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Circular runout Vs Total runout tolerance 3

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Sa-Ro

Sa-Ro

Mechanical
Jul 15, 2019
279
Refer below image

IMG_20201004_162819_rr7ivk.jpg


IMG_20201004_162942_h51odm.jpg


Circular runout should always less than total runout or greater than total runout or equal to total runout?
 
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You show them applied to different features therefore it is the requirements of each feature that dictate the tolerance value independently.

If for example you showed the two applied on the same feature and the circular was with larger or equal tolerance than the total, the circular would become redundant. Because the total "includes" the requirement that the circular imposes.
The circular smaller than the total would make sense geometrically (again - when applied on the same feature).
 
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In a nutshell, a circular runout tolerance only has to be less than the total runout when it is a refinement of the total runout tolerance.

John Acosta, GDTP Senior Level
Manufacturing Engineering Tech
 
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Can I get any reference from ASME standard regarding circular runout and total runout tolerance relationship as a evidence to convince my supplier?

Reference may be para number, figure number, statement etc.
 
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If you have Y14.5-2009, that idea is contained in paragraphs 9.4.1 and 9.4.2. Notice how 9.4.1 mentioned "circular elements." But 9.4.2 mentions "all surface elements." Obviously, "all surface elements" includes circular elements, but includes other elements (specifically, longitudinal elements).
There's your ammunition to explain it to the supplier.

John-Paul Belanger
Certified Sr. GD&T Professional
Geometric Learning Systems
 
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And if you have the 2018 version too you can use figures 12-7 and 12-8, show them one next to the other to visualize what Belanger pointed to.
 
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I have referred both standards.

But there is no explicit statement or figure to show the relationship between total runout tolerance and circular runout tolerance.

Many of the statements in the standard need a expert advice to understand the statement.

If it is explicitly demonstrated, it will be easy to understand.

Thank you.
 
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What's the disagreement over? What's on the drawing?
 
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Drawing represents the tolerance zone for circular runout and total runout individually.

No relationship mentioned.
 
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Which tolerance is bigger in the drawing?
And are they applied on the same feature (your sketch shows otherwise)?
 
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Regarding the figures from the 2018 standard, If the requirements were on the same drawing and on the same feature, the circular would need to be smaller because it would be redundant otherwise. Since they are't on the same drawing what relationship do you expect from them? I suggested you to use these figures to clarify the meaning of the tolerance zones. From the meaning of the tolerance zones one can draw the conclusion of their proper relationship when applied on the same feature in the same drawing.
 
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I understood the meaning with your first reply itself.

But my supplier mentioning, total runout will cover circular runout, circularity, concentricity, cylindricity, straightness. Hence even though the circular runout and total runout are specified in different features, total runout should be always more than the circular runout.

Supplier is asking for evidence in any drawing (may be from standard / some company) which is addressing total runout and circular runout at different features with equivalent tolerance in same part.
 
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Are you serious?
Your company needs to find another supplier.
 
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It is internal supplier. We have to convince them with evidence.
 
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If you have no stress report or the result of a variation analysis to show the effects of these callouts then the performance may not matter. If there is nothing more than an argument over a picture then it's not a requirement worth discussing.
 
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No you don't.
All you need to do is to explain to them that unless otherwise specified, each geometrical tolerance applies to the feature to which it is associated (by a leader or a note). So when you control one feature with a total runout, it won't influence the variation on another feature. I don't even think there is a statement from the standard for that, because I doubt the committee ever envisioned something like that can be questioned. This is ridiculous.
 
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