Reduce unmelted particles in Combustion Wire Spray

[Alberto Villalobos]

Somebody knows how can i reduce the unmelted particles in Combustion Wire spray, because i have problems with pores on the grinding surface.

Thanks in advance

[Vijay Deshpande]

Pl give more details about the fuel you use for combustion,
Vijay

[Gordon]

Hi Alberto

Somebody knows how can i reduce the unmelted particles in Combustion Wire spray, because i have problems with pores on the grinding surface.

Thanks in advance

Strictly speaking wire spray processes should not produce unmelted particles in the coating. The particles need to melt to be released from the wire unlike powder spray processes. Problems with pores in the surface of the finished coating will be due to a porous/high oxide/poorly bonded coating or maybe poor finishing.

To be more helpful, we would need to know far more information on your process, materials and parameters.

[plasmajet1990]

Somebody knows how can i reduce the unmelted particles in Combustion Wire spray, because i have problems with pores on the grinding surface.

Thanks in advance

Hello,

You can try to decrease the speed of the wire.

Ion

[Alberto Villalobos]

Hi All.

I am sorry but i stopped to follow this forum for some time

I am spraying Ti6Al4V parts with combustion wire spray (6C controller and gun 5k). We are using a wire of 99.9% Molibdenum; Feedrate of 21 inches per minute

When I spray the parts, i have a uniform texture, without cracks, without delamination, without any defect on the surface (visual inspection), but, when the parts are machined, People from cell area report me pores on the machined surface.

What do you recomend to avoid pores?.

I spray with Acetylen+Oxygen+Air with the next parameters:
Air
Pressure: 60 PSi
Flow: 78 SCFH
Oxygen
Pressure: 40 PSI
Flow: 52 SCFH
Acetylen
Pressure: 15 PSI
Flow: 28 SCFH

[Met.Eng.]

Do you finish by machining????? Dont you? Couse if you machining hard wires you can see some micro poros on your surface.
You have to finish by GRINDING.
Other wise your air qualty may be poor. With oil or not dry. You can use Ar or N2 with same air parameters.

Regards.

[Alberto Villalobos]

Do you finish by machining????? Dont you? Couse if you machining hard wires you can see some micro poros on your surface.
You have to finish by GRINDING.
Other wise your air qualty may be poor. With oil or not dry. You can use Ar or N2 with same air parameters.

Regards.

Thanks Metallurgy_eng, I will check the quality of our air, i'll be watching the air filters to see if we have oil or water.

[Stephen Booth]

Just a note to emphasize, make sure you do your finishing by Grinding. If you do not have a grinding machine, you can buy a tool post belt grinder from Dynabrade, and some good belts and most of the problems will probably go away....

[KevinS]

Normally the biggest problem I see when unmelts appear in wire spray is from bounce back getting reintroduced to the flame. Make sure that your angles and surfaces do not re-introduce previously sprayed particles.