Thermal Spray Standards
Harfords have adopted the use EN ISO 14921:2001 to guide their QA documentation when restoration of an engineering component is performed. We have been accessed and approved to ISO9001:2015 by QAS International.
Electric Arc Thermal Spray (The heavy duty metal spray)
The Arc Spray process advanced thermal spraying applications, when the equipment became commercially available in the early 1980’s. HST was the first to use the process in W.A (1981). Prior to the introduction of Arc Spray heavy duty components were unable to be reclaimed due to prior process coatings being of insufficient bond and inter-particle strengths. Harfords changed all of that using Electric Arc Thermal Spray. These coatings have five times greater bond strength and particle cohesion than previous processes.
Intelli-Jet AC- HVAF Process
AC-HVAF is a thermal spray technology used for simple and inexpensive application of premium quality coatings, which meet or exceed HVOF standards for hardness, density, bond strength and oxide content, as well as wear, corrosion and fatigue resistance. Particle velocities exceed 2300 ft/s, while particle temperatures remain slightly below the melting point of metal and metallic binders, allowing AC-HVAF to operate in a solid-particle spray mode.
The AC-HVAF process represents the highest quality thermal spraying technology on the market today. The highest coating quality is the result of unique coating morphology that is radically different from that of HVOF. HVOF coatings are formed from molten particles, which do not bond together properly due to solidification shrinkage and oxide scale. This results in coating defects in the form of voids and other imperfections, which reduce coating quality. AC-HVAF coatings do not exhibit such voids and imperfections, with all of the particles tightly bonded together.
HVAF Arc Process
The HVAF-ARC system produces dense and finely structured coatings from solid and cored wire stock. The TSR300H gun employs an electric arc for wire fusion and HVAF jet for atomization and acceleration of fused particles. The spray head, which is the size of a conventional arc head, includes a toroidal combustion chamber atomizer surrounding wire tips.
A hot catalytic insert activates air-fuel combustion and makes it stable within an extremely short chamber. Exhaust gases are directed into the arc zone. The resultant high velocity jet atomizes molten material, accelerates particles, and propels them toward the substrate where they form a coating. This jet is low in oxygen content and protects the liquid metal from oxidation in the arc zone.
An Oxy Acetylene torch using a means of injecting powder into the gas/flame stream melts the feedstock with the expansion of the gas accelerating the build up material onto the substrate crating a good general purpose protective coating. In most instances this process has been replaced by one of the above processes.