Hi every one
I dont know how do i calculate the k factor of a part ? Can anyone help me?
The k Factor is natural spec. of a material ?
Adjusting radii is another way to do it. We always made sure that the modeled parts bend radius matched the tooling that we were using. That way our offline brake press program and our operators were never confused on which punch to use. They used what the print said, even if the finished part didn't exactly match the radius. We adjusted the K-factor to get the blank to match. Both options will effectively do the same thing, and both have pro's and cons.
Number one tip, just be consistent. Find a way that you want you employees and vendors to do it, and always do it the same way. If you go back and forth, you will eventually run into problems.,
if you want to calculate the K factor for a specific material You could make some samples, bend them to exactly 90 degrees, measure with the caliper
and use this equation:
2014 SOLIDWORKS Help - K-Factor (you will have to pull the K from the equation)
as you will calculate a for few samples and average the value you could make it in excel spreadsheet.
la cosa migliore per calcolare il fattore K è fare una prova diretta per vedere l' allungamento del materiale.
io consiglio di fare 2 prove;una con un angolo a 90° e una a 45°, per verificare la correttezza dell' equazione.
Adel will also need the measure his samples before forming them.....
I recommend that you not put a flat pattern on a part drawing unless you plan to fabricate the parts in-house. For drawings sent to vendors, just dimension the finished product an let the vendor work out how to do it.
We have 2 vendors (cutting with plasma & bending ) so i have to make flat pattern for cutting process . But every time i have many problem with bending ( in calculate the flat pattern ) . I dont have enough experience in calculate the k factor . last day i fund a pdf file And read it . Can you say is it true?
Below is the passage that explains why I would not do the flat pattern myself. I am not experienced with sheet metal fabrication, and I don't know how close you can get just by guessing at the K-factor. I do believe that it is likely to be in a pretty narrow range. Your best bet is probably be to ask the bending vendor.
I second that the only way to make the correct K factor is through experimentation. The easiest way to reverse engineer the part, is to use a prototype blank, know that dimension of the flat, then bend it. Measure the final product and see how much you have to add or subtract. Then go back to the model, and check the blank length and adjust the K factor until the new blank adds or subtracts the amount of material that you need to make the final bend operation come out within tolerance. Keep in mind that this test is only valid if the part is made the same way every time. If you use a different punch, or a different bottom, it will be off some. Whether or not it's acceptable is determined by your tolerance. There is no book that can have every combination of material, and every die there could be and every punch that there could be, so there is no magic formula. If there was SolidWorks would just use that instead of K-factors.
Google Olaf Diegel BendWorks
He has a great little program to help with calculating bend deductions and a pdf that explains sheet metal forming.
His original website is no longer active, but his material has been shared on a few other sites.
We do all our own in house sheet metal fabrication so here are my tips.
K Factor - stick it to around 0.4. It will only make a tiny amount of difference if you have it somewhere between 0.38 to 0.44.
Bend Radius - in my experience, THIS is the main thing you need to get as close as possible to get your flat pattern correct. For example, with a 1.5mm thick part in Mild Steel I normally model it with 1.5mm internal rads and the flats work out pretty much spot on. However, with 1.5mm thick Stainless Steel, bent on the same machine, it does not come out the same. By measuring with a rad gauge we find that the internal rad is closer to 3mm. So I have to tell Solidworks that all the bend rads on a St/Stl part in 1.5mm thick material are 2.75mm. This then works out.
Other times our brake press operators may pick up different tooling to do a job we've previously done numerous times because the normal tooling is being used elsewhere. This can give the part tighter or looser bend rads, which again messes up the blank pattern.
So, the only truly safe way to produce an accurate flat pattern drawing is to have a test piece bent by the manufacturer, and then adjust your bend rads to suit until your flat pattern overall length matches the test piece.
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