Surface speed

[ahmadsahid]

Ok, thank for your answer. Actually, it answered my question.
But I am interesting about thickness per pass and traverse distance per revolution.
1. How much the thickness per pass for Ni-base, Al-base, and Steel base?
2. How do you calculate traverse distance per revolution?

AhmadSahid

[Gordon]

Hi ahmadsahid

1. How much the thickness per pass for Ni-base, Al-base, and Steel base?

Generally the metal based coatings are a bit more tolerant to being applied in thicker layers than ceramics and cermets. There are a few materials which seem to benefit from relatively thick coating per pass, particularly the exothermic bond coats and so called "one step coatings". NiAl bond coat is usual recommended to be applied to its final thickness (0.004 - 0.006" or 0.1 -0.15 mm) in just one single pass.

Heat transfer to the component being sprayed is significantly greater from material deposition than from the flame or heated gas stream. So the coating deposition rate/thickness per pass is a major consideration for controlling heat/temperature distribution in coating and substrate. So as general rule of thumb go for the minimum thickness per pass (high rotation and traverse speeds) practical for your set-up.

First look to see if there is any advice/guidance in the technical data sheets for application rates/speeds and feeds for specific the product. There are a few that like that extra heat abuse from heavy build ups per pass

2. How do you calculate traverse distance per revolution?

This depends on the width of your spray foot print which may vary depending on equipment/process/materials and parameters used. You want to set the traverse distance per revolution so that you get just enough overlap of coating to produce even coverage ie avoiding the point where you get a barber pole effect.

[thjjr]

How do you calculate traverse distance per revolution?

Need to know the following:

Desired Surface Rate for the applicaiton (mm/sec)
Spray Foot Width (mm)
Turn Table Speed (RPS)
Surface Radius (mm) (from Centor of Rotation)

Simple Traverse Rate (without consideration of application rate)
Turn Table Rate 60 RPM
Spray Pattern Foot Print Width 10 mm

Traverse Velocity 10.0 mm/sec = 10mm * 60RPM / 60 sec/min

That represents a feed rate parallel to the axis of rotation not knowing or considering applicaiton rate over the surface or desired application rate for your process, but is the first step in determining it. -

The next question is - what surface rate is contributed by the turn table rate? To calculate this, you need to know the radius of the surface from the center of rotation of the turn table. Larger radius gives you larger circumference, and vice versa.... C=Pi*2r

This tells us that you have to traverse or feed slower at larger radius, feed faster at smaller radius to keep the desired surface APPLICATION rate constant at the desired.

The relationship is Desired Appliction Rate / Turn Table Applicaiton Rate (This gives us a unitless ratio between the two at a given radius)

As the application radius position changes, so does the feed rate (traverse Rate) requirment parallel with the axis of rotation of the turn table.

With robotic application of plasma spray process, the "path" can be segmented into many targets, with a minimum distance between them (as small as practical and capable), and the velocity between those targets can be calculated based on the average coil distance between the two radius of the last position to the next position. -

For curved surfaces - the "foot print width" will change shape - and for those targets in that area, a scalar can be applied to the velocity calculation to slow it down or speed it up between targets.

Feed Rate = Spray Foot Width * RATIO (Turn Table Surface Rate(at radius) .vs. Desired Surface Rate)

You can enter this all in an Excel Spreadsheet and play with the input parameters to see the rate changes required for different surface radius, turn table speeds, and spray foot pattern width, etc...

Hope this helps or sparks some more interest...

PM me if you want an example Excel file with your e-mail address.

[Gordon]

Hi thjjr

to the Surface Engineering Forum.

Thanks for your input.

[DMan]

Dear All
Followed the threads and its quite informative.
Can anyone provide me suitable & Practical data for Surface speed , RPM and Traverse Speed for Oerlicon Metco Plasma Spray coating for Bond coat (Amdry510) and Top coat (Metco 6156).Recommended surface speed from Metco is 60m/min.
Your advise may be able to help me out of dull finishing on Al base.