Common problems in metal stamping and their causes;
First, the cause of the die wear too fast
(1) The gap of the die is too small, and increasing the gap appropriately can effectively reduce the wear of the die.
(2) Poor alignment of convex and concave dies, and insufficient precision of die holder, die guide assembly and turret insert will cause die wear.
(3) The temperature of the punch is too high, which is mainly due to the overheating of the punch caused by the continuous stamping of the same die for a long time.
(4) Improper grinding method will lead to mold annealing and aggravate mold wear.
(5) When local punching is carried out for many times, such as step punching, punching angle or shearing, the lateral force will make the punch biased to one side, resulting in serious die wear.
Second, the cause of the mold with material
(1) The sharpness of the die cutting edge, the bigger the fillet of the cutting edge, the easier it is to cause the waste to rebound. The mold should be kept sharp and degaussed frequently.
(2) Mold penetration modulus. When the punching modulus of the machine tool is small, it is easy to cause the waste to rebound. It is suggested to use a special anti-banding concave die.
(3) Whether the mold gap is reasonable or not, if the mold gap is not appropriate, it will easily lead to the rebound of waste materials. Increasing the gap between molds and installing stripper plates can avoid the occurrence of material entrainment.
(4) If non-special stamping oil is used, problems such as gluing and viscosity increase will occur due to oil oxidation. The above problems can be avoided by using special stamping oil.
Third, the causes of mold errors
(1) The design or accuracy of the turret of the machine tool is insufficient, mainly because the mold mounting seats of the upper and lower turntables are not aligned well. The centering rod should be used regularly to check and adjust the centering of the turret and mounting seat of the machine tool.
(2) The design or accuracy of the mold can't meet the requirements. Replace the mold guide sleeve in time, and select the convex-concave mold with appropriate clearance.
(3) Due to long-term wear, the mold mounting seat or mold guide sleeve is not aligned. The responsibility of operators should be strengthened, and the reasons should be found in time to avoid the expansion of losses.
Fourth, the causes of stamping oil quality
(1) Stamping workpiece is difficult to clean. When manufacturing materials that are easy to die-cut, generally for the cleanliness of finished workpieces, low viscosity stamping drawing oil will be selected on the premise of preventing die-cutting burrs.
(2) Stamping workpieces rust quickly. For the stamping process of cast iron, copper, aluminum and other materials, the metal surface will be corroded by chemical reaction under the action of high temperature and high pressure in the stamping process, so when selecting stamping drawing oil, the corresponding special model should be selected according to the different materials of the workpiece.
(3) The stamping workpiece has the problem of hardening and deformation. When stamping materials that are easy to harden, stamping drawing oil with high oil film strength and good sintering resistance must be selected. Generally, stamping drawing oil containing sulfur and chlorine compound additives is used to ensure extreme pressure performance and avoid burr and fracture of the workpiece.