Rubber mould is one of the simplest methods in rapid tooling. Generally, RP prototype is replicated with silica gel, but its life is very short, only about 10-30 pieces! It has good elasticity and duplication performance. Silicone rubber duplicating die can be directly poured without considering the slope of drawing die, without affecting the dimensional accuracy, and has good partition. Then cut along the predetermined parting line and take out the master die.

Room temperature vulcanized silicone rubber can be divided into two types: additive and condensation.

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

At room temperature of 20-25 degrees, A:B = 100:1.5. When the ventricle is low (but not below 10 degrees), 0.1-0.3 copies of component B should be added appropriately. High room temperature reduced 0.1-0.3 copies in group B. The specific method is to determine the total dosage according to the die volume, and then weigh components A and B in proportion accurately, and mix them evenly in a vessel.

Moulding: The prepared material can be poured into the clean material to be imitated. In order to save material, a thinner die can be made, and it can also be painted in stages. In order to increase the pulling force of the die, the gauze can be pasted and so on. It can be cured into elastomer in 2 hours at room temperature of 20 degrees, and can be used in one day.

Notices for Silicone Rubber Mould Manufacturing:

1. Component B is a catalyst and easy to be hydrolyzed by moisture. Therefore, the cover should be tightly sealed after use.

2. Once group A and B are mixed, the chemical reaction occurs; immediately, the viscosity rises gradually and cannot be stopped. In order to avoid waste, according to the dosage, the mixture should be used immediately and without delay.

3. The mixing ratio of group A and group B is related to the speed of chemical reaction and the performance of the die. The more B component, the faster the reaction, the higher the strength and hardness of the product, but the toughness decreases accordingly.  Therefore, weighing requires accuracy.

4. Before mixing, the ingredient A should be stirred up and down evenly and weighed again.

5. Casting method is suitable for relief and brushing method is suitable for three-dimensional die making. Casting relief mold should first make a frame whose length and width are larger than the original 4-6CM. The border should be straight and the inside smooth. Place the frame on a clean glass plate during pouring, then place the original in the frame, leaving a gap of 2-3CM on each side.

There are bubble solutions in the manufacturing process:

Improving 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 defoamers

Use of cold runners

Vacuum pumping by vacuum machine can increase exhaust operation on the mould.