Allowance added to the finished coating thickness, often about 0.1 to 0.25 mm per side, to absorb as-sprayed roughness, out-of-round and runout during finishing. Hard carbides and ceramics are diamond ground, while softer metallics can be turned. Too little stock leaves rough low spots after grinding; too much wastes powder and raises stress in thick layers.
Leave 10 mils of grind stock per side, the runout on these old shafts is bad.
Carbide wants a diamond wheel, light infeed and plenty of coolant; heavy cuts crack the coating instead of removing it.
Also heard as
- finish allowance
- stock allowance
- grind allowance
Related terms
Undercut
A recess deliberately machined below finished size so the coating can fill it to full thickness.
As-sprayed
Describes a coating straight from the gun, before any grinding, machining, sealing or heat treatment.
Top coat
The outer, functional layer of a multilayer coating, sprayed over the bond coat.
Mil
One thousandth of an inch (25.4 micrometers), the usual North American unit for coating thickness.