The new Zinc Arc Spray booth is located in workshop 10 following its change of use from a fabrication shop to a finishing and assembly shop. This has enabled BoA to offer alternative corrosion protection to Galvanising. This is because the protection properties of both Galvanising and Zinc Arc Spraying are similar with both processes creating a porous coating on the workpiece.
The two processes differ in the way in which the zinc is applied. Zinc Arc Spraying requires the workpiece to be shot blast to an SA 3 grade which provides an adequate surface for the zinc to adhere to. After shot blasting the zinc protective coating can be applied, this process involves two zinc wires being fed into a pistol which get electrically charged, one positive and one negative. The wires are forced together which forms an electric arc, melting the wire. Compressed air is then passed through a nozzle which atomises the molten metal and sprays it onto the workpiece. Upon contact, the particles flatten onto the surface, freeze and mechanically bond, firstly onto the workpiece and then onto each other as the coating thickness increases. The zinc sprayed surface can then be wet sprayed to give a sealed decorative finish.
ADVANTAGES
- Low heat exchange minimises the chance of distortion compared to Galvanising.
- No size restriction on components that can be protected.
- Coatings of zinc, aluminium, steel, copper, bronze and other materials can be sprayed for corrosion protection.