A Tolerance Adjustment Process for Dimensional Validation of Stamping Parts and Welded Assemblies

Product design dimensional specifications provide estimates of what the next process will require to ultimately produce desired finished vehicle specifications. During stamping and body assembly manufacturing validation activities, manufacturers typically reassess these original specifications and make adjustments as needed for monitoring product quality during regular production. These tolerance adjustment practices vary considerably between manufacturers, and often even within an organization. In some cases, different teams working in the same launch program may use different approaches. This paper describes the application of a methodology that was developed and has been adopted by a North American OEM as a standard practice for dimensional evaluation and revision of sheet metal components. The methodology was validated during a recent vehicle program launch by calculating tolerance recommendations for several stamping parts. The results showed that the methodology was able to predict over 90% of the actual variation levels and subsequent process monitoring demands observed later in production.