How to enhance the precision of plastic molds?

2024-10-25

For the injection mold, the precision of the plastic parts is 3 and 3a, the weight is 5 grams, the hardened gating system is adopted, and the number of cavities is 4-6; The plastic parts are of average accuracy (grade 4-5), the molding material is local crystalline material, and the number of cavities can be 16-20; The weight of the plastic parts is 12-16 grams, and the number of cavities is 8-12; For plastic parts with a weight of 50 grams, the number of cavities is 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 keeps increasing, multi-cavity molds are seldom utilized. For plastic parts of grade 7-9 accuracy, the maximum number of cavities is increased by 50% compared with the plastics of grade 4-5 accuracy indicated.

1. Determine the parting surface. The position of the parting surface should be conducive to mold processing, exhaust, ejection and molding operations, as well as the surface quality of plastic parts.

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

3. Select the ejection method (ejecting rod, ejecting tube, pushing plate, combined ejection), decide the side concave treatment method and the core pulling method.

4. Determine the cooling and heating methods, the shape and position of the heating and cooling grooves, and the installation position of the heating elements.

5. Based on the mold material, strength calculation or empirical data, determine the thickness and outline size of the mold parts, the outline structure and the location of all connections, positioning and guiding parts.

6. Determine the structure of the main forming parts and structural components.

7. Consider the strength of each part of the mold and calculate the working size of the molded parts.

If the above problems are solved, the structural form of the mold will naturally be resolved. At this point, you should start to draw a sketch of the mold structure to prepare for the formal drawing.