What is Surface Finish Ra?
Roughness average in micrometers. Tells inspectors how smooth a machined surface must be.
Ra 1.4 µm · spec 1.6 · pass
Ra on a drawing refers to…
Write it in your own words in the app.
In real work
Print calls Ra 1.6 on the bore. Hit it or the NDT hold stays open.
In the illustration
The stylus arm rides up and down over the tool marks as it traverses; the averaging dial settles at Ra 1.4 µm, under the 1.6 called on the print.
Add the surface finish ra requirement to the traveller in your shop-floor software: 1.6 micrometres on the sealing face, measured with the profilometer, logged per part.
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The fastest way to learn a word is to use it. Open this line in the agent you already work in and watch what it does. Change the tool to the one you use.
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