MIL-STD 810, Method 501 High Temperature Testing is used to evaluate the effects of high temperature conditions on performance, materials, and integrity.  Method 501 is applicable for temperature testing products that are deployed in areas where temperatures (ambient or induced) are higher than standard ambient.  Note, the latest revision of this method is 501.7 from MIL-STD-810H.

Method 501 is limited to evaluating the effects of relatively short-term (months, as opposed to years), even distributions of heat throughout the test item. This method is not typically practical for evaluating materials where solar radiation produces thermal gradients or photochemical effects.  Method 505 is used to test the effects of solar radiation.  It is also not practical to evaluate degradation that occurs from continuous long-term exposure to high temperatures where synergetic effects may be involved.

The following are typical failures that could occur from products used in high temperature environments.

• Parts bind from the differential expansion of dissimilar materials.
• Lubricants become less viscous; joints lose lubrication by the outward flow of lubricants.
• Materials change in dimension.
• Packing, gaskets, seals, bearings, and shafts become distorted, bind, and fail causing mechanical failures.
• Gaskets display permanent sets.
• Closure and sealing strips deteriorate.
• Fixed-resistance resistors change in values.
• Electronic circuit stability varies with differences in temperature gradients and differential expansion of dissimilar materials.
• Transformers and electromechanical components overheat.
• Operating/release margins of relays and magnetic or thermally activated devices alter.
• Shortened operating lifetimes.
• High pressures are created within sealed cases (batteries, etc.).
• Discoloration, cracking, or crazing of organic materials.
• Out-gassing of composite materials or coatings.
• Failure of adhesives.

MIL-STD-810 Method 501 Tests: High Temperature Procedures

1. Procedure I – Storage.  Procedure I is for testing products that are stored at high temperatures.  After the high temperature storage test is completed, an operational test at ambient conditions is performed.  Procedure I can be either a cyclic temperature test or a constant temperature test. 
2. Procedure II – Operation.  Procedure II is used to investigate how high temperatures could affect the performance of items while they are operating.  Temperature Procedure II can be performed as either a cyclic temperature test or a constant temperature test. 
3. Procedure III – Tactical-Standby to Operational.  This temperature procedure evaluates the material’s performance at normal operating temperatures after being presoaked at high non-operational temperatures.  An example of Procedure III is a product that is stored in an enclosed environment that develops high internal temperatures before being removed and then operated in a relatively short period of time.

What is the procedure for MIL-STD-810 High Temperature Testing? 

First, identify the high temperature levels, test conditions, and applicable procedures. DES can help determine the appropriate temperature ramp rates and durations of the tests based on the equipment’s intended use and the operating environmental conditions.  Consider the following climatic temperatures from Table 501.7-I. (MIL-STD-810H):

Next, determine whether a constant temperature test or a cyclic temperature test is appropriate.  Constant temperature testing is used only for items situated near heat-producing equipment or when it is necessary to verify the operation of an item at a specified constant temperature.  The duration for constant temperature test temperature is at least two hours following test specimen stabilization.

For cyclic exposure, there are two 24-hour cyclic profiles contained in Tables 501.7-II and 501.7-III.  The number of cycles for the Procedure I storage test is a minimum of seven to coincide with the one percent frequency of occurrence of the hours of extreme temperatures during the most severe month in an average year at the most severe location.   The minimum number of cycles for the Procedure II operational testing is three. This number is normally sufficient for the test item to reach its maximum response temperature.

You can trust the DES MIL-STD-810 High Temperature Testing lab

Advantages with DES : 

• DES is A2LA accredited to MIL-STD-810, Method 501 High Temperature Testing
• DES has extensive experience running MIL-STD-810 Method 501.7 high temperature Tests
• DES has multiple temperature chambers capable of performing MIL-STD-810 high temperature compliance testing

Contact us today to to discuss testing your product in our MIL-STD-810 accredited Test Laboratory. 

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These tests demonstrate the unique capability of Delserro Engineering solutions.  Not many labs are equipped to perform combined temperature and vibration testing at the extreme temperatures of this test or are able to produce the high levels required for random vibration and shock testing.

For more information on Combined Temperature and Vibration Testing or other vibration testing services, contact DES or call 610.253.6637.

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DES recently performed package testing per ASTM standard, ASTM D7386-12.  The test included shipping vibration testing which was conducted on DES’s Unholtz Dickie ED Shaker System.  ASTM D7386-12 requires packages to withstand random vibration levels of approximately ½ Grms over the frequency range 1 – 200 Hz.  This test is meant to simulate environments these packages could see in the field.  It is extremely important for manufacturers to test the effectiveness of their package designs prior to product shipment.  Shipping environments can put a lot of stress on products.

Improper package design can cause products to fail when the customer receives the product.  Environments such as high altitude, temperature, humidity, vibration and shock are common for most packages.  High return rates due to damage during shipment can cripple a company’s bottom line.  Prevent this from happening and send DES your packages to test!

Other package testing standards DES is capable of include (but not limited to):

• ISTA 1 Series
• ISTA 2 Series
• ISTA 3 Series
• ASTM D3580 Vibration (Vertical Linear Motion) Test of Products
• ASTM D4169 Performance Testing of Shipping Containers and Systems
• ASTM D4728 Random Vibration Testing of Shipping Containers
• ASTM D7386 Performance Testing of Packages for Single Parcel Delivery Systems
• ASTM D999 Vibration Testing of Shipping Containers

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Equipment with single or multiple chambers may be used to perform thermal shock testing. When using single chamber thermal shock equipment, the products or samples remain in one chamber and the chamber air temperature is rapidly cooled and heated. This usually results in a slower rate of change in the product response temperature as the entire chamber must be cooled down and heated up. However larger products can be tested in single compartment chambers. Some equipment uses separate hot and cold chambers with an elevator mechanism that transports the products between two or more chambers. This results in a more rapid rate of change in the air temperature. However, there is a limit to the size and weight than can be put in a chamber with an elevator mechanism.  DES has both types of chambers for thermal shock testing.

When performing thermal shock testing, the upper and lower temperatures must be carefully determined. Larger differences between the test chamber temperatures and the product normal use temperatures will result in higher acceleration factors as determined from the Coffin-Manson equation. However, the correct temperature limits must be chosen to not exceed the operating limits or material property limits of the product. For example, an upper temperature that exceeds the melting point of any material in the product would likely result in invalid test failures. It is therefore important that these temperatures be properly measured and monitored during the test through the careful placement of thermocouples on and around the products or samples.

Factors that can influence the test parameters include the thermal mass of the samples, the number of samples and the airflow around the samples that depends on the sample spacing in the chamber. The dwell time at each temperature should be included in the test specification along with the tolerances around the high and low temperatures. Test methods may also specify minimum rates of temperature change.

Products may be powered or unpowered during the thermal shock test. Products that are powered during the test need cables that are long enough to reach outside of the chamber and can fit inside the chamber feed through.

Delserro Engineering Solutions, Inc. (DES) has many years of experience performing thermal shock testing and can assist customers in setting up a test using the proper test conditions. So if you do not know what test conditions that you should use or what specification to choose, then we will help you because we are thermal shock testing experts!

Examples of some common thermal shock test specifications include:

• MIL-STD-202, Method 107, Thermal Shock
• MIL-STD-810, Method 503, Temperature Shock
• MIL-STD-883, Method 1010, Temperature Cycling
• JESD22-A104D, Temperature Cycling

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DES was awarded multiple contracts to perform combined temperature and vibration reliability testing of Mass Air Flow Sensors from various automotive part manufacturers and from a major auto parts supplier.

The applicable test specification was GMW 3172, a General Motors Specification for electronic component durability.  The test requirements in GMW 3172 were 13 Grms random vibration from 10 to 2000 Hz.  Simultaneously with the vibration testing, DES’s AGREE Chamber subjected the MAFS’s to temperature cycles between -40 °C and +125 °C.  In addition to the harsh temperature and vibration environment, the sensors were electrically powered and monitored for operation or failure during the test.  These harsh conditions had to be run for at least 44 continuous hours per axis along three different axes.  Sometimes they were run for longer durations.  Many sensors were tested simultaneously which added to the challenge.  Finally, a bench air flow tester was used to perform calibrated air flow measurements after each axis to verify the electrical output of each sensor.

This case study shows the advanced capabilities of DES to complete the most difficult temperature and vibration test projects.

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