Regardless of their years of experience, a machine operator can only be as productive as the machine allows. If a machine is in tip-top condition, the likelihood of producing top-notch parts is astronomically higher than it is with a machine that’s been neglected and in need of repair.
When it comes to press brakes and other modern fabricating equipment, a well-maintained machine is fundamental for avoiding damaged or poorly formed parts and detecting failures before they become serious problems. While keeping a press brake clean and tidy sounds simple, there are maintenance steps that should be made on a daily, weekly, monthly and yearly basis.
All maintenance must be carried out by qualified and experienced operators. For overall safety while performing maintenance on a press brake, do not put hands or other body parts between the tools. Be sure to use the right equipment for working at heights. Additionally, make sure that signs are posted that indicate the machine is being serviced.
Keeping safety in mind before cleaning or maintenance is paramount. The following guidelines can help to protect the operator performing the work as well as anyone else in the general vicinity.
- Delineate the space around the press brake with barriers and signals, ensuring that it is clean and unobstructed.
- Lower the ram until the punch is completely resting on the die. If the tools are too brittle or delicate, remove them and insert wood or plastic blocks as a support for the ram.
- Press the red motor stop button.
- Turn off any auxiliary devices by turning the selector switch to position 0.
- Turn the main switch on the electric cabinet door to position 0 and lock it with a padlock.
- Remove power from the main distribution panel to which the press brake is connected.
Daily, weekly tasks
To ensure a press brake is well maintained, daily and weekly cleaning are key. Daily maintenance is as straightforward as ensuring that a press brake is clean and free of dust and debris.
After each shift or at the end of the working day, clean the work area by removing all debris with a dry cloth. Clean the tools, bench, supports, slide guides and other accessories. Entering from the back, clean the backstops and guides of the backgauge. Do not use compressed air for cleaning, and protect hands with neoprene or PVC gloves.
Weekly maintenance tasks are often put in place to ensure that press brake components are functioning properly. Components can be anything from panel doors to pedals. To get started, ensure that the emergency stop is triggered.
When the emergency stop is triggered, the warning light turns on. To restore operation, disengage emergencies and push the blue button on the back of the machine. If the press brake does not have a reset pilot bulb, the main motor turns off.
With the machine off, check the integrity of all protections and doors. Turn the machine on and check efficiency of protection devices. With the machine on and in fast descent, perform the following:
Back protection panels (or back doors): Open the back door. Ram and backgauge must stop immediately, and the reset light must turn on.
Side protection panels: Open one of the side panels. Ram must stop immediately. Repeat test with the other panel. With one panel open the press brake can be used in slow descent, if safety has not disabled the pump. With both panels open, the press brake cannot be used.
Emergency stop: Check each of the red mushroom-shaped pushbuttons. Pushing one of these buttons should cause the ram and the backgauge to immediately stop and the reset light to turn on (if safety has not disabled the pump). Leaving the pushbutton engaged, push the “up” pedal; ram must move upward.
Three-position “down” pedal: Check the three-position pedal. Pushing the pedal down completely must cause the ram to stop. To resume the descent, release the pedal completely and push it again. Passing from third to second position should not cause the ram to resume descent. Make this check in both fast and slow descent.
Monthly maintenance tasks focus on more of the internal components of a press brake. Like the daily and weekly tasks, be sure that all safety precautions have been established before performing any of the work.
Pneumatic circuit: Disconnect the compressed air supply. If the exhaust valve is present, discharge the pressurized air from the system and lock the valve with a padlock.
Filters with manual discharge have a button valve on the bottom of the cup. Push the button to drain condensation. After this, reconnect the compressed air and check its proper functioning and for leaks.
Hydraulic circuit: Clean the hydraulic circuit on the outside (hydraulic block, valves, motor, pump, pipes, etc.), which then allows you to detect leaks, avoid contamination when replacing parts, and avoid reducing heat exchange between the circuit and environment. Avoid using detergents on valves near fittings and on the tank cover.
Visual inspection: Check all pipes, especially in the vicinity of the fittings, for leaks. If there are signs of swelling on the hose lines between the pump and the system, they must be replaced immediately. Check the pump, hydraulic blocks and valves, and valves and cylinders for leakage.
Oil level: Check the oil level on the tank sight glass with the ram up at the upper dead center. The sight glass is visible from the back of the press brake. If necessary, top off with the same type of hydraulic oil indicated on the nameplate and in the operating and maintenance manual of the machine.
If the machine has been stationary for a long time, clean the cylinder rods of dust and dirt. These substances can damage seals and cause oil leaks. Oil the rod surface and make the press brake run with no load and at a maximum cylinder stroke for about 5 min. to expel any air bubbles from the hydraulic system.
The oil level must also be checked after any maintenance work on the hydraulic system. Topping off the oil or changing the hydraulic oil must be done using an electropump with the oil filtered at 3 microns.
Hydraulic fittings: After the first month of work, fasten all connections of the hydraulic system. The inspection must only be carried out when the machine is switched off and not under pressure.
Tank air intake filter: The air filter located on the tank must be checked and cleaned once a month. Cleaning can be done with compressed air. The filter must be replaced every 3 years. The oil filler cap serves as an air filter even in the presence of a dedicated air filter, so it must be cleaned in the same way.
Heat exchanger: If a heat exchanger is present, check the cleanliness of the cooling coil and fan and, if necessary, clean with compressed air. Direct the air jet parallel to the radiator fins in order not to damage them. If the dirt is caused by oil or grease, disassemble the radiator and clean it with a jet of steam or hot water, always paying attention to the direction of the jet.
Electric circuit: For cleaning, compressed air with a maximum pressure of about 40 psi can be used, but be sure to wear protective glasses. Do not use cleaning products or chemicals that may damage cables.
Electric cabinet and inverter: Disassemble and clean air filters of the electric cabinet and inverter box.
Ground cables inspection: At the bottom of the control cabinet between the door and the fixed part of the cabinet, there is a grounding cable indicated by the appropriate symbol. Check for defects or breakages and that it is securely fastened. Open the rear guard and access inside the press. A grounding braid is attached to the central part of the ram. Here, too, check that there are no defects or breakages and that the connection is not loose.
Overall check: With the machine off, check the electrical cabinet and the foot pedal wiring. Clean cables in cable chains in the backgauge, removing dirt and dust.
Just as weekly and monthly maintenance should be placed on the calendar, there are yearly tasks that should be scheduled, as well. Some of these tasks, however, should be carried out by a specialized technician. For these tasks, it’s important to get them on the books early to ensure that the technician has availability.
Ram guides: Always use oils and greases recommended by the manufacturer. Clean the guide rails with a clean cloth, then apply grease using a brush.
Backgauge: This activity must also be carried out by a specialized mechanical maintenance technician with the machine switched off. As with other maintenance tasks, indicate with signs that the press brake is being serviced. After switching off the machine, clean the axes guides with a clean cloth and lubricate the gear racks with a brush and syringe pump through the grease nipples.
Y-axis hydraulic circuit maintenance: This intervention must be carried out by a specialized hydraulic maintenance technician. The press brake must be switched off and with the ram at the lower dead center. Indicate with signs that the machine is being serviced.
To carry out maintenance work on the hydraulic circuit, wear suitable gloves to avoid contact with the hydraulic oil. Before carrying out any work on the hydraulic circuit, check that the circuit is depressurized. Also, if an ACSG2 hydraulic crowning subcircuit is present, it must be depressurized. Be careful, though, as oil and some components may be hot. If the oil is still hot, use suitable protective equipment or wait until the oil has cooled down.
In addition to the regularly scheduled maintenance tasks, a few other recommendations will keep a press brake in top working order. Those recommendations include replacing the oil after the first 2,000 hours of work and then replacing it every 5,000 working hours.
Every change of the hydraulic circuit oil must be made with the same type of oil.
Have the oil analyzed each year by a specialized laboratory to decide when to replace the oil in the tank. And remember that each time the oil is changed, the tank must be cleaned. Furthermore, all top-offs must be made with the same type of oil. Do not mix oils of different brands or oils of different types. If the current oils are replaced with oils from other brands, it is necessary to completely clean the entire system.
When a press brake is maintained and cleaned on a regular basis, following a fully developed maintenance plan, the quality of the parts and the ease of the job improve. Overall, a considerable investment was most likely made to acquire the machine, so be sure to make that investment last as long as possible.