How does material thickness variation affect press brake bend angle?
How does material thickness variation affect press brake bend angle?
(OP)
I am researching purchasing a precision press brake, like a Trumpf 3066 or Amada HDS. We bend 14 gauge - 20 gauge stainless steel, and the thickness of the material varies by about 0.003". How does this variation in thickness affect bend angle? For example, does 0.002" thicker material result in 2 degrees underbending?





RE: How does material thickness variation affect press brake bend angle?
RE: How does material thickness variation affect press brake bend angle?
What becomes more of a problem is when you form something like a "U" in one tool where adjusting the shut height will make the bottom right but the sides will either pinch the material or have too much clearance.
RE: How does material thickness variation affect press brake bend angle?
RE: How does material thickness variation affect press brake bend angle?
Material thickness variations will cause variations in the finished part based primarily relative to your bottom die width of opening. The wider the die opening, the less variation. This is true for air bending, which is the most common. Dies which are specially constructed to bottom out will tend to peen or set the corner, regardless of slight material thickness variations, but this takes an operator with a little more finesse to avoid putting excessive tonnage on the press and tooling that may not be necessary.
How precise of bends are proposing to make (+/- what fraction of a degree) ?
Now, there are press brakes available with bend angle sensing that will correct for anomolies. If your requirements are very tight, this is definitely worth the investment.
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.
RE: How does material thickness variation affect press brake bend angle?
Variation in thickness say you are changing from one coil of material to another coil of material will require changing the penetration depth of the tooling. If you are talking about 20ga material which is .036" and changing to .033" I would expect a large amount of bend change. Normally in an air bending application the vee die opening is 8 x thickness or for about .300" wide but you may be using .375" wide vee die. You will have to find out what changes from experience.
In agree with ornerynorsk what is the tolerance you are attempting to maintain?
RE: How does material thickness variation affect press brake bend angle?
"Dies which are specially constructed to bottom out will tend to peen or set the corner, regardless of slight material thickness variations, but this takes an operator with a little more finesse to avoid putting excessive tonnage on the press and tooling that may not be necessary."
I think this is the type I've seen used - the operator would dial in a pressure/tonnage setpoint based on the nominal material thickness and part width. Or am I dreaming this?
RE: How does material thickness variation affect press brake bend angle?
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.
RE: How does material thickness variation affect press brake bend angle?
I basically have given up on accuracy and design out tight tolerance parts.
As far as flange length inaccuracies that can be calculated from K value and bend radius fairly well.