Both wire arc spray and wire flame spray processes are widely used for a variety of applications in the thermal spray coating industry. Typical applications include dimensional restoration, wear resistance, corrosion resistance, electrical conductivity, and many others.
With the twin wire arc spray process, two isolated wires are brought to an intersection point where voltage is applied across the wires, establishing an arc that melts the tips of the wire. An atomizing gas, normally air, is directed across the arc zone forcing the particles to accelerate towards the substrate.
Wire flame spray, on the other hand, uses a single wire that is fed into a flame, where the wire melts. An air stream atomizes the molten particles and propels them onto the substrate.
Although both processes have their strengths, wire arc spray has been rapidly replacing wire flame spray in most applications, due to several technical, operational, and economical advantages. The advantages and limitations of both processes can be outlined as follows:
Wire Arc Spray
Technical Advantages:
- Low heat input into the coating and substrate results in less stress
- High bond strengths (2-3 times greater than wire flame spray)
- Ability to spray thicker coatings
- Ideal for spraying onto non-metallic substrates such as plastic, ceramic, or glass
- Denser coatings
- Complete particle melting guaranteed
Economic Advantages:
- Much higher spray rates (typically 2-3 times greater than flame spray)
- Lower operating cost (1/2 that of flame spray)
Operational Advantages:
- Wide range of operating parameters
- Reproducibility
- Instant on-off is ideal for automation
- No gases needed – only air and electricity are used
Wire Flame Spray
Technical Advantages:
- Less oxide in most coatings
- Coatings can be easier to machine due to reduced oxide
Economic Advantages:
- Higher deposit efficiency with low melting point materials such as aluminum and zinc
- Lower initial equipment cost
Operational Advantages:
- Non-conductive wires can be sprayed
- Less fine dust created when spraying makes overspray less flammable or explosive
- More portable for on-site spraying
In summary, the wire arc spray process proves to be more advantageous. This process demonstrates greater bond strength, ability to spray thicker coatings, improved coating quality and higher spray rates. These advantages have led to wire arc spray to be the principal choice for most metallic spray materials and applications.
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