Many EPDM sealing strip manufacturers claim that their products are in accordance with the national standard gb12002 and can issue the test report qualified by the authority. According to the test of the sealing strip samples sent by relevant manufacturers, the heating weight loss target results in the hot air aging function project are surprising: of more than 10 samples, only 4 are qualified. Common problems are as follows:
1. Use cheap substitutes.
According to the rules of gb12002 standard, the heating weight loss target in the hot air aging function project of sealing strip shall be ≤ 3%. The heating weight loss of practical test results is 7.17% ~ 22.54%. Far beyond the scale of national standard rules. For such sealing strips, many low boiling point plasticizers or substitutes of plasticizers are added to the formula.
2. Over vulcanization
Generally, the surface is discolored, the hole is small, the hardness is high, and the edge of the product is cracked. The causes are improper operation, or the temperature is too high, the vulcanization time is too long or the instrument fails. Check whether there are problems with each valve and instrument, and then strictly implement the operation rules.
3. Under vulcanization
When the vulcanization is insufficient, the internal pressure of the air hole after the mold is out is greater than the external pressure. If the rubber continues to have holes, the hardness will be too low, the strength will be poor and the deformation will be large; The most serious is hole blasting. Check whether there are problems with instruments and valves, and strictly implement the operating rules.
This requires you to polish your eyes when buying EPDM sealing strips, find regular manufacturers and choose high-quality sealing strip products.
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