The business impact of product reliability Reliability assurance development is a key ingredient for improving the reliability performance of manufactured products, but there are a wide range of factors which are also incentive to this performance such as:• overall management of the reliability function;• the intensity of reliability assessment and evaluation during the design and development phase; • utilization of field failure data and the depth of subsequent technical and statistical analysis; • controlling the consistency of manufacture and assembly; • effective management and control of engineering changes. Improving the reliability of a product is an important part of the larger picture of improving product quality. A momentous quality characteristic, reliability is concerned with the performance of the product's function over a stated period of time. Therefore, whereas quality is defined as conformance to requirements, reliability on the other hand is defined as a failure or fault-free performance in all products provided to the customer. Compared with quality which embraces the whole organization, reliability has a more product specific definition and therefore should be the main impetus to continuously improving the performance of the product's functionality.BS 4778[1] defines reliability as the ability of an item to perform a required function under stated conditions for a stated period of time. The item can refer to a manufactured product or its constituent units and components, manufacturing and assembly systems (e.g. transfer lines), mechanical and electrical process systems and general mechanical, electrical and electronic systems. An expansion of the above formal definition of reliability leads to qualitative and quantitative expressions:• qualitatively -absence of functional failure during use or service;• quantitatively -the probability that an item will give failure-free performance of its intended functions for the specified duration of time. The advantages of reliability assurance development encompassing all the relevant business functions are both qualitative and quantitative. The main