Experimental Study of the Effect of Post Processing Techniques on Mechanical Properties of Fused Deposition Modelled Parts

Experimental Study of the Effect of Post Processing Techniques on Mechanical Properties of Fused Deposition Modelled Parts

Addanki Sambasiva Rao (Veermata Jijabai Technological Institute, Mumbai, India), Medha A. Dharap (Veermata Jijabai Technological Institute, Mumbai, India) and J. V. L. Venkatesh (SGGSIE&T, Nanded, India)
DOI: 10.4018/ijmmme.2015010101
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Abstract

FDM (Fused Deposition Modelled) parts are chemically treated with two types of chemicals viz Dimethyl ketone (Acetone) and Methyl ethyl ketone to reduce the surface roughness. This chemical treatment method technique not only reduces surface roughness but also makes effect on strength of chemically treated parts of ABS (Acrylonitrile Butadiene Styrene) material. In this study Taguchi method of DOE (Design of Experiments) is conducted on test specimen of “tensile”, “bending” and “izod impact” components which are manufactured through Fused Deposition Modeling process using ABS-P400 material. DOE is conducted to optimize the effect of chemical treatment process parameters on strength of above specimen parts. The process parameters considered for the DOE are “different levels of concentration of chemical, temperature, time, layer thickness etc. ANOVA (Analysis of variance) is used to know the significance of contribution of each of these parameters. Results reveal that the prototypes when treated at optimum condition the tensile strength, flexural strength and izod impact strength improved significantly.
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Introduction

FDM (Fused Deposition Modeling) is a direct digital manufacturing process patented by Stratasys Inc. The FDM process creates functional prototypes, tooling and manufactured goods from engineering thermoplastics, such as ABS, sulfones and polycarbonate, as well as medical versions of these plastics. Mechanical properties of FDM parts are much comparable to other RP processes. The drawback of FDM parts are its poor surface finish. Particularly, it is when the mechanical properties must go hand in hand with surface finish that the FDM technology shows its main limits (Galantucci et al., 2010).

In literature, there have been some studies done to improve the quality and mechanical properties of FDM parts. Controlling process parameters and applying post processing techniques are the two key methods among the other methods used to improve quality and mechanical properties.

Galantucci et al. (2009) and Rao et al. (2012) have presented the method of applying post processing techniques i.e. chemical treatment technique employed to enhance the surface finish of ABS fused deposition modeled parts that showed considerable promise, yielding significant improvements of the roughness of treated specimens. The proposed chemical treatment technique was economic, fast and easy to use.

The controlling parameters method for which various studies were carried out by several researchers to determine the optimum parameters of FDM for the improvement of mechanical properties like tensile strength, bending strength, impact strength and shear strength of the ABS prototypes.

One such method (Wang et al., 2007) is to control the process parameters like layer thickness, build orientation, raster width, raster angle, air gap etc. In this method process parameters were optimized using statistical techniques like design of experiments i.e. Taguchi method and integrating with gray relational analysis for obtaining the optimum process parameter values to improve tensile strength. The maximal tensile strength of the shaping test specimen was 24.36MPa, which was enhanced up to 90.48 percent. The most essential parameter to tensile strength was the deposition orientation – Z direction.

Sood et al. (2010) have reported that five process parameters such as layer thickness, orientation, raster angle, and raster width and air gap had an influence on three responses such as tensile, flexural and impact strength of test specimen. In this study, it was found that reduction in distortion was necessary requirement for good strength, further, they have reported that factor levels cannot be selected independent of each other because interactions play an important role, the desirability function concept have been used to determine optimal factor levels for improving tensile, flexural and impact strengths independently and all three strengths simultaneously. Sood et al. (2011) have claimed that weighted principal component method has been adopted to improve the multi response optimization problem in the taguchi method and also applied ANOVA to find the significance of each process parameters.

Z. A. Khan et al. (2005) have also used taguchi method of design of experiments to optimize the FDM process parameters and analysis of variance (ANOVA) was employed to investigate the process parameters in order to achieve optimum elastic performance of a compliant ABS prototype.

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