Plastic is used widely for its cheapness and light weight. In the manufacture of plastic products, optical measurement is always adopted for inspection purpose. There are three phases for a plastic part to be made. First, the rude injection mold must be refined to generate qualified products; then, the technical parameters of the injection machine must be adjusted to produce conforming products efficiently; in the end, the finished products are given. For each phase, optical devices are adopted to obtain point clouds of plastic samples, which are compared with the CAD model, so a registration operation is needed to align the point clouds with the CAD model. In this paper, three different evaluation metrics for registration are put forward for each manufacture phase to meet its special demands. In mold modification phase, a most overlap metric is used to find out the most distortion regions of the mold. In technical parameters adjustment phase, a combined weighted overlap metrics are used to evaluate how close the plastic samples to the CAD model. In the production phase, the samples are placed over a fixture, and a simple feature based registration is used. For each evaluation metric, a suitable algorithm is developed to realize the registration operation. A car's interior panel is used to verify the idea, and the test results proof the validity of the method.

Date Published: 11 November 2010
PDF: 6 pages
Proc. SPIE 7855, Optical Metrology and Inspection for Industrial Applications, 785522 (11 November 2010); doi: 10.1117/12.870568

Published in SPIE Proceedings Vol. 7855:
Optical Metrology and Inspection for Industrial Applications
Kevin Harding; Peisen S. Huang; Toru Yoshizawa, Editor(s)