By definition reliability is the ability to perform required functions in required time and under prescribed conditions. To put it more plainly, high-reliability prodcts has long life and seldom get broken in lifetime. For example, communication products especially equipment in key node the has high requirement for reliability which must be five nines or more. Without reliability test, the deficiency of product may make the product go wrong and thus cause clients to be seriously discontented. It is unallowed in this fierce competition industry.
To improve the reliability is only to improve the design and production control like better materials, more optimized structure design, more advanced technological levels and so on. Generally high-reliability products has high costs of product development and production but less costs of later maintenance. While Low-reliability products has low costs of product development and production but high cost of later maintenance. Therefore in theory there is a curve of product reliability and cost of product lifetime. When reliability reaches some point, the cost of product lifetime gets the lowest. Thus companies must pay attention to the reliability of product to be successful in business.
The purpose of ort reliability testing mainly aims at finding out the design flaw or the weak part of design. It accelerated motivates the underlying design flaw and let it performs as fault by mannly imposing the environmental stress and operating stress comparing to its normal operating stress. Then by failure mechanism analysis design flaw is positioned and improvement approaches are put forward. These are to improve the inherent reliability of products, shorten the design and production lifetime and decrease the production costs.
The rationale of reliability test is physics-of-failure which takes failure as main objects and discovers, studies and cure radically them to improve the reliability. It is not so easy to find out the potential failures especially the deeply potential failures or uneradicated interval failures for current high-tech and highly complex electronics or mechanical and electronical oroducts. Methods of increasing stress must be adopted to expose those flaws. So the rationale of reliability test is scientific in the aspect of fault prevention strategy.
Why it is necessary to improve the reliability? Firstly, because of the market competition. Competitor's products and current products on market has higher reliability than yours as their product lifetime is five years but yours is one year. How would you to dominate the market? Secondly low reliability product has high after-sale costs which means less profits. And for some product who has high requirement for safety requires high reliability for failures means human's life is not guaranteed. For instance the products of manned aerospace. Certainly high reliability dose not mean blind investment. It is necessary to peferct the design management of reliability and invest with controlled costs to satisfy the internal and external clients as well as investors.
Simply speaking reliability test is to discover the weak part and flaw of product and response to designers so as to improve the product reliability. High reliability products has low rate of failures which favors the users and helps to builds up the brand and increase the sales volume. Reliability test includes waterproof and rustproof, vibration, mechanical shock, autoclaving, package drop, fixed temperature and humidity, thermal shock, gaseous corrosion, salt spray, xenon arc aging, strength of extension, rigidity, tensile strength, high-low temperature test and so on.