(1) Wrapped into the air when melting glue. Pressure is too small or time is too short, the air wrapped in the injection process can not be fully discharged, resulting in products produce air bubbles.

　　Solution: If the air is wrapped in the melt, increase the back pressure, injection pressure, holding pressure and holding time appropriately.

　　(2) The rubber contains water.

　　Solution: Properly adjust the product formula, add stabilizers; thorough drying of the material to remove the low molecular material.

　　(3) Mold design is unreasonable, such as incorrect location of the gate or the cross-section of the gate is too small, the main flow channel and manifold are long and narrow, etc., which may cause air bubbles.

　　Solution: Reasonable design of the structure of the mold (including the structure of the runner, gate structure, etc.)

　　(4) Process conditions: molding temperature is too high; molding cycle is too long.

　　Solution: Reduce the molding temperature appropriately; shorten the molding cycle.