A parametric investigation of arc spraying process for rapid mould making

Arc spraying has recently found its application in rapid mould making and is used predominantly as a technique for the production of the mould crust. In this paper, the influence of the spraying parameters, i.e. air pressure, loading voltage, wire feed rate, spraying distance and gun transverse velocity, on the resulting crust qualities such as the surface finish and bond strength, was investigated. Since the crust is built layer upon layer by the deposition of metal particles, particle morphology was found to play a key role in the resulting crust qualities. It was found that the particle morphology varies with the spraying parametric settings and their relationships were studied by using a Taguchi experimental technique. The results also show that air pressure is the prevailing parameter, followed by loading voltage, in determining the metal particle size, and that small particles with high deposition density lead to better bond strength. In addition, there is evidence showing that the combined effects of the particle morphology, particle impact force and particle temperature determine the resulting surface finish of the crust.