Forging - Process, Types, forging operations, die materials, Defects and Remedies

The Mechanical engineering, is playing a vital role in today's Technology.
It Assist you to done things with ease, and also it brings the helpful technologies to modernize our society.

So keeping these things in mind, Lets learn about the forging- Process, Types, forging operations, die materials, Defects and Remedies.

Forging - Process, Types, forging operations, Defects and Remedies
Forging - Process, Types, forging operations, Defects and Remedies

Forging process:-

Forging is perhaps oldest metal working process and was know even during prehistoric days when metallic tools were made by heating and hammering.

Forging in that involves the plastic deformation between two dies to achieve desired configuration.
Depending upon the complexity of parts  the forging is carried out as open die forging and closed die forging.

In open die forging the metal is compressed by a mechanical hammer and shape is manipulated manually.
In closed die forging the required shapes are obtained by squeezing the workpiece between two shaped and closed dies.

Forging is a process in which the forces are applied on the raw material such that the stresses included are greater than yield and less than ultimate so that material is getting plastic (or) permanent deformation to get required shape by forging.

But in forging operation force applied can be either continuous force or intermittent impact load.

Types of forging methods:- 

1. Based on the method of force application

a) hand forging or drop hammer forging
b) machine forging or mechanical or       hydrostatic forging.

2. Based on method of shape obtained

a) open die forging
b) closed die forging
c) semi closed die forging

Types of forging operations:- 

1. Fullering
2. Driving
3. Upsetting
4. Edging
5. Flattening
6. Chamfering
7. Bending
8. Blocking or swaggering
9. Finishing operation
10 trimming

Die material for forging:-

The forging material required following parameters.

  • Strength and toughness at elevated temperature.
  • Hardenability and ability to harden uniformly.
  • Resistant to mechanical and thermal shocks.
  • Wear resistance and to resist abrasion wear due to scale present on workpiece.
By considering all these parameters the die materials are as follows. 
Tool and die steel with chromium, nickel, vanadium, Molybdenum.

Defects in forging with Remedies:-

The forging consisting following types of defects.

1. Cold shut

This defects happen because two surfaces of metal fold against each other without building completely.
This gives small cracks at the corner of the object.
It is caused by sharp corner less filling excessively chilling and high friction.

Remedy: this can be controlled by increasing plate radius on the die.

2. Surface cracking

It is happen because of excessive working on the surface and too low temperature.
High sulfur in furnace leading to hot shortness.

Remedy: to increase the work temperature can avoid surface cracking.

3. Unfilled section

This defect happen because of the die cavity is not completely filled by the material. Under this material is not going to corner of the work piece.

Remedy: proper design of the die.

4. Die shift

This gives the misalignment of the die halves. The two dice halves are not properly fixing so they may result in die shifting defects.

Remedy: descaling of die design cause die shift.

5. Flakes

It is a internal cracking caused by improper cooling of a forging. This caused the decreasing strength of the forging.

Remedy: it can be overcome by use of proper cooling methods.

6. Scale pits

It is impacting on the surface of the forging because of improper cleaning of the forging. It Caused irregular deputation on the forging surfaces.
 Remedy: by the proper and adequate cleaning of the forged work piece scale pit defects can be minimised.

7. Internal residue stresses

The main reason getting internal residue stresses are improper cooling of the forged components. And also by fast cooling of forced components.
Remedy: this defect is decreased by the slow cooling of the workpiece with the proper guideline followed of cooling.

8. Warping

This defects of forging occurs when the thin section of the forging is cools faster and thick section of the forging cools slower.this may result in huge warping in forging.
Remedy: the warping defect is controlled by by changing the cooling rate of the different sections of the forging.

9. Improper grain growth

The improper grain growth of the forging defect can be happen because of improper design of the die due to that the flowing of the material is not uniform throughout the workpiece.
Remedy: designing of the type must be in  proper format may result Minimized improper green growth.

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