Locating Point Synthesis in Fixture Design

A method for selecting and positioning locating points in fixture design is proposed. The types of fixture applications considered are for prismatic workpieces that use the 3-2-1 locating principle as the general structure of the fixture. The design synthesis problem uses six rules based on machining practice to select the secondary and tertiary locating datums for a workpiece stored in a boundary representation solid modeler. Once these edges are selected, kinematic rules are used to determine the position of the locating points so as to allow accessibility when loading and unloading a workpiece. Examples are given to illustrate this method, as well as the positioning of support points on the primary datum plane.