Sulzer Metco 58NS Copper-Nickel-Indium alloy powder question

[RaymondF2]

Hello All,

So for this powder it recommends a Coverage (ft^2/hr/.001) of 80. I am unsure how to convert that to surface feet per min, Can someone assist me?

many thanks!

[ServiceTech]

Hi Raymond;

What the spec is saying is that with the given parameter, density of coating, feed rate and deposit efficiency, the coating coverage will be 80 square feet per hour at a thickness of .001" of an inch. In order to use this specification to your best advantage, you must know in advance a few requirements:

1. The area of the component being sprayed.
2. The desired coating thickness, total.
3. The desired coating thickness per pass.
4. The gun offset.

Gordon posted a good tutorial on this site somewhere. In this example he is referring to carbides but just sub in the specs for 58NS. Here is a copy of what Gordon posted. Also, if you'd like, I can send you a quick spread sheet on these calculations. Let me know

Gordons Post:

This only covers rotating cylindrical work pieces. For other types you will need to modify method.

1. Calculate coating area (3.14DL)
2. Use COVERAGE (sqft/hr/0.001" or sqm/hr/0.1mm) found hopefully in powder/equipment bulletin/manuals for your particular coating to calculate SPRAY TIME
3. Divide desired coating thickness by the thickness per pass (for carbides and ceramics I would aim for ~ 0.0002" or 5 micrometres per pass) to get number of passes required
4. Part length x No. of passes divided by the spray time will give you TRAVERSE SPEED
5. Traverse speed divided by traverse distance per revolution (this distance should be slightly smaller than your spray footprint) to get rotational frequency RPM.

The theoretical calculations do not always work exactly in practise, but should give a good starting point for fine tuning.

Example: 6" diameter x 12" long cylinder coated with Metco 73F-NS-2 (P73F-10 spec) to 0.010" thick.
1. 3.14 x 6 x 12 = 226 sqin or 1.57 sqft coating area
2. Coverage from Metco 73F-NS-2 tech bulletin says 135 sqft/hr for 0.001" coating thickness.
for 0.010" coating thickness thats 13,5 sqft/hr
for 1.57 sqft thats (1.57/13.5) gives us 0.116 hrs or 7 minutes spray time.
3. 0.010/0.0002 = 50 passes
4. 12" x 50/7 mins = 86"/min or 7.17 ft/min traverse speed
5. Lets say 0.16" traverse per rev 86/0.16 = 537 RPM
6. So that gives us a starting point of 537 RPM (850 SFPM) and a traverse rate of 86"/min using 50 passes and spray time around 7 minutes.

There is a point particularly with high spray rate/high deposit efficient materials on smaller diameters where the part revolution frequency RPM becomes difficult to manage. We can only compromise in these situations, by excepting higher deposits per pass or reducing spray rates. In many situations carbide and ceramic coatings are applied much thicker per pass than I personally would like, but have proved adequate for purpose (I just know they are not as good as they could be
).

Beware my maths may not be that good



Regards Gordon

www.gordonengland.co.uk
www.surfaceengineer.co.uk