Factors affecting mold structure and system

1. Cavity arrangement. The number of cavities and their arrangement are determined according to the geometric structure characteristics of plastic parts, dimensional accuracy requirements, batch size, ease of mold manufacturing, mold cost, etc. For injection mold, the precision of plastic parts is 3 and 3a, the weight is 5 grams, and the hardened casting system is used, the number of cavities is 4-6; the precision of plastic parts in general (4-5), and the molding material is a local crystalline material, the number of cavities can be 16-20; the weight of plastic parts is 12-16 grams, the number of cavities is 8-12; and the weight of plastic parts is 50-100 grams, the number of cavities is 4-8. The number of cavities is 4-8.

The recommended number of cavities for amorphous plastic parts is 24-48, 16-32, and 6-10. The maximum number of cavities for plastic parts with 7-9 levels of accuracy is increased to 50% compared to the noted 4-5 levels of accuracy.

2. determine the parting surface. The location of the parting surface should be conducive to mold processing, exhaust, demolding and molding operations, the surface quality of plastic parts, etc.

3. determine the pouring system (main sprue, sub sprue, and gate shape, location, size) and exhaust system (exhaust method, exhaust slot location, size).

4. Choose the ejecting method (ejecting rod, ejecting tube, pushing plate, combined ejecting), decide the side concave treatment method and core extraction method.

5. Decide the cooling and heating method and the shape and position of the heating and cooling groove, and the installation part of the heating element.

6. According to the mold material, strength calculation, or empirical data, determine the thickness and external dimensions of mold parts, the shape structure, and the position of all connecting, positioning, and guiding parts.

7. Determine the main molding parts, the structure form of structural parts.

8. Consider the strength of each part of the mold and calculate the working size of the molded parts. If these above problems are solved, the structure form of the mold is naturally solved. At this time, you should proceed to draw the mold structure sketch, ready for the formal drawing.

9. Drawing mold drawing requires drawing according to the national drafting standard, but also requires combining the factory standard and the factory customary method not stipulated by the state. Before drawing the general assembly diagram of the mold, the process diagram should be drawn and should conform to the requirements of the part drawing and process information.

The dimensions guaranteed by the next process should be marked on the drawing with the word "process dimensions". If there is no mechanical processing after molding except for burr repair, the process diagram is identical to the part drawing. The part number, name, material, material shrinkage rate, and drawing ratio should be indicated below the process drawing. Usually, the process drawing is drawn on the general assembly drawing of the mold.