Feature-based fixturing analysis for machining parts represented with multiple sets of features

Abstract

In a feature-based model, a typical approach is to represent a part with a single set of features. However, in a part with feature interactions, there may exist multiple sets of features to represent the same part. The multiple sets of features represent different ways of machining the part. It is necessary to analyse and evaluate the various sets of features to measure their performance when using different machining methods. In a machining process, different fixturing parameters are required when different sets of features are used for machining. The purpose of this research is to determine a 'good' set of features that is more suitable from the fixturing point of view. A feature-based fixturing analysis method is developed based on the 3-2-1 and the 4-2-1 fixture design principles to analyse the supporting, locating, and clamping parameters. First, a set of fixturing parameters is determined for machining one set of machining features. Next, multiple sets of fixturing parameters are determined for the multiple sets of features. Finally, the multiple sets of fixturing parameters are evaluated based on the number of different fixturing setups and the number of changes in fixturing setups. A feature set that can be machined with the minimal number of changes in fixturing setups is considered a 'good' set. The workpieces considered in this research are prismatic machining parts and prismatic machining features represented in boundary representation. The result is to provide a way of analysing the different fixturing setups when different sets of features are used for machining. From a process planning point of view, a good or a more suitable way for producing a part can be evaluated and determined for the better integration of CAD and CAM.