1. Influence of demoulding force
During the demoulding process of precision shaft die casting processing, demoulding force is a key factor. If the demoulding force is too large, it will directly act on the surface of the shaft, which may cause surface scratches, scratches and even local deformation. This is because the shaft is tightly fitted with the mold cavity after die casting. When the demoulding force is uneven or exceeds the friction limit that the shaft surface can withstand, the integrity of the shaft surface will be destroyed. For example, when die casting some high-hardness alloy shafts, due to the strong affinity between the alloy and the mold, if the demoulding force is not properly controlled, it is very easy to produce obvious scratches on the shaft surface, which seriously affects its surface roughness and appearance quality. Additional grinding and other processes may be required to repair it later, but this may further affect the dimensional accuracy of the shaft.
2. The role of demoulding agent
The demoulding agent plays an important role in regulating the surface quality in the demoulding process of precision shaft die casting processing. A suitable demoulding agent can form a uniform isolation film between the shaft and the mold, reduce the friction between the two, and thus make the demoulding process smoother and reduce damage to the shaft surface. However, if the release agent is improperly selected, unevenly applied or used in an inappropriate amount, a series of problems may occur. For example, excessive release agent may remain on the surface of the shaft, affecting the matching accuracy of the shaft and other parts during subsequent processing or use; if the release agent is unevenly applied, the local friction force increases, which will still cause inconsistency in the surface quality of the shaft, local roughness or glossiness differences.
3. Influence of mold demolding structure
The design of the mold demolding structure is directly related to the method and effect of shaft demolding. Reasonable demolding structure, such as appropriate demolding slope and layout of ejection mechanism, can make the shaft evenly stressed during demolding and smoothly detach from the mold. If the demolding slope is too small, the friction between the shaft and the mold will increase, increasing the difficulty of demolding and the risk of surface damage; and if the ejection mechanism is not designed reasonably, such as uneven ejection position or inconsistent ejection speed, it will cause uneven force on the shaft during demolding, which may cause bending and deformation of the shaft and defects caused by local pressure on the surface, affecting key surface quality indicators such as cylindricity and straightness of the shaft.
4. Relationship of temperature factors
The temperature during demolding also has an important influence on the surface quality of shafts. After die casting, both the shaft and the mold are at a relatively high temperature. If demolding is too early, the shaft has not yet cooled and shrunk sufficiently, and the clamping force with the mold is large, which increases the difficulty of demolding and easily damages the surface; if demolding is too late, the shaft stays in the mold for too long, which may cause surface oxidation and structural changes due to temperature changes, affecting its surface hardness, color and other quality characteristics. At the same time, uneven mold temperature will also cause inconsistent shrinkage of different parts of the shaft during demolding, resulting in defects such as stress concentration and micro cracks on the surface, reducing the overall surface quality and service life of the shaft.
