How to reduce defects in plastic mold processing?

1, the reasonable use of cooling lubrication fluid, play the three roles of cooling, washing and lubrication, keep the cooling lubrication clean, so as to control the grinding heat within the allowed range to prevent the workpiece thermal deformation. Improve the cooling conditions during grinding, such as using oil sand wheel or internal cooling wheel. The cutting fluid is introduced into the center of the grinding wheel, and the cutting fluid can directly enter the grinding zone, play an effective cooling role, and prevent the workpiece surface burn.

2, the quenching stress after heat treatment is reduced to the minimum, because the quenching stress, the mesh carbonization structure under the action of grinding force, the structure phase change is easy to crack the workpiece. For high-precision mold in order to eliminate the residual stress of grinding, low temperature aging treatment should be carried out after grinding to improve toughness.

3, to eliminate grinding stress can also be the mold in 260 ~ 315℃ salt bath for 1.5min, and then in 30℃ oil cooling, so that the hardness can be reduced by 1HRC, residual stress reduced by 40% ~ 65%.

4, for the precision grinding of precision molds with dimensional tolerances within 0.01mm, attention should be paid to the influence of ambient temperature, and constant temperature grinding is required. According to the calculation, when the temperature difference of 300mm long steel is 3℃, the material has a change of about 10.8μm, (10.8=1.2×3×3, the deformation of 1.2μm/℃ per 100mm), and each finishing process should fully consider the influence of this factor.

5, the use of electrolytic grinding processing, improve the mold manufacturing accuracy and surface quality. Electrolytic grinding, the grinding wheel scrapes the oxide film: rather than grinding metal, so the grinding force is small, the grinding heat is small, will not produce grinding burrs, cracks, burns and other phenomena, the general surface roughness can be better than Ra0.16μm; In addition, the wear of the grinding wheel is small, such as grinding carbide, the wear of the silicon carbide grinding wheel is about 400% ~ 600% of the weight of the grinding carbide, and the wear of the grinding wheel is only 50% ~ 100% of the amount of the grinding carbide.