MIL-STD-810 TEST METHOD 503 TEMPERATURE SHOCK

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Jim Shaw, EVP of Engineering at Crystal Group, discusses MIL-STD-810 Method 503 Testing.

MIL-STD-810 Test Method 503 Temperature Shock

Hi, Jim Shaw here from Crystal Group. Wanted to spend a moment talking about MIL-STD-810 and we’re talking about MIL-STD-810G in this case. Other customers may specify any different revision but we just happen to be talking about G at this point. Wanted to talk for a bit about Temperature Shock and what that test is and that’s Method 503. What this test is supposed to do is simulate the transition of your equipment from say a hot environment to a cold environment very rapidly. And the test defines high speed transitions as essentially 10C per minute, although at the very least 10C per minute. So you can actually have much more rapid transitions than some of these testings.

So what is it that you are actually looking for when you take your equipment say out of a Humvee that’s heated and put it into a very cold environment or out of an air conditioned room and putting it into a very hot environment?  So the testing is tailored around your specific application needs. What is it that you are looking for when you are doing this kind of testing? These are essentially surface types of tests.  So you are looking at things that are more on the outside of the units.

You’re looking for shattered glass or thermal coefficient expansion changes that deform materials, crack materials, damage insulators or alter the performance of the electrical system. In the computer industry that’s essentially where we’re looking at, what’s happening to the circuit board components, what things are being damaged by very, very rapid types of transition in temperature? This testing for us is really about being able to take the unit out of one thermal chamber that’s maybe down very low and put it into another thermal chamber that’s very hot. And then basically go through that cycle of testing.

The test is centered around essentially four different procedures. There’s 1A through 1D. 1A is essentially a half cycle, so you just go say from cold to hot. B is a full cycle so you go hot to cold and then cold to hot again or visa versa. And then C is really multiple cycles. The spec recommends at least 3 but you can do more than that. In cycle D the testing is done really to more extreme levels buts its again multiple shocks.

What you are trying to do again is simulate rapid temperature changes whether that is taking a piece of equipment and throwing it out of a C-141 and you are doing an air drop, or you’re taking it out of an air conditioned facility into a desert environment. You are looking for can the equipment stand that kind of abuse. You’re looking for any changes to the performance, any damage to the equipment, any damage especially to those outer surface areas that are most easily impacted by thermal changes because those are the ones that are exposed to the most rapid change.

A couple of things that you want to make sure you specify during this testing is the test temperature, the transition duration and how long that you want to have the system at that temperature or the dwell time. And then the number of cycles, transfer time in terms of door open, door closed kind of a thing. And then how often are you going to actually check the performance of the unit? Just like every other test in MIL-STD-810 this is intended to be highly tailored for the application that you’re testing the unit for. It is very specific to application. So customers need to put some thought into what is it that I want to test in this Method 503.

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