Manufacturing Complexity Evaluation for Additive and Subtractive Processes: Application to Hybrid Modular Tooling

Reviewed, accepted September 10, 2008 The aim of this work is to determine how to combine a subtractive process (HSM) and an additive process (SLS) to realize tools (dies or molds). In fact, the design and manufacturing of tools may be optimized with hybrid and modular points of view. Tools are not seen as single pieces but as 3-D puzzles with modules; each module is manufactured by the best process. So a new methodology is proposed: the most complex-to-manufacture areas of a tool are determined (based on a manufacturability analysis from tool CAD model) and a hybrid modular tool CAD model with a reduced manufacturing complexity is proposed. 1. Context of the study: hybrid modular tooling In order to improve competitiveness in modern mass production industry, products have to be designed and manufactured with the following two goals that are often in opposition: Decreasing time and cost; Improving quality and flexibility. These objectives imply two design and manufacturing constraints: a rapid manufacturing and a high level of reactivity when design evolutions are required. The current field of tooling (dies and molds) does not break these constraints and one answer to the problem is to design and manufacture hybrid modular tools, with modular and hybrid points of views. Modular point of view: Instead of a single-piece tool, it is seen as a 3-D puzzle with modules realized separately and further assembled. The two advantages are: each module may be produced simultaneously and few modules may be changed without changing the whole tool. As it can be seen in the example in Figure 1, the two alternatives of the product may be advantageously manufactured with the same mold. Only one module of the mold is changed to provide new part functions. Fig.1. Two alternatives of a product model (Logicom®). Hybrid point of view: Each module of the tool is manufactured by the best process, in term of time, cost and/or quality. Presently, focus is put on comparison between a subtractive process (HSM: High-Speed Machining) and an additive process (SLS: Selective Laser Sintering). Another research topic investigates the combination of these two manufacturing processes. Figure 2 shows an example of a hybrid tool. Fig.2. Industrial injection hybrid mold [1].