This paper describes a systematic approach to analyzing manufacturability of parts produced using Solid Freeform Fabrication (SFF) processes with flatness, parallelism and perpendicularity tolerance requirements on the planar faces of the part. SFF processes approximate objects using layers, therefore the part being produced exhibits stair-case effect. The extent of this stair-case effect depends on the angle between the build orientation and the face normal. Therefore, different faces whose direction normal is oriented differently with respect to the build direction may exhibit different values of inaccuracies. We use a two step appraoch to perform the manufacturability analysis. We first analyze each specified tolerance on the part and identify the set of feasible build directions that can be used to satisfy that tolerance. As a second step, we take the intersection of all sets of feasible build directions to identify the set of build directions that can simultaneously satisfy all specified tolerance requirements. If ther is at least one build direction that can satisfy all tolerance requirements, then the part is considered manufacturable. Otherwise, the part is considered non-manufacturable. Our research will help SFF designers and process provides in the following ways. By evaluating design tolerances against a given process capability, it will help designers in eliminating manufacturing problems and selecting the right SFF process for the given design. It will help process providers in selecting a build direction that can meet all design tolerance requirements.
展开▼
