Mold design principle

 Different molding molds have been used in many fields, and the manufacturing technology of professional molds has also undergone certain changes and development over the years. Therefore, Pofi fixture manufacturers have summarized some general design rules for vacuum plastic molding molds.

The design of vacuum blister molding mold includes batch size, molding equipment, precision conditions, geometric shape design, dimensional stability and surface quality.

1. The batch size is used for experiments. When the mold output is small, it can be made of wood or resin. However, if the experimental mold is to obtain data about shrinkage, dimensional stability and cycle time of the product, a single-cavity mold should be used for the experiment, and it can be used under production conditions. The mold is generally made of plaster, copper, aluminum or aluminum alloy.

2. Geometric shape design, the dimensional stability and surface quality are often considered comprehensively when designing. For example, new product design and dimensional stability require the use of concave molds, but products that require higher gloss on the surface require the use of convex films. In this way, the plastic parts ordering party will comprehensively consider these two points, so that the products can be in the best Produce under optimal conditions. Tests have proved that designs that do not meet the actual processing conditions often fail.

3. Dimensional stability. During the molding process, the contact surface of the plastic part and the mold is better than the dimensional stability of the part leaving the mold. If the material thickness is required to be changed due to the need for material rigidity in the future, it may cause the male mold to be converted to female mold. The dimensional tolerance of plastic parts cannot be less than 10% of the shrinkage rate.

4. The surface of the plastic part, in terms of the range that the molding material can cover, the surface structure of the visible surface of the plastic part should be molded at the contact point with the mold. If possible, the smooth surface of the plastic part should not be in contact with the mold surface. It's like using female molds to make bathtubs and washtubs.

5. Modification, if you use a mechanical horizontal saw to cut off the clamping edge of the plastic part, there must be at least a 6-8mm margin in the height direction. Other dressing work, such as grinding, laser cutting or jet, must also be left over. The gap between the cutting lines of the crossing die is the smallest, and the distribution width of the punching die is also small when trimming. These should be paid attention to.

6. Shrinkage and deformation, plastics are easy to shrink (such as PE), some plastic parts are easy to deform, no matter how to prevent them, 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 deviated by 10mm. The mold base can be raised to adjust the shrinkage of this deformation.

7. The amount of shrinkage, the following shrinkage factors must be considered when manufacturing the blister molding mold.

A: The molded product shrinks. If the shrinkage rate of the plastic cannot be clearly known, it must be obtained by sampling or experimenting with a mold of similar shape. Note that only the shrinkage rate can be obtained by this method, and the deformation size cannot be obtained.

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

C: The shrinkage of the material used in the mold, such as the shrinkage when casting aluminum.