In the processing and production of silica gel products, in order to shorten the cycle time as much as possible, for the peroxide silica gel, you can choose relatively high vulcanization temperature. According to the different wall thickness of silicone products, the mold temperature is generally selected between 180℃ and 230ºC. However, there are often some thorny problems in the process of processing and production of silica gel products. It is necessary to pay attention to the following points.
(1) If the temperature is too high, there will be cracks around the parting surface, especially for the workpiece with large thickness. This is caused by excessive internal stress caused by expansion in the vulcanization process. In this case, the temperature of the mold should be lowered. The temperature of the injection unit should be set at 80℃ to 100℃. If you are producing parts with relatively long curing times or cycle times, this temperature should be lowered a bit.
(2) For platinized silica gel, it is recommended to use lower temperature. Generally, the temperature of the injection unit does not exceed 60℃.
(3) Compared with natural rubber, solid silica gel can fill the mold cavity quickly. However, in order to avoid and reduce the formation of air bubbles and other impurities, the injection speed should be reduced. The pressure retaining process should be set for a relatively short time and a small pressure. Too high or too long pressure holding will produce return notch around the gate.
(4) peroxide vulcanization system of silicone rubber, the vulcanization time is equivalent to fluorine rubber or EPM, and for platinized silica gel, the vulcanization time is higher and can be reduced by 70%.
(5) Release agent containing silica gel is strictly prohibited. Otherwise, even slight silica gel contamination will lead to the occurrence of mold sticking.
Post time: Dec-01-2022