The HVAF metal spray process is characterized by a low combustion temperature (1,960-2,010°C | 3,560-3,650°F), high particle velocities (800 to over 1,000 m/s | 2,625-3,281 ft./sec.), resulting in low-oxidized, ductile, non-porous high-bond carbide and metal coatings. With a spray rate up to 550 g/min (73 lbs./hr.) it makes the process much faster, providing a significant advantage over HVOF.
Kermetico HVAF equipment uses the energy of gas combustion in air to spray powders. The combustion temperature in a HVAF gun is typically 1,000°C (1,830°F) lower than that in a HVOF coating system.
The Adiabatic Combustion Temperature of Fuels in Oxygen and Air (a=1, 20°C, 1 Bar)
This lower temperature is ideal for the gradual heating of the feedstock particles of metals and cemented carbides to or slightly above the metal’s melting temperature. The initial oxygen content in the combustion gas mixture is 5-fold lower in our HVAF process compared to any HVOF coating process. Both factors prevent the oxidation of metals and the decomposition of carbides.
For more information on the comparison between HVAF and HVOF processes, Click Here.
- Environmentally Friendly - High Velocity Air Fuel (HVAF) technology has been shown to be very competitive as an environmentally friendly alternative to electrolytic hard chromium (EHC).
- Reduced Production Costs - The ecological aspects and shorter processing time reduce processing costs.
- Thicker Coatings - An option to apply thicker layers provides a way to repair heavily worn components.
- Higher Wear & Corrosion Resistance - HVAF carbide coatings are also superior to conventional HVOF counterparts regarding wear resistance, corrosion protection and production cost. The high velocity of our HVAF in-flight particles (higher than 1,000 m/s | 3,300 ft./sec.) ) enables the production of very dense coatings.
- Minimal Elemental Depletion - the low combustion spraying temperature (1,960-2,010°C | 3,560-3,650°F) and gentle particle heating lead to minimal feedstock phase transformation and almost nonexistent elemental depletion/decomposition of the in-flight particles.
- Reduce Oxide - Higher Performance Coatings - the replacement of pure oxygen necessary for HVOF with air in our HVAF process significantly reduces the oxide content of the coatings, which is desirable for high-performance coatings.
- Aerospace Components - Repair.
- Augers & Screws - Wear Resistant Coatings.
- Boiler and Waste Incinerator Tubes - Corrosion and Wear Protection.
- Chemical Plant and Oil Refinery Parts - Repair.
- Coating Stripping by Hot Grit Blasting.
- Compressor and Steam Turbine Blades - Erosion Protection.
- Electrical Submersible Pumps - Stainless Steel Coatings.
- Electronic Grade Coatings.
- Exhaust Fans - Carbide Coatings.
- Food Processing Equipment - Tin Plating (Tinning).
- Hard Chrome Replacement.
- Hydro Turbines - Erosion and Cavitation Resistant Coatings.
- Mud Motor Rotors - Wear Resistant Coatings.
- Paper Drying Cylinder - Wear and Corrosion Protection.
- Pressure Vessels - H₂S Resistant Coating.
- Shafts - Wear Resistant Coatings.
- Slurry Pumps - Abrasion Protection.
- Spraying Internal Diameters.
- Steel Rolls - Wear Resistant Coatings.
- Surface Cleaning and Preparation for Thermal Spray Coatings.
- Surface Restoration.
- Turbine Rotors - Wear Protection.
- Wear and Corrosion Resistant Metal Coatings.
- Winder (Reel) Drums - Anti-slip Coatings.
Cost Comparison of HVOF and HVAF Tungsten Carbide Coatings
HVAF and HVOF equipment investment costs are about the same if we speak of a one system installation. But the Kermetico HVAF system deposits coatings 4-5 times faster (15-33 kg/hour for Kermetico HVAF as compared to 4-5 kg for HVOF), which means you could use one Kermetico HVAF system instead of several HVOF coating systems.
What if you don’t have a large volume, but you do have high diversity?
The Kermetico HVAF AK line is an all-in-one system operating several specific guns: Universal, big OD, small OD, ID, rotating ID and hand-held. This requires less investment in a Kermetico HVAF system and makes the payback period shorter.
The key factors of the cost advantage of Kermetico HVAF technology:
- Kermetico's HVAF spray rate is 15-33 kg/hour with a deposition efficiency higher than 50%; fewer work hours means fewer hours to pay for; and with our systems, you need to spray just a fraction of the HVOF spray time.
- No oxygen in HVAF mode – just compressed air, which costs 10 times less.
- Easy-to-change specialized guns allow spraying each part in the most efficient way.
- The cost of consumed spare parts is 1/10 of the conventional HVOF expenses for the same work.
From this, you can see that one hour of Kermetico HVAF costs 30-40% less than one hour of HVOF spraying.
Let’s look at the cost per 5 kg (11 lbs.) of tungsten carbide coating HVOF or HVAF deposited.
HVOF vs HVAF Tungsten Carbide Coating Quality-Cost Analysis
Each kilogram of Kermetico HVAF deposited coating is up to two times less expensive than HVOF. Numerous academic and practical research studies that have been conducted at different universities and job shops around the world support these data. We can send you our calculations by request to recalculate with your in-house data.
Is it Worthwhile to Upgrade from HVOF to HVAF?
Your investment in a new Kermetico HVAF system will pay itself back while you are spraying your second metric ton of WCCoCr.
- You need to buy just the Kermetico HVAF system; it fits all existing HVOF infrastructure. (Well, probably you will need to upgrade a compressor if you have a really weak one).
- Your learning curve will be just a couple of weeks long – our HVAF systems are easy to use for operators familiar with HVOF.
- You gain $160 per deposited kilogram of E-mode HVAF WCCoCr compared to a conventional HVOF version of the same material.
- You’ll get back $160,000 per metric ton of tungsten carbide deposited, – more than enough to cover all of your expenses.
And some additional benefits come with using Kermetico HVAF as well:
- You can eliminate the blasting room – blast and spray with one setup to improve quality, shorten manufacturing time and reduce blast media consumption by a factor of 100.
- User thinner as-sprayed coating thicknesses and minimize grinding time due to the low roughness of the as-sprayed HVAF coating.
If you have questions on the HVAF/HVOF process, please call 07 3823 1004, or email us using our contact form.