Sheet Metal Guy Blog

28 Feb 2008   11:51:56 am
Is there a chart of k-factors I can use?
Every now and then I get email asking, “Where can I get a K Factor Chart? Original chart, not someone's calculations.” This one came from Noel this week. So I thought it might be a good time to answer it publicly. To the best of my knowledge this chart does not exist. You can find several technical manuals offering their theoretical chart. Back in the 70's I was taught a rule of thumb: Radius < Thickness, K=.25 Radius < 2 * Thickness, K=.33 Radius > 2 * Thickness, K=.5 While this is just a rule of thumb, try the math on a couple of your material thicknesses. The difference in the answer if you use a k-factor of .25 vs .33, it's only a couple of thousandths. Here a quick formula for Bend Allowance (BA) of a 90 degree bend is 1.57 * (radius + thickness * k factor). So for .048 thickness with a .0625 inside radius, with k = .25 the BA = .117, and with k = .33 the BA = .123, a difference of 0.006. The real issue is that the k-factor varies not only with the hardness of the material, but also with the tooling and method you use on your press brake. The k-factor which works for one shop does not necessarily work for the next shop. You may want to talk with people you know in other shops to see what they are using. Or perhaps a tech support rep for a press brake manufacturer. They should have a chart to get you started. From there, it is a matter of experience and adjustment. You must find out what works for you. If you have a k-factor chart you would like to share with others, email to me and I will post it.
		Category : Sheet Metal | Posted By : SheetMetalGuy | Comments[99] | Trackbacks [2536]
21 Feb 2008   03:56:27 pm
The Kitchen Sink - Can you model it?
Alright, this request came from a customer. We spent some time modeling it, we want to see if any else can come up with a better method. The dimensions are not as important as the concept of the part. It is a sink with large radius bends all around and yes they are equal in this case. The four sides go out at a 30 degree angle, or you could say the bends around the bottom of the part are 60 degrees. The sides then bent again to come up vertical. The ball corners will be made separately and welded in afterwards. The original from our customer was modeled as a thin wall shell, but would not convert to a sheet metal part. The images are to help you understand what we want to model. You can respond here or email your Solidworks file to us at books@SheetMetalGuy.com So the question is “how would you model this sheet metal part?”
		Category : SolidWorks | Posted By : SheetMetalGuy | Comments[264] | Trackbacks [3551]
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