Practical Activity on Reliability Control of the Components

Abstract Very high reliability is required for components used in a industrial instrument, due to enormous loss and danger in the case of its failure. To achieve such high reliability, we employed around 1975 a method to obtain a component with the best quality. Candidate components were purchased from some vendors using the same specification. The reliability of those components then were compared by utilizing general evaluation methods. And the component which showed the best reliability performance was selected for the use. Nowadays, however, the general methods became almost ineffective according to the improvement of the reliability of components and also of the evaluation techniques. Defect of a component is not easily detected by the relative evaluation, and it is revealed at the stage of mass production, or after long duration of usage. Even in this case, the rate of failure is small. Therefore, we consider a method important-we call the method “weighted evaluation” - and have emproyed it in these late years: we evaluate the reliability of component independently focusing on the weak points of the component based on our experience, while general evaluation of components is left to the manufacturer, in the following, our practical activity on reliability control of the components is described.