Even though it would seem like a simple operation, press brakes are actually quite complex. The pressure required to bend a piece of metal is a direct function of the hardness and thickness of the metal and with of the die across which metal is bent.
Press brake capacities are determined by the tonnage of the machine and width of the bed and/or width of material you wish to bed.
The principle parts of the press brake include:
The Bed: Stationary mounting for the lower die. It is usually of very heavy construction and should have a lower die holder mounted to the t-slot of the bed in order to secure your dies.
The Ram: Carries the upper die. It is mounted on top of the housing, reciprocates vertically and when engaged, bends the material.
The Backgauge: Controlled by a CNC control, buttons, dials, etc. It will move in/out to accurately measure out the bending area.
There are two major categories of press brakes: Mechanical and Hydraulic.
Mechanically driven press brakes have a fixed tonnage and generally deliver more force at the bottom of the stroke than midway. It will usually cycle its ram at a faster rate than it’s hydraulic cousin.
Hydraulic brakes tonnage and speed are variable up to the machine rated limit. By being able to control the tonnage/speed, you will have optimal control over the material being worked. It also prevents damage to the machine or die in case of overload.
When inspecting the brake, you should look for the following:
Casting: Definitely Check the casting of the machine for cracks and welds. It’s so important. If the casting is cracked, you may notice it may be repaired with a weld. However, the strength of the casting has weakened possibly causing damage to the machine or possible operator injury down the road. This may cause injury to you or someone near you
Ways: You should Check the ways carefully for scoring (scratches or grooves) This can impact the straightness of the stroke. For example, if one side is scored and the other is not as bad, the better side will slide easier than the rough side. This may cause an uneven stroke.
Cylinder: Check both cylinders for scoring. Rub your fingers on the column. They should feel smooth and appear shiny.
You should also measure the overall length of the bed as well as the distance between housing.
If you have the opportunity to inspect under power, look listen for noises when engaging the machine. For example, grinding or loud noises are bad.
Many press brakes use dual palm buttons to engage the ram, however, many press brakes do not and may only contain a pedal or treadle. This may be an issue when reselling the machine due to possible OSHA requirements. However, some machines can be converted to dual palm and its not too expensive
DO NOT ASSUME LIGHT CURTAINS WORK With safety equipment such as light curtains, you need to assume that they dont work and to have them checked out before putting them into service. If there is an issue with the light curtains, then it may be advisable to replace them.