【转帖】specifying minimum surface roughness

yang686526

specifying minimum surface roughness
i don't have the relevant asme/ansi standard to hand and genium drm doesn't seem to have it.
if you have an area where you want deliberately rough surface finish (in my case to scatter light) is there a 'standard' way of saying it.
i have a drawing from a designer in which .2" at the end of a bore needs to be 'rough'.
the area is indicated and has a callout saying approx .005 rough lathe marks in hatched area inside part.
until i spoke to the designer i didn't understand what she wanted although now it's fairly clear, also it contravenes para 1.4 of asme y-14.5m.
i don't think calling up a knurl is correct.  
is something like "surface finish of area indicated to be 4000 to 6000 rms per ansi b46.1" more correct?
i need to give a response by about 9am tomorrow pacific time, any help appreciated.
kenat, probably the least qualified checker you'll ever meet...
kenat: you can specify an over and under limit range of surface finish to the left of the check symbol e.g. 1000 over 500 (microinches).
if you have a copy of asme y14.36m new or old version, you can see it in the examples. in 1996 version it is fig. 5
kenat-
machinery's handbook is a good place to look.  it shows how to specify rms surface roughness limits and how to achieve different kinds of surface layups.
tunalover
thanks both, based on your info i just looked again and it was in genium, at least in the examples and in machineries.
sadly i've been in meetings for the last few hours so it's a bit late to change the affected drawing but i will know for future.
i suppose i'll have to work out what roughness guarantees good scattering of light based on wavelengths etc.
kenat, probably the least qualified checker you'll ever meet...
some good info:
thanks ctopher, your second link had it too.
i'm generally familiar with surface roughness i'd just never needed to specify a range before, only ever maximum.
kenat, probably the least qualified checker you'll ever meet...
kenat,
if the requirements on the surface finish are due to optical performance needs you may wish to look through the following available standards.
thanks pse
kenat, probably the least qualified checker you'll ever meet...