Rubber joint bubble, orifice

Reason: 1.Vulcanization is insufficient 2.Underpressure 3. Impurity or oil in mold or compound. 4.Vulcanization mold temperature is too high 5. Less vulcanizing agent, too slow vulcanization rate

Solution: 1. Compression 2. Lengthening sulfur 3. Adjust the formula to speed up the vulcanization speed 4. Multiple exhaust. 5. Mold temperature should not be too high. 6.Increase the amount of curing agent.