Arc Wire Spray
Arc Wire Spray
Arc wire (also referred to as twin wire arc spray) brings the operational simplicity and portability of MIG welding technology to the field of thermal spray. The result is a system capable of applying a quality surface treatment at virtually any location. The arc spray process begins by feeding two consumable electrode wires into the spray gun. The electrically charged wires are brought together at the gun nozzle where they form an arc that melts the wire. The molten droplets are then arc-sprayed onto the substrate, providing a coating that is resistant to wear and corrosion. Arc wire systems are significantly less expensive than traditional thermal spray systems, making them an attractive option for many applications. Whether you need to coat a small part or a large structure, arc wire thermal spraying provides a versatile and cost-effective solution.
Additionally, the high feedstock capacity of arc wire systems makes them ideal for coating large areas, such as structural surfaces and large rolls.
Arc Wire Spray Common Applications Include:
Journal and Bearing Repair and Buildup
Arc wire thermal spray coatings can be used to repair and rebuild worn or damaged journals and bearing areas. The coating helps to protect the journal from further wear and also provides a smooth surface for the bearing to rotate on.
Roll Resurfacing
Rolls are a vital part of many industrial processes and often suffer wear and tear over time. This can eventually lead to damage, which impacts the quality of the products being produced. In some extreme cases, it may even be necessary to replace rolls entirely. However, arc wire thermal spraying can provide an alternative to replacing damaged rolls. This process involves coating the roll with a layer of metal using arc spraying, and then machining or grinding the newly applied material to required dimension and finish. Hard coatings can help protect the roll from further wear and tear and restore its surface to a like-new condition. Arc wire thermal spraying is an affordable and effective way to extend the life of rolls, and it can help to keep production lines running smoothly.
Exposed Outdoor Structure Protection
Exposed outdoor structures are susceptible to a variety of weather-related damage, including corrosion. Arc wire thermal spray coatings of aluminum and zinc can help to protect these structures from the elements by providing a cathodic barrier against moisture and other corrosive agents.
Arc Wire Spray Method
Arc wire thermal sprayed coatings bear a similarity to flame wire coatings in that both are applied by completely melting and atomizing a wire feedstock before projecting the droplets onto the work surface. Rather than using an oxy-fuel flame to liquefy the metal, an arc wire system uses the heat of an electric arc. In a twin wire system, this arc is struck at the merging tips of two oppositely charged wires made of the material to be sprayed. The point of intersection of these wires is positioned directly in front of a jet of compressed air. As the heat from the arc melts the wire, the jet blows molten droplets forward onto the part. A mechanical feed mechanism pushes both wires forward to maintain the arc and the flow of material.
Arc Wire Spray Practice
The compressed air jet used in the arc wire system tends to promote oxidization of the molten particulate more readily than other systems using inert carrier gasses. As a result, photomicrographs of arc wire-sprayed coatings tend to reveal a higher percentage of oxidized material than those of coatings applied by plasma or HVOF systems. The added oxide content also increases the hardness of these coatings over those of other processes. Though this oxidation may be a concern in some applications, the high mechanical interlock of particles in an arc wire coating often makes this chemical feature irrelevant. Alternatively, nitrogen may be used as an atomizing gas to minimize oxide formation in the deposit.
Arc spray coatings also afford the unique opportunity to create custom 50-50 pseudo-alloy coatings. The arc must be struck between two wires, but the wires need not necessarily be of the same material. By using two wires of differing metals, the coating applied will be a blend of these. Though this feature is seldom requested, it is only possible through the use of an arc wire system.
