3. Causes of upsetting: the cutting knife isn’t adjusted properly so that the material can’t be sent to the center of the mold; the bar size is small or the position of the material in the mold is not correct because of larger die wear size; when stamping steel balls blank, the punch spring is loose or damaged and the press hook is not pressed steadily.
4. Burr, rolling and pressure wound: burr mainly refers to the resulting burr due to cutting knife is too blunt and the gap between the main cutting knife and cutting tube is too large or too small after the raw material is cut off. After creating and stamping the burrs, they are involved into the workpiece. The broken burrs fall into the die, causing pressure wound. Rolling cause steel balls blank crack, affecting the quality of steel balls seriously.
5. Causes of displacement and size over tolerance: the machine is not adjusted, the machine has the low precision or the mold is wear seriously. According to reasons for the production, it should be eliminated by adjusting the relative position of the mold or changing the gap of the main slider guide part.
6. There are three kinds of blank cracks: material cracks, upsetting cracks and folding cracks caused by burrs.