Arc Spray coatings

Among all the various material build-up and thermal spray systems that we utilize at MBI, the Twin Wire Arc spray process is considered a favorite.  This process is known to be the work horse of our industry. It allows us to apply and build up advanced coating materials fast, inexpensively and at high efficiency rates, which translates into savings to our customers.

Definition

Electric Arc Spray Process.  (aka the Twin Wire Arc Spray process).  Two wires of desired materials act as electrodes when they're fed thru a spray gun.  The gun is connected to a high-current (DC) power source to facilitate an arc between them.  An air stream thru the back of the gun atomizes and  propels  the molten particles towards a prepared surface.  With adjustable parameters including voltage and amperage arc temperatures can reach 5000° C, enough to melt any material, at the same time the part surface remains cool.  The process is considered energy efficient because all of the input energy is used to melt the spray materials.

Spray rates are driven primarily by the operating current and vary as a function of both melting point and conductivity. Generally materials such as iron-base alloys including stainless steel materials spray at 4.5 kg (10 lb)/100 A/h.  Aluminum and Zinc spray at 11 kg (25 lb)/100 A/h.

The MBI difference

At MBI we employ high velocity twin wire arc spraying to produce coatings that have extremely high bond strength (over 13,000 psi), lower stress and higher densities than what others can produce.

Also, with our process parts remains relatively cool during the coating build-up (Cold process) avoiding warping, damage and metallurgical changes to the substrate /part material. Our Arc spray processes produce coatings that are versatile in terms of properties and characteristics for favorable hardness, thickness and material composition.

Below is a partial list of some typical materials that are available to apply:

Coating group Average Hardness Bond strength As-sprayed finish (Ra) Applications areas Examples
Chrome steel alloys 62 Rc 8000 psi 300-500 Heavy build up and wear resistance Bearing journals, Crankshaft journals, general wear apps.
Nickel alloys 20 Rc, variable >13,000 psi 200-350 Ra Bond coat, Inconel, Monel and other Ni alloys work. General repair coating, corrosion applications, etc.
Stainless alloys 30-60 Rc >10,000 psi 140-180 Ra Wear with corrosion Pump components, chemical industry parts.
Carbide alloys 70 Rc >10,000 psi 150-500 Ra Hard-coatings with heavy build up Mixer blades, Fan blades, Granulators, Feed rolls, etc.
Copper alloys, bronze, brass Rb scale hardness >9,000 psi Average 250 Ra Rebuild non-ferrous alloy surfaces. Pump impellers, print rollers, bronze bearing areas, etc.
Aluminum and Zinc Low Rb 8000 psi 200-400 Corrosion protection Exceed galvanizing specs.

A Feed Roll is being Arc sprayed with a traction coating for a tough gripping non-slip application.

Typical Properties

  • Very high bond strength.
  • Versatile hardness, to machine or grind.
  • Versatile build-up .003” to >.0.300”
  • Versatile finishes, smooth to extra rough.
  • High ductility with low stresses
  • High density with low porosities.

Typical Applications

  • Feed Rolls & non-slip surfaces
  • Corrosion protection work
  • General journal build-up & repair
  • Specific alloy build up material
  • Replace galvanizing
  • Heavy build-up requirements
  • Chrome plating replacement coatings
  • And much more!

Call (803) 313-9292 or click here to contact MBI for more information.