We investigated the reasons for frequently appearing early failure of carbide punches in a progressive stamping die when they were used to produce magnetic shielding steel parts. The failure modes of the carbide punch...We investigated the reasons for frequently appearing early failure of carbide punches in a progressive stamping die when they were used to produce magnetic shielding steel parts. The failure modes of the carbide punches were statistically classified. Edge chipping and shoulder fracturing were the two types of failure modes that were found. The composition, hardness, and microstructure of the punches were analyzed. The cobalt content was found to be too low to ensure sufficient toughness. The brittle phase of tungsten carbide （WC）was prone to breaking off during the shear cutting process, and resulted in edge chipping. In addition, the material chips were easily bonded to the punch edge when there was a lack of press oil lubricity. It resulted in an uneven blanking clearance, which caused a lateral force and finally resulted in shoulder fracturing of the punches. Improvement measures were introduced to address the abovementioned issues. By using the carbide punches with greater toughness and shear cutting oil with high lubricity, the early damage problems of the punches are effectively solved, which ensures normal production of the magnetic shielding steel parts.展开更多
文摘We investigated the reasons for frequently appearing early failure of carbide punches in a progressive stamping die when they were used to produce magnetic shielding steel parts. The failure modes of the carbide punches were statistically classified. Edge chipping and shoulder fracturing were the two types of failure modes that were found. The composition, hardness, and microstructure of the punches were analyzed. The cobalt content was found to be too low to ensure sufficient toughness. The brittle phase of tungsten carbide （WC）was prone to breaking off during the shear cutting process, and resulted in edge chipping. In addition, the material chips were easily bonded to the punch edge when there was a lack of press oil lubricity. It resulted in an uneven blanking clearance, which caused a lateral force and finally resulted in shoulder fracturing of the punches. Improvement measures were introduced to address the abovementioned issues. By using the carbide punches with greater toughness and shear cutting oil with high lubricity, the early damage problems of the punches are effectively solved, which ensures normal production of the magnetic shielding steel parts.
