Six Sigma tolerance analysis for functionality and assemblability: designing locking systems

Assembling can be seen as process of joining manufactured parts to create final product-assembly. In Six Sigma terms, overall performance of final product is highly affected by design/manufacturing characteristics of each component. The key role for successful fitting plays the specified target of dimensions/tolerances of parts. Assembling parts are designed/studied using CAD/CAM systems, which are great for reducing design time but lack methods/functions to allow selecting optimal geometrical/functional parameters. This slows down the design for Six Sigma (DFSS) process. In this work, the following issues are addressed while elucidated through a case study: 1) method for Six Sigma designers to check for possible part defects which may present misalignment opportunities during assembly; 2) approach for evaluating part/assembly dimensions/tolerances while ensuring functionality; 3) corrective action approach for design changes which avoids endangering increasing of overall cost. The simple unified framework may aid Six Sigma designers assessing/making product-assembly decisions by offering more robust information.