Improving dimensional accuracy of fused deposition modelling (FDM) parts using response surface methodology

Abstract

Fused deposition modelling is one of rapid prototyping process that uses plastic materials such as ABS (acrylonitrile-butadiene-styrene) in the semi molten state to produce prototypes. FDM is an additive process and the prototypes are made by layer by layer addition of the semi-molten plastic material onto a platform from bottom to top. Primary process parameters such as layer thickness, raster angle and part orientation in addition to their interactions are studied in the present dissertation that influences the dimensional accuracy of the part produced by the process of Fused Deposition Modelling (FDM). Due to shrinkage of the filaments, the dimensions of the CAD model does not match with the FDM processed part. The shrinkage dominates along length and width of the build part but a positive deviation is observed along thickness direction.
Influence of each parameter on responses such as percentage change in length, width, and thickness of the build part are essentially studied. The effect of process parameters on responses are studied via Response surface methodology (RSM). RSM is used to calculate the regression coefficients and the function is made with the significant factors. Then optimization of process parameters is made by genetic algorithm so as to minimize the percentage change in length, width and thickness.