Sheetmetal Hem 0 radius ??

[tmalinski]

In sheetmetal Is there a way to get a zero rad. Hem? I keep on getting a .002 rad even when I select the closed option and I cant find what controls this.

thanks Tom..

 

[CorBlimeyLimey]

Hmmmm ... apparently not with the Hem function. A .004" gap appears to be the limit.

You cannot actually have zero because it would effectively merge with the main body, and you cannot have varying thickness in SW Sheet Metal parts.


Helpful SW websites faq559-520
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[tmalinski]

I'm working with .006 and .010 thick materials. I would think that any gap as long as there is a gap would prevent SW from looking at it as thicker material. A .004 gap with .006 material looks huge, especially when the customers print and the actual part we make is folded onto itself and then hammered flat. Maybe there is an alternative to the Hem function, but still lets me unfold???

 

[ctopher]

I have never heard of a zero R in sheetmetal. What is wrong with .002?

Chris
Systems Analyst
SolidWorks/PDMWorks 05
AutoCAD 05
ctopher's home site (updated 06-21-05)
FAQ559-1100
FAQ559-716

 

[tmalinski]

I work for a metal stamping Progressive Die house and we commonly use thin stainless steel strip sheetmetal, anywhere from .004 to .020 inches thick. So if I make a Hem with a .004 gap with .004 material thickness, it looks like a candy cane rather than a closed Hem as it should.

 

[ctopher]

WOW. I have never worked with .004 sheetmetal.

Chris
Systems Analyst
SolidWorks/PDMWorks 05
AutoCAD 05
ctopher's home site (updated 06-21-05)
FAQ559-1100
FAQ559-716

 

[tmalinski]

Ya I dont know how we do it either. Sometimes I wonder how I got into this trade. Anyway, I was able to create a simple sketch of the hem representing the inside edge of the material with a .0001 rad. Then I created a Base Flange and told it .006 thickness and .125 wide. It extruded it as it should and I am able to unfold it. So I end up with a .0002 gap. I could have made the rad even smaller but this is fine.

 

[J-C]

Also submit an enhancement request. My bet is they hard coded that lower end value cause they thought no one would need go that low. They should have used a percentage of the thickness.

Jason

UG NX2.02.2 on Win2000 SP3
SolidWorks 2005 SP5.0 on WinXP SP2
SolidWorks 2006 SP1.0 on WinXP SP2

 

[beachcomber]

Hi Chaps,
Just thought you might be interested to know that I tried this in Solid Edge V15 and it produces a min gap of 0.0001575".
If you round this dimension to the 4th decimal it's 0.0002"
I'd suggest that the limitation is to do with what tolerance the systems can work to before they consider the faces to be coincident.
It's also possible that this is a limitation of Parasolid rather than SW or SE.
Producing the hem is simple in SE - it uses what they call a 'Contour Flange'. This lets you produce any shape of flange along all or part of an existing edge. All you do is draw a line representing the folded part, back along the face that you are folding down on to.
Regards
beachcomber.

PS.
.004" sheet!! that's for wrapping sandwiches in isn't it??

 

[smcadman]

If you had a radius of zero, wouldn't the bodies merge and the hem become 1 with the rest of the part? Would it be considered a "self intersecting contour?

I tried to create a zero hem from a sketch and got the following alert: " The fillet could not be added because the specified radius would eliminate one of the elements".


Flores
SW06 SP2.0

 

[tmalinski]

Thanks everyone for your input. ya .004 is like aluminium foil, but being Stainless Steel it's more workable than you might think. We progressively stamp and form this stuff into complex medical cutting blades and things. We also process very thin Titanium sheetmetal into surgical staples. I tried modeling one of these guys but that was a chore because the material is coined and formed to different thicknesses. SW sheetmetal didn't like that too much...
But as I stated in an earlier reply, I am able to model this with sheetmetal by drawing a profile of the inside of the hem as a sketch with a .0001 rad and then using Base Flange to extrude it. It then unfolds as it should. Using the Hem tool may be more politically correct, but in this case I was able to work around it.
Thanks, Tom...

 

[CorBlimeyLimey]

Interesting! Using SW05, I just opened a sheet metal job I did in SW03/4. It had several hems (created using the Hem function) which had an inside bend radius of .0002" (actually .005mm).

So it appears the Hem function has been ... ... "improved" in SW05.


Helpful SW websites faq559-520
How to get answers to your SW questions faq559-1091

 

[J-C]

Sounds like a regression. If that's true, this should be reported to get fixed.

Jason

UG NX2.02.2 on Win2000 SP3
SolidWorks 2005 SP5.0 on WinXP SP2
SolidWorks 2006 SP1.0 on WinXP SP2