Defects in forging are inevitable, despite it being one of the best manufacturing processes that gives better mechanical properties. Examining these defects is necessary for their prevention.
Forging defects can be controlled by careful consideration of work material volume, good design of the forging die, and the process.
To prevent this forging defect, the smith must have forging experience and exercise caution during the operation. Well, in this reading, we’ll explore the different types of forging defects, their causes, and remedies.
Let’s Get Started!
Related: What is Forging? its Applications, Diagram, and How it Works
Types of Forging Defects
Types of forging defects include unfilled sections, cold shuts, scale pits, die shafts, flakes, improper grain growth, incomplete forging penetration, surface cleaning, and residual stresses in forging.
1. Unfilled section: These types of forging defects left some portions of the object unfilled. It is caused by poor design of the die, less raw material, poor forging techniques, and poor heating. To avoid the occurrence of the defect, proper care must be taken on the die design and heating, and there should be enough raw materials.
2. Cold shut: These types of forging defects occur as small cracks at the corners of the object. It is caused by improper design of the forging die, sharp corners of the object, and excessive chilling of the forged product. These forging defects can be avoided when the fillet radius of the die is increased.
3. Scale pits: This forging defect occurs due to improper cleaning of the forged surface. Scale pit is usual in forging carried out in an open environment. It causes irregular depositions on the forging surfaces. This defect can be avoided by adequate cleaning of the forged surface.
Related: 11 Different Types of Forging Operations
4. Die shift: Die shift forging defect is caused when the upper and lower dies are not aligned with each other. This will result in improper dimensions of the product. The defect can be avoided when the die is properly aligned. To match both parts, place half of the workpiece on the upper die and half on the lower die.
5. Flakes: These types of forging defects occur due to improper cooling of the forged product. It is internal cracks caused when the forged products cool quickly, and it reduces the strength of the forged product. Flakes can be avoided when proper cooling is performed.
6. Improper grain growth: These forging defects are caused by improper flow of metal during the casting process, which changes the predefined grain of the product structure. It can be avoided by performing a better design of the die.
7. Incomplete forging penetration: These types of forging defects occur due to light or rapid hammer blows that lead to incomplete forging. It can be prevented by proper usage or control of the forging press.
8. Surface cracking: Surface cracking is a forging defect that arises when the forging operation is performed at low temperature, which leads to the occurrence of cracks on the workpieces. It can be controlled by working at a proper temperature.
9. Residual stresses in forging: This type of forging defect takes place when the forged parts are not properly cooled. Overly rapid cooling can cause it, while slow cooling of the forged part can prevent it.
Related: The Four Common Types of Metal Casting