An automated GD&T inspection system based on non-contact 3D digitization

Abstract

Rapid developments and improvements in advanced manufacturing technology mean that the inspection process plays an important role in the quality control of manufactured products. The Geometric Dimension and Tolerance (GD&T) inspection process is used in industries to examine the conformity of manufactured parts with the part specification defined at the design stage. However, as the modern manufacturing trend is towards producing low-volume, high-variety, high-complexity, and large products, current inspection techniques show difficulties in coping with this. This is especially true in automatically inspecting the geometric tolerance items of a manufactured part, such as parallelism and perpendicularity. This paper proposes a non-contact digitization-based automated GD&T inspection system. In this study, we defined a Nominal Inspection Frame (NIF) for a nominal CAD model or a digitized model, in which every GD&T item required may be defined and specified. Using the NIF, an algorithm for automatically extracting the GD&T information on a measured model was developed and implemented in a Reverse Engineering (RE) environment with software. We examine this proposed approach with several applications on dimension tolerance, geometric tolerance, and free-form surface inspection, and discuss the inspection results in the paper.