The constant temperature and humidity test chamber is also called "environmental test machine", which is mainly used for heat resistance, cold resistance and wet performance of materials. Suitable for electronic, electrical, communication, instrumentation, vehicles, plastic products, metal and other quality inspection, using touch screen intelligent instrument, can set the program cycle test, in the test phase, tell the cause of the cycle failure of the constant temperature and humidity test machine Situation, below we analyze the cause of failure:
1. Basic parameters of temperature cycle stress:
There are six basic parameters: 1 upper limit temperature; 2 lower limit temperature; 3 temperature change rate;
4 upper limit temperature holding time; 5 lower limit temperature holding time; 6 cycles.
2. Temperature Cyclic Stress Analysis: In the temperature cycle test, the uniformity of the gas flow in the constant temperature and humidity chamber is an important parameter that will affect the rate of temperature change of the product. This requires that when multiple test products are tested simultaneously, there should be appropriate spacing between the test products, between the test product and the test chamber wall, so that the air flow can freely circulate between the test products, between the test product and the tank wall. .
3. The mechanism of temperature cycle stress induced failure and sensitive components: temperature cycling causes different materials with different expansion coefficients to expand differently, resulting in peeling, cracking, and sensitive components such as paint coating.
3.1 temperature cycle to loosen the screw joint or riveted joint, its sensitive components such as screws, riveted parts, etc.;
3.2 The temperature cycle relaxes the press-fit joint with insufficient mechanical tension; the temperature cycle of the high-low temperature alternating test chamber makes the brazed contact resistance of the poor
material increase or induces an open circuit, and its sensitive components such as resistive elements;
3.3 Temperature cycling causes contact corrosion and contamination, and its sensitive components such as alloy materials.
The above description of the reasons for the cycle failure of the constant temperature and humidity tester may make everyone more aware of the knowledge of the constant temperature and humidity test chamber. Can use the operating machine more clearly.