Design for AM: Contributions from surface finish, part geometry and part positioning

With the increase in production final parts by Additive Manufacturing, the study of the surface finish and dimensional accuracy become critical, in order to determine if it is possible to avoid costly and time-consuming post-production, especially when using Fused deposition Modelling of Polymers. This is especially true when the goal is functional parts, where the surface quality and dimensional accuracy may preclude the use of FDM. With that in mind a study was performed to evaluate the surface finish and dimensional deviations of FDM parts, when considering multiple processing parameters, by way of a design of experiments coupled with response surface methodology. The results showed that the critical parameters were face orientation, layer height and printing speed, and equations predicting the surface finish and dimensional accuracy were obtained, with further experimental results validating the equations. With these equations we propose guidelines for manufacturing part by FDM when surface finish and/or dimensional accuracy is of importance, so that a designer knows what changes can be made to a part and what precautions must be taken when printing said part, in order to comply with a specified surface finish/dimensional tolerance.