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CNC press brake programming · Lesson 2 of 4

CNC press brake programming: materials, standards and design constraints

Why the control predicts the angle from a model, the vee, radius and springback inputs, why a gauge number is not a thickness, where angle error comes from, angle and thickness sensing, and the rules and AFS limits that apply.

You will be able to: Explain which material and tooling inputs a press brake control uses to predict an angle, why thickness, strength and alignment errors show up as angle errors, which rules bind, and which AFS limits govern AFS orders.

12 min · 12 slides · 9 questions

All lessons in this module
Slide 1 of 12

The control predicts the angle

Cincinnati notes that CNC controls that take a bend angle depend on mathematical models; dies not closely aligned to the tooling centreline can make the angles inaccurate.

For a 90 degree air bend, Cincinnati gives die penetration as about 40% of the vee die opening.

Every input feeds that model. A wrong input gives a confident, wrong angle.

Sources

Videos for this lesson

What this video shows: Per its description, sensors find the actual angle with springback and guide the ram; it introduces ACB Laser (optical) and ACB Wireless (tactile). A press brake, not AFS equipment.

Video: TRUMF bending: How the ACB angle measuring systems work by TRUMPFtube, on YouTube. AFS checked its description against this lesson.

What this video shows: Per its description, TRUMPF's thickness-controlled bending compensates for sheet thickness variation on the fly for angle accuracy. A press brake, not AFS equipment.

Video: TruBend 5000 - Thickness Controlled Bending by TRUMPF Inc., on YouTube. AFS checked its description against this lesson.

What this video shows: Per its description, Cincinnati's Dynamic Thickness Compensation automatically compensates for material thickness variation, and it is standard on Cincinnati's XFORMc and XFORMe models. Not AFS equipment.

Video: Dynamic Thickness Compensation Explained in 60 seconds #pressbrake by Cincinnati Incorporated, on YouTube. AFS checked its description against this lesson.

Glossary

Vee die opening
The width of the V in the lower die. Cincinnati's rule for mild steel up to 1/2 in is eight times the thickness, rounded up to the next 1/8 in.
Springback
The amount a bent sheet opens up when the forming force is released. Cincinnati gives 2 to 4 degrees as normal for mild steel.
Thickness compensation
A press brake option that measures each sheet's actual thickness and adjusts the pressing depth, as TRUMPF describes its thickness-controlled bending.
Angle measurement (press brake)
Sensors that read the actual bend angle and springback during forming and steer the ram to the target angle, as TRUMPF describes its ACB systems.
Gauge (sheet)
A number naming a sheet thickness from a table. The thickness differs by material and table: 22 ga is 0.0299 in on Cincinnati's mild steel chart and 0.0336 in for galvanized in the AFS register.