Metal additive manufacturing has been developed rapidly for its capability to produce metallic objects with complex structure directly. In metal additive manufacturing, the heat source is an important factor determining forming properties, and laser, electron beam and arc plasma are used as main heat sources currently. However, some problems should be noted. When laser is used as heat source, the forming of some powder materials, such as copper alloys and aluminum alloys, is difficult due to their high reflectivity. For the case of electron beam, vacuum environment is necessary resulting in high cost. As for current arc additive manufacturing, it is difficult to achieve high accuracy as a result of high energy and wire material used. This paper developed a new method for metal additive manufacturing. In this method, voltage is applied between the tool electrode and metal powder bed to cause the breakdown of the dielectric forming the micro arc plasma, which is adequate to melt the metal powder, and parts can be formed layer by layer. With this method, the better accuracy can be obtained by means of smaller current and powder bed. In addition, the plasma can be generated easily with less environmental requirements making lower cost. In this paper, the forming principle of this method was studied, and the prototype device was set up. The single point and single pass discharge melting experiments were carried out, and the influence of processing parameters on forming quality was investigated. The feasibility of this method can be verified.
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