Flame Spray

Flame Spray

Flame spray is among the oldest methods of applying thermal sprayed coatings.

Its long history has afforded a great deal of refinement and improvement, and although the guns used today still perform the same basic function, their operation, and even the materials they spray, continue to reflect the latest innovations in thermal spray technology.

Common Applications

  • Corrosion Resistance
  • Small Part and Spot Coating
  • Wear Surface Buildup and Repair

Method

The Flame Spray label actually covers a wide range of systems capable of spraying an equally broad array of materials. All flame spray guns, however, perform the same essential function of heating and projecting the coating material through the use of an oxy-fuel flame and a pressurized carrier gas jet.

Materials sprayed with this process come in both wire (flame wire process) and powder (flame powder process) forms, depending on the gun used. In either case, the gun serves to melt and atomize or soften the material as it is fed into the flame, and eject the soft or molten particulate in a directed stream through the gun’s nozzle.

Practice

Flame spray guns typically require very little additional equipment. Most powder-fed guns have a hopper built into the gun body. Others use a small external powder feed unit. Wire guns usually have a mechanism built into the gun body to guide the feed of wire and regulate its speed. Typically, only supply lines for oxygen, fuel, and, occasionally, compressed air are required. Beyond the obvious ease of transport and installation this feature affords, this simplicity also significantly reduces setup time and the margin for operator error.

 

The relatively low particle velocity of the flame spray process leaves a coating of moderate but not outstanding density. As a result, flame sprayed coatings of self-fluxing alloys are often candidates for spray and fuse processes where the additional fusing stage can allow the coating to flow more freely and fill many of the voids that the spray process may have left.