Flame wire spraying

Autogenous wire spraying or wire flame spraying is the oldest process in thermal spray technology. Using an electric or air motor a material is transported as a wire through a spray gun and melted down centrally in a burning gas-oxygen mixture (usually acetylene-oxygen). Subsequently, compressed air is used to spray the molten material onto the substrate to form a coating.

Flame wire spraying2

The extrudable materials for this process are metals and alloys that can be drawn into a wire shape, and have a melting point that is far below the temperature of the heat source used. If zinc, aluminium, or a zinc-aluminium alloy is used for the wires, it is also called metal spraying.

Process properties

Material Form: Wire (sometimes cord or rod shape)

Thermal energy source: by combustion of a fuel and oxygen

Process fuel: propane, hydrogen, acetylene

Process temperature: < 4,000ºC

Spray particle speed: < 150 m/s

Some features:

  • Micro porous lamellar structure
  • Relatively high degree of oxidation in the coating
  • Moderate tensile strength
  • Good compressive strength
  • Low elongation properties
  • Economic thermal spraying process
  • Transportable process, coating on location possible

Economic thermal spraying process

Typical coatings

  • Various stainless steel alloys
  • Nickel-based alloys
  • Molybdenum
  • Aluminium
  • Copper and copper alloys
  • Zinc, Tin, etc.

Various applications

  • Piston rings with molybdenum for improved wear resistance and running properties (coefficient of friction)
  • Corrosion protection for locks, bridges, etc. with aluminium, zinc and their alloys
  • Repairs or dimension corrections of worn drive shafts or bearing seatings with stainless steel alloys
  • Sleeve bearing surfaces with white metal (Babbitt) or bronze
  • Electrical shielding with tin, zinc, etc.

 

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