Short answer: Wire arc spray (twin wire arc spray) is a thermal spray process that melts metal wire with an electric arc and propels molten metal particles onto a prepared substrate. It is used for dimensional restoration, wear protection, corrosion resistance and as an environmentally safer alternative to hard chrome plating. AST offers wire arc spray in chrome, stainless steel and nickel.
When an industrial component wears beyond tolerance, the traditional options are replacement or electroplating. Wire arc spray offers a third path: rebuild the worn surface with a dense metal coating, machine it back to specification, and return the component to service. It is faster than plating, builds thicker coatings, and avoids the environmental hazards of chromium plating baths.
How wire arc spray works
Twin wire arc spray feeds two electrically conductive metal wires toward a spray gun head. One wire is positive, the other negative. When the wire tips meet, an electric arc forms at extreme temperatures, melting the wire tips into molten metal. A high-pressure compressed air jet atomises the molten metal into fine droplets and accelerates them toward the workpiece.
On impact, particles flatten, cool rapidly, and mechanically interlock with the roughened substrate surface. The coating builds up layer by layer into a dense lamellar structure. The result is a metallurgically bonded coating that can be machined, ground or polished to finished dimensions.
Materials: Chrome, stainless steel and nickel
The wire material determines the coating properties. AST offers three primary material families:
Chrome wire spray
The primary alternative to hard chrome plating. Chrome wire spray coatings achieve hardness comparable to electroplated chrome and can be ground and polished to a mirror finish — suitable for hydraulic rods, cylinder bores and sealing surfaces. Unlike electroplated chrome, wire spray coatings do not develop micro-cracking (fine crack networks that create corrosion pathways under the surface).
Stainless steel wire spray (304 / 316)
Corrosion-resistant coatings for general engineering, marine, food-grade and chemical environments. 316 grade provides superior chloride resistance due to its molybdenum content, making it the preferred choice for marine and saltwater applications. Both grades offer good machinability after spraying.
Nickel wire spray
Pure nickel and nickel-chromium alloy coatings for high-temperature service, caustic environments and marine applications. Nickel coatings provide excellent corrosion resistance in seawater, alkali and chemical process environments. Also used as bond coats in multi-layer coating systems.
Key applications
- Dimensional restoration: Rebuilding worn shafts, journals, bearing housings, rolls and cylinders back to OEM specifications. Coatings from 0.1 mm to over 6 mm thick, machined to finished tolerances.
- Wear protection: Abrasion, erosion and sliding wear resistance on industrial components. Chrome wire spray provides hardness comparable to hard chrome plate.
- Hard chrome replacement: An environmentally compliant alternative to hexavalent chromium plating for hydraulic rods, cylinders, print rolls and sealing surfaces.
- Corrosion resistance: Stainless steel and nickel coatings for marine, chemical, atmospheric and high-temperature corrosion protection.
Wire arc spray vs hard chrome plating
| Factor | Wire Arc Spray | Hard Chrome Plating |
|---|---|---|
| Environmental impact | No hazardous chemicals | Hexavalent chromium baths |
| Max thickness | 6+ mm | 0.025-0.1 mm typical |
| Micro-cracking | None | Common — creates corrosion pathways |
| Turnaround | Faster (no tank immersion) | Slower (bath process) |
| Finish quality | Ground/polished to mirror | Ground/polished to mirror |
| Complex internals | Line-of-sight only | Non-line-of-sight (advantage) |
Industries served
Surface preparation
Surface preparation is the single biggest factor in coating adhesion. Components are abrasive blasted to create a clean, angular surface profile for mechanical interlocking. The prepared surface must be coated promptly to prevent oxidation that would compromise bond strength.
AST uses silica and glass bead blasting for substrate preparation — a more controlled process than sandblasting that preserves substrate integrity while achieving the required anchor profile.
AST's metal spray capability
AST (Australia Surface Treatments) provides wire arc spray metal coating services from our Melbourne facility, servicing customers across Australia. We spray chrome, stainless steel (304/316) and nickel wire, with in-house machining and grinding to return components to finished dimensions.
Metal spray is one of three coating technology families AST offers — alongside fluoropolymer coatings (Teflon, Halar, Tefzel) and Resigraph graphite-resin coatings for glass manufacturing. All backed by a lifetime workmanship warranty.