Surface Roughness Ra 3.2um 3

[Acester]

What is the tolerance for a Surface Roughness Ra 3.2um. Is it 3.2 ± the general tolerance on the print. Or is 3.2 the max reading as in 0 - 3.2

 

[KENAT]

Roughness is usually given as an RMS statistical average number.

I think a resource like Machineries may have enough info to help you out.

Other wise looke in ASME B46.1 or equivalent.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[TVP]

Surface roughness is a maximum, meaning Ra 3.2 micrometers maximum.

 

[mrainey]

I have seen sealing surfaces rejected for being "too smooth".


Software For Metalworking

http://closetolerancesoftware.com

 

[KENAT]

Which is why ASME B46.1 allows you to specify an upper and lower limit.

Normally though, only the upper limit is specified.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[Acester]

My readings range from .97 - 1.02. is this "too smooth" from the 3.2 callout

 

[KENAT]

Unless they explicitly list a lower limit I don't think there is such a thing as 'too smooth'.

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[Acester]

There is no lower limit callout. Thank you KENAT