Assembly Based Part Design to Improve the Additive Manufacturing Productivity: Process Time, Cost and Surface Roughness

In design for assembly (DFA), minimizing part numbers is a significant guideline for product design improvement. For this reason, producing a single product regardless of its geometric complexity has been noted as one of the key advantages of additive manufacturing (AM) in the literature. This paper, however, points out that designing assembly parts also has positive influences on AM productivity. In fact, assembly designs enable AM manufacturers to reduce the build time by lowering the height of parts, to decrease the material cost by reducing the amount of support, and to improve the surface quality by deciding the proper orientations for build-up parts. For applying to AM, we propose the assembly design procedure that includes two main phases: designing assembly parts employing design guidelines and evaluating the assembly parts with a quantitative method. In the guidelines for assembly designs, there are mainly two categories: (1) basic principles for assembly designs; and (2) connection types for part assemblies. The former deals with how we separate a single product into several parts and how we make a decision about a build-up orientation in order to improve the AM productivity. The latter covers connection methods that explain how divided parts are connected into a single product again. To assess the assembly part designs quantitatively, we suggest a simple estimation model based on the digital light processing (DLP), an AM technology that results in high efficiency in terms of the build time. A numerical example is provided to show how different assembly designs are compared to select the best one with the highest AM productivity.