Variation stack-up analysis using Monte Carlo simulation for manufacturing process control and specification.

In modern manufacturing, a product consists of many components created by different processes. Variations in the individual component dimensions and in the processes may result in unacceptable final assemblies. Thus, engineers have increased pressure to properly set tolerance specifications for individual components and to control manufacturing processes. When a proper variation stack-up analysis is not performed for all of the components in a functional system, all component parts can be within specifications, but the final assembly may not be functional. Thus, in order to improve the performance of the final assembly, a proper variation stack-up analysis is essential for specifying dimensional tolerances and process control. This research provides a detailed case example of the use of variation stack-up analysis using a Monte Carlo simulation method to improve the defect rate of a complex process, which is the commutator brush track undercut process of an armature assembly. Variations in individual component dimensions and process mean shifts cause high defect rate. Since some dimensional characteristics have non-normal distributions and the stack-up function is non-linear, the Monte Carlo simulation method is used. This research also attempts to generalize from the case example a methodology of variation stack-up analysis using a Monte Carlo simulation method for manufacturing process control and specification. The methodology identifies situations where design specifications are incomplete and incorporates existing specifications and production data for missing specifications into a simulation model to determine manufacturability with predetermined reject rates.PhDIndustrial and Operations EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/103440/1/9319571.pdfDescription of 9319571.pdf : Restricted to UM users only