1. It is used for batch size experiments, and the output of the mold is small. It can be made of wood or resin. 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 can be guaranteed to be used under production conditions. Molds are generally made of plaster, copper, aluminum or aluminum-steel alloys, and aluminum-resin is rarely used.
2. Geometric shape design. When designing, it is often necessary to consider dimensional stability and surface quality comprehensively. For example, product design and dimensional stability require the use of female molds (concave molds), but products with higher surface gloss require the use of male molds (convex molds). In this way, the purchaser of plastic parts will take these two factors into consideration. point, so that the product can be produced under the best conditions. Experience has proved that the design that does not meet the actual processing conditions is often a failure. the
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 leaving the mold. If the material thickness needs to be changed due to the material stiffness in the future, it may lead to the conversion of the male mold to the female mold. The dimensional tolerance of the plastic part cannot be lower than 10% of the shrinkage rate. the
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 formed at the contact with the mold. If possible, the smooth side of the plastic part should not come into contact with the mold surface. As is the case with bathtubs and laundry tubs using female molds. the
5. For trimming, if a mechanical horizontal saw is used to cut off the clamping edge of the plastic part, there must be at least 6-8mm margin in the height direction. Additional finishing work, such as grinding, laser cutting or jetting, must also have allowances. The gap between the cutting lines of the knife die is the smallest, and the distribution width of the punching die is also very small when trimming. These are all things to pay attention to. the
6. Shrinkage and deformation. Plastics are easy to shrink (such as PE), and some plastic parts are easy to deform. No matter how to prevent them, plastic parts will deform during the cooling stage. Under such conditions, it is necessary to change the shape of the molding die 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. the
7. Shrinkage, the following shrinkage factors must be taken into account when manufacturing blister molding. ① The molded product shrinks. If the shrinkage rate of the plastic cannot be clearly known, it must be obtained by sampling or testing with a mold of a similar shape. Note: Only the shrinkage rate can be obtained by this method, and the deformed size cannot be obtained. ② Shrinkage caused by adverse effects of intermediate media, such as ceramics, silicone rubber, etc. ③ Shrinkage of the material used in the mold, such as shrinkage when casting aluminum.
