Hard chrome plating is a coating process which deposits chromium 2-250µm in thickness onto a substrate. Chrome plating is used for wear and corrosion resistance, as well as providing a low-friction surface. Unfortunately, the chroming process presents a significant environmental and health concern, as the hexavalent chromium (Cr6+) used is highly toxic, carcinogenic and requires expensive disposal via specialised waste contractors. Chroming is also a ‘one-size-fits-all’ approach, and service life will depend heavily on the operating environment of the component.
HVOF (High Velocity Oxy-Fuel) is an excellent alternative to chrome – it is a thermal spray process which mechanically bonds metal coatings to a substrate. HVOF offers far superior abrasion wear and corrosion resistance, the coatings result in negligible fatigue on the substrate and the coatings can be tailored to suit the operating environment and budget. This includes specific coatings for acidic, alkaline, saline and corrosive environments, or situations where components will be subjected to high heat, impact or abrasion damage. HVOF can also be built up to more than 6mm in thickness, providing greater refurbishment potential and significantly extending the life cycle of components. This results in less downtime and a more cost-effective, long-term repair solution.
Two 793 front suspension rods from the same machine (same operating environment, same operating hours) – the rod on the left was coated with hard chrome, the rod on the right with HVOF. Whilst the chromed rod required a full re-coat, the HVOF rod required only a quick polish to restore it to specification and full working order
HVOF can be applied to just about anything requiring added strength and resistance to harsh environments and operating conditions, such as hydraulic areas, bearing journals, drilling equipment, oil tools, vehicle and machinery parts, casting molds and even plastics.
Specialising in exotic material and cast iron welding, HVT (formerly United Welders) can weld just about anything! With welding experience and knowledge spanning several generations, we’re sure to have the expertise to make your welding project a success. Contact us to discuss if a welded product is mechanically suitable and cost-effective for your needs.
Yes, we do! If you have a large quantity of components requiring work at HVT, we can design and manufacture specialised equipment to improve efficiency, reduce turnaround time and reduce the cost of your long-term projects.
High Velocity Technologies is a proud supporter of both youth and adult apprenticeships for prospective fitter machinists and welders. To enquire about apprenticeships or other job opportunities, please follow the Facebook page for listings, look out for us on Seek or contact us directly on (08) 9493 1355 or at firstname.lastname@example.org.
“Metal spray” or “thermal spray” are generic terms which can refer to a number of processes, including thermal arc, flame spray, plasma spray and HVOF. “Metal spray” is often used to describe thermal arc spray, and some coating providers may purposefully use the term “metal spray” so as not to specifically allude to their process.
Thermal arc is a cheap, low-energy process, and the coatings are normally quite porous compared to high-energy coatings like HVOF (which have low porosity). The high porosity of thermal arc sprays provides a lower-density coating compared to HVOF, as well as lower resistance to environmental or chemical aggressors (ie. a mode of corrosion), allowing more opportunity for liquids, vapours and gases to permeate the coating to the substrate.
Though the price might be more attractive than a HVOF coating, thermal arc is not usually recommended for hydraulics or sealing surfaces, and the coatings provide inferior performance (compared to high-energy sprays) on bearing surfaces. The various coating processes and materials are suited to different applications, so chat to HVT today for your custom coating solutions.