Tolerance chart-based methodology for integrated CNC machining and in-line inspection planning

摘要

In this work, a methodology based on a new and extended use of tolerance charting, that allows incorporation of in-line inspection operations to improve the machining process plan, is presented. The methodology is applied to every process plan setup, from the last to the initial one, and is based on a unified approach for the different active part features (machining features, inspection features and setup datum features) in the setup. A direct transfer of the inter-setup specifications to working and offset specifications tolerances is proposed. In this way, the variability sources originated by setting and tool deviations can be separately considered. This circumstance allows a more accurate calculation of operation capability indexes and eases the analysis and improvement of critical operations, reducing the manufacturing and quality loss costs. To prove methodology potential, an application on a part process planning on a CNC machine with on-machine measurement capability is illustrated.