Some Explanations on the Production Process of Silicone Rubber Raw Materials and LSR Injection Molding Products

1. Properties of silicone rubber materials:

   A. The raw materials of silicone rubber are generally gelatinous, somewhat similar to plasticine, colorless, translucent and odorless.B. Its main characteristic is high temperature (300 ℃) and low temperature resistant (minimum - 100 ℃), is currently the best cold resistant, high temperature resistant rubber;At the same time, excellent electrical insulation, thermal oxidation and ozone stability is very high, chemical inertia.Disadvantages are low mechanical strength, oil resistance, solvent resistance and acid and alkali resistance, more difficult to vulcanize, more expensive price.Temperature: - 60 ℃ ~ + 200 ℃.The above is the description of silicone rubber in the manual.

   
   C. use temperature: as above, Syria, generally set to 40 ℃, 200 ℃, work in a short time of up to 230 ℃.D. aging problem:
   Poor oil resistance, acid and alkali resistance, and the stress is not much.
   E. Adhesion problem: before surface treatment, in addition to using silica gel products as adhesives with silica gel parts, adhesion with other parts must go through surface activation, vulcanization treatment of the surface to adhere.All materials that can vulcanize or crosslink with rubber are collectively referred to as vulcanizing agents, also known as crosslinking agents.There are many kinds of vulcanizates, and they are increasing. The sulfides already in use are sulfur, selenium, tellurium, sulfur-containing compounds, metal oxides, peroxides, tree esters, quinones, and amines.
   F. Material hardness: the plastic parts can be theoretically selected between 10 c and 80 c according to shore hardness in the domestic market.The most commonly used ones are 40 to 50 degrees.

   
   

2. Silicone rubber production process:

   General production process of Silicone rubber products:
   A. shape and color of Silicone rubber raw materials
   B. After color mixing, the sheets of various colors are modified by milky Silicone rubber.

   C. After mixing and shaping, the raw materials are pressed into strips and cut into strips.

   D. vulcanization molding E dressing, dismantling, inspection, packaging.

   F. finished product figure

3. Product size and features:

   A. Limit size: 15~20MM at the thickest part, 30MM in diameter if it is A sphere.The recommended size for general thickness is no more than 3MM, when it is greater than 3MM, it will take more time and increase the cost of vulcanization.The thinnest part can reach 0.2mm in theory, but the thinnest part is generally 0.3mm in design, and 0.4mm is recommended.
   B. Relative size: in terms of thickness difference, the thinnest part and the thickest part are not recommended to exceed 3 times.This kind of problem mainly depends on the material vulcanization temperature and pressure requirements.
   C. shrinkage.The shrinkage of silica gel material is related to the hardness of the material. The secondary materials provided by the manufacturer are mostly between 1.022 and 1.042. For materials with 40 to 50 degrees, the shrinkage rate of 1.03 is generally taken.Compared to plastic, silicone products do not shrink to produce similar obvious surface defects.
   D. Dimensional accuracy: because the silicone products are mostly one mold with many holes, compared with the plastic products, the number of holes is very large.Therefore, it is not as convenient as plastic products in size control.The general accuracy is plus or minus 0.1, and the precision product is plus or minus 0.05.When the fit is used to fit the holes and keys of the plastic parts, the minimum clearance is unilateral 0.1 and the recommended value is unilateral 0.2.
   E.shape design: for the plastic cover parts, generally according to the shape of the product to the mold factory to provide the original drawing, with the problem to make the explanation, by the mold factory to decide.Under normal circumstances, depending on the size of the product, the fit between the rubber cover and the product is generally a negative deviation of 0.2-0.5 in one side.