Rubber mold is the simplest method in rapid mold. Generally, the RP prototype is re-molded with silica gel, but its life is very short, only about 10-30 pieces! It has good elasticity and replication performance. The silicone rubber replication mold can be used without considering the draft angle, and will not affect the dimensional accuracy. It has good segmentation, and can be directly poured as a whole without dividing the upper and lower molds. Then cut along the predetermined parting line and take out the master mold!

RTV silicone rubber can be divided into two types: addition type and condensation type:

The raw material and formula are special mold silicone rubber, which is sold in double packaging. Component A is rubber and component B is catalyst. The room temperature, the strength and hardness of the mold shall be taken into account during preparation to determine the weight preparation ratio of AB components.

At room temperature of 20-25 ℃, A: B=100:1.5. When the room temperature is low (but not lower than 10 ℃), add 0.1-0.3 portions of component B appropriately. If the room temperature is higher, 0.1-0.3 portions of group B will be reduced. The specific method is to determine the total dosage according to the mold volume, and then weigh the components A and B accurately in proportion, and put them in the container and stir them evenly.
Mold making: pour the prepared material into the clean object to be copied. In order to save materials, thinner molds can also be painted in several times. To increase the tension of the mold, gauze can be pasted. It can be cured into elastomer at room temperature of 20 ℃ for 2 hours and can be used after one day.

Precautions for silicone rubber mold manufacturing:
1. Component B is a catalyst which is easily hydrolyzed by moisture, so the cover should be tightly closed after use.
2. Once mixed, group A and group B undergo chemical reaction; Start immediately, the viscosity gradually rises, and cannot be stopped. In order to avoid waste, it should be prepared as soon as it is used according to the dosage. After preparation, it should be used immediately without delay.
3. The mix ratio of group A and group B is related to the speed of chemical reaction and the performance of the mold. The more component B, the faster the reaction, the higher the strength and hardness of the product, but the lower the toughness. Therefore, accurate weighing is required.
4. Before preparation, mix up and down component A evenly, and then weigh.
5. The pouring method is suitable for the relief type, and the painting method is suitable for the production of three-dimensional molds. For casting relief molds, a frame with length and width of 4-6 cm greater than the original length and width shall be made first. The frame should be flat and the inner surface should be smooth. Place the frame on a clean glass plate during pouring, and then place the original in the frame, leaving a 2-3cm gap on each side

Solution for bubbles in the production process:
Improve the design of flash groove and exhaust system
Increase the pressure of the press
Reduce the amount of release agent and spray evenly
Material control moisture
Try adding some defoamer
Use cold runner
Use the vacuum machine to vacuum the air, and the exhaust operation can be added on the mold.