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world gathers for metal finishing
Q&As since 1989


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Inquiry for surface roughness

I want to know how to convert value of millimicron to Grit. I have a value of surface roughness in millimicron & I want to convert it in to Grit. So please tell me how to convert it.

Prashant G. Prabhu
- Mumbai, Maharashtra, India
2003

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There are charts available in either millimeters or inches that correspond to grit sizes, or at least a size range. Meaning, grit is that size which falls through a certain screen hole. That separation or classification system gives you a range of grit size and can be shown as a 4 digit high and low number when media gets to a larger size. The surface finish of the materials being worked do not directly relate to grit sizes.

AF Kenton
retired business owner - Hatboro, Pennsylvania
2003

Dear Sir,

You have mentioned that there are tables - Grit to Microinches/Micrometres. Where can I get them?

Thanks in advance.

Ranganathan Elaneera
Engineering Consultancy - Singapore
2004

We convert the reading (Ra 0.007 ìm ) into micro mm to micro inches.

Chetan M Shah
- Hosur,Tamil nadu, India
2004