ISO 2768 Broke Edges 2

[joecool1964]

Question regarding 2768

Table II (2) :

Permissible Deviation for Broken Edges:

Looking for the definition for “Broken Edges”
This tolerance callout ISO 2768 is on a drawing for stampings. The logical definition for "Broke Edges" on a stamping surface would be the shear surface.

Question:

Is the “Broken edge” reference on table II the shear edge on a steel stamped part

 

[CheckerHater]

No.
The table 2 refers to ”external radii and chamfer heights” – says it right there in the standard.
If it necessary to describe condition of the edges other than chamfers and fillets, ISO now has special standard, ISO 13715-2000 to specify “workpiece edges”.
Any extra material then is referred as “burr” on the outside corners or “passing” on the inside, and missing material is called “undercut”.

 

[joecool1964]

Thanks for taking the time to reply.

But it does not state in Annex (A) what the meaning is for "Broken Edges".

I am still unclear as to what ISO 2768 means by "Broken Edges".
yes...It states "External Radii and Chamfer heights for broken edges"

Does the stamping process have broken edges ?

I am trying to establish what stamping features can table two on page two of ISO 2768 be applied against.

 

[pmarc]

joecool1964,

While I agree that usage of term "broken edges" in ISO 2768 is not fortunate, I also agree with CheckerHater - the standard specifically designated for edges of undefined shape is ISO 13715:2000.

The purpose of Table 2 in ISO 2768-1 is to define tolerances for "classic" chamfers and external radii. If you have access to the second part of ISO 2768, there is a picture in appendix B.6, where you can see two 2 x 45deg chamfers dimensioned. Notice that on the upper picture the chamfers have no tolerances assigned, but on the bottom picture +/-0.2 appears right after dimension value. Now, if you come back to the Table 2 in part 1 of the standard, you will easily notice that this +/-0.2 corresponds to tolerance class m (exactly as defined on the drawing B.6) for dimensions in a range from 0.5 to 3.

 

[joecool1964]

Thanks for the reply,

Yes ISO specification 13715:2000, does clearly state the edge condition (page 9) based on appropriate callout. But that has nothing to do with ISO 2768, ISO specification 13715:2000 is not referenced with in ISO 2768-2.

Term "broken edge" is not defined on 2768-2. I am trying to define that term, "broke edge" for a stamped part.

See attached picture regarding the typical terms used to describe a trim line condition produced from a stamping tool. Picture is of a stamped-tool hole, but the same terms are used for periphery trim lines as well.

I appreciate the explanation provided for a chamfer, it was helpful.

 

[CheckerHater]

I am trying to establish what stamping features can table two on page two of ISO 2768 be applied against.

There is no such feature.
ISO 2768 applies to DESIGNED features like chamfers and fillets.
It does not apply to manufacturing artifacts like burrs, rollover, flash, splatter, etc., etc.
Even if ISO 2768 is invoked on your drawing, it is not applicable to the cut edges.

 

[joecool1964]

Thanks for the reply.

I understand the artifacts statement.
I not sure what your saying regarding cut lines.

See attached picture, shear is the measurement points.
ISO 2768 does include the trim lines(shear)on a stamped product.

Broken edges means what in specification ISO 2768 ...is the question.