Sun Jun 04 00:54:41 CST 2023
Because different forming molds have been applied in many fields, plus the manufacturing technology of professional molds has also changed and developed over the years, so in this part, the general design rules of vacuum blister forming molds are summarized.
The design of vacuum suction molding molds includes the batch size, molding equipment, precision conditions, geometric shape design, dimensional stability and surface quality.
1, the size of the batch for experimental use, mold production hours, can be manufactured using wood or resin. However, if the experimental mold is used to obtain data about shrinkage, dimensional stability and cycle time of the product, etc., a single-cavity mold should be used for experiments, and it can be guaranteed that it can be used under production conditions. Molds are generally made of plaster, copper, aluminum or aluminum-steel alloy, rarely used aluminum - resin.
2, geometry design, design, often to consider the size stability and surface quality. For example, the product design and dimensional stability requires the use of a negative mold (concave mold), but the surface requirements of high gloss products require the use of a positive mold (convex mold), so that the plastic parts ordering party will take into account the two points, so that the products can be produced under the best conditions. Experience has proven that designs that do not meet the actual processing conditions are often failures.
3 、 Dimensional stability, during the molding process, the surface of the plastic part in contact with the mold is better than the dimensional stability of the part leaving the mold. If the material thickness is required to be changed later due to the need of material stiffness, it may lead to the conversion of the positive mold to the negative mold. The dimensional tolerance of the molded part should not be less than 10% of the shrinkage rate.
4, the surface of the plastic part, as far as the molding material can be wrapped, the plastic part can meet the surface structure should be formed at the contact with the mold. If possible, the glossy surface of the plastic part should not be in contact with the surface of the mold. Just like the case of using negative mold to make bath tub and laundry tub.
5、Finishing, if using mechanical horizontal saw to saw off the clamping edge of the plastic part, there should be at least 6~8mm margin in the height direction. Other trimming work, such as grinding, laser cutting or jet, must also leave a margin. The gap between the cutting lines of the knife edge die is minimal, and the distribution width of the punching die trimming is also small, which are to be noted.
6 , shrinkage and deformation , plastic easy to shrink (such as PE) , some plastic parts easy to deformation , no matter how to prevent , plastic parts in the cooling stage will be deformed . Under such conditions, the shape of the molding mold should be changed to accommodate the geometric deviation of the plastic part. For example: although the wall of the plastic part is kept straight, its reference center has deviated from 10mm; the mold base can be raised to adjust the shrinkage of this deformation.
7, the amount of shrinkage, in the manufacture of blister molding mold must take into account the following shrinkage factors. ① shrinkage of the molded product. If the shrinkage of the plastic is not clearly known, it must be obtained by taking samples or using similarly shaped molds through tests. Note:Only the shrinkage rate can be obtained by this method, not the deformation size. ② Shrinkage caused by the adverse effect of intermediate medium, such as ceramic, silicone rubber, etc. ③ Shrinkage of the material used in the mold, such as shrinkage when casting aluminum.
Mold is a model, according to this model to make products, but the mold is how to produce it, except for mold professionals may not answer most of them. Mold has played an irreplaceable role in our life, most of our daily necessities can not be separated from the mold, such as computers, telephones, fax machines, keyboards, cups and so on these plastic products, needless to say, in addition, like the car and motorcycle engine cover is also made out of the mold, a variety of automotive molds are used more than 20,000. So that the role of modern life mold irreplaceable. As long as the mass production can not be separated from the mold.