Thickness unit equal to 0.001 inch or 25.4 micrometers, used for coating thickness and surface profile in North American shops and field specs. A typical TSA spec of 8 to 12 mils is about 200 to 300 micrometers. Machinists say thou for the same unit. In British and Australian shop talk mil means millimeter, 39 times larger, so mixing the two on a drawing or spec is a classic and expensive mistake.
Bond coat 4 to 6 mils, top coat 15 to 20, measure it on the coupon, not by passes.
Also heard as
- mils
- thou
- thousandth
Related terms
Pass
One sweep of the gun across the area being coated; the coating is built up pass by pass.
Anchor profile
The peak-and-valley roughness grit blasting leaves on a surface, which the coating locks onto.
Grind stock
Extra coating thickness sprayed beyond the final size so it can be ground or machined to finish.
TSA
Thermally sprayed aluminum: arc- or flame-sprayed aluminum that protects steel from corrosion.