Press brakes

A press brake is a machine that bends sheet metal and plate along a straight line by pressing it between a punch and a V-die. CNC press brakes set the bend depth and backgauge position from a program, so they suit any shop turning flat blanks into enclosures, brackets, panels, channels or structural parts.

How a press brake bends

Most modern work is air bending: the punch pushes the sheet into the V-die without bottoming, and the depth of the stroke sets the angle. Backgauge fingers position the blank behind the tools, and the CNC controls both ends of the ram (the Y1 and Y2 axes) so the beam stays parallel. Springback is handled by bending slightly past the target angle. Bottoming and coining press the sheet fully into the die and need several times more force, so they are kept for special cases.

Bending force depends on the square of the material thickness, the bend length and the die opening. Our press brake tonnage guide gives the air-bending formula, the rule of a V-die about 8 times thickness, stainless and aluminium factors and a worked example, so this page concentrates on the machine itself.

Drive types

Hydraulic

Two synchronised cylinders drive the ram. Hydraulic machines cover the widest range of force and length and remain the default for general fabrication and heavy plate. On a conventional hydraulic brake the pump motor runs all the time, which costs energy and adds heat and noise.

Electric servo

Servo motors drive the ram through belts, rollers or screws, with no hydraulic oil. SafanDarley's E-Brake uses steel-reinforced belts and a roller drive, draws energy only while the beam is moving, and the maker reports energy savings of up to 70 percent against conventional hydraulic brakes. Electric machines are strongest in small and medium tonnage; the compact SafanDarley E-Brake 40-1600 (44 US tons over 60 in) is built for fast small-part bending, seated or standing.

Hybrid and servo-hydraulic

Here the cylinders stay hydraulic, but servo-driven pumps deliver oil only when it is needed, keeping the force of hydraulics with less energy and noise. Bystronic says the Servo Dynamic drive on its Xpert Pro cuts energy consumption by up to 60 percent. The layout also reaches heavy capacity, as on SafanDarley's hybrid-hydraulic H-iBrake 400T-4200 at 441 US tons. Our hydraulic versus electric comparison weighs the options in more detail.

How to choose: specs beyond tonnage

• Tonnage and length. Size the machine for your worst bend with about 20 percent headroom, and check the per-metre load limit for short, heavy parts.
• Open height, stroke and throat. Deep boxes and tall return flanges need enough daylight and stroke to fit the tools and still remove the part. Throat depth matters when a part is longer than the distance between the side frames and has to pass into the frame opening.
• Axes. Y1, Y2, X and R plus CNC crowning, often sold as 4+1, covers most job shop work. The Accurl Euro Pro B 32110 is a four-axis example with a Delem DA58T control. Z1 and Z2 finger axes help high-mix work with staged tooling.
• Crowning. The ram and bed deflect under load, so long bends open up in the middle unless crowning compensates.
• Backgauge speed and accuracy, which decide cycle time on parts with many bends.
• Tooling system. Clamping style, manual or hydraulic clamping, and a tool set that covers your thickness range. Budget tooling together with the machine.
• Control and programming. Offline programming and bend simulation move setup work away from the machine, which Bystronic highlights as a way to keep production running while the next job is prepared.

Safeguarding in Canada

The main hazard is the point of operation, where the punch closes on the die, with further pinch points at the backgauge. Provincial occupational health and safety rules apply. In British Columbia, WorkSafeBC guideline G12.29 points to CSA Z142, the Canadian code for punch and brake press operation, for point-of-operation safeguarding and for the design, construction and reliability of operating controls. Guideline G12.31 allows the minimum number of safeguarding devices to be disabled temporarily for custom bends that cannot be made otherwise, as long as they are restored when the work changes. Other provinces have their own regulations, so confirm requirements with your regulator.

The devices you will see in quotes:

• Laser guards (active optoelectronic protective devices) mounted on the ram, which protect the point of hazard and let the operator hold parts close to the dies, useful for box bending and tall flanges.
• Light curtains across the front, which stop the stroke when the light plane is broken but keep hands further from the tools.
• Fixed and interlocked guards at the sides and rear, and two-hand controls for some work.

Ask for the safety system to be named in the quote, and have it checked against your provincial rules before the machine goes into production.

What your plant needs

• Power. Hydraulic motors grow with tonnage, and imported machines are often wired for 380 or 400 V. Ask for a 600 V build or plan a transformer; see 600 V power for imported machines.
• Floor. A 3 m hydraulic brake weighs several tonnes and concentrates its load under the side frames. Heavy and tandem machines such as the LVD PPEB 640/61 may need their own foundation built to the maker's drawing, as our floor preparation guide explains.
• Hydraulic oil for hydraulic and hybrid machines, with proper storage and disposal; electric machines avoid it.
• Handling space. Room in front for blanks and finished parts, a tool cabinet, and a hoist or crane for long, heavy tools and plate.

Running costs

• Tooling: punches, dies and segments wear or get damaged, and new part families often need new tools.
• Energy: electric and servo-hydraulic drives use less than a pump that runs all day.
• Hydraulic oil and filters on hydraulic machines, changed on the maker's schedule.
• Safety system upkeep: regular checks of guards, light curtains or laser guards and stopping performance.
• Setup time, often the largest hidden cost in high-mix work, which is where good controls, offline programming and quick clamping pay back.

Typical applications

Press brakes form electrical enclosures and cabinets, HVAC components, machine guards, brackets and panels in sheet metal fabrication; channels, chassis members and plate parts for trailers and farm equipment; and long sections for poles, towers and building products. Most shops pair a press brake with a laser or a shear that produces the flat blanks.