High and low-temperature experiments are the must-test items for product reliability. So what impact does high and low temperature have on the product? experimental method. United Precision Services | Bost Heavy Duty Machines
The effect of high and low temperature on product reliability
The effect of low temperature on the product
Elastic materials such as rubber have reduced elasticity and cracks;
The brittleness of metals and plastics increases, resulting in cracking or cracking;
Because of the different shrinkage coefficient of the material, when the temperature change rate is relatively large, it will cause the moving parts to jam or rotate;
The viscosity of the lubricant increases or solidifies, and the friction between moving parts increases, causing sluggish movement and even stopping work.
Changes in the electrical parameters of the components affect the electrical performance of the product;
Icing or frosting cause product structure damage or moisture. United Precision Services | Bost Heavy Duty Machines
Low-temperature environment effect
Hardens and embrittles the material.
The different shrinkage characteristics of different materials make the parts stuck.
Loss of lubrication due to increased viscosity of the lubricant.
Electrical changes (such as resistance, capacitance, etc.).
Transformer and electromechanical components have changed functions.
The impact base hardens.
Explosives burst, such as ammonium nitrate. United Precision Services | Bost Heavy Duty Machines
Causes cracks, embrittlement and changes in impact strength and strength
Glass produces static fatigue.
Let the water condense and freeze.
Reduce people’s dexterity and degrade hearing and vision.
Change the burning rate.
High-temperature impact on the product
Due to the different expansion coefficients of various materials, resulting in the adhesion and migration of materials;
Loss of lubricant or reduced lubricating properties increased wear between moving parts;
Sealing packing, gaskets, seals, bearings and rotating shafts, etc.
Mechanical failure or complete failure due to adhesion;
Changes in the electrical parameters of components affect the electrical performance of the product
Transformer, electromechanical components overheat;
Flammable or explosive materials cause combustion or explosion;
The increased internal pressure in the seal causes cracking;
Aging, discoloration, blistering, cracking, or cracking of organic materials;
The insulating properties of the insulating material decrease. United Precision Services | Bost Heavy Duty Machines
High-temperature environment effect
The different expansion characteristics of different materials make the parts stuck.
The lubricant loses its viscosity and causes loss of lubricant and causes the joint to lose its lubrication.
All or part of the test piece is resized.
Mechanical or complete failure due to skewed jammed and failed packaging, gaskets, seals, bearings, and spindles.
The gasket is permanently deformed (gel-like).
Airtight function degradation.
The resistance value changes.
The stability of the circuit changes with temperature gradients and different expansion characteristics of the material.
Transformer and electromechanical components are overheated.
Change the role of the relay and the magnetic and hot starter components.
Keep your operating life short.
The internal crystal structure of the solid material produces separation.
High pressure is generated inside the sealed specimen.
Accelerates the burning of explosives and propellers.
Explosive casting shell expands.
Explosives dissolve and exude.
Organic materials deteriorated and cracked. United Precision Services | Bost Heavy Duty Machines
Impact of temperature changes on the product
The falling of the composition coating layer, the cracking of the potting material and the sealing compound, and even the cracking of the sealing case and the leakage of the filling material cause the electrical performance of the component to decrease.
Products made of different materials, the product is heated unevenly when the temperature changes, resulting in product deformation, cracking of sealed products, broken glass or glassware and optical devices;
The large temperature difference causes condensation or frost on the surface of the product at low temperatures and evaporates or melts at high temperatures. As a result, this repeated action leads to and accelerates product corrosion.
Temperature change environment effect
Glassware and optical equipment burst.
The movable parts are stuck or loose.
The structure produces separation.
Electronic or mechanical failure due to rapid condensation or freezing.
Cracks occur in granular or grainy form.
Different shrinkage or expansion characteristics of different materials.
Deformed or broken components.
Surface coating cracks.
Sealed compartment leaks. United Precision Services | Bost Heavy Duty Machines
Application Comparison of Various Test Methods for High and Low-Temperature Test Chambers
First, the thermal test sample with and without forced air test
In the high and low-temperature test chamber industry, the method of ensuring the fluctuation of the uniformity is to adopt the wind circulation mode. The motor drives the wind turbine to generate the wind circulation to form the direction of the wind speed. The test without forced air circulation is an experiment simulating the influence of free air conditions. For testing of heat-dissipating test specimens, there are forced air circulation tests where forced air circulation is used when it is difficult or impossible to guarantee the specified test conditions: 1 and 2, and Method 1 is used for the test chamber Large enough to meet the test requirements without forcible air circulation, but when the inside of the box cannot maintain the specified low temperature without forced air circulation, the cooling or heating of the high and low-temperature test box requires forced air circulation.
Second, the on-heat-dissipation test sample and heat dissipation test sample
After the temperature of the test sample is stabilized during the condition test, the maximum hot spot temperature on the surface of the test sample is higher than the ambient air temperature by more than 5 degrees in the free air condition, and it is considered to be heat dissipation, and conversely it is a non-heat-dissipation test sample. During the test and during the test, the test samples shall be non-heat-dissipation test samples with no electricity or load, and the test shall adopt a low-temperature test method. United Precision Services | Bost Heavy Duty Machines
Third, the on-thermal test sample
High-low temperature test chamber temperature gradient test (the former is a rapid temperature change test chamber and the latter is a high-low temperature test chamber)
1Temperature change test: firstly put the test sample with room temperature into the same test chamber at room temperature, and then start the cold source to gradually cool the inside temperature to the specified test temperature, if the test sample is too large or too heavy, or because Complex functional test wiring should also be used when the mutation test cannot be put into a cold box without frosting.
2 temperature mutation test: first test chamber temperature is adjusted to the specified test temperature, and then placed in a test sample with room temperature, this test method is suitable for a known temperature change on the test sample when no operation.
8 points for selection of high and low temperature chambers
1. The user shall meet the temperature conditions stipulated in the test requirements no matter whether he is selecting a high or low temperature test box or other test equipment;
2. To ensure the uniformity of the temperature in the test zone of the test chamber, the choice of whether to use forced air circulation or forced air circulation may be selected according to the heat dissipation of the sample;
3, heating or cooling system device of high and low temperature test box has no effect on the sample; United Precision Services | Bost Heavy Duty Machines
4, the test box to facilitate the relevant sample rack to place the sample, and the sample rack will not change its mechanical properties due to high and low temperature changes;
5, high and low temperature test box should have protective precautions. For example: there are observation windows and lighting, with power off phase, over-temperature protection, various types of alarm devices;
6, according to the customer’s request whether there is a remote monitoring function;
7, the implementation of the test box in the implementation of the cycle test must require the installation of automatic counters, indicators and recording equipment and automatic shutdown and other instrumentation, and requires a good record and display functions;
8, according to the sample temperature with the upper wind and the use of the downstream sensor temperature measurement method, the temperature and humidity control sensor in the high and low temperature test chamber position and control method can be selected, the eye according to the customer’s product test requirements to select the appropriate equipment . United Precision Services | Bost Heavy Duty Machines