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Machinability Study of Polymeric Parts Fabricated by Additive Manufacturing Under a Dry Milling Process

Abstract:

Additive manufacturing (3D printing) is rapidly becoming a viable substitute into material subtraction processes due to the design flexibility it offers for complex parts fabrication. Being a relative novelty, meeting specific applications’ requirements, such as dimensional tolerances and surface roughness, implicate an aggressive increase in fabrication costs. Machining of 3D printed parts is proposed by the authors as a method to attain these requirements. This study focuses on the influence of cutting parameters on the machinability of pieces produced by two different AM technologies: MultiJet Printing (MJP) and fused deposition modelling (FDM). All tests were performed on acrylonitrile butadiene styrene (commonly referred to as ABS), measuring improvement of surfaces’ roughness as a machinability indicator and comparing it to injection moulded polyoxymethylene copolymer (POM) for reference purposes. With cutting speed, feed rate and cut depth as the process parameters, 13 terns were formed. Milling processes were executed on 30 x 30 x 10 mm block-shaped 3D prints and surface roughness values were obtained via a portable roughness tester. It was found that the most influential parameter was feed rate, consistently with previous studies conducted in metallic elements. Parts fabricated by FDM presented a higher machinability ratio when compared to MJP, with a value of 1.27. This is interpreted as a high machinability with respect to the reference material, proving that the surface of a 3D printed ABS part could be improved with post-fabrication machining.