the rate of cooling within the microstructure. 31

Complex heat treating schedules are often devised by metallurgists to optimize an alloy's mechanical properties. In the aerospace industry, a superalloy may undergo five or more different heat treating operations to develop the desired properties. This can lead to quality problems depending on the accuracy of the furnace's temperature controls and timer.

ANNEALING: Annealing is a technique used to recover cold work and relax stresses within a metal. Annealing typically results in a soft, ductile metal. When an annealed part is allowed to cool in the furnace, it is called a full anneal heat treatment. When an annealed part is removed from the furnace and allowed to cool in air, it is called a normalizing heat treatment. A stress relief annealing is when only the first stage of annealing is performed. The second stage of annealing is recrystallization, where new stress-free grains grow. The third stage is grain growth, which causes the existing grains to grow.

Hardening and tempering (quenching and tempering): To harden by quenching, a metal (usually steel or cast iron) must be heated into the austenitic crystal phase and then quickly cooled. Depending on the alloy and other considerations (such as concern for maximum hardness vs. cracking and distortion), cooling may be done with forced air or other gas (such as nitrogen), oil, polymer dissolved in water, or brine. Upon being rapidly cooled, a portion of austenite (dependent on alloy composition) will transform to martensite, a hard, brittle crystalline structure. The quenched hardness of a metal depends on its chemical composition and quenching method. Cooling speeds, from fastest to slowest, go from polymer (i.e.silicon), brine, fresh water, oil, and forced air. However, quenching a certain steel too fast can result in cracking, which is why high-tensile steels such as AISI 4140 should be quenched in oil, tool steels such as 2767 or H13 hot work tool steel should be quenched in forced air, and low alloy or medium-tensile steels such as XK1320 or AISI 1040 should be quenched in brine or water. However, metals such as austenitic stainless steel (304, 316), and copper, produce an opposite effect when these are quenched: they anneal. Austenitic stainless steels must be quench-annealed to become fully corrosion resistant, as they work-harden significantly.

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Untempered martensite, while very hard, is too brittle to be useful for most applications. A method for alleviating this problem is called tempering. Most applications require that quenched parts be tempered (heat treated at a low temperature, often 300 F or 150 C) to impart some toughness. Higher tempering temperatures (may be up to 1300 F or 700 C, depending on alloy and application) are sometimes used to impart further ductility, although some yield strength is lost.

Precipitation hardening: Some metals are classified as precipitation hardening metals. When a precipitation hardening alloy is quenched, its alloying elements will be trapped in solution, resulting in a soft metal. Aging a "solutionized" metal will allow the alloying elements to diffuse through the microstructure and form intermetallic particles. These intermetallic particles will nucleate and fall out of solution and act as a reinforcing phase, thereby increasing the strength of the alloy. Alloys may age "naturally" meaning that the precipitates form at room temperature, or they may age "artificially" when precipitates only form at elevated temperatures. In some applications, naturally aging alloys may be stored in a freezer to prevent hardening until after further operations - assembly of rivets, for example, may be easier with a softer part. Examples of precipitation hardening alloys include 2000 series, 6000 series, and 7000 series aluminium alloy, as well as some superalloys and some stainless steels.

Selective hardening: Some techniques allow different areas of a single object to receive different heat treatments. This is called differential hardening. It is common in high quality knives and swords. The Chinese jian is one of the earliest known examples of this, and the Japanese katana the most widely known. The Nepalese Khukuri is another example.

Case hardening: Case hardening is a process in which an alloying element, most commonly carbon or nitrogen, diffuses into the surface of a monolithic metal. The resulting interstitial solid solution is harder than the base material, which improves wear resistance without sacrificing toughness.

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Laser surface engineering is a surface treatment with high versatility, selectivity and novel properties. Since the cooling rate is very high in laser treatment, metastable even metallic glass can be obtained by this method.

CONVENTIONAL MACHINES: Lathe machine:

A lathe (pronounced /ˈleɪð/ is a machine tool which spins the workpiece to perform various operations such as cutting, sanding, knurling, drilling, or deformation with tools that are applied to the workpiece to create an object which has symmetry about an axis of rotation. Lathes are used in woodturning, metalworking, metal spinning, and glassworking. Lathes can be used to shape pottery, the best-known design being the potter's wheel. Most suitably equipped metalworking lathes can also be used to produce most solids of revolution, plane surfaces and screw threads or helices. Ornamental lathes can produce three-dimensional solids of incredible complexity. The material can be held in place by either one or two centers, at least one of which can be moved horizontally to accommodate varying material lengths. Other workholding methods include clamping the work about the axis of rotation using a chuck or collet, or to a faceplate, using clamps or dogs.

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Examples of objects that can be produced on a lathe include candlestick holders, cue sticks, table legs, bowls, baseball bats, musical instruments (especially woodwind instruments), crankshafts and camshafts.

Modes of use: When a workpiece is fixed between the headstock and the tailstock, it is said to be "between centers". When a workpiece is ed at both ends, it is more stable, and more force may be applied to the workpiece, via tools, at a right angle to the axis of rotation, without fear that the workpiece may break loose. When a workpiece is fixed only to the spindle at the headstock end, the work is said to be "face work". When a workpiece is ed in this manner, less force may be applied to the workpiece, via tools, at a right angle to the axis of rotation, lest the workpiece rip free. Thus, most work must be done axially, towards the headstock, or at right angles, but gently. When a workpiece is mounted with a certain axis of rotation, worked, then remounted with a new axis of rotation, this is referred to as "eccentric turning" or "multi axis turning". The result is that various cross sections of the workpiece are rotationally symmetric, but the workpiece as a whole is not rotationally symmetric. This technique is used for camshafts, various types of chair legs.

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Examples of work produced from a lathe:

Drilling machine: Drilling is a cutting process that uses a drill bit to cut or enlarge a hole in solid materials. The drill bit is a multipoint, end cutting tool. It cuts by applying pressure and rotation to the workpiece, which forms chips at the cutting edge.

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Process: Drilled holes are characterized by their sharp edge on the entrance side and the presence of burrs on the exit side (unless they have been removed). Also, the inside of the hole usually has helical feed marks. Drilling may affect the mechanical properties of the workpiece by creating low residual stresses around the hole opening and a very thin layer of highly stressed and disturbed material on the newly formed surface. This causes the workpiece to become more susceptible to corrosion at the stressed surface. For fluted drill bits, any chips are removed via the flutes. Chips may be long spirals or small flakes, depending on the material, and process parameters.[1] The type of chips formed can be an indicator of the machinability of the material, with long gummy chips reducing machinability. When possible drilled holes should be located perpendicular to the workpiece surface. This minimizes the drill bit's tendency to "walk", that is, to be deflected, which causes the hole to be misplaced. The higher the length-todiameter ratio of the drill bit, the higher the tendency to walk. The tendency to walk is also preempted in various other ways, which include:

Milling machine: 37

A milling machine (also see synonyms below) is a machine tool used to machine solid materials. Milling machines are often classed in two basic forms, horizontal and vertical, which refers to the orientation of the main spindle. Both types range in size from small, bench-mounted devices to room-sized machines. Unlike a drill press, which holds the workpiece stationary as the drill moves axially to penetrate the material, milling machines also move the workpiece radially against the rotating milling cutter, which cuts on its sides as well as its tip. Workpiece and cutter movement are precisely controlled to less than 0.001 in (0.025 mm), usually by means of precision ground slides and leadscrews or analogous technology. Milling machines may be manually operated, mechanically automated, or digitally automated via computer numerical control (CNC).

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Milling machines can perform a vast number of operations, from simple (e.g., slot and keyway cutting, planing, drilling) to complex (e.g., contouring, diesinking). Cutting fluid is often pumped to the cutting site to cool and lubricate the cut and to wash away the resulting swarf.

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