Math Question

[wseyller]

I am trying to determine the thickness in microns of a coating liquid that is being applied if evenly onto a urethane roller. Can somebody tell me if my math is good.


Dimensions of the roller: 12.25mm X 233.3mm

coating liquid weight/volume: (684g) 684,000mg per liter

amount of liquid applied mg: 176mg of liquid is applied to the surface of the roller within 48 seconds

So now I calculated in microliter
amount of liquid applied in microliter: 257.31 microliter

I found that 1 microliter = 1 cubic milimeter

So 257.31 cubic milimeter of liquid is being applied.


So I came up with:

38.465mm * 233.3mm * X = 257.31 cubic milimeters

X = .028672mm = 28.672 microns

 

[CycloWizard]

Looks ok, but where did the 38.465 mm come from? I think you wanted to use 12.25 mm there instead, but I'm not 100% sure because the roller dimension isn't necessarily the same as the film dimension. If the film length is 38.465 mm, then everything looks peachy.

 

[wseyller]

38.465 is the circumference of the roller. Forgot to mention that 12.25 is the diameter.

 

[TuxDave]

You answer is probably close enough due to the thinness of the film vs the radius of the roller. If you want to be really accurate, do it in terms of volume.

volume after = volume before + volume of liquid
radius after = radius before + film thickness

 

[TuxDave]

Or in fewer steps.

Volume After / Volume Before = [(Radius + Film Thickness)/Radius]^2

Film Thickness = 28.592um