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

In this article, you’ll be going to learn the Metal Forming Process. After reading this article you will able to find the answer to Types of Forming Processes, the Advantages and Disadvantages of this process and lastly the application of the Metal Forming Process. So let’s get started with the Definition.

What is Forming Process?

Forming Process also known as Metal Forming is a large set of manufacturing process by which a raw material converted into a product. In this process, we apply stresses like tension, compression, shear, etc. to deformed the raw material. The 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 there types, and those are:

  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

#1 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. Along with that, the bulk-forming process works due to different types of forces. They are the shear force, the combination of tensile, and the compressive force. The examples of Bulk Forming processes are mentioned below.

a. 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 than two rollers to make the metal plates thin and smooth surface finish.

Apart from that, the rollers that can be used in the rolling process rotate either in the same direction or in the opposite direction with respect to the other roller.

The main purpose of this 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 with respect to the necessity, as after the rolling process this width is increased due to pressing and decreasing the thickness.

Rolling Process Diagram
Rolling Process Diagram, Learn Mechanical

b. 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. Apart from that, in the extrusion process, the metal is heated so much that it becomes like a fluid as it can flow.

Extrusion Process Diagram
Extrusion Process Diagram, Learn Mechanical

c. Forging:

Forging is the process by which the metal can be heated at a very high temperature. This 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 given to the heated metal as the metal can get the shape of the die by deformation with the help of the force that is given by the hammer or the other piece of the devices to the metal. Hence, the metal takes its shape by deformation.

Forging Operation Diagram
Forging Operation Diagram, Learn Mechanical

d. Wire Drawing:

It is a kind of extrusion process, but not exactly. Here a wire-shaped die is used. The work-piece is passed through the die and takes the cross-section of the die opening. It is a pull process.

Wire Drawing Diagram
Wire Drawing Diagram, Learn Mechanical

e. Squeezing:

Squeezing is one of the most useful forming processes. In this process, die is used. The die should be closed type die. At first, the die has to be heated. Then the molten metal is placed to one part of the die. After that when the metal is going to be 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 takes out as the prepared shape.

Squeezing Operation Diagram
Squeezing Operation Diagram, Learn Mechanical

#2 Sheet Metal Forming:

Another important forming process is the Sheet Forming process. This sheet forming process works due to either the tensile force or the shear force. Usually, this force can be used in Hydraulic presses in order to produce 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 removes. Example of this type of forging is bending, deep drawing, shearing, etc.

a. Bending:

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

Bending Operation Diagram
Bending Operation Diagram, Learn Mechanical

b. Deep Drawing:

In this operation, a hollow cup shape die is used. The die is clamped using the blank-holder. In this process, the workpiece (sheet metal) placed over the die and a punch exerted the force on the workpiece, by this force sheet metal extend and filled the cavity and takes the shape of the die.

Deep Drawing Operation Diagram
Deep Drawing Operation Diagram, Learn Mechanical

c. Shearing:

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

Shearing operation Diagram
Shearing operation Diagram, Learn Mechanical

#3 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. In regards to that, in this process, the metal powders are heated under the melting point of the material.

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

a. Powder Forging:

As the name denotes Powder Forging, that means here we use Powder Metals to get finish product. In this process, a mixture of blended powder 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 completed into three steps:

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

b. Powder Injection:

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

Powder Injection Diagram
Powder Injection Diagram, Learn Mechanical

c. Powder Extrusion Moulding:

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

Powder Extrusion Moulding
Powder Extrusion Moulding, Learn Mechanical

Temperature in Forming Processes:

Temperature plays vital role in Forming Processes, by applying heat we can change the property of the forged material. So if we consider the temparature then there are three types of Forming Process.

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

#2 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 along with above the recrystallization temperature. As it is heated above the recrystallization temperature so that, it is known as Hot Working Forming Process.

#2 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 required less power and forces.

#3 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:

According to the above discussion, you already have an idea that we can categorized forming process broadly in two types Hot Forming, and Cold Forming, so each one has their own advantages and disadvantages, so let’s discuss them.

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 in amount.
  • The amount of the ductility, as well as other mechanical properties that are present within a material, which is produced through the hot forming process, is quite high.
  • Apart from the above advantages, less amount of residual stress can be 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.
  • Apart from that, poor interchangeability is another issue that is incorporated with the hot forming process.
  • Poor life cycle and handling issue.

In the above section, the advantages and disadvantages of Hot forming process are discussed. Now, the following portion includes the advantages and disadvantages of the cold forming process.

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.
  • Powerful and high-quality power is required 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.

Now also look at the application of forming process.

Applications of Metal Forming Process:

Some major applications of the forming process are as follows:

  • Seamless tubes, rods can be made with the help of the aforementioned 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 this forming process.
  • The 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 in order to develop plastic products.

So I hope you are able to understand the Metal Forming Processes. If you liked this article, do not forget to share this article on your favorite social media platform. We also have more topics like this, so hopefully, see you on some other articles as well. Till then good-bye, stay healthy, and keep learning with us.

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Anup Kumar Dey

A Mechanical Engineer with 19 years of working experience in various renowned MNCs.

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