topic K factor accuracy in Fusion Design, Validate & Document Forum

K factor accuracy

daniel_lyall — Fri, 02 Jun 2017 04:18:37 GMT

Quick question is the K factor in the default materials accurate. And yes I know next to nothing about sheet metal.

Re: K factor accuracy

promm — Fri, 02 Jun 2017 04:50:31 GMT

I would not rely on our default materials for accuracy. This for some people this can be a big debate, the rule of thumb is around .4-.5 and thats how .44 usually gets picked. It really depends on how accurate you need to get. In some industries you get a metal report from your vendor and adjust the K-Factor from there. I would google K-Factor standards for the material you are using. If you have any specific challenges, I am happy to help.

Cheers,

Mike Prom

Re: K factor accuracy

daniel_lyall — Fri, 02 Jun 2017 10:34:53 GMT

Thanks @promm I found a cheat sheet and it says about the rule of thumb .44

Re: K factor accuracy

Anonymous — Sun, 04 Jun 2017 14:26:37 GMT

Hi Daniel,

k factor can't be "standard" because it's related to the tools used by the factory.

I work with 4 carpentries (4 manufacturers of my sheet metal parts) and 2 of them use almost the same k factor, so say that the differences between the same part of both are quite nothing.

For the other two I've to recalculate the flat pattern each time. This is normal, however.

Regards

Marco

Re: K factor accuracy

TravisJoe — Mon, 05 Jun 2017 10:06:53 GMT

As others have said K-factors have a lot of variables but close "baselines" can be used. As Mike said .44 is a good general number. But if you want accuracy and consistency you will need to speak with your vendors. You have two main variables, the material and the tool. Different metals stretch and deform differently causing variations. Materials also have manufacturing inconsistencies in thickness and properties, even things like grain direction can effect the K factor. The machine and tooling will effect this as well. For example large radius tooling will effect the deformation less compared to sharp tooling.

Hope that helps

Re: K factor accuracy

CLmoss — Mon, 05 Jun 2017 17:11:19 GMT

Mike, are you saying that the automatic k factor in Fusion Sheet Metal is .44 or that this is what the industry average is?

If so, what is the k of the automatic k factor in Fusion Sheet Metal?

What I am being asked for, by a shop, is to select from the type examples below.

As I understand it Fusion Sheet Metal cannot do that yet.

Is that correct?

Jim

Re: K factor accuracy

Anonymous — Tue, 06 Jun 2017 07:02:04 GMT

Jim,

that are you talking of, is another thing.

You are talking of the reliefs that are not related with K - factor.

And yes, even if roughly yet, F360 can manage that reliefs.

You can find them in the bend dialog box unde "2 Bend corner override"; you have to choose "Round" and select a proper radius.

See the image below.

Bye

Marco

Re: K factor accuracy

daniel_lyall — Tue, 06 Jun 2017 07:08:16 GMT

Thanks @Anonymous that parts over my head at the moment it's been over 20 years since I last touched sheet metal.

Re: K factor accuracy

CLmoss — Tue, 06 Jun 2017 09:48:54 GMT

Yes, I agree. There are 2 different things. My sheet metal shop just said for me not to turn the STEP files into flat metal. They would rather do it in Solidworks (the program they use) as their customers always get the k factor wrong. Well, that is a load off of my shoulders. I asked them 3 times. They insisted that they would do the flat metal conversion there. Not to do it myself. So that takes the responsibility for making things (screw holes, components, etc) line up in their court. So I am back to F360 3D modelings. Can I produce a screen cast that only plays to the metal shop using F360? I guess to demo the design I could create a exploded video. I was looking at a video on that some time back.

Thanks for your help!

Jim

Re: K factor accuracy

Anonymous — Tue, 03 Nov 2020 18:08:47 GMT

What Fusion 360 needs is a way to edit the k-factor per bend. A 120 degree bend and a 35 degree bend have a big difference from the default 90 degree material k-factor. I'd love to see it on an update, or a way to adjust variables as a rule based on degree.

Adjusting k-factor per bend would help with multiple bend radius parts.

Re: K factor accuracy

TravisJoe — Tue, 03 Nov 2020 18:20:07 GMT

I agree that there is several critical missing parts to the sheetmetal portion of Fusion and worried that they stopped at "good enough". I will bring this up on some other Fusion channels to see if I can get more information.

Re: K factor accuracy

Anonymous — Tue, 03 Nov 2020 18:44:51 GMT

Yes, you get it! Why is this so overlooked? Tooling, Material type and grain, and Degree all change the k-factor. Even the calculators miss it when these factors are not accounted for. One bend, not a problem. 6 bends.....Houston, we have a problem, because the accumulated error adds up.