GD&T

[Vikas4auto2019]

Hello Guys,
Can you pls explain to me the meaning of such symbols..

 

[3DDave]

The M is metric, the g8 is the tolerance; there are tables for that.

It may be that this case is -0.005 to -0.027 mm from nominal, however MX *such as M8* is usually a thread designation. If that is the case then the g8 is incorrect as thread tolerances have their range as a prefix, such as M8-8g6g.

The others are surface roughness limit symbols. Rz is the average maximum peak to valley of five consecutive sampling lengths within the measuring length. The small horizontal line on the roughness check mark indicated that material is required to be removed to reach the final dimension.

I don't know why the one symbol has parentheses around it.
I also don't know why the 90 degree symbol/dimension is there.

 

[dgallup]

Parentheses indicate a reference dimension but it makes no sense to have a reference surface finish particularly when there is another surface finish callout right beside it. And I don't know that the W means. That is close to where you would specify lay (direction of machining marks) but W is not a recognized lay.

BTW, none of these are GD&T.

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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.

 

[3DDave]

Technically there's not a GD anyway, at least not per the Y14.5.

 

[Tmoose]

Attached image is from a 2004 vintage drawing by a major German Company. Not automotive. An 11,000 kg ductile iron casting.

The "no machining"symbol is outside the parentheses, and is the default for most of the part.
The two Rz100 and Rz25 symbols inside the parentheses are specified on the specific surfaces requiring the respective finish.

This interpretation is in one of the many DIN or ISO Standards. I thumbed thru several that I have with no success.

 

[IRstuff]

Looks like the OP cropped too much off the first image, since there's a hint of red at the edge, so at least one additional character was lopped off on the right side of the W.

TTFN (ta ta for now)
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