Reliability testing is the process of determining potential problems with the design of a product while it is in the design stage. The goal of reliability testing is to provide confidence and insight into the product’s ability to meet its reliability requirements over the expected lifespan of the product. Prior to testing a product, it is crucial for the manufacturer to define what a product failure is.
The reliability test program includes a number of qualification tests based on the type of product, the environment within which it is anticipated to operate in and estimated product weaknesses. Establishing an effective but practical and affordable test program can be a challenge. Reducing the number of units tested or the scope of testing might not yield a sufficient sample of results. Testing multiple units or having an expansive test program can be very time consuming and expensive. A very good resource for establishing a reliability test program is MIL-HDBK-781: Handbook for Reliability Test Methods, Plans and Environments for Engineering, Development, Qualification and Production. This handbook provides test methods, test plans and test environmental profiles which can be used in reliability testing during the development, qualification, and production of systems and equipment.
It is important to note that even though MIL-HDBK-781 was designed for military contracted procurements, many of the test plans, methods and environments can be customized to suit other products and equipment such as commercial products. MIL-HDBK-781 includes guidance on the following categories of equipment:
Category 1. Fixed-ground equipment
Category 2. Mobile ground equipment
- Wheeled vehicle
- Tracked vehicle
- Shelter configuration
Category 3. Shipboard equipment
- Naval surface craft
- Naval submarine
- Marine craft
- Underwater vehicle
Category 4. Equipment for jet aircraft
- Vertical and Short Takeoff and Landing (V/STOL)
Category 5. Turboprop aircraft and helicopter equipment
Category 6. Missiles and assembled external stores
- Air-launched missiles
- Assembled external stores
- Ground-launched missiles
Keystone Compliance is an accredited test lab with expertise in reliability testing. We assist manufacturers in determining their product’s reliability by offering the following testing called out in the MIL-HDBK-781:
- Electrical Stress includes equipment ON-OFF cycling, operation in accordance with the specified operating modes and duty cycles, and input voltage variation above and below the nominal operational value.
- Vibration Stress includes testing to levels and profiles tailored to the specified intended application of the equipment. The setup considers the mounting location and the classification category for field use. The factors considered in the definition of realistic vibration stress include a) type of vibration (sine sweep, complex, or random); b) frequency range; c) amplitude; and d) manner and axis of application. The intent is to produce in the equipment on test a vibration response with a character, magnitude, frequency range, and duration similar to that produced by the field service environment and mission profile.
- Thermal Stress provides a realistic simulation of the actual thermal environment that the equipment experiences in the service application. The factors considered in the definition of thermal stress include; a) starting temperature (heat soak. cold soak) and turn on (warmup) time; b) operating temperature (range, rate of change. And frequency of change; c) number of temperature cycles per mission profile; and d) cooling airflow (rate and fluctuation).
- Humidity Stress is often introduced during the temperature cycles to produce visible condensation and frosting or freezing, when such conditions can be expected in field service.
Reliability testing is an important step in determining the potential weaknesses of a product. Keystone Compliance works with manufacturers to design effective, yet practical and affordable reliability test programs. Our expertise in environmental testing, including vibration, temperature, altitude, solar radiation, salt-fog and shock, allow us to provide critical product performance feedback to manufacturers seeking lifecycle analysis. Our experienced staff and fleet of test equipment allow us to get the job done accurately, quickly and affordably. Contact us to partner with a lab that will work together to meet your reliability testing needs.