MIL-STD-810 Temperature Shock testing (Method 503) is used to evaluate equipment’s ability to withstand sudden changes in temperature. This laboratory test method is conducted in environmental test chambers and can be tailored to replicate the anticipated thermal profiles during storage, transit, and operation. Such shock could be experienced when a jet fighter on a tarmac in the desert rapidly climbs to high altitudes or conversely an article being air delivered by means of parachute to a high temperature environment.
Rapid change in temperature per this standard is defined as a change greater than 18 °F (10°C) per minute. Exposure to these environmental stresses can cause failures due to differential expansion and contraction of dissimilar materials. It can cause failures in electronics due to changes in components due to temperature changes. It can also cause failures in equipment due to the formation of frost.
The military standard MIL-STD-810 provides four test procedures for Temperature Shock:
- Procedure I-A: One-way Shock(s) from constant extreme temperature This procedure is appropriate for equipment that will be not regularly exposed to thermal shock and when those shocks will occur only in one direction. Equipment air dropped from aircraft would be an example.
- Procedure I-B: Single Cycle Shock from constant extreme temperature This is intended for equipment that is expected to be exposed to a single shock in each direction.
- Procedure I-C: Multi-cycle shocks from constant extreme temperature An example of this would be a jet fighter taking off from a desert location and then landing at the same location.
- Procedure I-D: Shocks to or from controlled ambient temperatures This would be applicable to equipment that is stored in environmentally controlled structures that must work in extreme hot or cold environments.
Determining Appropriate Test Values
It is necessary to tailor appropriate test temperature cycle and temperature range values from requirements, measurements, and those derived from the Life Cycle Environmental Profile (LCEP). Geographic climatic information is available in Part 3 of the standard to assist in value determinations. As with most MIL-STD-810 methods, measured data when available is preferred for determining test values. This is particularly the case in situations in which solar radiation may be a factor in determining maximum temperatures.
Generally, humidity is not a factor in Temperature Shock testing, but when required appropriate values should be determined based on expected areas of use. For testing of Air delivery the standard recommends a starting temperature equivalent to that found at 26,000 ft (8 km). These environmental conditions can be found in Method 520 Combined Environments.
Considerations During Testing
Temperature chambers specifically designed for thermal shock testing incorporate dual chambers side by side or on top of each other that allow a rapid transfer between the two test temperatures. Generally, availability of these chambers at test facilities is limited. When these chambers are not available the Unit Under Test (UUT) must be transferred between two separate chambers as quickly as possible.
Transfer time should be recorded during testing and be included in any required post test reporting. MIL-STD-810 encourages transfers between chambers to one minute or less. This can be challenging when the item is being tested in an operational mode or where the test item is large. When this is the case, justification for longer periods of transfer should be documented.
Detailed Environmental Test Plan Templates
CVG Strategy offers EZ-Test Plan Templates for MIL-STD environmental (climatic/dynamic) and EMI/EMC testing documentation. Our Detailed Environmental Test Plans (DETP)s are written as specified in MIL-STD-810 Task 405. They are available for specific applications such as Ground Mobile, Ground Stationary, and Shipboard Controlled, Shipboard Uncontrolled, and Aircraft Military.
These DETPs include appropriate test methods, (such as MIL-STD-810 Temperature Shock) addendums for product specific information, test labels for photo identification and data sheets for collection of required data. Profile (LCEP).
Our Electromagnetic Interference Test Plans are written as specified by the Department of Defense. They contain the test methodology, addendums for product specific information, test labels for photo identification and data sheets. These plans are available for procedures listed in MIL-STD-461 and are also available for MIL-STD-1275, MIL-STD-704, and MIL-STD-1399-300.
Custom Test Plans are also available for applications not covered in the EZ-Test Plan offerings. These plans can be written for any number of applications and their relevant standards.
Put CVG Strategy’s Experience to Work for You
Companies of all sizes, from start up to established product developers, face challenges in product test and evaluation. This can particularly be the case when a product is developed for a new market sector or expanding sales internationally.
Properly tested products prevent costly product recalls, product redesign, and product liability. They maintain customer satisfaction and keep your company’s reputation in good standing. Contact CVG Strategy to see how our testing services can assist your engineering team with MIL-STD-810 Low Temperature Testing or any other test and evaluation concern.