Rubber mold is one of the simplest methods in the rapid mold. Generally, it is used to duplicate the RP prototype with silica gel, but the life is very short, only about 10-30 pieces! It has good elasticity and replication performance, with silicon rubber replication mold can not consider the drawing die slope, will not affect the dimensional accuracy, has a good segmentation, without the upper and lower mold can be directly integrated pouring.

Room temperature vulcanized silicone rubber is divided into two types of molding and condensation type:

The raw material and formula adopt special mold silicone rubber, the strain is sold in double packaging form, A component is glue, B component is catalyst. The room temperature, the strength and hardness of the mold should be considered to determine the weight ratio of the AB component.

At room temperature of 20-25 degrees, A: B= 100:1.5. When the chamber is low (but not lower than 10 degrees), the B component should be appropriately increased by 0.1-0.3. At higher room temperature, group B was reduced by 0.1-0.3. The specific method is to determine the total dosage according to the volume of the mold, and then weigh the A and B components accurately according to the proportion, put them in A vessel and stir them evenly, and then it is finished.

Make mold: mix good material, pour into the clean kind that waits for imitation can. In order to save material, make a thinner mold, can also be divided into brushing. To increase the tension of the mold can be paste gauze. It solidifies into an elastomer in 2 hours at room temperature of 20 degrees and is ready for use a day later.

Precautions for making silicone rubber mold:

1, B component is a catalyst, susceptible to moisture hydrolysis, so the cover should be closed after use.

2, group A, B once mixed, chemical reaction; Start immediately, viscosity gradually rise, can not stop, in order to avoid waste, should be according to the amount, with with match, match should be immediately used, without delay.

3. The mix ratio of group A and B is related to the speed of chemical reaction and the performance of the mold. The more B components, the faster the reaction, the higher the strength and hardness of the product, but the toughness will decrease. Therefore, accurate weighing is required.

4. Before preparation, A component material should be stirred evenly up and down, and then weighed.

5, casting method is suitable for relief class, brushing method is suitable for three-dimensional mold production. Casting relief mold should first make the frame with length and width greater than the original length and width of 4-6cm. The border should be flat and the inside should be smooth.
 When casting, place the frame on a clean glass plate, and then place the original in the frame, leaving a gap of 2-3cm on each side

There are bubble solutions in the process of making:

(1) Improve the design of the flash groove and exhaust system
(2) Increase the pressure of the press
(3) Reduce the amount of release agent, and evenly spray
(4) Material control moisture
(5) You can try adding some defoamer
(6) Use cold runner
(7) With vacuum pump, exhaust operation can be added on the mold.