turbine blades and vanes HVOF appliaction

[anne]

Hello, Have anybody experience with spraying turbine components by HVOF? I saw that the blade was rotated on the rotating table and the gun moved from left to right with pitch up. if anyone of you apply the coating in a similar way? Depending on components size or coating thickess the whole spraying process may proceed to 30min or longer. Do you use cooling air during spraying? Or between the cycles? Regards

[Vadim Verlotski]

Hello, Have anybody experience with spraying turbine components by HVOF? I saw that the blade was rotated on the rotating table and the gun moved from left to right with pitch up. if anyone of you apply the coating in a similar way? Depending on components size or coating thickess the whole spraying process may proceed to 30min or longer. Do you use cooling air during spraying? Or between the cycles? Regards

Hi anne,
The colder the component (turbine blades) and thinner the single layer the lower the tension in the spray layer. So you have to cool the blade all the time (max temperature not higher that 200°C) and you need a relative movement speed (spray spot on the coated surface) of at least 700 mm/s.
To achieve this, the turbine blade must rotate quickly (> 300 rpm, better > 700 rpm) and the robot must be fitted with compressed air nozzles for a strong running cooling.
It would be even better if you operate several rotary tables with turbine blades at the same time and with the burner go alternately from one to another. In this case, you can also install stationary cooling for each turntable.
Regards
Vadim

[anne]

Yes, but what about speed gun? It should look like I described above? RPM should be adjusted to blades widtH and the s gun's speed adjusted in such a way as to achieve the required coating thickness?

Regards, Anne

[MVagusta]

Hello, Have anybody experience with spraying turbine components by HVOF? I saw that the blade was rotated on the rotating table and the gun moved from left to right with pitch up. if anyone of you apply the coating in a similar way? Depending on components size or coating thickess the whole spraying process may proceed to 30min or longer. Do you use cooling air during spraying? Or between the cycles? Regards

I spray turbine components everyday
As you said, depending on size and coating thickness to be applied the entire process can last many minutes. A vane tipically last longer for obvious reasons. To answer your question i don't use cooling air during spray.

[demionkrishan]

Hello, Have anybody experience with spraying turbine components by HVOF? I saw that the blade was rotated on the rotating table and the gun moved from left to right with pitch up. if anyone of you apply the coating in a similar way? Depending on components size or coating thickess the whole spraying process may proceed to 30min or longer. Do you use cooling air during spraying? Or between the cycles? Regards

Hi anne,
The colder the component (turbine blades) and thinner the single layer the lower the tension in the spray layer. So you have to cool the blade all the time (max temperature not higher that 200°C) and you need a relative movement speed (spray spot on the coated surface) of at least 700 mm/s.
To achieve this, the turbine blade must rotate quickly (> 300 rpm, better > 700 rpm) and the robot must be fitted with compressed air nozzles for a strong running cooling.
It would be even better if you operate several rotary tables with turbine blades at the same time and with the burner go alternately from one to another. In this case, you can also install stationary cooling for each turntable.
Regards
Vadim

Hi! anne,
We are doing Coating for Gas turbine blades, of course you need a Cooling Air for gun either you can use N2 for cooling purpose.
We have dust collectors are made for 16000 CFM max capacity and usually damped to 12000 CFM. For a plenum of 100 Square feet cross section, if you divide 12000/100 , We should be getting a velocity of 120 feet per minute. I think our plenum section is about 70-80 square feet. Which means we should get a velocity of 150 feet / minute right above the turn table.

Check your exhaust capacity and measure the required velocity. if your blowers working fine, you don't need to give any special/ additional cooling to your turn table.
Note: if your turn table is getting hot use pedestal and then use your fixture to protect from heat to avoid Servo motor malfunctions.
2) Coating Thickness and Turn table RPM
Usually for blades coating thickness will be 0.008 -0.014 mils , roughness grater than 200mi and the table rotation speed will be grater 300RPM
Coating thickness will calculate measuring After Weight minus before Coating weight and the Rpm/ gun speed will measure upon your diameter of your buckets/blades

3) Spray time will be 7-25 minutes up on your size of your blades.


Regards,
Krishan