Although forgings have good mechanical properties, there are some common defects that need to be checked and prevented during the production process. Xinlong Machinery has successfully achieved a number of technological breakthroughs by organizing technicians to optimize production processes and update production equipment.
1. Unfilled section: this type of forging defects left some portion unfilled. It is caused by poor design of 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, heating, and there should be enough raw materials.
2. Cold shut: this type of forging defect occurs 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 forge product. This forging defect can be avoided when the fillet radius of the die is increased.
3. Scale pits: this type of forging defect occurs due to improper cleaning of the forged surface. Scale pit is usual in forging carried out in open environment. It causes irregular deputations on the forging surfaces. This defect can be avoided by adequate cleaning of forged surface.
4. Die shift: this forging defect is caused when the upper and lower dies are not aligned with each other, this will lead to improper dimensions of the product. This defect can be avoided when the die is properly aligned. It can be done by placing half portion of the work piece on the upper die and half on the lower die, so that the both portion can match.
5. Flakes: this type of forging defect occurs 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 forge product. Flakes can be avoided when proper cooling is performed.
6. Improper grain growth: this forging defect is caused by improper flow of metal during the casing process which changes the predefined grain of the product structure. It can be avoided by performing better design of die.
7. Incomplete forging penetration: this forging defect occurs due to light or rapid hammer blow that lead to incomplete forging. It can be prevent by proper usage or control of forging press.
8. Surface cracking: this type of forging defects arises when the forging operation is performed at low temperature which leads to occurrence of cracks on the work pieces. It can be controlled by working on a proper temperature.
9. Residual stresses in forging: this type of forging defect takes place when the forged parts are not properly cooled. It can be caused by much rapid cooling and can be prevented by slow cooling of the forged part.