What is Reliability?

Windchill Risk and Reliability Desktop Help > Overview > Introduction > What is Reliability?

In textbooks, reliability is defined as the probability that an item will perform a required function without failure under stated conditions for a stated period of time. As illustrated by this definition, reliability is a very broad term that focuses on the ability of a product to perform its intended function.

The process of performing a reliability analysis often includes a number of different analyses on a product to anticipate how reliable that product is. Based on analysis results, it is possible to anticipate the effects of design changes and determine the corrections needed to improve reliability.

While the different analyses that you can perform are all related, they each analyze different aspects of product reliability. They each look at a product from a different angle to determine possible problems, and they work together to assist you in analyzing what corrections and improvements to make. Types of reliability analyses include reliability predictions, failure mode and effect analyses, and fault tree analyses.

The following table describes some of the many reasons why analyzing reliability is important.

Reason	Description
Reputation	A company's reputation is very closely related to the reliability of its products. If the products that a company manufactures are very reliable, then the reputation of the company experiences a direct benefit. The more reliable the product is, the more likely the company is to have a very favorable reputation.
Warranty costs	Oftentimes, a company begins to produce a product on which it has never performed a serious reliability analysis. Unfortunately, once this product is distributed, it may not perform its required function without failure for a stated period of time. If the product fails prematurely, an issue of warranty or replacement costs may be involved. These types of premature failures inevitably cause a negative impact on profits and often results in negative publicity. Introducing reliability analysis measures is an important step in taking corrective action. Even if the only initial purpose of performing a reliability analysis is to decrease costs, the end result is a better product that is more reliable.
Future business	To keep customers, it is very important that they remain satisfied. A concentrated effort towards improved reliability proves to customers that a manufacturer is serious about its product, and that the it is committed to customer satisfaction. Needless to say, this type of attitude has a positive impact on the stability of future business.
Contract requirement	Sometimes contracts may involve one or more of the following requirements: • A reliability prediction based on a specific model. • A reliability prediction that meets specific requirements for failure rates. • A FMEA (failure mode and effects analysis) performed and presented with specific report formats. • An LCC (life cycle cost) analysis evaluating all future costs, including maintenance and spare parts. Even if these issues are not contractually required, performing any or all of these tasks is beneficial to any product manufacturer.
Cost analysis	Companies are finding cost analyses to be very valuable tools. To illustrate the cost effectiveness of its products, a manufacturer may take reliability data regarding the product and combine this data with other cost information to illustrate the overall LCC of its products. This type of analysis can prove that although the initial cost of the product may be higher, the overall lifetime cost of that product is actually lower than a competitor’s product because fewer repairs and/or maintenance tasks are required.