accumulation of powder in hvof nozzle

[mlavar]

Dear Friends
Hi
we use hvof jet kote, during to apply of wc/co we have problem by accumulation of powder in nozzle, please lead me to solve this problem
thanks

[Met.Eng.]

Hi,

What do you mean about powder nozzle? If you say gun combustion nozzle, I can tell some solution for u.

First of all the cakeing problem has sometimes occur the low melting points metarial. For ex pure Cu vs. but it's hard to say that with Wc/Co.

First you check the nozzle barrel surface. The nozzle surface should be smooth and shiny. If it doesn't look like this, u have to change or polish nozzle. On the other hand if your gun has a gas mixing block you have to check this copper surface. The injetor holes and surface should be regular and smooth.

The other thing is spray parameters. You can choose the cool and slow spray parameter if you have nozzle cakeing problem.

Please write me spray parameters, coating system info ect.

Good day

[mlavar]

Hi,
many thanks for your answer, that is mean barrel, that accumulate the powder in outer mouth of nozzle and close slowly, after that we must remove them(melting powder hunk) from nozzle hardly,
parameters:
propane 5bar
oxygen 6.5 bar
powder carrier N2 6.5 bar
powder rate 45g/min
cooling water 70 c

in the other hand we have more porosity in the structural coating layer and can not get dense coating we want to get good roughness and without porosity in the surface after creep benching, please lead me how can we choose parameter and others issues

thanks

[loriolo]

Hi
Surely the powder you use has too much fines grains, so, or you change the powder, or you can eliminate fines by blowing the powder in front at the spray booth, with exhaust system on, passing powder from the bottle to a can, pay attention for contamination of powder.

[Intel55]

barrel length?
water supply temp?
powder cut?

[mlavar]

Hi,
Barrel length: 160mm
Water supply temp: 30 c
powder: woka3201(53+20)

[Met.Eng.]

Hi again,

The cooling tem is little bit high, You check the chiller and may be you start before coating. I think you have to set it 15 C + - 10 . The other thgs it you try to set 30 gr/min powder, take a cool spray parameter" you know how to change spray parameters with stoichiometry ??" and you can try the a little bit down to carrer gas flow .

on the other hand you can try to clean with a felt stick your nozzle after 5 pas

[mlavar]

Dear Friends
thanks for your advices, because that I solve my problems,
here i have question that because of problem to supply propane I want to use LPG gas but the pressure is low and to get only max 4 bar, is it possible to spray wc, crc, MCrAlY powder,
thanks