Table of Contents
What is forging?
Forging is a manufacturing process in which shape of a heated metal changed by applying external force. Heated metal is used in forging because it is much easy to reshape heated material compared to colder one.
However, in many forging operations cold metal is also used.
Forging operations
There are basically two types of forging operations
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Drawing out
In this type of forging operation, a metal is elongated and as a result its cross-sectional area decreases.
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Upsetting
Upsetting is opposite to drawing out operation. In upsetting cross-sectional area of the workpiece is increased and as a result length of workpiece decreased.
Forging types
There are basically four types of forging
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Smith forging
Smith forging is the same which a village blacksmith uses for making various tools. In smith forging the heated metal gets repeated blows of hammers to get desired shape.
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Drop forging
This is the operation done in close impression dies by means of drop hammers. Here the Force for shaping is applied in several blows.
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Press forging
Press forging is same as drop forging but, the force is applied here with the help of hydraulic machines.
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Machine forging
The only difference in press forging and machine forging is that, in press forging material is drawn-out but in machine forging material is upset.
Comparison between press forging and drop forging
| Press Forging | Drop Forging |
| More force is required to produce the same effect | Less force is required to produce the same effect |
| Draft angle is less | Draft angle is more |
| Impression obtained is clean and clear | Impression obtained is less clean and clear |
| Almost all force gets transferred to the stock | Some hammer force gets transferred to machine frame |
Forging defects
Though the products manufactured by forging are of superior quality as compared to other manufacturing process but there are still some defects which could arise.
- Unfilled sections
- Cold shut
- Scale pits
- Die shift
- flakes
- Improper grain flow
Advantages of forging
- Parts manufactured by forging are stronger
- It offers high ductility
- It is more reliable and less costly
- It offers better response to heat treatment
- It offers more consistent and better metallurgical properties
- It refines structure of metal
- It offers broad size range of products
- It requires fewer secondary operations
- It has great design flexibility
Disadvantages of forging
- In hot forging it is difficult to perform secondary operations
- It is limited to simple shapes
- Capital cost is more
- Very high man and material safety procedures need to be followed
- Forged metal surface is prone to rapid oxidation due to very high temperature
- It is difficult to maintain close tolerances
Applications of forging
- Automobile industry
- Valves and fittings
- Hand tools and hardware
- Machinery and equipment
- Defense
- Aerospace
Image source:
Attribution: By Rainer Halama – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=10689973