Mechanical and Microstructure Investigation of Weld based rapid Prototyping

Abstract

At present the commercially available rapid prototyping (RP) machines can mainly produce parts that can be used either as models for visualization or for rapid tooling. The emphasis of the on going research in this field is to produce parts that can physically imitate and work like a component produced by a conventional manufacturing technique. Thus the idea is to produce “form-fit-functional” parts rather than prototypes for visualization. Parts made by metals are of specific interest and welding based RP has good prospects in this regard; with the specific possibility to produce fully dense metallic parts and tools. However, the big draw back of using welding as the deposition process is the large heat input to the substrate or to the previously deposited layers, thus causing high temperature gradients and resulting in deformations, warpage, residual stresses, delamination and poor surface quality. In addition the layer by layer additive manufacturing nature results in non-homogeneous structures, porosity and anisotropic material properties. Parts thus produced are of near net shape and out of tolerance. In order to predict and minimize these problems, knowledge of thermal gradients and temperature history during manufacture is important. Moreover, to overcome the problem of surface quality and out of tolerance parts a hybrid welding/CNC milling based RP system can be a good option. These problems associated with the use of welding as RP tool needs to be minimized by the