Experimental Studies on Assessment and Reduction of Surface Waviness for Weld Deposition based Additive Manufacturing

Balu, Kumthekar Nitin and S, Suryakumar (2017) Experimental Studies on Assessment and Reduction of Surface Waviness for Weld Deposition based Additive Manufacturing. Masters thesis, Indian institute of technology Hyderabad.

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Abstract

Weld deposition based Additive Manufacturing (AM) is one of the economical and efficient ways for fabricating mesoscale metallic objects. This study focuses on the use of Gas Metal Arc Welding (GMAW) based weld-deposition for obtaining the near-net shape of the object, subsequently to be finish machined to the final dimensions. The near-net shape in most of the techniques is obtained through a series of weld-deposition and face milling for each layer. The interlayer face milling is needed because of the uneven surface produced during welddeposition. However, this operation increases the total time of the process and also reduces the material utilization. Hence, this study focuses on reducing the surface waviness of a given layer eliminating/minimizing the need for interlayer face milling. The surface waviness is caused mainly due to improper process parameters and repetitions/gaps arising in area-filling paths. While there is sizable literature on suitable process parameters, the effect of the area-filling path on the surface waviness is not fully analysed. The current work presents different experimental studies carried out for studying the effect of different areafilling features on the surface waviness. Accordingly, three area filling patterns namely spiral-in, spiral-out, and rectilinear with different surface waviness have been described. The material utilisation is measured using a 3D scanner and face milling. Both approaches gave similar results signifying the suitability of 3D scanner approach. Subsequently, the multi-layer experiments are also carried out for different area filling patterns and surface waviness is measured for 5-layer. Rectilinear is found to be the best. In the rectilinear pattern, different overlapping methods namely offset overlap, and criss-cross overlap is also explored. Among these methods, criss-cross shows the best Rt value.

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