HVOF thermal spray coating process is widely used for products of harsh environments, especially for cylinder rods in coal mining and offshore projects. To increase wear resistance, corrosion resistance and high temperature resistance, there are several different coating materials like CrC-NiCr, Tungsten Carbide, Inconel 625, etc. It can perfectly instead hard chrome plating. But the production efficiency is comparatively lower because the spray speed is lower and only 1 piece of rods can be coated each time, furthermore, it’s more difficult to do the grinding and polishing because of higher hardness.