Recommended environmental reliability testing laboratories

Get the order wrong and you pay twice: define the tests first, then find the lab

Most people start with "who can do this" and then ask "what can they do". The correct order is the reverse: list every test you need first, then verify the laboratory's capability item by item. The phrase "we do environmental reliability" can mean anything from a single temperature chamber to a full suite of vibration and salt spray, and the difference between laboratories is enormous.

Following the structure of ISO 16750 / GB/T 28046, environmental loads fall into four groups:

• Climatic load: high and low temperature storage, temperature cycling, damp heat, thermal shock, solar radiation, salt mist, ingress protection
• Mechanical load: random vibration, sine vibration, mechanical shock, free fall, stone impact
• Chemical load: oils and fluids, cleaning agents, flame retardancy
• Electrical load: supply voltage range, overvoltage, voltage dip, reverse voltage, short circuit

Every item on the list needs three parameters attached: range (temperature span / acceleration / concentration), duration or cycle count, and the acceptance basis. Without those three, neither the quotation nor the test plan can be aligned.

To check equipment capability, look at four specifications

• Temperature chamber: internal dimensions, temperature range, ramp rate, and whether the sample can be powered during the test. If the ramp rate is insufficient, the temperature cycling slope will not meet the standard.
• Vibration shaker: force rating (kN), table size, frequency range, and whether combined temperature-vibration testing is supported.
• Salt spray cabinet: internal dimensions, temperature control range, and whether it runs neutral or cyclic salt mist.
• Shock machine: peak acceleration, pulse duration, waveform type.

What decides whether a sample fits is the combined weight and envelope of the sample plus fixture, not the sample alone. Fixtures are often heavier than the sample.

Three things that are easily overlooked

Powered monitoring. Many failures are functional anomalies rather than visible damage — the unit looks intact but its output drifts or communication drops out. Test it with the power off and that class of failure is never captured. Confirm whether the laboratory can power the sample and monitor it throughout the test.

Mounting method. Fixture rigidity directly shapes how vibration is transmitted. A rigid mount and a flexible mount that mimics the real vehicle bracket produce two different data sets. The mounting method must be stated in the report.

Intermediate inspection points. Some standards require functional checks between cycles rather than only before and after the whole test. That needs the corresponding process and staffing on the laboratory side.

Four things to check on the quotation

• Whether the test items map one to one onto the reference standard (omitting items is common practice)
• Sample quantity and number of test runs (some items require several samples and take the worst case)
• Whether re-testing after a failure is included
• Whether the pass/fail conclusion follows the standard or the customer agreement

Where we stand

TMC LAB holds both CMA and CNAS accreditation, with a laboratory of roughly 10,000 m² and over 500 sets of equipment, covering all four environmental load groups — climatic, mechanical, chemical and electrical — entirely in our own laboratory. Powered monitoring, combined temperature-vibration testing, site visits and witness testing are all available.

Send us the product's mounting location and your customer's acceptance standard, and we will set out the test list and severity parameters first, then confirm whether the equipment can take it on.