Generally, the 3D printed prototype is re-molded with silica gel, but the life span is very short, only about 10-30 pieces. It has good elasticity and replication performance. The use of silicone compound molds does not need to consider the draft angle, does not affect the dimensional accuracy, and has good partitionability. It can be directly poured as a whole without dividing the upper and lower molds, and then along the predetermined division. Cut the mold line and take out the master mold.
Room temperature vulcanized silicone rubber is divided into two types: addition type and condensation type. The raw materials and formula use special mold silica gel. This product is sold in a double package. The A component is a rubber compound and the B component is a catalyst. When preparing, consider the room temperature, the strength and hardness of the mold to determine the weight ratio of the AB component. When the room temperature is 20-25 degrees, A:B=100:1.5; when the room is low (but not below 10 degrees), increase the B component by 0.1-0.3 parts; if the room temperature is higher, reduce the B group by 0.1-0.3 Copies. The specific method is: determine the total dosage according to the mold volume, then weigh the A and B components accurately in proportion, and place them in a vessel and stir evenly. Serve.
Mold silicone operation method
- 1. Stir the mold silicone and curing agent evenly. The appearance of mold silicone is a flowing liquid, component A is silica gel, and component B is curing agent. For example, take 100 grams of silicone and add 2 grams of curing agent. (Note: The silicone and curing agent must be stirred evenly. If it is not evenly stirred, The mold will have uneven curing and drying, which will affect the service life of the silicone mold, the number of mold reversals, and even cause the mold to be scrapped. 2. Vacuum and remove air bubbles. After the silicone and curing agent are evenly stirred, vacuum and exhaust Bubble link. The vacuuming time should not be too long, generally no more than 10 minutes, otherwise, the curing of the silica gel will cause a cross-linking reaction, and it will not be able to be painted or poured, resulting in waste of materials.
- 3. Brushing operation process. Pour the bubbled silica gel on the master mold by brushing or pouring (before brushing or pouring, apply release agent or release agent on the master mold), brush the mold evenly, and stick a layer after 30 minutes Sand cloth or glass fiber cloth to increase the strength and tensile force of the mold; paint a second time, then paste a layer of gauze or glass fiber cloth, and then apply silica gel. The mold processed in this way has a service life and a reversal. More times, long service life, cost saving and improved efficiency.
- 4. The production of outer molds. The generally used method is: surround the mold with rubber or wooden boards, one is to fill the mold frame with plaster, and the other is to use resin to paint the outer mold, applying a layer of resin and coating. Brush a layer of glass fiber cloth, then paint and paste, repeat two or three layers to complete the outer mold.
- 5. The situation reflected by the ratio of silica gel (silicone, silicone) and curing agent. It is recommended that the amount of hardener added should not exceed 5%. The larger the proportion of hardener added, the faster the curing time, the more brittle the mold and the shorter the service life. According to the product and process requirements, the appropriate amount of silicone oil can be added to make the mold better. Note that the silicone oil should not be excessive (5%-10%), otherwise it will affect the tensile force and hardness of the silicone mold.