Virtual Process Capability


Mackertich, Neal A.; Stephens, Vic   (1997, ASQ)   Raytheon Electronic Systems, Sudbury, MA; Raytheon Aircraft, Wichita, KS

Annual Quality Congress, Orlando, FL    Vol. 51    No. 0
QICID: 10621    May 1997    pp. 769-773
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Article Abstract

Defect prevention in design is enhanced through simulation methods and CAD (computer aided design) systems. At Ratheon Aircraft, the Virtual Process Capability (VPC) method helps drive down the non-conformance quality costs usually associated with initial production runs. An early step in VPC is to evaluate the mechanical design of a new product. A model equation mathematically represents a design nominal, which can be spatially located using CAD. Next, it is necessary to know how far from nominal would be the manufactured product. This requires understanding of the statistical distribution of each variable in the model equation. Data for these distributions preferably come from statistical process control analyses, though estimations based on design specifications are acceptable. Monte Carlo simulation methods manipulate this information into a statistical distribution of an output characteristic. For example, Raytheon's design of the Beech Model 3000 landing gear system included analysis of clearance for the rivet attachment of the upper bearing to piston. The simulation gave a 5% estimated defect rate. Further analysis determined how each component contributed to model equation variability, thereby suggesting opportunities for improvement in the design. VPC supports Raytheon's ability to be a learning organization, and it has produced ten-fold savings based on the VPC investment.


Manufacturing,Design of experiments (DOE),Design,Computer-Aided Design (CAD),Simulations,Case study

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