What are the differences between plastic precision mold design and ordinary plastic molds? What should I pay attention to when designing injection molds?
From the design point of view, the difference is not particularly big, mainly the post-processing, the mold material is good, the rigidity is sufficient, the dimensional accuracy of the cavity, the smoothness and the positioning accuracy between the templates are high; the precision injection molding machine is used to replace the conventional injection molding machine; the precision molding process is adopted; Choose materials suitable for precision molding.
Secondly, the drawings must be comprehensive, complete and accurate. Use inserts as much as possible, consider processing more, and rely on machines to ensure the dimensions as much as possible. The role of master fitter's technology in precision plastic molds is to strictly follow the drawings. Most of the mold parts must have strict design tolerances, not only the working part of the cavity and core, but also the relevant dimensions of the installation position of all inserts, which are generally controlled at +/-0.005.
The main content of injection mold design can be summarized as follows.
1. According to the rheological behavior of the plastic melt and the flow resistance in the runners, the mold cavity is analyzed to obtain the filling sequence, and the problem of the plastic melt being split and re-fused in the mold cavity and the mold cavity are considered at the same time To analyze the location of the weld marks and determine the number and positioning of the gates for the problem of the original air export in the interior.
2. According to the thermal performance data of the plastic melt, the shape of the cavity and the arrangement of the cooling water channel, the changes in the temperature field of the plastic parts during the pressure holding and cooling process are analyzed to solve the shrinkage and feeding problems of the plastic parts, and minimize the temperature caused by And the residual internal stress and warping deformation caused by uneven pressure, inconsistent crystallization and orientation.
3. The problems of demoulding and lateral parting of plastic parts can be solved through empirical and theoretical calculation analysis. At present, the computer expert system software based on empirical and theoretical calculations is also being vigorously researched.
4. Decide the parting surface of the plastic part and the inlay combination of the cavity. The above issues do not exist in isolation, but affect each other, and should be considered comprehensively.