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Mold Manufacturing Defects And Prevention Measures
Dec 23, 2014

1, forging
High carbon, high alloyed steel, for example, Cr12MoV, W18Cr4V and other, widely used in the manufacture of molds. But there is this type of steel of different degrees of segregation, coarse carbide defects such as asymmetry and asymmetry. Selection of high-carbon, high-alloy steel die, reasonable rough forging forming module must be used, this will not bring the steel to rough dimensions and specifications of the module, we could improve the microstructure and properties of steel. Thermal conductivity of high-carbon, high-alloy tool steel is not heating not too fast, and the heat uniformly, in the forging temperature range, reasonable forging ratio should be used.

2, machining
Die cutting process shall strictly maintain dimensional transition radii, arcs and lines should be smooth. Die cutting processing poor quality, likely to be caused in the following 3 mold damage, 1) due to improper cutting, resulting in sharp angular or rounded corners RADIUS too small will cause mold to serious stress concentration at work. 2) after cutting surfaces are too rough, there are marks, nicks, cuts, and other defects that may exist, they are both stress concentration points and Fang crack, crack, struggle or thermal fatigue crack initiation. 3) machining does not fully and evenly remove mold hair worse in rolling or forging of decarburized layer, it may produce uneven mold heat treatment-hardening layer, resulting in decreased wear.

3, grinding
Die in a fire, tempering General grinding to reduce surface roughness value. Due to grinding speed had big, and wheel grain degrees fine or cooling conditions poor, factors of effect, caused of mold surface local overheating, caused local micro organization changes, or caused surface softening, hardness reduced, or produced high of residual pulled stress, phenomenon, will reduced mold of using life select appropriate of grinding process parameter reduced local fever, grinding Hou in May of conditions Xia for to stress processing, on can effective to prevent grinding crack of produced. Measures to prevent overheating in grinding and grinding crack more, such as: using coarse grinding cutting force strong of less bonded grinding wheels, reducing mould grinding feed rate; choose the right coolant; 2.5013 million ℃ tempered eliminated by grinding grinding stress.

4, EDM
EDM machining mold discharge current density, produces a lot of heat, mould processing temperatures up to about 10,000 of the region, because of the high temperatures, heat affected zone microstructure is bound to change, mold surface melting due to high temperature, followed by rapid cooling, solidification quickly, forming a solidified layer. Can be seen under a microscope, then solidified layer is white light, there are more microscopic cracks. In order to extend the tool life may take the following measures: adjusted parameter in EDM electrolysis or mechanical grinding grinding of EDM surface, remove white layer in the exception, especially to get rid of micro-cracks. Arrange a low temperature tempering after the EDM, unusually stable to prevent micro cracks.