Forging is one of the oldest metal manufacturing processes, and it is still in use today. But if care isn’t taken, forging defects may occur. For those who don’t know what forging is, it’s simply a process of transforming metal by deforming it into intended shapes using certain equipment. This deformation can occur through hot, warm, and cold forging processes.
The difference between these forging processes is often the temperatures. For instance, cold forging temperature is below the metal recrystallization temperature or just at room temperature. However, forging defects have a way of destroying the visual appeal of metals and make them irrelevant.
These defects can be avoided from the beginning. First of all, special care should be given to the metal during the process and the smith must be a professional with years of experience under his/her belt.
There are several kinds of forging defects. They include scale pits, unfilled section, flakes, abnormal grain growth, cold shut, partial forging penetration, residual stress, surface cleaning, die shaft etc. Forging defects shouldn’t attack your metal in the first place because the signs will always be there even when it has been controlled
In this article, we will be looking at some of these defects, and how they can be avoided. Shall we?
Types of forging defects
1. Cold shut:
This is a type of forging defect that appears as small cracks at the object’s corners. This is often caused by a poor design of the forging die and excess chilling of the products. This forging defect is bad because the effects can’t be removed completely. The best thing to do is to avoid it totally by increasing the fillet radius of the die.
2. Scale pits:
This often occurs when the forged surface is not cleaned properly. This type of defect is common when the forging process is done in an open environment. This defect also creates irregular patterns on the surface. To avoid this defect, clean the forged surface properly.
As a manufacturer, it’s super important to choose a good forge professional that will carry out your job in a closed and conducive environment to avoid unsustainable damages like this.
3. Unfilled section:
This is one of the commonest forging defects there are. What does it do?
This defect leaves a part of the metal unfilled. This is often caused by the bad design of the die when the metal bar is inserted into it or during the compression stage. It can also be caused by inadequate raw materials, poor heating conditions, and bad forging techniques.
4. Die shift:
This defect often happens when the lower and upper dies are not properly aligned. This leads to inaccurate product dimensions. To avoid this defect, ensure that the die is well aligned before inserting your metal bar. Then, place half part of the metal workpiece on the lower die, and the other half on the upper die, so that they can match.
This occurs when the forged product is not well cooled. When the products are cooled quickly, internal cracks are created, it reduces the product strength. Flakes can be prevented when the product is properly cooled.