1. Characteristics of siliconematerial

A. The raw material of silicone is generally gel-like, colorless, translucent, and odorless.

B. Its main feature is that it is resistant to both high temperature (300°C) and low temperature (low -100°C). It is the current cold-resistant and high-temperature-resistant rubber; at the same time, it has excellent electrical insulation, high stability to thermal oxidation and ozone, and chemical inertness. big. The disadvantage is that the mechanical strength is low, oil resistance, solvent resistance and acid and alkali resistance are poor, it is difficult to vulcanize, and the price is more expensive. Operating temperature: -60°C-+200°C. The above is the description of silicone rubber in the manual.

C. Operating temperature: As mentioned above, it is generally set at -40°C-200°C, and it can reach 230°C in a short time.

D. Aging problem:

Oil resistance, acid and alkali resistance are poor, and have little to do with the stress.

E. Adhesive problem: Before surface treatment, except for using silicone products as adhesives to bond with silica gel parts, it must undergo surface activation and vulcanization treatment to bond with other parts. All substances that can vulcanize or cross-link rubber with rubber are collectively called vulcanizing agents, also known as cross-linking agents. There are many types of vulcanizing agents, and they are still increasing. The vulcanizing agents that have been used include sulfur, selenium, tellurium, sulfur-containing compounds, metal oxides, peroxides, resins, quinones, and amines.

F. Material hardness: Plastic parts can theoretically be selected between 10 degrees and 80 degrees according to Shore hardness in the domestic market. The ones that can be easily found are generally 20 to 70 degrees, and the commonly used ones are 40 to 50 degrees.

Second, the production process of silicone products

A raw material shape and color

B After color mixing and mixing, the flakes of various colors are transformed from milky white silica gel

C After kneading and shaping, press the raw materials into strips and cut them into strips.

D vulcanization molding

E trimming, edge removal, inspection, packaging.

F. Finished picture

3. Product size and characteristics

A. Limit size: the thickness can be 15-20MM, if it is a sphere, the diameter can be 30MM. Generally, the recommended thickness size is no more than 3MM. When it is larger than 3MM, it will take more vulcanization time and increase the cost. In theory, the thickness can reach 0.2MM, but the thickness is generally 0.3MM in design, and 0.4MM is recommended.

B. Relative size: In terms of thickness difference, it is recommended not to exceed 3 times between the thin and thick parts. Such problems mainly depend on the temperature and pressure requirements of the material during vulcanization.

C. Shrinkage rate. The shrinkage rate of the silicone material is related to the hardness of the material. Most of the secondary materials provided by the manufacturer are between 1.022-1.042. For materials with a temperature of 40 to 50 degrees, the shrinkage rate of 1.03 is generally taken. Compared with plastic, silicone products will not produce similar obvious surface defects due to shrinkage.

D. Dimensional accuracy: Because most of the silicone products have multiple holes in one mold, the number of holes is very large compared to plastic products. Therefore, it is not as convenient as plastic products in size control. The general accuracy is plus or minus 0.1, and the high precision product is plus or minus 0.05. When matching with the hole of the plastic part and the button, the minimum clearance is 0.1 on one side, and the recommended value is 0.2 on one side.

E. Shape design: For rubber sleeve parts, it is generally enough to provide the original drawing to the mold factory according to the outline drawing of the product, and explain the matching problems, and the mold factory decides by itself. Under normal circumstances, depending on the size of the product, the matching between the rubber sleeve and the product is generally a negative deviation of 0.2-0.5 on one side.

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