Because different molding molds have been applied in many fields, and the manufacturing technology of professional molds has also undergone certain changes and developments in recent years, in this section, the general design rules of vacuum forming molds are summarized. The design of vacuum forming molds includes batch size, forming equipment, precision conditions, geometric shape design, dimensional stability, and surface quality.

1. For batch experiments with small mold production, wood or resin can be used for manufacturing. However, if the experimental mold is used to obtain data on shrinkage, dimensional stability, and cycle time of the product, a single cavity mold should be used for the experiment, and it should be ensured that it can be used under production conditions. Molds are generally made of gypsum, copper, aluminum, or aluminum steel alloys, and aluminum resin is rarely used.

2. Geometric design often requires comprehensive consideration of dimensional stability and surface quality. For example, product design and dimensional stability require the use of a female mold (concave mold), but products with high surface glossiness require the use of a male mold (convex mold). In this way, the plastic parts ordering party will comprehensively consider these two points to ensure that the product can be produced under ***** conditions. Experience has shown that designs that do not meet actual processing conditions often fail.

3. Dimensional stability: During the molding process, the surface of the plastic part in contact with the mold has better dimensional stability than the part that leaves the mold. If the material thickness needs to be changed in the future due to the need for material stiffness, it may result in the need to convert the male mold to the female mold. The dimensional tolerance of plastic parts cannot be less than 10% of the shrinkage rate.

4. The surface structure of the plastic part that can be covered by the molding material should be formed at the contact point with the mold. If possible, do not contact the surface of the mold with the light cleaning surface of the plastic part. Just like the case of using a negative mold to manufacture bathtubs and laundry basins.

5. Modification: If a mechanical horizontal saw is used to saw off the clamping edge of the plastic part, there should be at least 6-8mm of clearance in the height direction. Other finishing work, such as grinding, laser cutting, or jetting, must also have a margin left. The gap between the cutting lines of the die cutting edge is small, and the distribution width of the punching die during trimming is also very small, which should be noted.

6. Shrinkage and deformation, plastic is prone to shrinkage (such as PE), and some plastic parts are prone to deformation. No matter how preventive measures are taken, plastic parts will deform during the cooling stage. Under these conditions, 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 plastic part wall remains straight, its reference center has deviated by 10mm; The mold base can be raised to adjust the shrinkage of this deformation.

7. When manufacturing vacuum forming molds, the following shrinkage factors must be considered Shrinkage of molded products. If the shrinkage rate of plastic cannot be clearly known, samples must be taken or similar shaped molds must be tested to obtain it. Note: This method can only obtain the shrinkage rate, not the deformation size Shrinkage caused by adverse effects of intermediate media, such as ceramics, silicone rubber, etc The shrinkage of materials used in molds, such as the shrinkage when casting aluminum.