Inventor 2019: Wrong measurements in flat pattern

[Anonymous]

Hi,

I have this issue, this is my folded geometry:

Dimensions are correct and also the one requested by the customer, but when I unfold the sheet the overall dimension is wrong (484 mm instead in the workshop is 489 mm):

Also the folding line are correct just the overall unfold is wrong.

What I'm doing wrong?

I'm attaching also the file, thanks,

Andrea

---

@Anonymous,

marius.gildehaus has edited your subject line for clarity
Original: Sheet metal unfolding issue

---

[JDMather]

Are you familiar with Bend Allowance?

When you bend a part - the material stretches on the outside of the bend and compresses on the inside of the bend.

The neutral plane - neither stretching or compressing is generally not in the middle of the thickness.

This depends on Material, Thickness, Bend Radius and Bend Angle.  Grain might also be a factor.

[Cadmanto]

Are your bend radii in line with what the customer is requesting?

The radii can speak to the OAL.

Windows 10 x64 -16GB Ram
Intel i7-6700 @ 3.41ghz
nVidia GTS 250 - 1 GB
Inventor Pro 2018

[johnsonshiue]

Hi! Let me walk you through how Inventor computes the unfold length. In your case, "tab" rule, a Bend Table has been applied to all bends. Based on the Bend Table, the bend allowance is 9.7mm. For every given bend, the unfold length equals to the sum of length on each side (measured from outside of the bend) minus the bend allowance.

55 + 105 + 188 + 105 + 70 = 523 (the outside measurement)

4 * 9.7 = 38.8 (4 bend allowance)

523 - 38.8 = 484.2 (unfold length)

To get 489, you will need to apply 8.5mm bend allowance, not 9.7mm.

Many thanks!

[blair]

I've attached a great Excel spreadsheet on Bend Allowance and calculating K-Factor

[Anonymous]

Thanks everyone for the answers, it's really helpful.

But still, maybe I didn't explain it well, the 9.7mm I used in the bend allowance comes from a table in the workshop and it gives us the right positioning for the bend lines, but not for the overall dimension of the flat pattern. 

I also tried with the excel file posted but either I'm getting the total dimesion or the right position of the bends.

Again thanks for the help,

Andrea