How to choose the hardness of silicone rubber for molds?

In the daily reception of customers, many of them are not sure which model of mold silicone rubber they want to choose. Often, customers ask me what hardness of mold silicone rubber I want to choose for food molds. I do precision casting, and what hardness of mold silicone do I want to choose? Below, Hongtu will explain in detail the selection of silicone hardness for molds.

At present, the hardness units of silicone on the market are generally Shore A and a small amount of Shore C. The common hardness ranges from 0 to 70, with a hardness interval of 5 and a hardness error range of about ± 2. There is no good or bad difference in silicone hardness, so choosing the appropriate silicone hardness is the best. Generally, for models and patterns that are more complex, choose low hardness, while for large models with simple patterns, choose higher hardness.
For the production of silicone molds for food products, such as chocolate, candy, and sugar flipping, it is recommended to use silicone molds with an additional hardness of 10-20, because the flipping of silicone molds for food products is generally done by pouring, and these materials are relatively crispy. On the one hand, using low hardness silicone can better demould, and on the other hand, it can ensure that the product is not damaged due to the high hardness of the silicone during demolding, which can achieve good detail replication effect. In addition, when making sugar flipping molds, it is always necessary to repeatedly pull the silicone mold. Low hardness silicone has better tensile performance, which is conducive to extending the service life of the silicone mold and increasing the number of mold flipping times. For the production of precision casting silicone molds, it is recommended to choose 40 hardness plus molded silicone because the silicone of the plus molded mold has better high-temperature resistance and shrinkage compared to the condensed mold.

Flipping the mold is generally based on the size and complexity of the product to choose whether to use a pouring mold or a brushing mold. In principle, the size of the product is directly proportional to the hardness of the silicone used. If it is a small product, products within 30 centimeters or with very fine patterns can be molded using soft silicone with a hardness of 15-20 degrees. This will facilitate demolding and will not damage the fine patterns of the product; If it is a medium-sized product, such as a product with a thickness of about 50 centimeters, it is recommended to use silicone at a temperature of 25-30 degrees for mold opening. If you are creating a three-dimensional product with fine or complex patterns, you can use silicone at around 20-30 degrees to open the mold using a brushing method. The method is to brush a layer of silicone onto a layer of fiberglass cloth, then brush a layer of silicone onto a layer of fiberglass cloth, and repeatedly increase the tensile and tear properties of the silicone mold twice. The outer mold can be made with gypsum or fiberglass to protect the product from deformation.