A Systematic Use of Reverse Engineering in Evaluating the Overall Accuracy of the Fabricated Parts

摘要

In this paper a systematic approach is proposed that evaluates the overall accuracy of a part. In this approach, by using the feature taxonomy, a part is decomposed into primitive features. Then, each feature is compared to the original CAD. Features are evaluated based on their size, form, orientation, and position. Laser scanning technique is used to collect a feature's data and its conversion into CAD data. To reduce data processing time for non-freeform features, manual digital dial indicators were customized and used for data collection. To process and evaluate the part's accuracy, statistical and CAD methods are applied. One benefit of the proposed hybrid system is that different errors can be differentiated and separated. In this study the manual method and statistical line fitting showed that, in addition to the surface quality deviation error, there was a trend error in the data; as the part got closer to the front right side of the printer it was steadily increasing. Further observations clarified that the trend error is caused by the build orientation; as the printer lays down a new layer of powder it drags the previous layer binder and powder from the back of the printer to the front of the printer.