METAL FORMING PROCESS�ME 1107

RAJU AHAMMAD

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LECTURER

DEPARTMENT OF MECHANICAL ENGINEERING KHULNA UNIVERSITY OF ENGINEERING & TECHNOLOGY

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Metal Forming Process

• Forming means changing the shape of an existing solid body. It includes a large group of manufacturing processes in which plastic deformation is used to change the shape of metal work-pieces.

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• Plasticity is the ability of a material to flow as a solid without deterioration of properties.

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• Deformation results from the use of a tool, usually a die in metal forming, which applies stresses that exceed the yield strength of the metal.

• Metal forming or metal working is the shaping of metals in either a cold or hot state by some mechanical means and does not include the shaping of metal by machining, casting or grinding.

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• Metalworking is the process of working with metals to create individual parts, assemblies, or large scale structures.

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• The term covers a wide range of work from large ships and bridges to precise engine parts and delicate jewellery.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Metal Forming Process

Purposes:

1. To reduce the original block or ingot to the finished dimensions of the part, thereby saving material machining costs and time.

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• To improve the mechanical properties of the metal through –
• Refinement of grain structure
• Directional control of ‘flow lines’
• Break up and distribution of unavoidable inclusions.

• Ductility is the property of a material enabling it to be drawn into wire with the application of tensile force.

• Malleability is the ability of the material to be flattened into thin sheets without cracking by hot or cold working.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

RECRYSTALISATION

• During the process of plastic deformation in metal forming, the plastic flow of the metal takes place and the shapes of the grains are changed.
• If the plastic deformation is carried out at higher temperatures, new grains start growing at the location of internal stresses caused in the metal. If the temperature is sufficiently high, the growth of new grains is accelerated and continuous till the metal comprises fully of only the new grains.

• This process of formation of new grains is known as recrystallisation and is said to be complete when the metal structure consists of entirely new grains. That temperature at which recrystalisation is completed is known as the recrystallisation temperature of the metal.

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• It is this point, which draws the line of difference between cold working and hot working processes.

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• Mechanical working of a metal below its recrystalisation temperature is called as cold working and that accomplished above this temperature but below the melting or burning point is known as hot working.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

RECRYSTALISATION

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Metal Forming Process

Classification:

There are two types of metal forming process-

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1. Hot working: Working above recrystallization temperature.

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• Cold working: Working below recrystallization temperature.

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Recrystallization temperature is the temperature at which metals reach into plastic state. It is also called lower critical temperature of metal.

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The major difference of these two is that residual stresses are produced in cold working but not in hot working

• Residual stresses are those stresses that remain in an object (in particular, in a welded component) even in the absence of external loading or thermal gradients. In some cases, residual stresses result in significant plastic deformation, leading to warping and distortion of an object.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Hot Working Process

• Mechanical working processes which are done above recrystallisation temperature of the metal are know as hot working processes.
• In hot working, the temperature of completion of metal working is important since any extra heat left after working aid in grain growth. This increase in size of the grains occurs by a process of coalescence of adjoining grains and is a function of time and temperature. Grain growth results in poor mechanical properties. If the hot working is completed just above the recrystallisation temperature then the resultant grain size would be fine.

Advantages:

1. Refinement of grain
2. Porosity of the steel ingot can be eliminated
3. Great latitude in shape and size of form is possible due to reduction of elastic limit
4. Uniformity is established (impurity)
5. Mechanical properties improved
6. Power required is less
7. Rapid and economical process

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Metal Forming Process

• Due to high temperature in hot working, rapid oxidation or scale formation and surface de-carburization take place on the metal surface leading to poor surface finish and loss of metal.
• On account of the loss of carbon from the surface of the steel piece being worked the surface layer loses its strength. This is a major disadvantage when the part is put to service.
• The weakening of the surface layer may give rise to a fatigue crack which may ultimately result in fatigue failure of the component.
• Some metals cannot be hot worked because of their brittleness at high temperatures.
• Because of the thermal expansion of metals, the dimensional accuracy in hot working is difficult to achieve.
• The process involves excessive expenditure on account of high cost of tooling. This however is compensated by the high production rate and better quality of components.
• Handling and maintaining of hot working setups is difficult and troublesome.

Limitations :

Hot working processes:

1. Rolling 2. Forging 3. Extrusion

4. Piercing 5. Drawing 6. Spinning

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

1. Hot Rolling

• In metalworking, rolling is a metal forming process in which metal stock is passed through a pair of rolls.

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Hot rolling consists in compressing and lengthening the metal above recrystallization temperature as it is fed between two rolls rotating in opposite direction.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

1. Hot Rolling

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

The machine in which Rolling is done is called rolling mill. There are four types of rolling mills.

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1. Two high mill: The work can be passed back and forth through the rolls by reversing their direction of rotation. A two-high rolling mill has two horizontal rolls revolving at the same speed but in opposite direction.

Non reversing Reversible

1. Hot Rolling

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

1. Hot Rolling

2. Three High mill: It consists of three parallel rolls, arranged one above the other as shown in Fig. The directions of rotation of the upper and lower rolls are the same but the intermediate roll rotates in a direction opposite to both of these.

• This type of rolling mill is used for rolling of two continuous passes in a rolling sequence without reversing the drives. This results in a higher rate of production than the two-high rolling mill.

Less expensive and High output compared to two high reversing mills.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

1. Hot Rolling

3. Four-High Rolling Mill: It is essentially a two-high rolling mill, but with small sized rolls. Practically, it consists of four horizontal rolls, the two middle rolls are smaller in size than the top and bottom rolls as shown in Fig. The smaller size rolls are known as working rolls which concentrate the total rolling pressure over the workpiece. The larger diameter rolls are called back-up rolls and their main function is to prevent the deflection of the smaller rolls, which otherwise would result in thickening of rolled plates or sheets at the centre. The common products of these mills are hot or cold rolled plates and sheets.

• Used for both hot and cold rolling
• Several mills are arranged in series

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

1. Hot Rolling

4. Cluster Rolling Mill: It is a special type of four-high rolling mill in which each of the two smaller working rolls are backed up by two or more of the larger back-up rolls as shown in Fig. For rolling hard thin materials, it may be necessary to employ work rolls of very small diameter but of considerable length. In such cases adequate support of the working rolls can be obtained by using a cluster-mill. This type of mill is generally used for cold rolling work.

It may be necessary to employ work rolls of a very small diameter but of considerable length.

In such cases adequate of the working rolls can be obtained by using a cluster mill.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

1. Hot Rolling

5. Continuous Rolling Mill: It consists of a number of non reversing two-high rolling mills arranged one after the other, so that the material can be passed through all of them in sequence. It is suitable for mass production work only, because for smaller quantities quick changes of set-up will be required and they will consume lot of time and labor.

For large thickness reduction

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

2. Forging

• Forging is the operation where the metal is heated and then a force is applied to manipulate the metals in such a way that the required final shape is obtained. Forging is generally a hot working process though cold forging is used sometimes.

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• Forging is defined as the plastic deformation of metals at elevated temperatures into a predetermined size or shape using compressive forces exerted through some means of hand hammers, small power hammers, die, press or upsetting machine.

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• Hand forging process is also known as black-smithy work which is commonly employed for production of small articles using hammers on heated jobs. It is a manual controlled process even though some machinery such as power hammers can also be sometimes used.

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Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

2. Forging

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

2. Forging

Forging by machine involves the use of forging dies and is generally employed for mass production of accurate articles. In drop forging, closed impression dies are used and there is drastic flow of metal in the dies due to repeated blow or impact which compels the plastic metal to conform to the shape of the dies.

Forging Machine

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

2. Forging

Advantages:

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1. Forging can produce a piece that is stronger than an equivalent cast or machined part
2. After forging the grain is continuous throughout the part, giving rise to a piece with improved strength characteristics
3. Uniform in density and dimension

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Disadvantages:

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1. Initial cost of die and their maintenance is high
2. Oxidation of metal surface at high temperature
3. Limited to simple shapes

Details from Textbooks

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

2. Forging

Forgeability: The ease with which forging is done is called forgeability. The forgeability of a material can also be defined as the capacity of a material to undergo deformation under compression without rupture.

Some forgeable metals are given as under in order of increasing forging difficulty-

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1. Aluminium alloys 2. Magnesium alloys 3. Copper alloys. 4. Carbon and low alloy steels 5. Martensitic stainless steels 6. Austenitic stainless steels 7. Nickel alloys 8. Titanium alloys 9. Columbium alloys 10. Tantalum alloys 11. Molybdenum alloys 12. Tungsten alloys.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

2. Forging

Forging Operations:

1. Drawing down or swaging: It is a operation of spreading or thinning action with the help of flat die. Thickness reduces and length increases.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

2. Forging

2. Upsetting: Increasing of cross sectional area usually by pressing or hammering in a direction parallel to the original ingot.

Heavy hammer Light hammer Local Upset Heating middle portion

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

2. Forging

3. Punching: Process of producing holes generally cylindrical by using a hot punch over a cylindrical die.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

2. Forging

4. Roll forging: Roll forging is a forging operation involving reduction of the work piece diameter (with increase of its length) by rolling it between two grooved rolls rotating at the same rotating direction.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

2. Forging

5. Hollow forging: To decrease the thickness of hollow cylinder and increase its length.

6. Expanding: To decrease the thickness of hollow cylinder and increase its diameter.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

2. Forging

ADVANTAGES OF FORGING IN COMPARASION TO CASTING AND MACHINING

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Because of inherent improvement in the grain size and introduction of un-interrupted grain flow in the structure of finished forged component forging has the following advantages in comparison to casting and machining. Some of such advantages are given as under.

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1. Greater strength and toughness.
2. Reduction in weight of the finished part.
3. Saving in the material.
4. Elimination of internal defects such as cracks, porosity, blowholes, etc.
5. Ability to withstand unpredictable loads during service.
6. (Minimum of machine finish to be carried out on the component especially when it is forged in dies

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

3. Extrusion

• The process of pushing heated billet or slug of metal through an orifice provided into a die, thus forming an elongated part of uniform cross section corresponding to the shape of die orifice.

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The operation is identical to the squeezing of toothpaste out of the toothpaste tube.

Hot extrusion process is classified as-

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1. Direct or forward hot extrusion
2. Indirect or backward hot extrusion
3. Tube extrusion

Explain Extrusion Principle?

Self Study

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

3. Extrusion

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

3. Extrusion

1. Direct or Forward Hot Extrusion: Fig. shows the direct extrusion operational setup. In this method, the heated metal billet is placed in to the die chamber and the pressure is applied through ram. The metal is extruded through die opening in the forward direction, i.e. the same as that of the ram.

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• In forward extrusion, the problem of friction is prevalent because of the relative motion between the heated metal billet and the cylinder walls. To reduce such friction, lubricants are to be commonly used.

At lower temperatures, a mixture of oil and graphite is generally used. The problem of lubrication gets compounded at the higher operating temperatures. Molten glass is generally used for extruding steels.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

3. Extrusion

2. Indirect or Backward Hot Extrusion: Fig. shows the indirect extrusion operational setup. In indirect extrusion, the billet remains stationary while the die moves into the billet by the hollow ram (or punch), through which the backward extrusion takes place.

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• Since, there is no friction force between the billet and the container wall, therefore, less force is required by this method.

However this process is not widely used because of the difficulty occurred in providing support for the extruded part.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

3. Extrusion

3. Tube Extrusion: Fig. shows the tube extrusion operational setup. This process is an extension of direct extrusion process where additional mandrel is needed to restrict flow of metal for production of seamless tubes. Aluminium based toothpaste and medicated tubes are produced using this process.

Mandrel

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

3. Extrusion

Characteristics of Extrusion:

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1. Faster process.

2. Good tolerances.

3. Mechanical properties are superior than rolling.

4. Good surface finish.

5. Complex shape can be made easily.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

4. Piercing

The round billet is gripped by the rolls, which rotate and advance it into the piercer point, which creates a hole through its length. A method of manufacturing a seamless tube.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

5. Drawing

Process of making cup-shaped parts from sheet metal blanks by pulling it into dies with the help of punch.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

6. Hot and cold Spinning

Metal spinning, also known as spin forming or spinning, is a metalworking process by which a disc or tube of metal is rotated at high speed and formed into an axially symmetric part

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

6. Hot and cold Spinning

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Cold Working Processes

• Cold working of a metal is carried out below its recrystallisation temperature. Although normal room temperatures are ordinarily used for cold working of various types of steel, temperatures up to the recrystallisation range are sometimes used. In cold working, recovery processes are not effective.

The common purpose of cold working is given as under –

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1. Cold working is employed to obtain better surface finish on parts.
2. It is commonly applied to obtain increased mechanical properties.
3. It is widely applied as a forming process of making steel products using pressing and spinning.
4. It is used to obtain thinner material.

• Cold working leads to crack formation and propagation if performed in excess and it should therefore be avoided. Residual stresses developed due to inhomogeneous deformation cause warping or distortion when the part is released from the tooling and during subsequent machining. Magnitude and distribution of residual stresses should therefore be controlled.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Cold Working Processes

ADVANTAGES OF COLD WORKING

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1. In cold working processes, smooth surface finish can be easily produced.
2. Accurate dimensions of parts can be maintained.
3. Strength and hardness of the metal are increased but ductility decreased.
4. Since the working is done in cold state, no oxide would form on the surface and consequently good surface finish is obtained.
5. Cold working increases the strength and hardness of the material due to the strain hardening which would be beneficial in some situations.
6. There is no possibility of decarburization of the surface
7. Better dimensional accuracy is achieved.
8. It is far easier to handle cold parts and it is also economical for smaller sizes.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Cold Working Processes

DISADVANTAGES OF COLD WORKING

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1. Some materials, which are brittle, cannot be cold worked easily.
2. Since the material has higher yield strength at lower temperatures, the amount of deformation that can be given to is limited by the capability of the presses or hammers used.
3. A distortion of the grain structure is created.
4. Since the material gets strain hardened, the maximum amount of deformation that can be given is limited. Any further deformation can be given after annealing.
5. Internal stresses are set up which remain in the metal unless they are removed by proper heat-treatment.

LIMITATIONS OF COLD WORKING

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1. The cold worked process possesses less ductility.
2. Imparted directional properties may be detrimental
3. Strain hardening occurs.
4. Metal surfaces must be clean and scale free before cold working.
5. Hot worked metal has to be pickled in acid to remove scale, etc.
6. Higher forces are required for deformation than those in hot working.
7. More powerful and heavier equipments are required for cold working

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Cold Working Processes

Cold working operations are-

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1. Shearing: Cutting of sheet metal by shearing forces. Such as: (i) Piercing (ii) Blanking (iii) Cutting (iv) Parting (v) Punching (vi) Notching (vii) Slitting (viii) Nibbling (ix) Lancing (x) Trimming
2. Drawing: Making different shape by bending and stretching with the application of Die and Punch.
3. Squeezing: Forming or creating impression on metal by squeezing.
4. Bending: Bending of sheet metal into different angles.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Shearing

1. Blanking:
1. Blanking is the operation of cutting a flat shape from sheet metal.
2. The product punched out is called the “blank” and the required product of the operation the hole and the metal left behind is discarded as waste.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

2. Punching: It is a cutting operation by which various shaped holes are made in sheet metal. Punching is similar to blanking except that in punching, the hole is the desired product. The material punched out from the hole being waste.

Shearing

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Shearing

For Blanking:

Die size = Blank size

Punch size = Blank size – 2C

For Punching:

Die size = Blank size + 2C

Punch size = Blank size

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Shearing

Determine the die and punch sizes for blanking a circular disc of 20 mm diameter from a C20 steel (shear strength = 294 MPa) sheet whose thickness is 1.5 mm.

C = 0.10 mm

For Blanking:

Die size = Blank size = 20 mm

Punch size = Blank size – 2C = 19.8 mm

For Punching:

Die size = Blank size + 2C = 20.2 mm

Punch size = Blank size = 20 mm

P = 27.709kN

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Shearing

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Shearing

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Shearing

3. Perforating: This is a process by which multiple holes are very small and close together are cut in a flat sheet metal.

4. Trimming: This operation consists of cutting unwanted excess of material from the periphery of a previously formed component.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Shearing

5. Lancing: This is a cutting operation in which a hole is partially cut and then one side is bent down to form a sort of tab. Since no metal is actually removed and there will be no scrap.

6. Notching: This is cutting operation by which metal pieces are cut from the edge of the sheet , strip or blank.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Shearing

7. Slitting: It refers to the operation of making incomplete holes in a work piece that is a straight line cut.

8. Nibbling: Punching a series of small overlapping slits or holes along a path to cutout a larger contoured shape. This eliminates the need for a custom punch and die but will require secondary operations to improve the accuracy and finish of the feature.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Drawing

1. Blank Drawing: Blank drawing is a cold metal forming process, in which a flat metal blank is forced into a die cavity by hydraulically driven punch. A cup-like cylindrical part, having the depth greater than its diameter, is formed as a result of deep drawing.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Drawing

2. Bulging: Forming of sheet metal by the application of pressure with the help of rubber or liquid.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Drawing

2. Bulging: Forming of sheet metal by the application of pressure with the help of rubber or liquid.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Drawing

3. Tube and wire drawing: Drawing is a metal forming process involving pulling a work piece (cold or hot) through a die providing reduction of the cross section of the work piece.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Drawing

4. Embossing: Bending of sheet metals for providing dimples on sheet metals to increase their rigidity.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Drawing

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Squeezing

1. Cold Rolling: Cold rolling consists in compressing and lengthening the metal below recrystallization temperature as it is fed between two rolls rotating in opposite direction.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Squeezing

2. Riveting: To join two or more metal sheet rivet is used which made of ductile material and easily squeezed to any shape. When hammered it squeezes and make a joint.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Squeezing

3. Coining: A cold forging operation except for the fact that the flow of metal occurs only at the top layers. Coin, medals etc are made by this process. It is basically a cold working operation, which is performed in dies where the metal blank is confined and its lateral flow is restricted.

The operation involves placing a metal slug in the die and applying heavy pressure by the punch. The metal flows plastically and is squeezed to the shape between punch and the die. The process, on account of the very high pressures required, can be employed only for soft metals with high plasticity.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Squeezing

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Bending

• Bending is a metal forming process in which a force is applied to a piece of sheet metal, causing it to bend at an angle and form the desired shape.

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For bending in all sheet material are stressed beyond the elastic limit in tension on the outside and in compression on the inside of the bend. There is only one line, the neutral axis which retains its original length.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Bending

Air Bending

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Bending

Bottoming

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Bending

Coining

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Bending

Wipe Bending

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Bending

Dr. Md. Arifuzzaman, Department of Mechanical Engineering, KUET, Khulna 9203

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Bending

Bend Allowance: The bend allowance (BA) is the length of the arc of the neutral line between the tangent points of a bend in any material. Adding the length of each flange taken between the center of the radius to the BA gives the Flat Pattern length. The BA can be calculated using the following formula:

K = K-Factor, which is t / T

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Screw Thread

A screw thread, often shortened to thread, is a helical structure used to convert between rotational and linear movement or force.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Screw Thread

Lead: Linear distance traveled during one rotation.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Screw Thread

Method of making screw thread:

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1. Casting
• Sand casting
• Die casting
• Permanent mould casting
• Shell moulding
• Lost wax casting
2. Rolling
3. Chasing: Single point tool and multi point tool
4. Die and tap cut
5. Milling
6. Grinding

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Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

GEARS

Gears: Gear is toothed wheel which when meshed with other gears transmit motion from one shaft to another.

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Classification:

1. Spur Gear: Tooth is parallel to the rotating shaft and transmit power between parallel shaft.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

GEARS

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Gears

2. Helical Gear: Tooth elements are helical or twisted. These can transmit power between two parallel or non parallel shaft.

3. Bevel Gear: Bevel gears are gears where the axes of the two shafts intersect and the tooth-bearing faces of the gears themselves are conically shaped. Bevel gears are most often mounted on shafts that are 90 degrees apart, but can be designed to work at other angles as well.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Gears

5. Herringbone gear: A herringbone gear, also known as a double helical gear, is a special type of gear which is a side to side (not face to face) combination of two helical gears of opposite hands.

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Gears

Gear Manufacturing Methods:

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1. Casting

a. Sand Casting b. Die Casting

c. Injection Moulding d. Sintering

2. Hot rolling

3. Powder Metallurgy

4. Extrusion

5. Coining

6. Stamping

7. Machining method

a. Form tooth process (Milling, Shaping, Broaching)

b. Template process

c. Cutter generating process

I. Hole cutter process

II. Rotary cutter process

III. Reciprocating process

Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Metal Forming Process

1.Punching & Blanking https://www.youtube.com/watch?v=P7N4zktv8dw&ab_channel=KeshavJadhav

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2. Recrystalization https://www.youtube.com/watch?v=YkL4U7Rwvlo&ab_channel=MechVidya

3. Types of Rolling Mill https://www.youtube.com/watch?v=dpbQK7D97H4&ab_channel=AniMech

4. Rolling Mill

https://www.youtube.com/watch?v=AuuP8LWppI&ab_channel=H%C3%B6gskolanDalarna

5. Forging https://www.youtube.com/watch?v=zskg3xKAR0Q&ab_channel=SkillLync

6. Roll Forging https://www.youtube.com/watch?v=LuGNhEwZs0s&ab_channel=ROLLPEDIA

7. Extrusion https://www.youtube.com/watch?v=Y75IQksBb0M&ab_channel=ToolingU-SME

8. Metal spinninghttps://www.youtube.com/watch?v=43N44ICyuEU&ab_channel=rebeccamortimer1

9. Bulging https://www.youtube.com/watch?v=-yI8VK2tERk&ab_channel=JessieSunglory

10. Embossing: https://www.youtube.com/watch?v=Z7zNcDj_YeA&ab_channel=SolidworksFun

11. Coining https://www.youtube.com/watch?v=eKoXhplG56I&ab_channel=MechLearning

12. Gear https://www.youtube.com/watch?v=4ROtKKuSaBI&ab_channel=TheEngineeringMindset

13. Blanking punching https://www.youtube.com/watch?v=ECA390jloJg&ab_channel=ShubhamKola

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Raju Ahammad, Lecturer, Dept. of ME, KUET, rajuahammad@me.kuet.ac.bd

Metal Forming Process