Let’s talk about crowning!
When we are forming metal on folders and press brakes, we must remember Newton’s Third Law. His third law states, “that for every action (force) in nature there is an equal and opposite reaction. In other words, if object A exerts a force on object B, then object B also exerts an equal and opposite force on object A.”
Forming metal is no different!
Think of object “A” as the folder and object “B” as the material you are forming. As we increase the thickness of the material we are forming, the more that material pushing back on the machine. Specifically, on folders, when the folding beam activates, the material is pushing back. This action will be most pronounced in the middle of the folder, especially the longer the folder.
Machines will often have different ways to compensate for crowning. On simple and older machines, an operator will ‘shim’ the folding beam. Some machines, (fig B) will have crowning adjustment built in to folding beam to counteract the material. Depending on the material, different pressure can be applied.
On advanced machines, especially those built for heavier material, crowning can be CNC controlled taking the human elements and guesswork out of the process!
In the roofing and architectural markets, most machines are capable of folding common materials like 29ga to 24ga without the need to account for crowning. However, as we get to 22ga… 18ga… 14ga… 10ga and even thicker, crowning is needed in order to get the accurate bends you need!
The next time you are considering a folder, do not forget about the crown!