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How to solve the problem of large shrinkage of silicone molds?


The shrinkage of silicone molds is a normal phenomenon. Any kind of mold will shrink after the silicone solidifies and becomes a mold. Shrinkage occurs because the silicone liquid has different molecules and different densities when it is solid. When it is converted from liquid to solid, it shrinks. The shrinkage rate of good silicone is small, while the shrinkage rate of poor silicone is greater. The direct result of mold silicone shrinkage is that the size of the products coming out of the mold is different. The shrinkage rate of good quality addition mold silicone is ≤0.1%.

Reasons for large shrinkage of mold silicone:

  1. Any material has a certain degree of shrinkage. Compared with many materials, the shrinkage rate of silicone rubber is very small;
  2. The mold storage method is incorrect;
  3. The larger the product size, the more obvious the shrinkage;
  4. No fiberglass cloth is added to large-scale products;
  5. The master who opens the mold often does not adjust the glue according to the manufacturer’s mixing ratio of AB components, but increases the proportion of curing agent according to his own experience;
  6. The mold is not completely cured and the hardness of the silicone is not stable. If you rush to demould or produce in advance, the silicone mold will easily deform and shrink.

Solutions to the large shrinkage of silicone molds:

  1. After the mold is made, it is best to leave it for 24 hours before use;
  2. Enlarge the model according to the shrunk size;
  3. When storing the mold after use, put the mold type in the product and store it together. If it is an extra large product, it can be preserved by pouring plaster;
  4. For slightly larger products, add gauze or fiberglass cloth when opening the mold;
  5. If you use the brush-on mold, you need to make a master mold.

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