Liquid silica gel is relative to solid high-temperature vulcanized silicone rubber. It is a liquid rubber with the characteristics of good fluidity and fast vulcanization. It is safer and environmentally friendly, and can fully meet the requirements of food grade. Liquid silicone has excellent transparency, tear strength, resilience, yellowing resistance, thermal stability, water resistance,
Good air permeability, heat aging resistance and weather resistance. At the same time, the viscosity is moderate, easy to operate, and the product has high transparency. It can be seen whether there are defects such as bubbles in the casting material in the mold. The linear shrinkage rate is ≤0.1%.
Precautions for liquid silica gel:
1. Combination line: The injection speed and pressure need to be adjusted. Adjust the parameters according to the mold structure, and the degree of visibility will moderately increase the material temperature or mold temperature.
2. Concavity (shrinkage): Insufficient holding pressure can increase holding pressure moderately. Insufficient amount of glue (mixing inferior materials affects the amount of blanking). Confirm that the shrinkage at the feed opening is too thick or uneven.
3. Breaking head: Check whether there is any residual rubber influence on the grab pin, the temperature of the nozzle is too low or the part of the vertical material mouth is damaged, and the mold opening speed is too fast to slow down the first stage speed.
4. Deformation: Insufficient holding pressure, insufficient cooling of the finished product, need to increase the cooling time, poor ejection and demolding, confirm whether the ejection speed is too fast, and confirm whether there are barb burrs on the mold.
5. Spray marks: The spraying phenomenon will be improved if the shooting speed is too fast. The material drying is not reliable. The injection port of the mold part is too small and the shooting is slow and cannot be formed. The injection port must be adjusted appropriately.
6. Flow mark: It is caused by the plastic cold material flowing out of the spiral tube. It can be improved by loosening it later, and it can also reduce the nose temperature or adjust the back pressure appropriately, but pay attention to the mixing of raw material masterbatch.
7. Silver thread: Whether the material is really dried, whether it has been left for too long to absorb moisture again, whether the added secondary material (grinding material) is dried again, the mold core leaks or the water pipe joint leaks, and the mold temperature is mostly different from the ambient temperature. .
8. Color difference: check whether the amount of color masterbatch is sufficient, confirm whether the batch number of the color masterbatch is correct, increase the screw speed to mix the color masterbatch evenly, confirm whether the color masterbatch meter is abnormal, and there is color difference or obvious ring at the glue feeding point You can try to make some adjustments after the injection is not made and reduce the holding pressure to reduce the stress here.
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