Hem flange issue

[pamakela]

Hi,

I have a sheet metal part that consists of multiple sheet metal solids. Everything works, all pieces flatten successfully etc. But there's this one sheet metal part that just won't accept a Hem Flange on any edges - what's going on here? What are the things I must ensure to make Hem Flange work?

I can add regular Flanges to that same sheet's edges.

 

[pamakela]

Okay, I noticed why Nx can't do Hem flange. I had applied a Dimple feature on the sheet part earlier and apparently no hem flange can exist on the "wrong material side" of a Dimple. Is this really so? This causes so much extra re-work..

 

[CAD2015]

Can you post the file? We can see better what's going on.......

MZ7DYJ

 

[JohnRBaker]

What version of NX are you using?

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[JohnRBaker]

I just tested every version of NX back to NX 5.0, where the Hem Flange was first introduced, and I've had NO problems adding Hem Flanges to either 'side' of a sheet metal part with a Dimple feature. Could you please provide at least a picture of what the model looks like when you're attempting to add the Hem Flange?

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[pamakela]

Hi,

we are using NX 8.5 and I was able to reproduce the situation on a trivial plate, see image links:


1. Here we get the error:

Link


2. Then flip the sidedness of the Dimple feature:

Link


3. Now apply Hem Flange on the same edge and Hem works (even if it overlaps other geometry):

Link



Can any of you also reproduce this situation?

 

[JohnRBaker]

Using NX 8.5.3.1 (first phase of the next Maintenace Release) I had no problem creating Hem Flanges that interfered or not with the Dimple feature, both before and after flipping the direction of the Dimple.

Could you upload your example file to see if it works with this version of the software?

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[pamakela]

You can acquire the small .prt file at

https://www.facebook.com/photo.php?fbid=10151292293849229&l=d3eb52ee54.

It is left in the state where it produces the error.

 

[pamakela]

..oops! Wrong link, instead try this one:

https://dl.dropboxusercontent.com/u/11427789/engtips_HemFlange_issue_NX8.5.prt

 

[JohnRBaker]

OK, I see now what has happened.

During the creation of the Dimple feature I suspect that you noted that it was going in the wrong 'direction' and you probably double-clicked the 'handle' on the side of the Dimple to change the 'direction'. Unfortunately, despite it being labeled as the 'Direction' handle, this was NOT the 'direction' that you should have been looking for. To do what you wanted you should have doubled-clicked the 'Depth' handle as this would have reversed the actual 'direction' of the Dimple, that is, caused it to be on the opposite side of the 'Tab'.

What the so-called 'Direction' handle does is control which part of the sketch, the inside or the outside, is to be used to created the 'Dimple' feature. When you reversed this 'direction' by double-clicking the handle on the side, which admittedly may have been poorly named, it forced the 'Dimple' feature to use the area formed by the sketch AND the outer edge of the tab, as it's 'profile' thus making what were the edges of the 'Tab' to now be the edges of the 'Dimple' (you can verify this by selecting the 'Dimple' in the Part Navigator and noting what part of your model is highlighted), and it appears that the system does not allow the creation of 'Hem Flanges' on the edges of a 'Dimple'. And while you mentioned that you had no problem adding a normal 'Flange' to the edges of your model, this was only possible because you were using NX 8.5. Prior to NX 8.5 you were not allowed to add 'Flanges' to a 'Dimple' (check the 'What's New' guide to see the cases that we were thinking of when this NX 8.5 enhancement was implemented, which was NOT exactly what you've stumbled into).

Anyway, now that you understand the behavior of the 'Dimple' feature better, I suspect that you should be able to avoid this sort of issue in the future. That being said, I am going to share your model with the Product Manager responsible for Sheet Metal since we might want to reconsider the name that we've given to the so-called 'Direction' handle.

John R. Baker, P.E.
Product 'Evangelist'
Product Engineering Software
Siemens PLM Software Inc.
Industry Sector
Cypress, CA
Siemens PLM:
UG/NX Museum:

To an Engineer, the glass is twice as big as it needs to be.

 

[pamakela]

Hi,

yes, I think that what you say is exactly what is going on. All in all I gained some new pointers as how to use the Dimple and Hem features, while I also think that maybe some interface re-thinking could be in order.

Again, thanks for you time and effort!