topic Re: Sheet Metal Defaults wrong??? in Inventor Forum

Sheet Metal Defaults wrong???

Anonymous — Wed, 12 Jul 2017 23:05:36 GMT

Hello all,

First time posting here. I have been using Inventor for quite a few years for work. But never have I done anything with Sheet Metal. Recently I have been tasked with sheet metal designs for a new customer.

The customer uses Solidworks, we use Inventor. So i am trying to produce the same dimensional results the customer would normally get using Solidworks, in Inventor. It will not work for me.

I am certain it has to do with the way I am using the Sheet Metal Defaults.

Sheet metal design is already foreign to me, and trying to do it properly in Inventor has been a hassle. I do not know how to correctly set up the defaults even though I have the information from the customer (tooling sizes, bend deductions, ect(he uses bend Deduction in his designs)). The result I get is starkly different than what I get in Solidworks.

Solidworks seems to be a bit more intuitive with sheet metal design than Inventor is. I have attached a few photos for comparisons.

The parts overall dimensions are:

28" long

3.244" high

2.269" wide

material thickness is .119". Steel.

Inner and outer radii are both the same in SW and Inventor. .029 and .148

Bend Deduction is known from the custom: .230

When designing in SW i=I can just enter in the BD and everything is ok.

In Inventor, it doesn't seem to be so simple, so I get very different outcomes.

The flat pattern width (as per the customer) should be the 8.297"

As you can see, the Inventor flat pattern is much larger.

Even the flat pattern bend line areas are MUCH different.

Can anyone help with this? I have no idea where to even begin to try and fix it all. I am having a very hard time finding anything online that is helpful.

Thank you!

-Tyler

Re: Sheet Metal Defaults wrong???

johnsonshiue — Thu, 13 Jul 2017 01:56:46 GMT

Hi Tyler,

Could you check what K-factor you used in Inventor? Default is 0.44. Is it the same as in Solidworks? If not, change either one to the same value and then compare. When unfolding using K-factor, it is pretty simple to see if the result is correct. K-factor basically defines the neutral layer where the unfold length is equal to folded length. 0.44 means the layer is at 0.44 of thickness from the inner face. If you cannot figure out, attach the file here, I am more than happy to take a look and prove to you that Inventor is correct.

Many thanks!

Re: Sheet Metal Defaults wrong???

Thomas_Savage — Thu, 13 Jul 2017 08:44:54 GMT

Hello,

I am sure the default k factor for solidworks is .5.

The k factor would obviously make a difference to the flat pattern.

But I am sure it wouldn't make that much difference in the flat pattern.

I think there could be a problem with the model somewhere else.

Thomas

Re: Sheet Metal Defaults wrong???

Thomas_Savage — Thu, 13 Jul 2017 08:51:00 GMT

I quickly modelled up you part.

With .44 k factor I got a flat pattern of 8.421

With .5 k factor I got a flat pattern of 8.443

So not much difference. They could be something wrong with the way its modelled in Solidworks.

Thomas.

Re: Sheet Metal Defaults wrong???

JDMather — Thu, 13 Jul 2017 12:25:06 GMT

There seems to be a confusion of terminology in the responses.

k-factor is not equivalent of Bend Deduction.

(when I use the identical k-factors in both Inventor and SolidWorks I get, of course, identical solutions)

@Anonymous

Can you attach your Inventor file here?

How are you entering Bend Deduction in Inventor?

When I enter a Bend Deduction of .23 in Inventor I get, of course, the identical solution to SolidWorks.

So - identical results in both programs. Now, I would want to verify that the SolidWorks user is using the correct Bend Deduction for this material and bend radius and bend angle.

I should note that in image above I only use a 2.8 inches length of part rather than 28 inches as the length of part is irrelevant for this discussion.

Re: Sheet Metal Defaults wrong???

Thomas_Savage — Thu, 13 Jul 2017 12:12:01 GMT

Hello,

I know k factor is not equivalent to bend deduction.

I was just saying the k factor wouldn't make much difference to the flat pattern.

If he has the correct Thickness, k factor, bend radius then it should be fine?

That's why I was thinking there could be something wrong with the solidworks model they done?

Especially if you have done it in Solidworks and its the same.

I was also thinking he could of got mixed up with Bend Deduction and Bend allowance?

As I have had people tell me Bend Deduction when I've flat patterned by hand, and when I've worked it out it is Bend Allowance.

As there is obviously a difference.

Thomas

Re: Sheet Metal Defaults wrong???

Hochenauer — Thu, 13 Jul 2017 13:09:27 GMT

Can you please post the file you are using here?

Re: Sheet Metal Defaults wrong???

Anonymous — Thu, 13 Jul 2017 19:20:58 GMT

All,

Thank you so much for your comments and your help on this. Great to know there are many folks willing to lend a hand.

JDMather

You hit it right on the nose! After I had typed this up and sent it off, I decided to just keep playing with numbers and see what happens.

In the end, I ended up changing the "Custom Equation" to .23. Since I knew the bend deduction from the customer, naturally I set the fields to "Custom Equation", "Bend Deduction" and eventaully just typed in .23 into the Custom Equation line. Still nothing. I then set the "Backup KFactor" to .23(not sure if this is good practice at all), still nothing changed.

Then, I kind of looked into the "Bounding Condition" and what it said as I hadn't made any changes to that. I decided to just play around some more and set the first number to 0 and second to 180.

Still, no change. So I just deleted the equation that was above it. (No idea what it was or what it was controlling) but that did the trick. I finally got good results.

My inputs look just about identical to your inputs.

As far as Solidworks goes, as you create the Edge Flange, one of the boundaries you fill in, is just what ever the bend deduction was, and since I knew that number, I knew the number to plug in, and it gave me correct result.

I now get identical results with Inventor.

I think my main hang up is NOT understanding KFactor, Bend Allowance, and Bend Deduction ect... And the equations and bounding conditions and what they mean and so on.

This is merely one instance that I was attempting to replicate results within two different software's.

I have zero training when it comes to Sheet Metal so making sense of it all has been difficult at times.

I would like to understand why I need to set up those inputs a certain way for certain results and why.

Thank you all for your help!