Hot and Cold Shock Chamber is a device that simulates alternating high and low temperature environments. It is widely used in industries such as electronics, automotive, aerospace, plastics, and metals to test the performance, stability, and durability of products under harsh temperature conditions. By rapidly switching between high and low temperature environments, it simulates the temperature changes that products may encounter during actual use, thereby testing their temperature resistance, thermal shock resistance, and crack resistance.
Working Principle
Refrigeration Working Principle
This system simulates rapid changes in temperature to quickly reflect the performance changes of test items under natural temperature variations. A fan blows air of different temperatures onto the test items, using a switching airflow method to allow only the high-temperature or low-temperature air to be blown in at a time. This method is also known as thermal shock testing. The thermal shock testing machine has adjustable temperatures; the low-temperature zone ranges from -70℃ to ambient temperature (RT), and the high-temperature zone ranges from ambient temperature (RT) to 200℃. Furthermore, the time required for the high-temperature zone to rise from ambient temperature to the highest temperature is approximately 35 minutes, and the time required for the low-temperature zone to drop from ambient temperature to the lowest temperature is 55 minutes. The thermal shock test can withstand up to 9999 shock cycles, with each shock lasting up to 999 hours.
The specific process is as follows:
Refrigeration System:
Composition: Mainly composed of an evaporator, compressor, condenser, and expansion valve.
Process: The refrigerant evaporates and absorbs heat in the evaporator, then is compressed into a high-temperature, high-pressure gas by the compressor. It then releases heat through the condenser, and finally, after being depressurized by the expansion valve, returns to the evaporator to continue operation. This cycle allows the test chamber to rapidly decrease its temperature.
Heating System:
Typically, electric heating elements are used.
By controlling the energizing time and current of the heating elements, the temperature inside the test chamber is gradually increased.
Temperature Control:
The thermal shock test chamber employs a PID+SSR precision control system.
This system automatically adjusts the output power of the refrigeration and heating systems according to the set temperature range and rate of change, ensuring that the temperature inside the test chamber changes according to the preset requirements.
What is Thermal Shock Testing?
A thermal shock test is an environmental reliability testing method used to evaluate the performance and reliability of a product under conditions of rapid temperature changes. By simulating the rapid switching between extreme high and low temperatures, it tests whether a product can withstand the stress caused by drastic temperature changes and verifies its durability, functionality, and structural integrity.
The main purposes of thermal shock testing are:
To test product reliability: To assess the product's ability to withstand rapid temperature changes.
To discover potential defects: To expose problems in the product's design, materials, or manufacturing processes.
To verify product lifespan: To simulate extreme temperature change environments and predict the product's lifespan.
To ensure safety: To prevent product malfunctions or hazards under drastic temperature changes.
There are two main types of thermal shock testing:
1. Two-chamber thermal shock (gas shock): The equipment has two chambers (high-temperature zone and low-temperature zone). The sample is placed in a basket, and the effect of thermal shock is achieved by the movement of the basket between the high-temperature and low-temperature zones.
2. Two-box temperature shock (liquid shock): This equipment has two boxes (high temperature zone and low temperature zone). The high temperature zone and the low temperature zone are filled with silicone oil. The sample is placed in a basket. The thermal shock effect is achieved through the movement of the high temperature zone and the low temperature zone.
Maintenance and Care Items
When operating this equipment, we cannot only focus on using the testing equipment; we also need to perform regular maintenance and care to ensure its long-term stable service. The same applies to the thermal shock test chamber. As a precision testing instrument, it requires both proper operation and careful maintenance. So, what maintenance items are necessary for the equipment? Let's take a look!
1. The radiator (condenser) of the refrigeration unit should be maintained and kept clean regularly. Dirt adhering to the condenser can cause the compressor's high-pressure switch to trip, resulting in false alarms. The condenser should be maintained monthly. Dirt on the condenser cooling screen can be brushed off with a stiff brush after power is connected, or blown away with a high-pressure air nozzle.
2. The refrigeration system is the core of the thermal shock test chamber: it must be checked every six months for snow leakage. If there is any oil leakage at the flared joints and welded joints, please handle it promptly or contact a professional.
3. High-current contacts on the distribution board: The distribution room should be cleaned and inspected at least once a year. Loose contacts can put the entire equipment in a dangerous operating condition, potentially causing burns to parts or even fires, alarms, and personal injury. Use a vacuum cleaner to remove dust during cleaning.
4. The distribution room should be cleaned at least once a year. Use a vacuum cleaner to remove dust. The outer surface of the casing should be cleaned at least once a year; soapy water can be used for cleaning.
5. The settings of the two over-temperature protection devices inside the distribution box must not be arbitrarily adjusted: They have been adjusted at the factory. These protection switches are used to protect the air-fuel pipe and heat pipe from alarms, with a set temperature of +20℃ to 30℃.
6. After product testing: The power must be turned off when retrieving the product. Personnel must wear moisture-proof, anti-electric shock, and high-temperature resistant gloves when handling the product.
Requirements for the Thermal Shock Test Chamber Site
1. Environmental Requirements: Free from strong vibrations and electromagnetic fields, high concentrations of dust, flammable, explosive, volatile, and corrosive substances, direct sunlight, or direct radiation from other heat sources (very important);
2. Temperature and Humidity Requirements: Ambient Temperature: 5℃~28℃; Relative Humidity: ≤85%RH; Atmospheric Pressure: 86~106Kpa
3. The equipment will generate heat during operation, so a space of 50~80CM should be reserved around the equipment for future maintenance by engineers;
4. Drainage Interface: Suitable for drainage ditches and pipes for overflowing water;
5. Ground Requirements: The thermal shock test chamber should be placed horizontally in a well-ventilated test chamber, with at least 1.5 meters of space around it for operation and maintenance.
The importance of thermal shock test chambers as key equipment for evaluating product performance and reliability under extreme temperature changes is self-evident. From in-depth analysis of their working principles to meticulous maintenance and strict control of site requirements, every step is crucial to the accuracy of test results and the lifespan of the equipment. Correct use and careful maintenance of thermal shock test chambers not only provide strong support for improving product quality but also lay a solid foundation for enterprise research and development innovation and enhanced market competitiveness. Therefore, we should pay full attention to every detail of the thermal shock test chamber to ensure that it is always in the best working condition, thus safeguarding the reliability and safety of the product.
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