Introduction to the cavity layout and various factors of plastic mold processing

2021-03-23 16:34:14 admin

Introduction to the cavity layout and various factors of plastic mold processing

1. Cavity layout.

Determine the number of cavities and their arrangement according to the geometric structure characteristics of the plastic parts, the dimensional accuracy requirements, the batch size, the difficulty of mold manufacturing, and the mold cost.

For injection molds, the accuracy of plastic parts is 3 and 3a, and the weight is 5 grams. The hardening casting system is adopted, and the number of cavities is 4-6; the plastic parts are of general accuracy (level 4-5), and the molding The material is a partially crystalline material, the number of cavities can be 16-20; the weight of plastic parts is 12-16 grams, and the number of cavities is 8-12; and the weight of plastic parts is 50-100 grams, the number of cavities is selected 4-8.

The recommended number of cavities for amorphous plastic parts is 24-48, 16-32 and 6-10. When the weight of plastic parts continues to increase, multi-cavity molds are rarely used. For plastic parts with 7-9 accuracy, the maximum number of cavities is 50% higher than the indicated plastic with 4-5 accuracy.

2. Determine the parting surface.

The position of the parting surface should be conducive to mold processing, venting, demolding and molding operations, and the surface quality of plastic parts.

3. Determine the pouring system (shape, location, size of the main runner, sub-runner and gate) and exhaust system (exhaust method, exhaust slot location, size).

4. Select the ejection method (ejector, pipe, push plate, combined ejection), determine the undercut treatment method and core pulling method.

5. Determine the cooling and heating method, the shape and location of the heating and cooling groove, and the installation location of the heating element.

6. According to the mold material, strength calculation or empirical data, determine the thickness and external dimensions of the mold parts, the external structure and all the connections, positioning and guide positions.

7. Determine the structural form of the main forming parts and structural parts.

8. Considering the strength of each part of the mold, calculate the working size of the molded part. If these problems are solved, the structure of the mold will naturally be solved. At this time, we should start to draw the mold structure sketch to prepare for the formal drawing.