Ordinary flame spraying

Ordinary flame spraying process includes wire flame spraying and powder flame spraying. Here we mainly introduce the powder flame spraying process.

working principle

Powder flame spraying uses oxygen or gas (the most common is acetylene gas) flame as the heat source, and uses powdered materials as spraying materials. The spray gun often adopts the gas flow mixing method in which the oxygen gas flow is inhaled into acetylene. After the two gases are mixed, a combustion flame is generated at the outlet of the annular or plum blossom nozzle. The ideal combustion state of the spray gun can be obtained by adjusting the ratio of oxygen and acetylene.

Some spray guns use a powder feeder to deliver powder, and most spray guns are equipped with a powder hopper on the gun, using the negative pressure generated by the airflow to suck the powder, so that the powder enters the flame with the airflow. Here the powder is heated to melt or soften and at the same time accelerated. Some spray guns are equipped with compressed air nozzles to form a conical air curtain, which acts to compress and restrain the flame flow and increase the jet velocity. The spray powder, which melts or softens after heating, is then sprayed onto the surface of the substrate and forms a coating.

equipment composition
The flame spraying equipment is mainly composed of a gas supply system and a spray gun.
The air supply system consists of an air source, a pressure reducing valve, a flow regulator, a flashback preventer and corresponding pipelines. The system should be able to deliver gas, oxygen and compressed air separately.
In order to obtain a stable gas supply, bottled acetylene is generally used. The connection of the gas system is pressure reducing valve (pressure regulation and pressure indication)→regulating needle valve→flow meter→backfire preventer (for gas)→spray gun.
The pressure and flow of oxygen should be continuously adjustable within the parameters specified for the spray gun.
In addition to the requirements of pressure and flow, compressed air should also be water-free and oil-free, and a condenser and an oil-water separator should be configured.
main feature
The equipment has low investment, simple structure, easy maintenance and convenient use on site.
There are many types of materials that can be sprayed.
Since the temperature and speed of the flame are relatively low, the bonding strength and self-strength of the coating are relatively low. The porosity of the coating is high, and the material is easily oxidized.