Silicone molding process and vacuum casting process

(Here is an article from silicone supplier, wanted to sharing with you.)

1. Definition of silicone mold Mold silicone rubber is a kind of silicone room temperature two-component mold glue, referred to as RTV. This is a two-component compound. Part A contains the crosslinker and Part B contains the catalyst. Crosslinkers and catalysts must be separated during packaging. Its vulcanization is carried out at room temperature. As long as the two components are mixed in a certain proportion (the specific proportion can be determined according to the operation time and product performance), the two-component rubber will undergo a cross-linking reaction to form a soft and elastic colloid. . Suitable for glass resin, epoxy resin, Pu foam resin, gypsum, cement, candles, electronics and other craft factories, toy factories, electronics factories, lighting factories, silk screen factories, candle factories, making decorative crafts and replicas, and making molds.

2. Mold silicone rubber molding process (1) Raw materials Mold silicone rubber is generally composed of base rubber, crosslinking agent, catalyst and filler. The base rubber is 107 silicone rubber, the full name is hydroxyl-terminated polydimethylsiloxane. This type of mold silicone rubber can be cured at room temperature, has good fluidity, no deformation, and only slight linear shrinkage. The crosslinking agent is ethyl orthosilicate. The addition of crosslinking agent has a significant effect on the vulcanization time, tear strength and elongation of silicone rubber. Practice has proved that the amount of cross-linking agent added is 5% (mass fraction) of the base glue. The catalyst is dibutyltin dilaurate. The amount of catalyst added is directly related to the curing time. It should not be too much, generally 1% to 2% (mass fraction). Fillers include talc, quartz powder and silica. Talc is generally used as a filler. When using silica as a filler, mechanical strength, tear strength and uniformity are significantly improved.

  3. Vacuum casting process 1. Configure ABS solution according to product weight (A:B=10:1)
        Mix AB solutions and degas (operate in a vacuum cabinet) Degas before and after mixing. Watch and prevent liquid spillage while degassing. 3. Spray the release agent into the silicone mold cavity 4. Use ABS to adapt to the climate and enter the vacuum cabinet 5. Use plastic film to make a vacuum machine in the pouring channel 6. Operate the vacuum machine for silicone mold casting 7. Vacuum degas and observe the ABS Whether the cavity is filled, make up if necessary. 8. After the pouring is completed, wrap the silicone mold and send it to the oven. After baking for several hours, the ABS solution is solidified and the mold can be opened. 9. Be careful when opening the mold to avoid damaging the silicone Mold 10. For products with higher requirements, do plastic post-processing (bonding, grinding, etc.).