A Novel Approach for the Inspection of Flexible Parts Without the Use of Special Fixtures

In a free state, flexible parts may have different shapes compared to their computer-aided design (CAD) model. Such parts may likewise undergo large deformations depending on their space orientation. These conditions severely restrict the feasibility of inspecting flexible parts without restricting the deformations of the part and therefore require dedicated and expensive tools such as a conformation jig or a fixture to maintain the integrity of the part. To address these challenges, this paper proposes a new inspection method, the iterative displacement inspection (IDI) algorithm, that evaluates profile variations without the need for specialized fixtures. This study examines 32 models of simulated manufactured parts to show that the IDI algorithm can iteratively deform the meshed CAD model until it resembles the scanned manufactured part, which enables their comparison. The method deforms the mesh in such a manner so as to ensure its smoothness. This way, neither surface defects nor the measurement noise of the scanned parts are concealed during the matching process. As a result, the case studies illustrate that the method’s error essentially only represents the scanned part’s measurement noise. The inspection results, therefore, solely reflect the effect of variations from the manufacturing process itself and not the deformation of the part.