Determination of fabrication direction to minimize post-machining in FDM by prediction of non-linear roughness characteristics

Rapid Prototyping (RP) is a technology that generates physical objects directly from CAD data. As a prototype can be rapidly built by using this technology, the product cycle is remarkably reduced in manufacturing. However, the surface quality of RP processed parts is not sufficient for general mechanical parts because of the use of the layered manufacturing process. Therefore, additional post-machining processes are required such as grinding and coating. But, these processes are time-consuming and detrimental to the original part's geometry. In this paper, a methodology for determining fabrication direction which aims to minimize the post-machining process in FDM (Fused Deposition Modeling) is proposed. In order to enhance the accuracy and the computational speed in determining the fabrication direction, a surface roughness model that is considered even non-linear surface roughness characteristics is presented. And, a required post-machining volume is newly introduced as a objective function. Also, a genetic algorithm is applied to obtain a reliable solution. Finally, it is verified that the proposed approach can be very efficient with the developed system.