Arc spray gun is a form of thermal spraying that uses wire material as a feedstock. An arc spray gun is used to provide the heat source and melting the fed material by utilizing two current-carrying wires an anode and a cathode.
In an electric arc spray gun as the wires are fed towards each other the electric current short circuits between an anode and a cathode wires creating a high temperature of around 4000°C. This temperature melts the wire and once molten compressed air is used to atomize and accelerate the feed molten metal towards the substrate.
The arc spray gun has the advantage that two different wires can be used simultaneously to produce a pseudo alloy. In the gun cored wires are also used to produce a coating with unique properties. It process is often used for corrosion resistance on large components and building up of worn components.
In this type of gun no moving drive component so that the chance of wear and tear is less thus it reducing the weight of this gun. Because of having the absence of moving drive components also eliminates downtime and maintenance costs. In this gun to drive the fed material two methods are used.
One is an air drive and another is an electric motor drive. In the air drive arc spray gun spool holder is attached to the wire unit and placed at the top of the spray gun. Compressed air is used to rotate the turbine and forward the fed material.
In an electric motor drive, an electric motor is used to forward the fed material for coating and this is connected to the control panel. An electric drive gun is used for precision and atomization.
Typical Coatings Materials In Arc Spray Gun
- Iron & Nickel based alloys
- Babbitt wire alloys
- Aluminum wire, Zinc wire, copper and their alloys
- Bronze wire, Molybdenum wire
Main Applications Of Arc Spray Gun
- To provide wear resistance
- Protection from corrosion
- To provide dimensional restoration
- For bond coating
What Is The Twin Wire Arc Spray Process ?
Two conductive wires are charged with opposite polarities and fed simultaneously into an arc gun during the twin wire arc spray process (TWA). The wire tips collide, melt, and turn molten. The coating is created by atomizing the molten substance using dry compressed air.
Why Apply Arc Spray Coatings ?
Anodic metal coatings on aluminum are used on steel. The method both galvanizing and arc sprayed coatings protect steel is identical: they both build a protective anodic layer on top of the metal. The anodic coatings will self-destruct in order to absorb the corrosion that nature intended for the steel in the first place. The difference between arc spraying coatings and galvanizing is that arc spraying creates a more porous and pure coating, whereas galvanizing tends to incorporate iron into the coating. The coating created by arc spraying contains no iron.
Reduce exposure and the dissolution process that results from protecting steel from galvanic corrosion. The end result is that the arc sprayed coating life is far longer than that of galvanizing, and the sealer controls the quantity of zinc exposed for dissolution to provide steel with corrosion protection for more than 50 years. Steel is additionally galvanically protected by alloys made of aluminum wire or zinc metalizing wire. In an extremely aggressive corrosion environment, these materials can offer longer life protection. These materials dissolve less quickly than pure zinc, but they still adequately shield steel from the more aggressive anodic couple.