What is a press brake?
Posted by admin on 10 Feb 2010 at 10:03 am | Tagged as: Press brake
What is a press brake?
A press brake is a form of brake, which allows bending sheet metal by pressing a special tool,
called a punch down, on the workpiece, which in turn is placed on a negative version of the punch, called a die.
A basic punch/die configuration could be an arrow-shaped punch, pressing the workpiece into a v-shaped die.
A hydraulic press brake uses a hydraulic ram to press the punch down on the workpiece.
The pressing power of the hydraulic ram is referred to as tonnage, and for most press brakes, it is somewhere between 20-200 tons. The heavier gauge material you want to bend, the more tonnage you need.
A hydraulic press brake
Bending techniques:
There are two basic ways of bending sheet metal on a brake press.
- Bottoming/coining is where the punch and die have the same angle. This way, the workpiece is pressed all the way to the bottom of the die, resulting in a bend of allmost the same angle as that of the punch and die.
- Air bending is where the angle of the die is greater than that of the punch. Furthermore, the punch does not “bottom” on the workpiece – it just presses it partially into the die. The result is that the bend on the workpiece now has an angle which is somewhere between the punch-angle and the die-angle. The greatest advantage of air bending, is that it requires less energy to bend sheet metal, meaning a smaller press brake machine can do the job.
Advantages to manual brakes:
Since press brake dies and punches are removable, and can have any length or size that will fit in the press brake,
the press brake is the industrial substitute to not only the manual sheet metal bender, but also to the box and pan brake;
simply use a punch/die set that has the width of the fingers you would have used on a manual box and pan brake,
and you can make the same bends – only faster and with more precision.
The sheet metal press brake is a great tool to have in your arsenal, if you’re serious about sheet metal fabrication.
Here is a great video of a cnc-press brake in action. You can get a very good idea of what press brake bending is and what it can do.
This is really a great video, as it shows clearly the ram in action, the way the press brake tooling (punch and die) work, how the machine is set up, cnc-functionality, etc.
Did you notice the clever way of setting the press brake up for a series of different bends, without having to change dies and punches all the time?
Another cool part of this video was the demonstration of the back gage, especially the differences between a 5-axis and a 6-axis back gage on a cnc press brake. It’s certainly easy to see the difference in potential.
Also notice the bending technique used is air-bending – workpiece doesn’t touch the bottom of the die.
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