Rubber mold is one of the most simple method in rapid tooling, is generally used RP silica gel prototype mode, but life is very short, only about 10-30! He has good elasticity and reproduction performance, with silicone rubber mold can be copied without considering the draft, will not affect the dimensional accuracy of segmentation well, not on the die can be directly integralpouring. Then along the parting line for cutting out predetermined mold on it!
Room temperature vulcanized silicone rubber can be divided into two types: addition and condensation!
Raw materials and formula
Using special silicone rubber mold, the product line is sold in two forms of packaging, A component is a rubber material, component B is a catalyst. The preparation should be taken into account when the room temperature, mold strength and hardness, in order to determine the weight ratio of AB components. Room temperature at 20-25 degrees, A:B = 100:1.5. When the room is low (but not less than 10 degrees), it is appropriate to increase the B component of 0.1 - 0.3 copies. Room temperature high is reduced in the B group 0.10.3 copies. The specific method is based on the mold volume to determine the total amount, then the A and B components according to the proportion of accurate weighing, placed in containers evenly in the mixing, namely.
Mold: the deployment of good materials, into the imitation of the clean material can be. In order to save materials, the system made a thin mold, but also sub brush. In order to increase the tensile force of the mold can be paste gauze. At room temperature 20 degrees under the condition of 2 hours can be cured as elastomer, one day after use.
Matters needing attention：
1, B component is a catalyst, easy to moisture hydrolysis, it should cover the lid after strict.
2, A B, a group of chemical reaction through mixing, starting immediately; viscosity increased gradually, unable to stop, in order to avoid the waste, should be based on the amount, with the match, with a good immediately after use, can not be delayed.
3, A, B ratio of the group, related to the speed of chemical reaction and mold performance. The more B components, the faster the reaction, the higher the strength and hardness of the product, but the toughness decreased. Therefore, weighing requires accurate.
4, before the preparation, should be composed of A ingredients up and down, and then weighing.
5, pouring method suitable for relief, brushing method applicable to the production of three-dimensional mold. Pouring relief type of mold should be made longer and wider than the original length and width of the 4 - 6cm frame. The frame to be fair, in the surface to be smooth. When pouring the frame placed on a clean glass plate, then put in the original box, each side clearance of 2 - 3cm. (silicone rubber 61 yuan /KG)
Note: bubble solution in the production process:
1, improve the design of the flash tank and exhaust system
2, increase the pressure of the press
3, reduce the amount of release agent, and uniform spraying
4, material control moisture...
5, you can try to add some defoaming agent
6, the use of cold runner.
7, vacuum pump with vacuum, the mold can increase exhaust operation.