Forming Process: Definition, Classification or Types, Advantages, Disadvantages, and Applications [Notes with PDF]

What is Forming Process?

Forming Process also known as Metal Forming. It is a large set the of manufacturing processes by which a raw material is converted into a product. In this process, we apply stresses that can be in the form of tension, compression, shear, etc. to deform the raw material. Example of forming processes are sheet metal manufacturing, forging, rolling, extrusion, wire drawing, thread rolling, rotary swinging, and so on.

Classification or Types of Forming Process in Detail

Forming Process can broadly be categorized into three types :

1. Bulk Forming
   • Rolling Process
   • Extrusion Process
   • Forging Process
   • Wire Drawing
   • Squeezing
2. Sheet metal Forming
   • Bending
   • Deep Drawing
   • Shearing
3. Powder Metal Forming
   • Powder Forging
   • Powder Injection
   • Powder Extrusion Moulding

Bulk Forming

One of the most important forming processes is the Bulk Forming process. This process can be used when the volume ratio of the metal is higher than the surface area. The bulk-forming process works due to the influence types of forces. The forces that have influence are shear force, the combination of tensile, and the compressive force. The examples of Bulk Forming processes are as follows:

Rolling

Rolling is one of the most useful processes of forming. It falls under the bulk-forming process. The rolling process consists of two or more two rollers in a combination with the metal plate. In regards to the rolling process, the metal plates are passed between the combination of two or more two rollers to make the metal plates thin and smooth surface finish.

The main purpose of the rolling process is to reduce the thickness of the metal plates. In the forming processes, metal is not removed. Hence, before the rolling process starts, less width metal is taken as per the need. After the rolling process the width is increased due to pressing and decreasing the thickness.

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Extrusion

The extrusion process is much different from other processes. In this process, the metal is heated at high temperatures. Then the metal is pressed by the comprehensive force of the die.

The die has an opening, through which the heated metal flows at the time of pressing by RAM. Hence, the proper shape can be made. In the extrusion process, the metal is heated at an extremely high temperature such that it becomes like a fluid.

Forging

Forging is the process by which a metal can be heated at a very high temperature. The forging process can be used to give a particular shape to the metal. It usually works due to the compressive force.

At first, the metal is heated at a very high temperature. Then this metal is placed in a die. After that, the compressive force is applied to the heated metal so that the metal can get the shape of the die by deformation. Hence, the metal takes its shape by deformation.

Wire Drawing

Here a wire-shaped die is used. The workpiece is passed through the die and takes the cross-section of the die opening. It is a pull process.

Squeezing

Squeezing is one of the most useful forming processes. In this process, a die is used. The die should be a closed type die. At first, the die has to be heated. Then the molten metal is placed on one part of the die. When the metal starts to become solid then the other die part is placed on the first die part and a compressive force is given to it. After solidifying the metal, it comes out as the prepared shape.

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Sheet Metal Forming

Another important forming process is the Sheet Forming process. The sheet-forming process works due to either the tensile force or the shear force. It can be used in Hydraulic presses to make the product from the sheets however some more steps like squeezing, bending, and so on are also included in this process. In this process, no material is added or removed. Example of Sheet metal forming is bending, deep drawing, shearing, etc.

Bending

Bending is the process of forming where an angle is used in order to be pressed by the compressive force of the metal plate. This helps the material to bend at a particular angle so that, the plate can get its necessary shape. The shape of the angle usually looks like either the English letter “V” or “U”.

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Deep Drawing

In this operation, a hollow cup shape die is used. The die is clamped using the blank-holder. The workpiece (sheet metal) is placed over the die and a punch exerts the force on the workpiece. Due to this force, sheet metal extend and fills the cavity to take the shape of the die.

Shearing

In this operation, the metal sheet is in a cantilever position, and a punch coming from the top exerts a force on the cantilever position of the sheet. Shearing is just a cutting operation of the metal sheet.

Powder Metal Forming

Nowadays, the most innovative forming process is the Power Metal forming process. In this process, metal powders are used to form products. It is a computer-controlled process. The metal powders are heated under the melting point of the material.

The product of any complex shape which cannot be produced by any other forming processes can be done with the help of Powder metal forming. Generally, this process is used to minimize the machining stages like grinding, polishing, etc. It also minimizes production cost. The examples of Powder Metal Forming Processes are as follows:

Powder Forging

In this process a mixture of blended powder is poured into the die through the hopper, and the pressing is done by using a preform. Generally to get solid bonding we need to heat the Preform.

This process is divided into three steps:

1. Preform is heated, so that binding can be easily done.
2. Pre-Alloy powder (180–325 µm, source Open Learn) is put into the die and pressed by the Preform. In this process, we get 80–85% solid density.
3. After pressing is done by preform, it again goes for Mechanical Pressing, so that we can increase the density up to 98–99.5%.

Powder Injection

The powder Injection process is also called metal injection molding. In this process, the metal powders (<10µm) are blended with wax or polymer-based binder. The blended mixture undergoes compaction due to the pressure exerted by the screw and comes out through the die to take its shape of it.

Powder Extrusion Moulding

In this process, a hydrostatic compressive force acts on the powder metal. A die is fixed at the opposite side of the force applied, so when a force act on the powder, it comes out through the die and takes the shape of the die.

Temperature in Forming Processes

Temperature plays a vital role in Forming Processes, by applying heat we can change the property of the forged material. When we consider the temperature, the Forming Process can be classified into the following types :

1. Hot Forming
2. Warm Forming
3. Cold Forming

Hot Forming Process

The hot-forming process mainly depends on the recrystallization temperature. In the Hot Forming Process, the metal is heated under its melting point. As it is heated above the recrystallization temperature it is known as Hot Working Forming Process.

Warm Forming Process

It stands between Hot and Cold Forming process. Here the temperature is maintained above the room temperature but below the recrystallization temperature. By doing so we can achieve intricate work geometry, and also less power and force is required.

Cold Forming Process

Cold Forming Process also depends on the recrystallization temperature. In the Cold Working Forming Process, the metal is heated under the crystallization temperature of the metal. Hence, it is known as Cold Forming Process.

Advantages and Disadvantages of Metal Forming Process

Advantages of Hot Forming Process

• The amount of hardening strain in the case of the hot-forming process is low as compared to the cold forming process.
• Due to the temperature of the material, the amount of force required to deform the material is very low.
• The amount of ductility, as well as other mechanical properties that are present within a material, which is produced through the hot forming process, is quite high.
• Less amount of residual stress is generated in the hot forming process.

Disadvantages Hot Forming Process

• The amount of heat required is high.
• Oftentimes, the major flaw present within the hot-formed process is the poor surface finish.
• Accuracy or precision is quite low as compared to the cold forming process.
• Poor interchangeability is another issue that is incorporated with the hot-forming process.
• Poor life cycle and handling issue.

Advantages of Cold Forming Process

• Heating is not required at all in this process.
• The surface that can be obtained at the end of this process is of very premium quality.
• The existence of directional properties.
• Wear and tear properties are very high.
• The strength is good in the case of the cold forming process.
• The major benefit of this process is the negligibility of contamination.

Disadvantages of Cold Forming Process

• For the deformation of a material, a high amount of force is required.
• High power requirement to deform a material.
• As compared to the hot forming process, the ductility level is bad.
• Hardening stress is more in the case of the cold forming process.
• Existence of residual stresses.

Applications of Metal Forming Process

Some major applications of the forming process are as follows:

• Seamless tubes and rods can be made with the help of the Metal Forming process.
• Turbine rings can be produced by this method.
• Cement kilns can also be made with the help of this process.
• Bearings, plates, steel sheets, and various components of an automotive car can be developed with the help of the Metal forming process.
• Missile & aircraft components are also manufactured through this process.
• Along with that, hinge, bolt, nails can also be formed by this process.
• Moreover, agricultural tools & military products are also produced with the help of this process.
• Furniture, hook, pin, screws can also be made from this process.
• Windows, doors, and other components of a car can be developed with the help of the forming process.
• Furthermore, the forming process can also be used to develop plastic products.

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FAQ’s

Conclusion

Hence we con conclude by suggesting that the forming process is essential in manufacturing and can be used for wide range of applications. It involves applying mechanical forces to reshape the material. By leveraging the power, manufacturers can create strong and durable parts for several industries.