1、Insufficient foaming holes

Causes:

(1) quality problems of foaming agent;

(2) low plasticity of the rubber material;

(3) too high mixing temperature and early decomposition of the foaming agent;

(4) The rubber is parked for too long or at too high a temperature, and some of the foaming agent evaporates or decomposes;

(5) The vulcanization speed of the rubber is too fast;

(6) the pressure is too high, exceeding the internal pressure formed by the gas of the foaming agent, resulting in insufficient foaming holes;

Countermeasures:

(1) check whether the foaming agent is within the limited period and whether it is qualified;

(2) check whether the plasticity of the rubber material meets the standard, plasticity is too low should be supplemented by mixing, increase plasticity to facilitate the development of holes;

(3) Check whether the discharge temperature of the mixing machine is too high, whether the roll temperature is too high, and whether the rubber is burnt. Some rubber materials with high mixing temperature can be mixed with a small amount of treatment or add foaming agent heavy industry;

(4) The rubber should be returned to the refining for supplementary processing after too long a parking time;

(5) formula adjustment, check whether the critical temperature of vulcanizing agent and the decomposition temperature of foaming agent are close to each other, and coordinate with each other to make the vulcanization speed and foaming speed match;

(6) adjust the pressure of the machine.

2. Insufficient filling mold

Causes:

(1) Insufficient amount of rubber used;

(2) Insufficient mold finish or mold used for too long without cleaning, the flow of rubber is subject to resistance;

(3) The cavity structure is complicated and the flowability of the rubber does not match, and often cannot fill the top of the mold after the hole is issued, forming defects;

(4) The air in the dead corner of the mold cavity can not be discharged, so that the rubber is not filled with the cavity, resulting in the edge of the lack of glue;

Countermeasures:

(1) Weighing one by one to ensure the weight of glue material;

(2) improve the fluidity of the rubber;

(3) Modify the mold, reasonable design of air venting holes, mold structure, etc.

3. Uneven foaming holes (too big or too small)

The foam hole is too big, the hardness and density of the product are not standard, the closed hole will become joint hole, the micro hole becomes small hole, some parts collapse or some parts can't be sent up.

Causes:

(1) foam agglomeration or particles are too coarse;

(2) uneven mixing;

(3) high water content of the compounding agent, air or impurities mixed in the rubber;

(4) Insufficient vulcanization, continue to develop holes after the mold;

Countermeasures:

(1) check the foaming agent, if the phenomenon of agglomeration should be sieved, coarse particles should be crushed, fully mixed (or thin pass) to make it evenly dispersed;

(2) with agent moisture should be too high after drying, remove the air or impurities in the rubber material, so that it is fully vulcanized.

4. over-vulcanization or under-vulcanization

(1) Over-vulcanization

General surface discoloration, small eyelet, high hardness, product edge cracking, resulting from improper operation, or too high temperature, too long vulcanization time or instrument failure, should check whether the valves and instruments have problems, and then to strictly implement the operating rules.

(2) under vulcanization

When the vulcanization is insufficient, the inner pressure of the pore is greater than the outer pressure after leaving the mold, and if the rubber continues to send holes, the light will cause low hardness, poor strength and large deformation; the heavy will cause the holes to burst. It should check whether there is any problem with the instrument and valve, and strictly implement the operation rules.

Note: Foam products control quality indicators

(1) Apparent density, the smaller the better;

(2) mechanical strength is generally 0.5-1.6Mpa;

(3) static compression permanent deformation;

(4) hardness;

(5) impact elasticity;

(6) continuous dynamic fatigue;

(7) aging test (70 degrees * 70 hours; 100 degrees * 24 hours);

(8) low temperature test.