The Droplet Transition In Rapid Prototyping By P-MIG Of Al-alloy

The arc rapid prototyping is one kind of the latest advanced manufacturing technologies. Based on the principle of dispersion and deposition, it uses the welding arc as heat resource to fabricate molds or parts with the figuration technique of point-by-point & layer-by-layer as well as the 3Ddata of CAD.Due to short period, good performance, low cost, good controllability and diversity of figuration shape, dimension and material, it has become a key technology of high-efficiency and smart production nowadays. Focused on arc welding technics, droplet transition and the figuration of microstructure and performance, this paper presents an investigation of droplet transition in the RP experiment of P-MIG using the wire of 5183Al-alloy.Firstly, the effects of various pulse processing parameters on droplet transition are studied by high-speed video camera. The mode, rate and size of droplet transition are investigated with five parameters as pulse frequency, peak current, peak-current time, droplet-detachment current and droplet-detachment time. In the experiments, each pulse parameter has different influences on the behaviors of droplet transition. During the figuration process, correct pulse parameters should be chosen and matched to obtain good behaviors of droplet transition as well as the ultimate figuration.Secondly, the effects of the behaviors of droplet transition on the figuration of both single-pass and passes-layers from three aspects of the surface appearances, microstructure and performance. In this experiment, as the pulse frequency, peak current, peak-current time, base current, droplet-detachment current and droplet-detachment time are respectively 125Hz, 380A, 1.6ms, 50A, 60A, 0.76ms and 125Hz, 380A, 2.4ms, 50A, 60A, 0.76ms, the droplet transition is one droplet one pulse(ODPP).Both six-passes - four-layers samples assure good surface appearances, uniform integral figuration dimension.In the other hand, it obtains homogeneous microstructure and performance, good density and higher hardness than the original figuration materials.Lastly, several simple parts are fabricated with P-MIG as the heat resource. Both the overlap among passes and the accumulation among layers are well controlled with favorable figuration appearances. The efficiency of Al-alloy P-MIG RP is (4.7~7) times of the Laser RP's, which demonstrates the high efficiency.