Forging Hot, Cold Forging Process Defects Controlling with Process Improvement and Experimental Analyses

Forging Hot, Cold Forging Process Defects Controlling with Process Improvement and Experimental Analyses

Vijay B. Jadhav, Vikrant A. Mallav, Sandip F. Jadhav, Archna B. Pathare

Department of Mechanical Engineering, Sanjivani Pratisthan Institute of Technology 412210, India.

DOI: https://dx.doi.org/10.47772/IJRISS.2025.909000790

Received: 13 October 2025; Accepted: 18 October 2025; Published: 30 October 2025

ABSTRACT

This study examines the hot and cold forging procedures of a variety of parts composed of low carbon steel and other materials that are created using the hot forging process. Initially, this product is analysed in a temperature range of 850°C to 1200°C in 50°C increments. After that we finding various forging defects are carried out having different location and operation.  It is determined that the forging defects and there causes of defects in different forgoing operations.

Additionally, by using extra grinding, polishing, and reworking procedures as remedial measures, the forging die and its set can be utilised for HOT forging and die life improvement processes. And experimental analyses is done by forging waste controlling methods to controlling flash waste of products.

Keywords-  Die Life, Rolling Operational crack, Hot Padding, Flashed waste.

INTRODUCTION

Working Principle Forging

Die impressions or die cavities can be used for one or more closed die impressions or impressions. To keep the right forging temperatures, these dies are frequently heated. This kind of forging is frequently carried out using both hammers and heavy presses. Workpieces might have flat discs or a cross-section that is circular or rectangular. [5]

While more intricate objects may require multiple strokes and die cavities to reach their final form, simpler shapes can be forged in a single stroke. A small layer of metal known as the “flash” will emerge between the dies during the final forging. After that, this flash is manually removed or cut with specialized dies.

Fleshless forging is feasible when the size and shape of the pre-form are precisely regulated. The lubricants utilized are graphite, just like in open-die forging. These lubricants, which can be water- or oil-based, improve metal flow, reduce die wear, delay heat loss, and help remove work from the die. Compared to open-die forging, the resulting forged item is substantially more closely shaped like a net shape and has better metallurgical and dimensional quality. The circumferential expansion and cross-section of a disk-shaped workpiece with a central piercing are known as seamless ring forging. The ring rolling machine, which has a driven outer wheel and an undriven mandrel, can produce both external and interior profiles.[3]

Forging operations

• Flantner
• Blocker
• Finisher
• Trimming

Process Parameters

I. Surface defects: –

1) Burr lap (Operation defects)

2) Scale Pit (Manual defects)

3) Under Fill (Location, Operation defects)

4) Dent Mark (Manual defects)

5) Punch Mark (Location or misalignment of die)

6) Under Cut (Trimming defects)

II. Inspection defects: –

1) Mismatch (Die shifting)

2) Size Variation (Temperature variation)

3) Bend

4) Crack (Overheating and force)

 III. Process Wastage: –

1) Cutting operation (End piece)

2) Flash wastage (After Trimming)

Proposed Machines for Project Work

• Press Machine
• Hardness Testing Machine
• Shot Blasting Machine
• Magnetic Particle Testing

Fig 01 gets showing information about the basic classification of forming process with hirer different operation carried out in forging industries.  Hand forging process carried out manual operation eg. Hammering process, hammering operation carried out eccentric load carrying operation. Drop forging operation small job manufacturing process. Rolling operation carried out as per requirement of operational process.

Fig 01 Chart of Forging Process.

Raw material inspection.

Fig 02 Forging Operation

In above fig 2 showing general forging operation which carrying in hot forging process, Step by step.

Table 01 Raw material grading system

Table 01 shown the how to identify raw material initial stage  of forging process by using different colour coding system with material grade.[8]

Classification of die

1. Open die
2. Closed die
3. Trimming die

Die heating process

In the die heating process variety of thermal processing methods are used used for die heating. Most commonly used for the dies are heated with several gas flame torches.  The gas torches are arranged in such a manner as to produce a distributed heat source on the die surface.[11]

1. Flame gas heating
2. Ingot heating

Disadvantages and problems of the prior art techniques for forging die heating

• Long heating time so it time consuming process.
• Operational time losses,
• Energy losses,
• Causing environmental pollution due to combustion gasses,
• Decarburization on forging die surface due to gas flames,
• Non-uniform temperature distribution on forging dies,
• High die surface wear that results in increasing the number of rework of the forging dies,
• Undesired rapid cooling of forging dies,
• Poor part quality due to forging die wear,
• Reduce batch size,
• Risk of broken or damaged forging dies,

The aims of this internal heating system for forging dies are;

• To eliminate/reduce thermal fatigue.
• To obtain operational ease and convenience,
• To eliminate operational time losses through short preheating time,
• To apply heating energy directly to the forging dies,
• To create a heating system that generates no combustion gasses and pollution,
  • To eliminate decarburization on forging die surfaces,
  • To increase the uniformity of the temperature distribution on the forging dies,
• In order to improve the forging die’s high impact toughness uniformity,
• To prevent forging die cooling during the forging process,
• To slow down the decreasing of hardness
• To keep forging dies structurally intact,

 Table 02 – Die life analyses Maintenance and Inspection

Table 02 gives information about the production of product given die life target and actual production done by die by using die life maintenance and precaution technicians.

In that research concentrated about Die life analyses Maintenance and Inspection in shift-wise corrective analyses of die and corrective action taken on the die show in the above figure analyses step by step. [1]

Step first- die failure analyses accuses are finding out such are.

• Overheating Fluctuating Load
• Scaling and Metal Flow Rate
• Die-Cooling System

The methodology can be applying the improvement of Die life

1. Preheating
2. Descaling,
3. Polishing
4. Resinking
5. Stress Relieving.

Table 03 Die Life Improvement Operational Parameter

Above data get to inform that die no 106 having die life 15000 no’s. We are manufacturing total number of nose after some die get wear out and they get cracked. Than by repairing Gauzing operation that die get repair and some rework carry by welding process. After that on that die some nose are get forged. It time consumable process but you get die life improvement total rework and repairing of die two to three days are required.[7]

To avoid this forging defect, some care should be taken during the operation in forging by taking corrective action and process correction. Types of forging defects are listed below.

Types of Forging Defects

The following are the important types of forging defects:

1. Unfilled section
2. Scale pits
3. Cold shut
4. Die shift
5. Improper grain growth
6. Flakes
7. Surface cracking
8. Incomplete forging penetration
9. Residual stress in forging
10. Incomplete filling of dies
11. Cracking at the flash
12. Internal cracks

Unfilled Section:

These types of forging defects are carried out due to some portions of the object being unfilled.

It is caused by

• Poor Design of the Die,
• Less Raw Material,

Cold Shut:

These types of forging defects are carried as small cracks at the corners of the object.

 It is caused by

• Improper Design of the Forging Die,
• Sharp Corners of the Object,
• Excessive Chilling of the Forged Product.

These forging defects can be avoided when the proper design of the die, routing polishing of the die, and chilling of the forged in air.

Scale pits:

This forging defect is carried out due to improper cleaning of the forged surface.

Scale pit is usual in forging carried out in an

• Due heavy used of spraying liquid.
• Open Environment.

It Causes Irregular Deputations on the Forging Surfaces.

Die shift:

When the upper and lower dies are not oriented in the centre of each other, die shift forging error occurs.

It is caused by

• This will result in improper dimensions of the product.
• This will occur due to improper allocation.
• Miss alignment of die.

The defect can be avoided when the die is properly aligned. It can be done by placing half a portion of the workpiece on the upper die and half on the lower die so that both portions can match. The fillet radius of the die is increased.

Incomplete forging penetration:

These types of forging defects are carried out due to light or rapid hammer blows that lead to incomplete forging.

It is caused by

• This will occur due to press working conditions.
• This will occur due to certain cooling of the job.

It can be prevented by proper usage or control of the forging press.

Residual stresses in forging:

This type of forging defect is carried out when the forged parts are not properly cooled.

It is caused by

• It can be caused by rapid cooling and can be prevented by slow cooling of the forged part.

It can be controlled by using an air-cooling system.

Defects avoiding technics.

 All the above parameters control the forging defects by using such preventive action in the forging operation.

Rolling operational defects

1. Doing proper heating process on job
2. Maintain the temperature heating process.
3. Performing the rolling operation with skilled workers.
4. Cleaning of rolling operation from time to time.

To maintain all the above parameters in rolling operation controlling rolling defects such as edge cutting, carrying of job, underfilling of job, such types of defects we get controlled.

Upsetting operation –

1. To control the temperature of the billet.
2. To carry out the preheating process on the open die.
3. To maintain the cutting length of the job.

Blocking operation and Finishing –

1. To carry out the preheating process on the closed die.
2. To carry out in-process and after-process grinding processes on the closed die.
3. To maintain central distance in between die.

To maintain all the above parameters in rolling operation controlling rolling defects such as edge cutting, carrying of job, underfilling of job, crack formation internal and external, and mismatch problems avoided such defects in forging operation.

Trimming operation –

• To carry alignment of die with their center.
• Polishing and reworking of die from time to time.
• To maintain the sharpness of the die.

To maintain all the above parameters in rolling operation controlling rolling defects such as edge cutting, carrying of job, and undercutting of job, avoided such defects in forging operation.

CONCLUSION

1. The results in the first series to controlling various forging defects under filling and twisting and bending defects get controlling by addition of one operation. Hot padding having different location. To control in process defects and improvement on bending defects controlling process by addition of one new operation (Hot padding).
2. To minimizing the forging waste in formation of flash by statistical analysis in forging process. Due to that process, we get increased forging process yield ratio and increase the utilization of raw material.
3. To minimising in process defects with die life improvement process with regular repairing operations, (Resink, Stress relieving, Gauzing operation) such operation get to get controlling regular forging defects such as serration mark and dent mark in forging operation.
4. One of major problem in forging process crack formation it will get controlling by in process crack with roiling operation corrective action. All types of crake get to be control by taking preventive action of rolling operation.

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