CAD-based measurement planning strategy of complex surface for five axes on machine verification

Dimensional inspection of engineering components comprising free-form surfaces demands accurate measurement of a large number of discrete points, such that the actual shape may be fully characterized. This paper presents an on-machine verification (OMV) measurement planning strategy for CAD-based measurement of such components on five-axis machines. The main shortcoming of the conventional methodology with coordinate measuring machines (CMMs) has been identified to do with relation to repetitive position error. However, by employing the CAD model and on-machine platform, the proposed methodology maximizes the measurement accuracy, and such problem does not exist. The steps are as follow: adaptive sampling strategy is used to obtain effective measured points, probe path optimization, verification, post-processing, and measurement. The OMV process of surface on "S"-shaped test piece is implemented, and the obtained deviation is compared with another set of data measured on a coordinate measurement machine.