and the rationale
The multi-factor integrated test chamber integrates four environmental stresses: temperature, humidity, vibration and altitude (low atmospheric pressure) to simulate and verify the reliability and performance of products in complex and coupled environments. At its core, it enables precise, independent and coordinated control of various stress parameters, reproducing the comprehensive environmental conditions in the real world or specific standards. System selection should be based on strict engineering requirements and compliance with standards, rather than a single parameter comparison.
Stress parameters
The primary task of selection is to clarify the technical range and control accuracy of each stress parameter, and it is necessary to refer to relevant national standards, international standards (such as IEC, MIL standards) and industry-specific specifications.
Temperature system:The effective volume and temperature range of the working chamber need to be determined. The rate of temperature change is a key indicator, usually expressed as a linear average rate, such as 5°C/min. Control accuracy is usually required to be better than ±0.5°C (in steady state). The temperature uniformity needs to meet the standard requirements, and the calculation formula can be referred to: Δ T_u = max| T_i - T_avg|, where T_i is the temperature at each measurement point, and T_avg is the average temperature at each point.
Humidity system:Attention should be paid to the relative humidity range (e.g., 10% RH to 98% RH) and control accuracy (e.g., ± 2% RH). In low dew point or high humidity conditions, the system's dehumidification and humidification capabilities are critical. There is a strong coupling relationship between humidity and temperature, and the following ability and stability of humidity control should be evaluated during the whole temperature change process.
Vibration system:The frequency range, maximum acceleration, thrust and displacement should be determined according to the test criteria (e.g., sinusoidal vibration, random vibration). The thrust calculation should consider the total mass of the table extension device and the specimen. The formula is: F = (m_t + m_s) × a, where F is the required thrust, m_t is the moving coil and table mass, m_s is the mass of the specimen, and a is the target acceleration.
Altitude (low pressure) system:The simulated altitude or air pressure range (e.g., normal pressure to 0.1 kPa) needs to be clarified. Focus on pumping and leakage rates to ensure that the target air pressure can be quickly reached and maintained stable during comprehensive testing. The change of air pressure may interfere with the temperature and humidity control, and the system needs to have good decoupling control capabilities.
System integration
4. The technical difficulty of the integrated system lies in the interaction between stresses and the decoupling of control. The maturity and reliability of the integration solution must be evaluated during selection.
Structural Compatibility:The shaker usually runs through the bottom or top of the temperature and humidity cabinet. It is necessary to confirm the influence of opening size and sealing method (such as bellows sealing) on vibration transmission characteristics and box insulation and air tightness. The heat generated by long-term vibration operation needs to have an effective heat dissipation design to avoid interfering with the temperature field in the box.
Control logic and safety interlocks:The control system should be able to implement sequential, synchronous or combined programming of four factors. It must have complete safety interlock protection, for example, when operating at low air pressure, the system should be able to automatically adjust or alarm if the humidity exceeds the safe range. The faults of each subsystem should be able to be diagnosed independently and not implicated with each other and cause secondary damage.
Installation and O&M requirements:The base load-bearing capacity of the installation site, power capacity (especially the instantaneous power of the vibration system), cooling water supply (if required) and exhaust channels of the installation site should be assessed in advance. The system should facilitate routine calibration, maintenance, and sensor replacement.
Selection process
It is recommended to follow the following systematic process for equipment selection to ensure the effectiveness of the investment.
| Stage 1: Requirements definition | Clarify the test conditions, profiles and tolerances according to the environmental profile of the product life cycle and relevant test standards (such as GB/T 2423, IEC 60068). |
| Stage 2: Technical specification review | Check the technical parameters provided by the supplier one by one, especially the compound indicators when the four stresses work at the same time, and request a third-party test report. |
| Stage 3: Integration scheme evaluation | Review specific designs for mechanical, electrical, and control integrations, evaluate historical cases and potential technical risk points. |
| Stage 4: Factory acceptance test | Before the equipment leaves the factory, witness or review key performance tests, especially test data for the transition between extreme conditions and stress transitions. |
| Stage 5: On-site acceptance test | After the equipment is installed and debugged, standard specimens or actual samples are used for comprehensive working condition verification to confirm that all scheduled test requirements are met. |
The final selection decision should be based on a comprehensive trade-off between technical compliance, long-term operational stability, technical service support capabilities, and full life cycle costs.
Reference Standards
GB/T 2423.1-2008 Environmental tests of electrical and electronic products - Part 2: Test methods Test A: Low temperature
GB/T 2423.2-2008 Environmental tests for electrical and electronic products - Part 2: Test methods Test B: High temperature
GB/T 2423.3-2016 Electrical and electronic products environmental test - Part 2: Test method Test Cab: constant humidity and heat test
IEC 60068-2-64 Environmental testing - Part 2-64: Tests: Test Fh: Vibration, broadband random and guidance
MIL-STD-810H Environmental Engineering Considerations and Laboratory Tests