Improvement of surface finish by staircase machining in fused deposition modeling

A semi-empirical model for evaluation of surface roughness of a layered manufactured part by fused deposition modeling is presented. Surface roughness resulting due to staircase effect in rapid prototyped parts is one of the major problems. Even though there have been some attempts to improve the surface finish of the rapid prototyped components, the drawback of those attempts is the accessibility of certain areas of the prototyped component. An attempt is made to address this problem using a simple material removal method namely hot cutter machining (HCM). A fractional factorial design of experiments, with two levels and four process parameters, is adopted to understand the effect of various process variables. ANOVA is used to find the significance index for process variables, and confidence level for the statistical model developed for the surface roughness of hot cutter machined surface. It is concluded that the proposed machining method is able to produce surface finish of the order of 0.3 μm with 87% confidence level. This machining process provides a key for development of a hybrid rapid prototyping system, which will have features of both layer-by-layer machining and deposition simultaneously, in order to achieve improved surface finish and functionality of RP parts.