topic Re: K-faktor bend table - What is what in the table? in Inventor Forum

K-faktor bend table - What is what in the table?

MatsNorway1 — Tue, 11 Apr 2023 11:04:07 GMT

I want to adobt a K-faktor by thickness table..

As such:

This video got me going.https://www.youtube.com/watch?v=_rffkLWT-jI

But i would prefer to do this in excel. And there is a bend rule template file in the CAD setup folder. but its not being used?

Re: K-faktor bend table - What is what in the table?

CCarreiras — Tue, 11 Apr 2023 10:55:33 GMT

You can´t insert the data in your chart in a Inventor bend table, it's a different method, with different data input.

There's all explained here:

https://www.youtube.com/watch?v=eTY0hyF5_lY

Re: K-faktor bend table - What is what in the table?

MatsNorway1 — Tue, 11 Apr 2023 11:11:47 GMT

I exported, opened in excel, and imported back to TXT after editing.

But testing it i get 1.25 inner radius on a 1.25mm plate

Re: K-faktor bend table - What is what in the table?

MatsNorway1 — Tue, 11 Apr 2023 11:12:35 GMT

Default is set to

Re: K-faktor bend table - What is what in the table?

MatsNorway1 — Tue, 11 Apr 2023 11:16:19 GMT

How i can i get Kfaktor by thickness? Why is that not in the table?

Re: K-faktor bend table - What is what in the table?

MatsNorway1 — Tue, 11 Apr 2023 11:29:36 GMT

I guess its impossible to have a preset radius by a table of thickness.. I guess i go back to letting production people deal with production problems since Autodesk does not even let me try to set it up correctly for them (production)

Re: K-faktor bend table - What is what in the table?

CCarreiras — Tue, 11 Apr 2023 11:59:36 GMT

As i told you before, you can create the styles for each thickness you use, respecting the respective bend radius and kFactor... is just following your table and fill the values for each style.

Later, when designing plates, you just have to select the propper style.
So, it's on you to solve the production people problems.

Again, the bend radius table explore another method. Is based in a correction value, not in the kfactor value, btw, the kfactor doesnt matter so much, since the correction value will impose the correct final measure.
To create the table you have to produce real samples for several bend angles, measure them and insert the correction value in the chart.

For example, the tables you export, have the same deduction value (0.27), doesnt make any sense.
If you have the same deduction value across all the bend degrees, why have a table?

Just check the video.... it works like that, and not as you want to be...

Re: K-faktor bend table - What is what in the table?

MatsNorway1 — Tue, 11 Apr 2023 13:57:13 GMT

I dont understand.

Currently i have this, different K-faktors (bend deduction?) for different thicknesses

1mm

1.25mm

But these are not giving me 1mm radius in my model.. which is confusing.

Re: K-faktor bend table - What is what in the table?

CCarreiras — Tue, 11 Apr 2023 15:20:19 GMT

No... because that table will not change the model... it will only add a compensation value in the flat pattern, in the models that have already the specifications present in the table.
0.27, or 0.22 in that table IS NOT A KFACTOR... is a deduction value...
For the method and data you have... FORGET THAT TABLE... it will not work like you are expecting... it needs diferent imputs that came from measure real samples.

Just check the video................

Re: K-faktor bend table - What is what in the table?

CStilesCARE — Tue, 11 Apr 2023 20:15:04 GMT

Not sure if @CCarreiras already mentioned this, but one work-around you could try is to create different "Sheet Metal Unfold" rules for each thickness, then just set each at the desired default linear K-factor value. You'd just have to remember to change the rule every time you change thickness (or create an iLogic rule to switch automatically maybe).

As it was already said though, bend calculations can be one heck of a rabbit hole to fall down, and getting accurate K-factors can be a big pain in the neck. Things like material type, bending process, equipment, even material heat number, can all make little differences which might throw everything off later on, even if you get it down accurately at one point.

Re: K-faktor bend table - What is what in the table?

Frederick_Law — Tue, 11 Apr 2023 20:26:52 GMT

@MatsNorway1 wrote:
I guess its impossible to have a preset radius by a table of thickness.. I guess i go back to letting production people deal with production problems since Autodesk does not even let me try to set it up correctly for them (production)

You don't understand how to do it doesn't mean it's impossible.

It's not simple.

We kinda, sorta told you how to do it already.

There are a few things need to get setup for sheetmetal.

Re: K-faktor bend table - What is what in the table?

MatsNorway1 — Wed, 12 Apr 2023 06:15:32 GMT

I just wanted Radius to be set according to a table that follows sheet thickness.

Re: K-faktor bend table - What is what in the table?

CCarreiras — Wed, 12 Apr 2023 09:28:45 GMT

Hi!

you can create an iLogic routine in the template to set that:

if thickness = x then Bend radius =y

BUT... several people already sugest you to create the styles accordingly the chart you have, probably is the way to do it...

@CStilesCARE , yes we refer the styles method a couple of times ... in a couple of posts... but seems that somebody is stuck in a table...

Re: K-faktor bend table - What is what in the table?

CCarreiras — Wed, 12 Apr 2023 10:49:19 GMT

@MatsNorway1 , test this file:

Re: K-faktor bend table - What is what in the table?

Frederick_Law — Wed, 12 Apr 2023 14:09:36 GMT

@MatsNorway1 wrote:
I just wanted Radius to be set according to a table that follows sheet thickness.

I just want the software model everything for me 😉

Or boss just pay me while I don't go to work.

Try ask ChatGPT to do it for you.

Re: K-faktor bend table - What is what in the table?

Frederick_Law — Wed, 12 Apr 2023 14:14:47 GMT

The table you shown, is that from your shop?

Is it from a CNC brake?

With my over 20 years in fab and sheetmetal, I didn't know anyone in the shop that use k-factor.

Most had no idea with k-factor is and didn't care.

They all use allowance because they can measure allowance on the floor.

k-factor cannot be measured with a tape or caliper.

Hence most use a bend table with allowance, not k-factor.

You want a k-factor table but you NEED a bend allowance table.

Are we there yet?

Re: K-faktor bend table - What is what in the table?

MatsNorway1 — Wed, 12 Apr 2023 14:30:40 GMT

Its from the manufacturer. "Tillegg" can be translated into addition. Not sure if that helps in understanding the chart.

in my ten years total i always let the manufacturer deal with the sheet metal fine tuning. It seems to be very common to redraw parts on each of the manufacturer plants. Rarely they complained to me at least. It is just too much work for me to redo three different models for three different requests etc. You can do it once you have established a production run and a MF that will be used repeatedly. We are kinda moving towards that. I also want to learn and setup something that is understood and ready to be chanced if we move production somewhere else.

This is moving slow because i also got vault/Inventor issues, i can check out the sheet metal rule file. But it still gives me read only access message.

Re: K-faktor bend table - What is what in the table?

CCarreiras — Wed, 12 Apr 2023 14:56:20 GMT

I already insert your chart (some lines, not all) in the file i attached.
Did you try it?

Re: K-faktor bend table - What is what in the table?

CStilesCARE — Wed, 12 Apr 2023 15:26:01 GMT

If you're just concerned with the bend radius itself, that (for our general purposes) doesn't have anything to do with the k-factor. In Inventor, by default anyway, the inside bend radius is controlled by a sheet metal parameter (BendRadius by default), and is usually set to be equal to material thickness.

If the bend radius stays as a constant ratio of the thickness, you could just alter your Sheet metal styles to change that parameter to the new ratio.

Alternatively, create a User parameter (maybe called "InsRad" or similar) and have it in all parts (add to template), then update your style to refer to this user parameter for bend radius. That way you can change the user parameter at will (or control via iLogic) to have easier control without updating styles all the time.

The k-factor is just used when calculating flat patterns, since it represents the location of the "neutral plane" of a bend (as ratio of thickness), where no compression or expansion occurs. So, k-factor of 0.5 would mean the "neutral plane" of a bend is exactly halfway into the thickness of a piece.

Re: K-faktor bend table - What is what in the table?

Frederick_Law — Wed, 12 Apr 2023 15:49:51 GMT

Great, we got more information.

"Its from the manufacturer. "Tillegg" can be translated into addition. Not sure if that helps in understanding the chart."

What does the "Tillegg" add to? Developed length?

Usually it's substract from flange length.

"This is moving slow because i also got vault/Inventor issues, i can check out the sheet metal rule file. But it still gives me read only access message."

You need to check out the whole "Design Data" folder.