Revolutionary Forging 7 Types, Operation, Defects, Pros, and Cons [PDF]

In this article, we shall be talking about the definition, types, operation, defects, advantages, and disadvantages of forging. We have also provided a PDF for the same.

Forging PDF

Forging Definition

Forging is one of the forming processes. This is a process in which metal deforms plastically to another requires shape and size with the help of a hand or Machine with a certain temperature. This is done by two processes which are as follows

  • Hand forging
  • Machine forging

Hand Forging

The workpiece is heated in the furnace after heating Keep the heated workpiece (with the support of blacksmith tongs) onto the anvil and take the hammer are a strike on it, make the required shape and size.

Machine Forging

In this process, the operation is performed by the machine but we (Human) regulate the machines.


Types of Forging

  • Open Dies Hammer
  • Impression Die Drop
  • Press forging
  • Upset forging

There are also two major types also which are as follows

  • Hot forging
  • Cold forging

Open Dies Hammer or Smith Forging

In the early days, we use this type of process. In this process what we do once we heat the workpiece to the required temperature then we put the workpiece on the anvil with the use of tongs. And now we strike on it with the use of a hammer for the required shape and size.

The length of the workpiece decrease and the cross-section area of the workpiece increases. This process does not require any external machine. Done by a human. This is a very simple type of process.

Drop Forging
Photo By BB Prices

Impression Die Drop or Closed Die

It gives a more accurate size. In this, we make a complex shape like a crank, connecting rod, wrench, etc. To operate we must have two dies (Upper and lower) lower is fixed and the upper is moveable. In this operation, the workpiece is under the die to operate as you can think from the name.

Closed Die Forging
Photo By Pradeep Metals

There might be needed more than 2 operations to perform this process. You can see the diagram as mentioned.

Open Die Forging VS Closed Die Forging

Here in open die method the workpiece is forged between two open dies which means there are two dies parallel to each other and compressing the workpiece. Then workpiece material comes out while the operation is carried out.

Open Die forging vs Closed Die Forging
Photo By Greg Sewell Forging

Whereas, the closed die method it is like a completely specified shape in which two dies are compressing the workpiece to each other to get the desired shape. Here the workpiece does not come out of the system.

Press forging

This method is a little faster than the other two operations because in this we provide continuous squeezing action. This is much faster than a closed die because here only one squeeze is needed.

Press Forging
Photo By Thomasnet

The final object we get from this process has good smooth, close tolerance and there is no such problem of alignment of the die in this operation. The operation forms only in a single squeeze.

Upset forging

Let me illustrate this concept with a simple example. Are you familiar with a cylinder head? The process involves heating the areas of the material that we want to modify, such as a rod, and then shaping it to the desired size and shape during the upset process.

This can be achieved by heating the upper portion of the rod and then molding it to the required specifications.

Cold Forging

This process involves forging at room temperature. Unlike other methods, it does not require the use of a furnace to heat or cool the workpiece.

Cold Forging
Photo By Vrudhi Steel Pvt. Ltd.

The machines have two dies and in between the die, we place the workpiece between them and apply the load on it so as per the shape and size we want we apply the required forces on it. The advantage of clod forging is this is less costly.

Hot Forging

This is performed at extremely high temperatures (up to 1150 °C for steel, 360-520 °C for al-alloys, and 700-800 °C for CU-alloys). This temperature is necessary because when you operate, the strain hardening problem comes while deforming the workpiece.

To avoid strain hardening problems, you must work between the temperature as suggested. The advantages of this technique are one good surface texture can be obtained, and the second improves mechanical properties.

What is the difference between cold forging and hot forging?

Cold MethodHot Method
It is performed at room temperature.It is not performed at room temperature. For specific materials having a specific temperature limit.
Dimension can be controlled when the operation is carried out.Dimension can not be controlled when the operation is carried out.
Material is more ductile.Material is less ductile.
Lower surface finish.Better surface finish.

forging tools

There are a number of tools used in hand operation which are as follows

  • Anvil
  • Tongs
  • Set hammers
  • Punches
  • Swage block
  • Swages
  • Fullers
  • Chisels
  • Flatters


  • Here workpiece is to be kept and with the use of a hammer, we strike the workpiece for changing its shape and size.
  • It is made of Mild steel.
  • It works like the bed of the system.
Anvil Forging Tool


  • Tongs are used for holding the workpiece. When the workpiece is heated, tongs are used to hold it.
Tongs Forging Tool

Set hammers

  • It is used for striking the workpiece.
Hammers Forging Tool


  • It is a tool used for punching the workpiece.
Punches Forging Tool
Photo By Water Oak Forge

Swage block

  • It is used for getting different sizes of workpieces.
  • It contains multiple shapes and size holes in it and we can insert the workpiece into it and strike it with the hammer to get shape and size as we want.
Swage Blocks Forging Tool


  • Chisels are used for cutting metals in hot forging operations.
Chisel Forging Tool


  • Flatters are used for flattening the workpiece.
  • Flatters and fullers both are the same types of equipment used as a tool in these operations.
Flatters Forging Tool
Photo By Rigoni Ironworks

Forging Defects

The general defects are as following

  • Unfilled sections
  • Cold shut
  • Scale pits
  • Die shift
  • Flakes
  • Improper grain flow
  • Surface cracking
  • Residual stresses
  • Incomplete forging Penetration
Forging Defects

Unfilled sections

The unfilled section defects can be because of the improper design of Die or Improver heat treatment of metals. Imagine there are two dies: one is upper (Moveable) and the second is lower (fixed), In between we place the heated metal to form another require shape but due to the above line listed reason the defects can occur.

Cold shut

Cold shut defects occur in the forging operation when unable to fill the workpiece at the corner of the complete die.

Scale pits

The scale fit defects cause low strength of the forging operation because in these defects the slag or some dust particles are available in the die and we are not cleaned before the forging operation so it sticks to the forged metal.

Die shift

The unfilled section defects can be because of the improper design of Die or Improper adjustment of Die. To overcome this defect, we must have a good design of the die.


The flakes defects can cause because of the fast cooled of the upper die which is unable to makes proper forged operation.

Improper grain flow

You must have to design a proper die to not to perform such defects.

Surface cracking

The reason for the defect is the improper temperature provided. To overcome these defects you must provide the required temperature for the working metals.

Residual stresses

The reason for this defect is the fast cooling of improper parts. To overcome these defects you must do proper and slow cooling of forged parts.

Incomplete Penetration

While hammering on the workpiece by hand due to improper hammering this defect generates. To overcome, you must do proper hammering on it.

Forging Defects

Forging Advantages

  • The process gives higher-strength products as compared to casting.
  • A good number of shapes can be made through this process.
  • The process does not require a skilled operator, anyone can do it. The only thing is to have to teach once.
  • Low-cost operation.
  • The Mechanical Properties (Hardness, Strength, and others) are fairly good.
  • It refines the structure of the metal.
  • The forged parts can be easily welded.
  • A reasonable degree of accuracy can be obtained in this process.

Forging Disadvantages

  • The secondary finishing process requires.
  • The size might be limited because of the press size.
  • The maintenance cost is high.
  • The metals get distorted if it is worked below the required temperature.
  • The initial setup cost is high.
  • Some materials can not be forged by the this process.
  • The close tolerance is difficult to maintain.
  • Rapid oxidization in forging of a metal surface at high-temperature results in scaling which wears the dies.
  • While performing the operation by Hand you must have good energy to strike the workpiece with the hammer.
  • A huge safety requires because you are working near more than 2000 degrees centigrade.


  • This is useful in the ship-building process.
  • This process gives higher fatigue strength so like the camshaft, the crankshaft is made by the forging operation.
  • Cold operation is used for making knives, chisels, bolts, and many more.
  • These operations can be used in defense equipment.
  • Automobile Industry
  • Hand tools and Hardware
  • Machinery equipment.
  • Industrial tools.

Why forging is required?

It is a manufacturing process in which we obtain different shapes and sizes of a metal by the operation of hot and cold forging. In other manufacturing processes like casting where liquid metals are poured into a mold and the operation is carried but when we talk about forging, the operation performs on metals. In simple words, the forging is required to change the shape, and size of the same workpiece by heating or compressing.

Video Demonstration of the process

Video by LA Machines


What are the most common types of forging defects

The general defects are as following

  • Unfilled sections
  • Cold shut
  • Scale pits
  • Die shift
  • Flakes
  • Improper grain flow
  • Surface cracking
  • Residual stresses
  • Incomplete Penetration

Difference between forging vs casting

Forging involves shaping metal through compressive forces, resulting in stronger, more durable parts with aligned grain structure. It’s suitable for smaller, simpler components but is more expensive. Casting pours molten metal into molds, producing larger, more complex parts with random grain structure.

It’s cost-effective but may have lower mechanical properties and rougher surface finish. The choice depends on part characteristics, size, complexity, and cost considerations.

How to perform forging of steel

To perform the forging of steel, follow these steps. First, heat the steel to a specific temperature range suitable for operations. Next, place the heated steel onto an anvil or within a die. Use a hammer or a press to apply compressive forces, shaping the steel into the desired form.

Continue to shape the steel while maintaining the optimal forging temperature. For more complex shapes, multiple operations may be required. Finally, perform any necessary post processes like heat treatment or machining to achieve the desired properties and dimensions. Skilled labor, proper equipment, and knowledge of the steel’s characteristics are essential for success.

What is forging press operation

This involves using a forging press machine to shape metal into desired forms. The process begins by placing the heated metal workpiece onto the lower die of the press. The upper die then applies a significant amount of force, ranging from hundreds to thousands of tons, to deform the metal.

This force can be applied in a single blow or through a series of blows, depending on the complexity of the shape. The high-pressure forces exerted during the forging press operation allow for precise control over the shaping process. Skilled operators and proper die design are crucial for achieving accurate and quality forged components.


In conclusion, forging is a manufacturing process that involves the shaping of metal through the application of pressure. There are various types of forging methods, each with their own advantages and disadvantages. While the process has some potential defects, such as cracking and porosity, it also offers several benefits, including improved strength and durability. Overall, it is a critical process in the production of high-quality metal components.


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