The increasing complexity of industrial, transportation, nuclear, defense and aerospace programs has made testing and reliability evaluation critical. Wyle's testing experience dates from 1949 and covers every conceivable reliability program from microcircuits to complete systems. The most extensive capabilities for qualifying components and systems in the country are found at Wyle's facilities in Huntsville, Ala. and Norco and El Segundo, California. At these locations, multi-disciplined, engineering personnel routinely design and perform test programs in dynamics, climatics, acoustics, EMC and reliability in strict accordance with government and industry standards and specifications.
For instance, major telephone equipment manufacturers are using Wyle engineers to help them improve the reliability and durability of their electronic products. Wyle's failure analysis laboratory analyzes field or usage failures and advises the manufacturers on design and manufacturing improvements. Some manufacturers are getting Wyle reliability engineers involved in the very early product development stages so that improvements can be made before production. At the same time, Wyle verifies the products' compliance with government and industry standards. It is easier and much more cost effective to do it right the first time than to do over.
Wyle believes that reliability engineering technology should be an integral element in product and system development. To Wyle, reliability engineering technology means all of the activities necessary to assure that the product is safe for use, is appropriately designed and manufactured for ease of usage, is reliable in everyday application, is durable over the expected useful life and is producible at minimum cost.
This technology embraces a host of related systems engineering disciplines of:
- Reliability engineering
- Maintainability engineering
- Human factors engineering
- Durability analysis
- Operations and maintenance analyses
- Product Liability assessment
- Logistics engineering
- Risk assessment
- System safety engineering
- Accelerated life testing
- Accelerated stress screening
Whether your need is to assure compliance with a government or industry specification or to make a more reliable and robust product, Wyle is ready to provide the necessary support.
You may know exactly which aspects of reliability engineering technology impact your components, parts, assemblies, systems or products and the customer expectations or requirements you want or need to satisfy. If you are not sure what needs to be done, or if you do not have the appropriate skills on your staff, Wyle Laboratories is ready to assist you in meeting your product assurance and reliability goals by analyzing your requirements and recommending a tailored program of cost effective activities.
Specialized skills and involvement in unique testing and design programs have put Wyle on the leading edge of reliability engineering technology services such as:
- Reliability predictions for electrical/electronic and mechanical items (MIL-HDBK-217F, DTC 90/010, etc.)
- Failure Mode and Effects Analysis (FMEA) (MIL-STD-1629A, etc.)
- Criticality analysis
- Weibull and Bayesian methods
- Accelerated aging
- Fault Tree
- Maintainability predictions (MIL-HDBK-472)
- Maintenance analysis (MIL-STD-1390)
RELIABILITY ENGINEERING
For decades, reliability has been recognized as an essential need in military systems and particularly electronic systems. More recently, worldwide competition has forced a recognition of the need for reliability in commercial products as well. Reliability must be looked upon as a means for reducing costs from the factory where rework of defective components adds a nonproductive overhead expense to the field where repair costs include not only parts and labor, but also transportation and storage. Unreliability and down time are direct costs and are measurable. The indirect immeasurable costs - loss of customer goodwill and patronage - could be the largest cost of unreliability.
RELIABILITY PREDICTION
The reliability prediction provides the quantitative baseline needed to have a knowledge of the goodness of a design very early in the development process. Costly weaknesses can be found and improvements made long before full-scale production begins. It is much cheaper to find the flaws during design and correct them then, than to redesign and correct after customers find the problems. The reliability prediction process is a relatively inexpensive method of assessing the quality of the design. It identifies the highest contributors to failure and enables the designer to select other parts or make changes that produce a more reliable and durable product. Predictions may be used to evaluate the need for environmental controls, to employ redundancy, or to tradeoff other reliability enhancing techniques against cost, space or volume, and other resource limitations.
Since the physics of failure of electronic/electrical components differs greatly from that for mechanical components, different prediction models and procedures are required for each. Wyle provides predictions for any type of product, any environment, and any recognized standard (MIL-HDBK-217F, Bellcore, SAE, DTC, etc.). For most electronics, a constant failure rate assumption can be used and an exponential model employed. Mechanical components behave according to a variable (not constant) failure rate requiring a more complex model such as Weibull. Reliability predictions are not always as simple as some reliability software packages advertise them to be and, therefore, you may want to use an experienced professional outside source to provide prediction support.
SAMPLE FAILURE RATE EQUATION FOR MICROCIRCUITS, MEMORIES
lp = [C1 PT + C2 PE + lcyc] PQ PL
The sample failure rate mathematical model illustrates that the failure rate is composed of a number of factors that govern the failure behavior of the part. Each of these factors is made up of quantitative parameters that vary as a function of the manufacturing processes, materials, usage environments, years in production, temperature, parts screening, number of operational cycles, and others. All of these provide insight to the designer for improving the product in a variety of ways.