Finish vs. roughness
Finish vs. roughness
(OP)
On some of my drawings that do not require a finish, I've left the default note "NONE"... this has led to some questions despite the roughness Ra value in the general tolerance block. As if the two callouts contradict each other.... ?
So help me understand finish callouts. I’m not a machinist, but I always thought a machinist would look at the surface roughness callout and adjust his setup accordingly! Is this correct? What are the steps in machining a part to a desired surface roughness, say 32 or 125µin? So why would you call that roughness, a finish?
So help me understand finish callouts. I’m not a machinist, but I always thought a machinist would look at the surface roughness callout and adjust his setup accordingly! Is this correct? What are the steps in machining a part to a desired surface roughness, say 32 or 125µin? So why would you call that roughness, a finish?
lightweight, cheap, strong... pick 2





RE: Finish vs. roughness
From a drawing point of view finish usually means plating/treatment etc.
How to make sure this doesn't get misunderstood I'm not sure, could it be as simple as striking through the finish box rather than stating none?
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Finish vs. roughness
"Roughness" is a measure of surface asperities. Sometimes the term "microfinish" is used. If a lower number is specified, a machinist will reduce the transverse feedrate.
Mike Halloran
Pembroke Pines, FL, USA
RE: Finish vs. roughness
John Acosta, GDTP S-0731
Engineering Technician
Inventor 2013
Mastercam X6
Smartcam 11.1
SSG, U.S. Army
Taji, Iraq OIF II
RE: Finish vs. roughness
No.finishing process like passivation, anodization, epoxy coating, cleaning etc comes under finish.
Suppose you just want to machine an AL6061T6 block. and you are not at all concerned with the surface finish. Then the part will be having its stock finish or the finish based on your method of manufacturing process.As like general sheet tolerances there should be a separate column for surface finish and finish.
In finish column, indication will be none. surface finish General surface finish value will be indicated.
To achieve your desired surface finish & Lay. The machining process will vary and as well there could be additional process like Hand polishing, buffing etc, after machining.
Suppose you are designing cylindrical part with a sealing surface with 32µin, circular lay. u should go for CNC LATHE turning to achieve the surface and lay direction.
Hope i am clarified you.
Regards
Vimal VV
RE: Finish vs. roughness
lightweight, cheap, strong... pick 2
RE: Finish vs. roughness
My understanding is that is the maximum or better (smoother) roughness/finish to be achieved for the final product. Meaning that no grit blast (to make it close to 63Ra) or polishing (to make it smoother) required for the second operation. Is that valid?
If it is maximum or better, is there any tolerance apply to this?
RE: Finish vs. roughness
thread1103-318284: Surface Roughness General Coverage Specification
Chris
SolidWorks 13
ctopher's home
SolidWorks Legion
RE: Finish vs. roughness
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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
RE: Finish vs. roughness
That help me to be more certain about this.
RE: Finish vs. roughness
Is it just me, or is the Wikipedia article opposite what we see from a drafting point of view?
http://en.wikipedia.org/wiki/Surface_finish
lightweight, cheap, strong... pick 2
RE: Finish vs. roughness
----------------------------------------
The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
RE: Finish vs. roughness
John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems