Deposition effect of Metco 42C

[Met.Eng.]

Hi SEF members,

We are coating with Metco 42 C powders on Stainless steel barrel.

as an example, diameter: 70 mm, Length 140 mm, Rotation speed: 180 RPM,
Traverse speed: 25mm/sec.

Our spray parameters 42 O2, 26 c2h2, 37 Ar and 76 gr Powders, and 205 mm distance.

To obtain only the thickness of 250 microns with 600 gr powders. When we looked at the catalog, DE is %95 for this powders. But during the process, We saw lats of rebond powders scattering around. I suspect that a very low adhesion efficiency during the porocess. Is this normal? I think DE is less than %50

[Gordon]

Hi Metallurgy_eng

I guess you are using Metco 6P-II gun, if so your deposit efficiency sounds extremely poor, I reckon less than 50% and that's with only a 50% target efficiency. But maybe that's because of the parameters you are using. 95% DE is quoted for a specific parameter set which you appear not to be following.

Try using oxygen 45 flow and acetylene 55 flow (26 sounds far too low)

[Met.Eng.]

Hi Gordon Thank you for your answer.

I want to ask something else to you. Metco Parameter catalog has several different definitions. Which one do you use these values​​. For Ex. 2GF(FMR), 3GF(FMR) or FLOW (NLPM). As you know, we have 6P-II system with PLC control. In our system we can set SLPM.

In addition, What is The difference between High Spray rate and Normal spray rate. what we must choose According to these parameters, ?

[Gordon]

Hi Metallurgy_eng

I want to ask something else to you. Metco Parameter catalog has several different definitions. Which one do you use these values​​. For Ex. 2GF(FMR), 3GF(FMR) or FLOW (NLPM). As you know, we have 6P-II system with PLC control. In our system we can set SLPM.

Yes, very important point. The flow meter units I thought we were taking about were from the 2GF. Converting these values:

Oxygen 2GF 45 FMR @ 35psi = 3GF FMR 42.3 @ 35psi = 42.3 NLPM
Acetylene 2GF 55 FMR @ 15psi = 3GF FMR 27.6 @ 15psi = 27.6 NLPM

This indicates your values are in fact correct (without nit picking) if your original quoted values are in NLPM or SLPM.

Sorry I was not aware you were taking about a 6P-II system with PLC control, in fact I was guessing that you were using a 6P-II in the first place

In addition, What is The difference between High Spray rate and Normal spray rate. what we must choose According to these parameters, ?

Spray rate. High spray rate uses a different parameter set and nozzle. I do not see any parameters for Metco 42C though (maybe my info is getting old). I would choose high spray rate system only if the higher spray rate was beneficial to production. Quality and %DE if anything will be better with the normal set-up.

Going back to your original question, your situation does not sound normal, but I'm at a loss to suggest what might be wrong at this stage. I would conduct a deposit efficiency test and evaluate microstructure of coating produced to confirm whether your suspicions are correct.

[Met.Eng.]

I want to add somtg,

In our system we can set only SLPM value of gases. Our system has mass flow controlers and we cant set any pressure of the gases. So What is the difference between NLPM and SLPM. Totally confused. You said to me your parameters may be wrong , go to the Acetylene 55 to 26. Can I use NLPM values. Information: NLPM is used in Europe and refers to the standard temperature of 0 Deg C where SLPM refers to the standard temperature of 70 Deg F or 21.1 Deg C

[Gordon]

Hi Metallurgy_eng

In our system we can set only SLPM value of gases. Our system has mass flow controlers and we cant set any pressure of the gases.

That's because you are measuring mass flow (which is then converted or normalised to volumetric flow), which unlike volumetric flow is not dependent on temperature and pressure. NLPM is now often used as a mass flow measure

So What is the difference between NLPM and SLPM. Totally confused.Sad

Join the club, I think many are. Look at this thread

Converting-LPM-to-SLPM

Unfortunately, there does not appear to be a standard standard or normal normal

The important thing is to know and to quote conditions of temperature and pressure.

You said to me your parameters may be wrong , go to the Acetylene 55 to 26.

I initially thought you were quoting 2GF FMR's

Can I use NLPM values. Information: NLPM is used in Europe and refers to the standard temperature of 0 Deg C where SLPM refers to the standard temperature of 70 Deg F or 21.1 Deg C

I would first check which SLPM calibration conditions are used in your mass flow controller. I know many use 0 C and 1 bar much the same as NPLM, but there are many others. See this good write up on on wikipedia

Standard conditions for temperature and pressure