Sheet Metal K-Factor (What it is & How to Measure)

[@TheEngineeringToolboxChannel]

Anyone that's good at math out there see a way too simplify this formula for calculating K-Factor? My algebra skills aren't the greatest!

[@benmk21600]

Better than mine!! I wish I didn't leave school at 16! Thanks

[@TheEngineeringToolboxChannel]

Haha never too late to learn in the age of information!

[@remiew45]

The easiest way to figure you length of an angle or K factor is to use .50 To figure out the length, the formula is Length = (radius x angle x 3.1416) / 180 For instance, if you are bending a piece of .125 thick material, and you have an inside radius of .250, use the radius + 1/2 T which is .0625. That gives you a radius of .3125 (at the middle of the material) Now say that you want to bend the angle at 45 degrees. So your formula would be Length= (.3125 x 45 x 3.1416) / 180 which is 44.17875 / 180 That gives you a length of .2454 for the length of the radius. And say the straight portions of the bends are 1" on each side of the radius, your blank length would be 2.245.

[@TheEngineeringToolboxChannel]

I feel like you didn’t watch the video. You described how K factor is used when it is already known - in your case you said it’s always .5. But every material, thickness, tool combination, angle, grain direction, etc results in a different K factor so for precision sheet metal companies (who need to achieve tolerances within .03”) you need to figure it out for each scenario. In my video I am explaining how to back calculate K factor of a specific bend scenario (from the physical part).

[@UdayKumar-uh4gm]

sir can you please tell me one book name through which i can get some what knowledge on sheet metal calculations and on other manufacturing calculations

[@mat4i]

Fast, straight forward and easy to understand material. Keep it up!

[@SCOOTI12]

AMAZINGwork. I was searching K Factor in relation to statistics-just wanted to learn more. Came across your channel and started going through videos. BEAUTIFUL. Absolutely mind bending. I seriously cried at times from being able to understand lmao. So random.

[@SamChaneyProductions]

Thank you, this really helped me understand k-factor which will help me in designing sheet-metal formed junction boxes for my employer.

[@michaelluderschmidt3512]

Series of tests were carried out with each machine. The measured K values ​​were entered in tables together with the parameters of the machines. Simplified K-values ​​are used for construction and drawing. The expanded views are revised depending on the machine that is used by work preparation.

[@michaelluderschmidt3512]

The K-factor is a parameter in the deformation of a sheet metal. There are formulas to calculate the K-factor (see ISO 6935). The result is a theoretical value. Which must be noted on every drawing. The actual K-value also depends on how the sheet is bent, how the sheet was made, how warm the sheet is, etc.

[@TheEngineeringToolboxChannel]

Thanks for sharing the additional info. While this may be true in the design specs, where as a designer you do not know precisely how the bend will be made. In practice, as a manufacturer, an actual (not theoretical) K factor can be observed empirically by taking measurements with a given combination of tooling and material.

[@agstechnicalsupport]

Sheet Metal K-Factor well explained. Thank you for posting such instructive content !

[@강민성-y2v]

This was an amazing video. Thank You!

[@suheladesilva2933]

Great video, many thanks.

[@leehaag2947]

How do you predetermine the inside radius of each bend? Does the inside radius change if your top punch does or does not have a radius on it, or is the inside radius determined by the material thickness and the size of the bottom die?

[@TheEngineeringToolboxChannel]

To answer you question...the short answer is: it depends. Mostly on process and material. When coining or bottom bending the inside radius will match the punch size. When air bending the inside bend radius is estimated using the 20% rule. For more on that see the link below and read up on more of Steve Benson's work. He has put together a lot of good information on this topic. www.thefabricator.com/thefabricator/article/bending/bending-basics-how-the-inside-bend-radius-forms

[@zakaroonetwork777]

Is there a formula or best practice of a Natural Bend Radius? What do I send bend radius relative to material thickness. Example if I tell Solidworks 1/4” radius for 1/4” thick material. Like what would result from a standard V mold press brake at 90 degrees… ?

[@TheEngineeringToolboxChannel]

This is a very vague question. What do you mean by natural bend radius? What do you mean by “what would the result be”?

[@Moltimer5050]

Amazing 🎉

[@EOJ266]

Can you please recommend a book that gather the information you mention in your videos for sheet Metal? Your video is great, I just need something to get back to as a reminder.

[@TheEngineeringToolboxChannel]

Hi! Thanks for watching. I recommend work by Steve Benson. He has a book and also writes plenty of informative content for thefabricator.com. www.thefabricator.com/author/steve-benson

[@leosmi1]

Hi, is this possible to use for a steel rounded wire? It's for a wire bending machine...I need the length of material needed to make the bend...thx

[@TheEngineeringToolboxChannel]

Interesting question. Are you asking if K-factor can be used to develop the cut length of wire blanks? If that is the case then that answer is yes. The same formulas apply since they really just come down to geometry. As long as you do the testing and control for the proper variables you should be able to determine some reliable K-factors. I am not that familiar with wire forming so you will have to determine what the variables are that you need to control for. (I picture you are talking about something similar to this..kzbin.info/www/bejne/oF7KkpWbeq9qe6c) That being said, I imagine material thickness, material type, bend angle, stationary die radius, the distance the moving die is from the stationary die, etc. Basically you will need to test and measure the results of each different bending scenario.

[@ConstantinDancu]

I use inventor but their K factor is not the same as my presaved bend allowance numbers. What to do?

[@TheEngineeringToolboxChannel]

I am not as familiar with Inventor so I dont know what features are available. I know Solidworks had BD tables that could be assigned to different materials and radius. If K-Factor is the only thing that Inventor allows you to use, I would suggest converting your BA numbers to K-Factor .

[@ConstantinDancu]

I modified the K factor unfold rule from 0.44 to 0.49 and now the overall size matches my saved bend deduction numbers. Hope this works. Thank you for getting back though

[@TheEngineeringToolboxChannel]

Just keep in mind that the k-factor will change for various materials and bend radii.

[@eminalpoktem5334]

Hi friend, thank you for this explanatory video. My question is about machine's die and knife selection. Do they affect the result? How to select them? How to identify the bending lines dimensions that will be given to operator?

[@TheEngineeringToolboxChannel]

Yes, the tooling you use affects both the radius of the bend and k-factor which in turn affects the bend deduction. Here is a video I have that explains a best practice for selecting die. kzbin.info/www/bejne/jJeyaWCJjtKdnZI

[@ГнусныйШкольнек]

I don't understad. Does the location of the neutral axil depend on the bending angle?

[@TheEngineeringToolboxChannel]

Yes it absolutely does (among many other things - material, tooling, etc). The exact location can only be determined through testing.

[@govardhanbutta2913]

Hi How can i believe that there will be neither tension nor compression at the neutral axis because i see some deformation in the neutral axis as there is in inner part and outer can u kindly answer my question !

[@TheEngineeringToolboxChannel]

Hi Govardhan, thanks for the question. What do you mean you can see deformation in the neutral axis? The neutral axis should be DEFINED as the axis (or plane) where there is not any deformation or stress in the material. The outside part of the material is under tension and the inside material is under compression..... so EXACTLY ON THE AXIS, there will be no stress in the material.

[@SamChaneyProductions]

It depends on what you mean by "deformation". Yes, the material within the neutral axis plane does move of course since the whole sheet is being bent, but along that plane (it's now a curved plane which is a bit confusing), none of it stretched or compressed. That's what he means when he says there is no deformation.

[@TheEngineeringToolboxChannel]

Sam Chaney ohhh I guess I can see how that might be confusing. Thanks for clarifying. So maybe deformation isn’t the best word. Maybe it’s better to say there is not stress or change in length along the neutral line.

[@govardhanbutta2913]

@@TheEngineeringToolboxChannel i would like to see a practical sample in which there will be no stress or no strain when we apply load on it

[@balakumaran9358]

good work

[@ashokkumar15061985]

Excellent video, Thanks. I just tried for my values and got some false results. If possible, could you help me to figure out. T=0.075, R=0.075, Bend Angle=90 Degree, Bend Deduction=0.146. I want to know the k factor for this part.

[@TheEngineeringToolboxChannel]

What value did you get for a k factor?

[@ashokkumar15061985]

@@TheEngineeringToolboxChannel T=0.1, Radius=0.1, B.D=0.179, Bend Angle=90 Degree.(All are inches). I am getting a K value is 0.73. I hope the k factor will not exceed 0.5. Please let me know if the correct value? Is it possible to find the k factor only using material thick, Bend angle, and Inner Radius? I found one calc(www.machinemfg.com/k-factor-calculator/) on the website and they are providing k factor by only using that three inputs. is it correct? Please suggest. Thanks

[@maheshshivagoud7830]

you said that this formula only works for 90 degree bend , but what if the bend angle is less or more than 90 ?.

[@TheEngineeringToolboxChannel]

Where did I say it only works for 90 degree bends? The formula works with all bend angles. The challenge with non-90 degree bends is measuring the part to determine Bend Deduction. While it is a challenge if you don’t have the right measuring tools, it can still be done.

[@krishnakumar-dq7co]

Are these applicable for tubes ?..if not can you refer me some books.

[@TheEngineeringToolboxChannel]

This application is for sheet metal but the same formulas can be applied to tube bending. The most important thing is that you do testing to understand the relationship between flat and bent parts based on the bending process that will be used. See the Machinery Handbook for more information. Or I would suggest googling more about tube bending online. There should be plenty info out there.

[@ritchieron1]

Your video is missing a very important piece of information: How do you calculate the bend deduction? You use the flat length to calculate the bend deduction and then use the bend deduction to calculate the bend allowance, but you need either one of these two to calculate the flat length, so pretty much you can't determine any three of this variables.

[@TheEngineeringToolboxChannel]

I think you are confused. Where do you think BD, BA, k-factor come from? They come from empirical results (measuring real trial pieces). You are correct… flat length is calculated from BD, BA, or k-factor. But how do you get those values in the first place? You have to start with a sample of known length, then bend it and see what happens! From that you can interpret any of the bending factors you desire, store them in a library and use them in the other direction to estimate flat length given (bend radius, material type, thickness, etc etc).

[@ritchieron1]

Then I think including how you determined the bend allowance or the bend deduction from the empirical data or the type Of empirical data would greatly benefit the quality and comprehensiveness of your video. Of course I’m confused. I came to this video to understand sheet metal because I want to learn not because I already know about the topic

[@TheEngineeringToolboxChannel]

@ritchieron1 fair enough. The equations are really all you need. Just like any algebra problem you always start with what you know and calculate what you don’t know. In the case of sheet metal bending, you know what you physically have in front of you. The flat piece, the piece after it was formed, the tooling you used, etc. From the physical part (empirically) you know flat length, flange 1, flange 2, radius, material thickness. Plug these into formulas and that will allow you to calculate BD, BA, or k-factor as needed.

[@ritchieron1]

@@TheEngineeringToolboxChannel Thanks for your answer. Unfortunately in my case where I work, what I need to determine is the flat length. I receive materials to be used and rough geometries as inputs and from that I need to work the flat length to fabricate the final part. For this I need to either know the K factor or the bend allowance. The bend allowance can easily be calculated by knowing the neutral axis shift. Since I need the K factor to determine the Neutral axis shift I can't calculate the bend allowance or vice - versa. Hence my line of questioning.Thanks for the discussion and the exchange of ideas! Cheers

[@TheEngineeringToolboxChannel]

@ritchieron1 does your company do the fabrication internally or do you just design?

[@zenith9430]

What is bend deduction??

[@TheEngineeringToolboxChannel]

Bend deduction is the difference of the flat part length (before bending) from the sum of the two resulting lengths. L1+L2-FL=BD L1 & L2 = the legs of the bent part FL = flat length

[@theobject7326]

thank you

[@TheEngineeringToolboxChannel]

No problem! Hope it was helpful!

[@westcoastpreneur]

*Pulling out hair cause my answers aren't correct*...turns out calculator mode was in rad not deg.

[@dhondkurpadghabrey5959]

Too much long. Come to the point directly with examples

[@TheEngineeringToolboxChannel]

Thanks for the feedback and for watching!

[@josephbell4218]

4 minutes is too long? Lol. Don't listen to this guy.

[@king_james_official]

it's not bullshit. this is all useful stuff. i don't know why is 5 minutes even "too long" for you