1 rubber products forming, after large pressure suppression, due to the cohesion of the elastomer can not be eliminated, when forming from the mold, often produce unstable contraction (rubber shrinkage, because of different types of rubber and there is a difference), must be after a period of time, can be gentle and stable. Therefore, when a rubber product design at the beginning, regardless of the formula or mold, need to calculate carefully, if not, it is easy to produce product size instability, resulting in low quality products. 2. Rubber is thermosetting elastomer, while plastics are thermosetting. Due to the different main body of sulfide, the temperature range of rubber forming and curing is quite different, and can even be affected by climate change, indoor temperature and humidity. Therefore, the production conditions of rubber products, need to make appropriate adjustments at any time, if not, there may be differences in product quality