Design principle of mold(2)

4. As far as the surface of the plastic part can be covered by the molding material, the surface structure of the visible surface of the plastic part should be formed at the contact point with the mold. If possible, the smooth surface of the plastic part should not come into contact with the mold surface. As is the case with the use of female molds for bathtubs and laundry tubs.

5. For decoration, if a mechanical horizontal saw is used to saw off the clamping edge of the plastic part, there should be at least a 6-8mm margin in the height direction. Other finishing work, such as grinding, laser cutting or jetting, must also be left over. The gap between the cutting lines of the knife-edge die is the smallest, and the distribution width of the punching die during trimming is also small, which should be paid attention to.

6. Shrinkage and deformation, plastic is easy to shrink (such as PE), and some plastic parts are easy to deform. No matter how to prevent it, plastic parts will deform during the cooling stage. Under this condition, it is necessary to change the shape of the forming mold to adapt to the geometric deviation of the plastic part. For example: although the wall of the plastic part remains straight, its reference center has been deviated by 10mm; the mold base can be raised to adjust the amount of shrinkage of this deformation.

7. Shrinkage: The following shrinkage factors must be taken into account when manufacturing blister forming molds.

① Shrinkage of molded products. If the shrinkage rate of the plastic cannot be clearly known, it must be obtained by sampling or testing with a similarly shaped mold. Note: Only the shrinkage rate can be obtained by this method, and the deformation size cannot be obtained.

② Shrinkage caused by the adverse effects of intermediate media, such as ceramics, silicone rubber, etc.

③ Shrinkage of the material used in the mold, such as shrinkage when casting aluminum.