Kermetico AK6 HVAF Gun for Spraying Chromium and Tungsten Carbide Coatings
The AK6 HVAF gun can be used to deposit tungsten coatings onto internal or external surfaces of various parts and structures.
It is a heavy-duty system, made to endure harsh environments and to work long hours with high spray rates.
HVAF Process Description and Advantages
The AK6 HVAF equipment sprays powders, heated and accelerated by the combustion products of the air-fuel gas mixture.
When entering the gun, the compressed air cools the gun. Then the preheated air is used for mixing with the fuel for combustion.
The mixture of compressed air and fuel gas flows into the combustion chamber through the orifices of a catalytic ceramic insert.
Initial ignition of the mixture results in the heating of the insert above the mixtures’ auto-ignition temperature and the hot insert then continuously ignites the mixture.
The spray powder is injected axially into a wide combustion chamber, where the gas flow is very slow, less than 40 m/s (130 ft./sec.)
The long residence time and exposure to favorable heat transfer conditions at high gas pressure, allows the powder to heat efficiently in the chamber.
As an optional tool for accurate heating, controlled amounts of a high heat conductivity gas (hydrogen, helium) may be injected. Leaving the chamber, the powder is propelled into the nozzle of chosen length and configuration, where it is accelerated to a velocity that may be from 800 m/s to over 1,000 m/s (2,600-3,300+ ft./sec.), dependent on the chosen nozzle and combustion chamber pressure. When impacting a substrate, the spray powder particles form a coating.
Blast & Spray
Each Kermetico AK HVAF gun can be used in blast and spray operations.
You can eliminate blasting and masking for blasting in a different booth. Just prepare a part for coating, blast it with any AK gun (it is extremely fast and uniform) and spray with the same gun, spending 10x less time for the blasting operation.
It is much faster and more accurate than manual blasting. Furthermore, using HVAF blasting for surface preparation reduces blast media consumption by 100-times compared to blasting with compressed air.
Specifications
| Specified Characteristic | S.I. Units | U.S. Units |
| Total Heat Output | 130 kW | 442,000 BTU/h |
Spray Powder Size Ranges, µm WC and Cr3C2-base |
3-20, 5-30, 11-45 | |
| Maximum Spray Rate | 28 kg/hour | 62 lbs/hour |
| Fuel Gas | Propane, propylene, natural gas, propane-butane | |
| Optional Secondary Gas | Hydrogen, helium | |
| Consumption of Compressed Air* | 6,650 – 8,500 SLPM | 235 – 300 CFM |
| Maximum Inlet Air Pressure | 10.5 bar | 150 PSIG |
| Consumption of Fuel Gas, Propane | 70-100 SLPM | 2.5-3.5 SCFM |
| Maximum Inlet Fuel Pressure | 11.4 bar | 165 PSI |
| Consumption of Powder Carrier Gas, N2 | Max 25 SLPM | Max 0.9 SCFM |
| Consumption of Optional Secondary Gas, H2 | 5 – 20 SLPM | Max 0.7 SCFM |
| Gun Dimensions | 254(305) x 127 x 127mm | 10(12) x 5 x 5″ |
| Gun Weight with Fixture and Nozzle | 5.2kg | 11.5 lbs |
| Average Thrust During Gun Operation | 7.5kg | 16.5 lbs |
*During gun startup, the consumption of air and fuel is up to 30% higher than during operation.
Features
- Spray rate for a tungsten carbide coatings – 28 kg (62 lbs.)/hour.
- Spray powders: tungsten carbide, chromium carbide 1-20 to 15-30 microns (if you need to spray HVOF-cut powders, please refer to our Convertible systems).
- Axial powder injection.
- Fuel gas options: propane, propylene, natural gas, propane-butane, MAPP.
- Balanced mode for 45-50% deposit efficiency, hardness 1,250-1,350 HV300.
- Ultra-mode for WC-10Co-4Cr coating hardness up to 1,600+ HV300.
- Blast & spray operation saves 99% of blast media, 30-50% setup and preparation time.
- Air cooling (no need for a water chiller) makes the system on-site friendly.
- High coating quality: high density, low level of oxidation, impermeable to gas and liquids.
AK6 is a very simple and technologically efficient gun with a good record of high quality carbide deposition results.
Cemented Carbide Applications
The Kermetico AK6 system has been optimised to spray:
- Ball valves.
- Gate valves.
- Mud motor rotors.
- Pump impellers.
- Shafts.
- Hydraulic rods.
Hard Electroplated Chrome replacement is a fast growing area for the implementation of the HVAF technologies.
Chromium carbide coatings can be deposited onto vessels and heat exchangers; it can also be successfully used for the coating of other parts.
Chromium carbide layers have been applied onto thermowells, ball valves, ash hoppers, auger flights and bearing fits, process rolls, turbine clamp strips and blades.
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