Zinc arc spray process for weld seam of cold-rolled steel tube
Metallizing Equipment Co. Pvt. Ltd. (MEC), India, has developed an arc-spray thermal spray process that applies a zinc coating to reinstate the corrosion resistance of the weld seam on cold-rolled welded tubing. Applying the zinc arc spray while the weld seam is hot assures a metallurgical bond, improves the deposit efficiency and density of the zinc, and allows the coating to blend, thereby helping to hide the weld seam. Arc spray is the most user-friendly and, in terms of operating cost, the least expensive of the thermal or metal spraying processes. Any electrically conductive material in wire form can be arc sprayed.
A DC motor powers the wire pulling system, which is fitted in the gun to ensure precision wire-feed speed. The wires meet at the head of the gun and melt in the electric arc. The molten mass is atomized, and compressed air blows the particles onto the substrate, where the particles cool to ambient temperature and coalesce into a high quality metal coating. A small spray width minimizes over-spray and precisely controls material usage.