Because of the strong chemical activity of aluminum and its alloys, it is easy to form oxide films on the surface, and most of them are refractory materials (for example, the melting point of Al2O3 is about 2050℃, and the melting point of MgO is about 2500℃), and the thermal conductivity of aluminum and its alloys is strong, which is easy to cause incomplete fusion during welding. Because the specific gravity of oxide film is very close to that of aluminum, it is easy to become an inclusion of weld metal. At the same time, aluminum and its alloys have large linear expansion coefficient and strong thermal conductivity, and are prone to warping deformation during welding. This is a difficult problem when welding aluminum and its alloys. At present, the most commonly used argon arc welding is to destroy the oxide film by "cathode atomization", so that the oxide film can not be regenerated under the protection of argon. When welding aluminum alloy strengthened by heat treatment, the strength near the weld is greatly weakened, and warping deformation will inevitably occur. The metal surface restorer is mainly used to repair casting defects, which consists of inverter high frequency+pulse power supply, welding torch which can make welding wire rotate at high speed and control part. The mechanism of repairing defects is: using high frequency+pulse voltage to break through gas to form plasma gas, thus generating electric spark with temperature above 6000℃. EDM relies on instantaneous high temperature and mechanical friction between rotating welding wire and base material to melt the meltable rotating electrode (namely welding wire) and the base material in contact with it at the same time. Due to the short action time of electric spark, the base metal in direct contact with the welding wire melts locally, while aluminum has good thermal conductivity, which instantly dissipates the input heat into the air, and the matrix hardly generates temperature rise, so the matrix will not deform, and the defects of precision aluminum castings will be repaired after processing without affecting the dimensional accuracy. The repaired surface can be filed, polished or machined, and its appearance can be consistent with the matrix.