Kermetico AK7 HVAF Gun for Coating Large Parts
The AK7 HVAF gun is designed to deposit metal and cermet coatings onto external surfaces of various components and structures.
It is heavy-duty equipment, made to sustain harsh environments and to work long hours with high spray rates.
HVAF Process Description and Advantages
The AK7 HVAF system sprays powders, heated and accelerated by the air-fuel gas combustion products. 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 preheated compressed air and the fuel gas flows into the combustion chamber through the orifices of a catalytic ceramic insert.
Initial ignition of the mixture by a spark plug results in the heating of the insert above the mixture’s auto-ignition temperature and the hot insert 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 (131 ft./sec.)
Having a long residence time and being exposed to favourable heat transfer conditions at high gas pressure, the powder is efficiently heated in the chamber.
As an optional tool for accurate heating, controlled amounts of a high heat conductivity gas (hydrogen, helium) may be injected.
Exiting 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, 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 | 165-200 kW | 561,000 – 682,000 BTU/h |
|
Spray Powder Size Ranges, µm WC and Cr3C2-base Metal alloys |
3-20, 5-30, 15-45 10-30, 15-45 |
|
| Spray Rate | 550+ g/min | 73+ lbs./hour |
| Fuel Gas | Propane, propylene, natural gas, propane-butane, MAPP | |
| Optional Secondary Gas | Hydrogen, helium | |
| Consumption of Compressed Air* | 7,300 SLPM | 258 SCFM |
| Maximum Inlet Air Pressure | 10.5 bar | 150 PSIG |
| Consumption of Fuel Gas, Propane* | 100-190 SLPM | 3.5-6.7 SCFM |
| Maximum Inlet Fuel Pressure | 11.6 bar | 165 PSI |
| Consumption of Powder Carrier Gas, N2 | Max 25 SLPM | Max 0.9 SCFM |
| Consumption of Optional Secondary Gas, H2 | Max 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 – 33+ kg/hour (73+ lbs./hour)
- Spray powders, 3-15 to 15-45 microns
- Tungsten carbide.
- Chromium carbide.
- Pure metals.
- Alloys (from stainless steels to MCrAlY).
- Fuel gas choices:
- Propane.
- Propylene.
- Natural gas.
- Propane-butane.
- MAPP gas.
- Axial powder injection.
- Economy mode for the highest deposit efficiency (65+%).
- Balanced mode to spray WCCoCr with 48-58% deposit efficiency, 1,250-1,350 HV300 hardness.
- Ultra mode for WC-86Co-10Cr-4 coating with the hardness of 1350- 1,600+ HV300.
- Blast & spray operation saves 99% of blast media, 30-50% setup time.
- Air cooling (no need for a water chiller) makes the system mobile friendly.
- High coating quality: high density, low level of oxidation, impermeable to gas or liquids.
- High technological efficiency – it is hard to make a mistake with this gun.
The Kermetico AK7 HVAF System was developed in 2006.
Over the years its design has been improved and optimized substantially based on the gun performance in Kermetico spray shops.
Each part and assembly of the gun, each new improvement went through intensive scrutiny while spraying tons of cemented carbides and different metals.
Now it is a very straightforward and robust HVAF gun with many hardware variations and a good record of working parameters and results.
The Kermetico AK7 HVAF gun created a basis for later development of lower power systems and internal diameter spraying guns.
Applications
Kermetico HVAF AK7 equipment is comfortable spraying large rolls, cyclones and vessels.
It can also be useful for thermal spray coating of other parts.
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