Flame spraying can be seen as a similar concept to paint spraying. Once the system is connected up, the sprayer operates a valve to start the gases flowing and lights the gas stream. A trigger is then used to start/stop the wire feed into the flame and the coating deposited in a similar way to spray painting. These systems are used to reclaim surfaces by applying a similar material or give the surface different properties by coating it with a different material. Most metals can have an aluminium coating applied by the flame spray process. This can be for aesthetic, anti-corrosion, conductivity or many other reasons. Zinc can also be applied to most substrates using the flame spray process. This is often to provide galvanic protection of the substrate, but may be for a number of other reasons. The gas fuel and oxygen are mixed and ignited to produce a flame. The material, either a wire or powder is fed into the flame.
For wire flame spray, the material is melted and the compressed air, passing through a spray nozzle which atomises the molten metal and sprays it onto the work piece. The larger the wire diameter, the higher the spray rate. For powder flame spray, the powder particles (metal or ceramic) are softened in the flame and the speed of the flame gases through the nozzle sprays the softened powder onto the work piece. Anti-corrosion coatings are typically applied with oxy-propane systems. Engineering coatings are typically applied with oxy-acetylene systems. Where propane is not available, oxy-acetylene systems can apply anti-corrosion coatings. Flame spray systems are commonly manually operated but it is possible to semi-automate or fully-automate the process if required.