Strategic Uses of Different Shapes and Shifts in Weibull Plots

Abstract

During the product development processes, components and subsystems go through test-fix-test cycles until the final configurations surpass the design life to exceed the reliability goals. When failure modes are uncovered before reaching the design life, design configurations are improved to eliminate failures. Early failures can be mixed with several failure modes commonly lead to lower shape parameters. Systems that are mature that survive close to design life may have higher and steeper slope parameters. During the component-subsystem development process and design maturity, shape parameter changes associated with reliability growth are illustrated with examples. As designs reach or surpass design life with design maturity, failure modes can be single out to unique shape parameters. Separating different shapes and patterns of Weibull curves help identifying different failure modes thereby leading to failure mode-wise reliability analysis. Such analysis help prioritizing the fixing process of each failure mode based on returns on investment.On the other hand, if a product was launched before it reaches the design life and meets reliability goals, field failures become inevitable. Such field failures can also be modeled with Weibull Analysis. Parts that fail short of the design life are commonly called under-developed designs. Such designs can be mixed with multiple failure modes. Different shapes and shift of curves can be strategically isolated for separating design weaknesses and investigations before catastrophic failures erase evidence of root causes. For example, shape parameters and patterns of underdeveloped parts can be helpful in isolating manufacturing issues from design issues. This paper addresses how to perform data analysis in order to strategically enhance the further use of Weibull plots, its shapes and pattern recognition for speedier product development and customer satisfaction.