Press Brake

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CNC Press Brake Repair: Your Ultimate Guide

Looking to keep your CNC press brake in top condition? Regular maintenance is key!

In this comprehensive guide, we’ll walk you through everything you need to know to keep your machine running smoothly.

From lubrication to mechanical checks, hydraulic system maintenance to electrical component cleaning, we’ve got you covered.

So if you’re ready to get the most out of your press brake, read on!

General requirements

Lubrication part:

Check the lubrication of guide rail, bearing, screw, chain and all moving and transmission parts to ensure that they are clean, rust free and adequately lubricated (replace the lubricating oil if necessary).

Fill lubricating oil according to the specified brand, check and dredge the lubricating nozzle and pipeline to ensure their normal operation.

Mechanical part:

Check whether the transmission parts operate normally and wear, and the bolt fastening of key parts.

Hydraulic part:

Clean or replace the filter, dredge the hydraulic pipeline, clean the oil tank, check the state of the oil, filter or replace the appropriate hydraulic oil if necessary, check the hydraulic pipeline, tighten the pipe joint to prevent oil leakage.

Electrical part:

(Turn off the power supply) clean the electrical cabinet, wipe the motor surface, tidy the wires and trunking in the cabinet, ensure that they are neat and beautiful, there are no sundries in the cabinet, and remove the dust in the cabinet.

Check the working status of the exhaust fan and motor fan to ensure their good operation.

Replace damaged switches, buttons, indicator lights and instruments, and tighten the main circuit terminal of electrical appliances above 5kW in the electrical cabinet.

Machine surface:

Scrub the external surface of the machine, such as guide rail, column, protective cover, etc.

Safety devices:

Various safety devices of the equipment are effective without missing, such as photoelectric protection switch, emergency stop button, etc.

Press brake maintenance table

▲Spot check  ■Cleaning  ●Supplement ★Replace

PositionNo.ItemRecommended cycle
Lubrication part1Check the lubrication of ram guide rail, chain and lead screw Quarterly 
Mechanical part1Check the looseness of bolts (e.g. hydraulic valves, oil circuit pipe joints, motors / pumps, etc.)    
2Check the cleanliness of the guide rail and lead screw for pulling, grinding and bumping    
3Check whether the geometric accuracy of the equipment meets the requirements    
Hydraulic part1Clean the hydraulic station    
2Check the oil level of the hydraulic oil tank and replenish it if necessary   
3Check whether each pressure value of the hydraulic unit is normal    
4Check the temperature rise of hydraulic oil tank or hydraulic oil cooling system    
5Check and clean various filters and replace them if necessary  ▲■  
6Check the cleanliness of hydraulic oil, filter or replace appropriate hydraulic oil if necessary  ▲● 
7Check whether the hydraulic pipeline is unobstructed, free of damage and leakage    
Electric part1Check whether the cooling fan of the electrical cabinet works well    
2Clean the dust screen of the electrical cabinet    
3Clean the interior of the electrical cabinet, and there shall be no sundries and dust in the cabinet    
4Tighten the main circuit terminal of electrical appliances above 5kW in the electrical cabinet    
5Check the temperature rise of each motor and whether the motor fan works well    
6Clean each heat sink of the motor to ensure that there is no scale    
7Check all emergency stop switches, buttons and limiters   
Cooling part1Check whether the oil cooling device works normally    
Machine cleaning1Clean the external surface of the equipment    
2Clean the surrounding environment of the equipment to ensure that there are no iron filings and sundries    
Safety device1Check whether various safety devices on the equipment are effective without missing. For example: photoelectric protection switch, emergency stop button, etc    

Maintenance of CNC press brake

Hydraulic system

Hydraulic oil

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1) Filling method of hydraulic oil

  • Move the ram to the upper dead center and support both ends of the ram with equal height wood blocks.
  • Unscrew the plug on the oil drain at the bottom of the oil tank to drain the hydraulic oil.
  • Clean the oil tank.
  • Refill new hydraulic oil through the air filter at the oil filler to the 2 / 3 position of the oil standard, and stop the ram at the top dead center position.
  • Allow the hydraulic oil to circulate for about 1 hour before restarting the machine
  • After circulation, reinsert a 10um filter element

2) The following hydraulic oils are recommended for press brake

ManufacturerHydraulic oil

Note: do not mix hydraulic oils of different brands.

3) Some precautions

The oil level must be checked every quarter.

When the ram is at the top dead center position, the oil level can be seen by observing the scale line of liquid level and liquid temperature agent.

If necessary, fill hydraulic oil through the air filter at the oil tank filler.

When the ram is at the top dead center position, the oil level must reach the upper scribed line of the liquid temperature agent (visible from the rear of the oil tank).

After working for 200 hours, the filter element must be cleaned and checked every 6 months or 1000 working hours.

The oil temperature in the oil tank works within the range of 10 ℃ ~ 60 ℃. If it exceeds this range, temperature rise or drop measures shall be taken.

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The hydraulic oil must be replaced every 2 years or 4000 working hours, and the first time should be after 2000 working hours of machine operation. 500 working hours for the first time change and 2000 working hours for the future use will be a good option.

Oil filter

Regularly clean the oil filter in the system with solvent (gasoline, trichloroethylene, etc.).

The CNC press brake shall be cleaned for the first time one month after commissioning, and then regularly every two months.

Air filter

The air filter is installed on the oil tank cover.

It shall be cleaned for the first time two months after the commissioning of the machine.

After washing in solvent (gasoline, trichloroethylene, etc.), it shall be cleaned regularly every four months.

Connection of pipes

In case of leakage, tighten the pipe joint. If this is not helpful, replace the joint.

Sometimes, the high-pressure oil pipe in the hydraulic oil circuit must be replaced.

When installing the ferrule type pipe joint on the high-pressure pipe, the following provisions must be observed:

  • The angle of pipe sawing shall be correct and the pipe orifice shall be deburred
  • The nut and ring can slide on the tube, and the thick edge of the ferrule faces the nut
  • The pipe joint thread, ferrule and nut must be lubricated and screwed on by hand at the beginning
  • Then tighten it with a wrench until the pipe cannot rotate on the pipe joint
  • Then screw the nut with a wrench for 1 ~ 1.25 turns


If the valve block leaks, please replace the corresponding O-ring or combined seal ring in time.

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If the oil cylinder leaks, please replace the sealing ring of the oil cylinder in time.

Mechanical parts

Regularly check the fasteners of all mechanical parts for looseness and lubrication and wear of sliding block guide rail.

If any abnormality is found, it must be corrected in time before it can be used again.

Good lubrication is an important condition to ensure the normal operation and prolong the service life of the press brake.

The machine should be lubricated weekly (or every 40 working hours). No. 3 calcium base grease is selected and injected into each lubrication point with a grease gun.

Even if there is no lubrication point on the sliding surface of exposed parts and rolling bearings, it should also be lubricated once a week.

The location and name of each lubrication point are shown in the figure below:

lubrication point of press brake
Lubrication pointNameOil quantityRefueling clearance timeType and brand of lubricating oil
1Left and right lead screwsMiddle40 hoursNo. 3 calcium base grease
2Left and right guide railsMiddle40 hoursNo. 3 calcium base grease
3Ram left and rightMiddle40 hoursNo. 3 calcium base grease

Main overflow valve

The adjustment of the main relief valve is very important for the operation of the machine. The normal setting value is equal to the maximum allowable pressure.

Weekly inspection

  • Basic detection
  • Check parallelism
  • Inspect the drive components
  • Mold: check cleanliness and damage
  • All screw connection tests
  • Guide rail detection
  • Guide rails: Lubrication
  • Sensor signal transmission detection
  • Ram tightness test
  • Rear stop: check the tension of the synchronous belt
  • The reference point position of each axis of the rear stop must be tested once a week. If there is any deviation, it shall be compensated on the NC system
  • Rear stop drive detection
  • Rear retaining material tightness test

Precautions for maintenance

When operating or overhauling the press brake, please follow the following specifications to ensure safety.

1. When energizing the machine, confirm the safety of the surrounding environment.
2. Stop the machine and cut off the power supply before replacing components, checking and repairing.
3. Do not wear loose clothes, gloves and ties to operate the machine.
4. When operating the machine, the electric cabinet door must be closed, and the external power supply must be cut off during maintenance in the electric cabinet.
5. At the beginning of the operation, it is necessary to check whether there are obstacles within the movement range of each axis.
6. Do not unplug electrical components, cable plugs and wiring when the machine is powered on and operating.
7. In order to ensure safety, the machine must operate in a bright, clean and orderly environment.
8. When entering the dangerous area of the machine, make sure whether the emergency stop button on the operation panel is pressed.

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