Dimensional accuracy analysis of coupled fused deposition modeling and vapour smoothing operations for biomedical applications

Fused Deposition Modeling (FDM) is one of the most extensively used Additive Manufacturing technique which has substantially shortened the product development time and cost. The application has been extended to fabricate biomedical implants through investment casting process. But the FDM replicas exhibit poor surface quality which requires further post finishing. Thus, it is very difficult to achieve adequate dimensional accuracy as surface finishing techniques resulted in material removal and erosion of upper surface. The vapour smoothing is an advanced finishing technique which eliminates tool-workpiece contact and yield ultra smooth finish but dimensional accuracy of FDM replicas is yet to be ascertained. In present research, the efforts are made to explore the influence of FDM and VS process parameters in dimensional features of complex designs. The influence of six parameters on radial (head diameter) and linear dimensions (neck and stem thickness) is studied using Taguchi orthogonal array. The CMM measurements showed shrinkage in head diameter while positive deviation has been observed in linear dimensions before vapour smoothing with maximum impact of orientation angle. The vapour smoothing process caused shrinkage in both linear and radial dimensions with maximum effect of smoothing time. The process parameters and their levels are optimized and confirmatory experiments indicated reduced deviations in dimensional features with consistency in IT grades.