Defect Cost Analysis

The defect cost analysis investigates the various contributions of conflicting quality objectives towards the total cost, using a probabilistic approach estimating the total effect of defects on product quality cost. Two cost drivers occur in every design, material cost and processing cost. The additional cost due to defect parts is usually seen only as one cost driver, however, it can be broken down towards the cost created by each defect type, based on the likelihood of the occurrence of those defects. By reducing those defect-related costs, a more robust design is achieved. Introduction Engineering design is a complex and sophisticated task in order to create a successful product. One major element of a successful product is to reduce the cost of the product while satisfying the specifications. Specifications are the requirements towards the design responses to satisfy the user requirements. This is done by constraining the design responses. Here the development team has to achieve a trade-off between the satisfaction of the constraints and the cost minimization. However, the constraint satisfaction and the total cost of the design are coupled, because increased quality usually creates increased cost, but also reduces the likelihood of defects. The demonstrated methodology will aid the development team in understanding this coupling in order to minimize the total cost of the product by decomposing the total cost and assigning the cost towards the different cost drivers. Then the development team can analyze what causes the cost of the product and thus improve the design towards a more economic design. This enables the development team to improve the design focused on the actual cost drivers, avoiding the improvement of design responses which do not contribute towards the total cost. However, it has to be taken under consideration that a design performance is driven by other reasons than cost. This value analysis is not discussed in this paper. System Overview The engineering design model consists of input parameters, which are determined by the product development team, and output responses, which are a function of the input parameters. Furthermore a design is subject to noise, distorting the input parameters and the resulting output responses. Figure 1 visualizes the system as utilized in this methodology. Preprint of: Roser, Christoph, and David O Kazmer. “Defect Cost Analysis.” In Proceeding of the Society of Plastics Engineers Annual Technical Conference. New York, NY, USA, 1999. Cost Driver Analysis Material Cost Process Cost QualityResponses Input Parameter Noise