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Maintenance of Hydraulic Systems of PBH Profile Bending Machine

hydraulic profile bending machine

Maintenance of Hydraulic Systems of PBH Profile Bending Machine

Daily Maintenance

  • Check the oil level in the tank once a week. If repairing the hydraulic system, check the oil level. If the oil level is below the sight glass, hydraulic oil should be added.
  • The hydraulic oil used for the PBH profile bending machine is ISO HM46 or MOBIL DTE25;
  • The oil should be replaced after the machine has been working for 2000 hours, and the oil should be replaced every 4000 to 6000 hours of operation. The oil tank should be cleaned each time the oil is changed;
  • The system oil temperature should be between 35°C and 60°C, and should not exceed 70°C. Excessive temperature can cause oil degradation and component damage.


  • Filters should be replaced or cleaned every time the oil is changed;
  • Other filters, if the machine tool indicates an alarm or if the oil is contaminated, should be replaced;
  • The air filter on the fuel tank should be checked and cleaned every 3 months, and replaced every year.

Hydraulic Components

  • Hydraulic components (plates, valves, motors, pumps, oil pipes, etc.) should be cleaned once a month to prevent dirt from entering the system, and cleaning agents should not be used;
  • After one month of use, check if there are any deformations in the oil pipe elbows. If abnormalities are found, replace them. After two months of use, tighten all accessory connections. When performing this task, ensure the system is depressurized.

Three Ways to Determine the Oil Change Period

Once the hydraulic oil is produced, it will gradually deteriorate. During the long-term storage, the particulate contaminants in the oil tend to agglomerate. If the hydraulic machine is subjected to vibration during transportation, it will also coalesce in tiny particles. After joining the hydraulic system, the fission speed will be greatly accelerated. Taking mineral oil hydraulic oil as an example, more than 96% of the components are carbon and hydrogen compounds—hydrocarbons, and the rest are sulfur, nitrogen, and ash. Also according to the need to add anti-oxidation, anti-wear, rust, defoaming, pour and other additives. In use, due to external causes such as air, moisture, impurities, heat, light, and mechanical agitation, the internal causes of the chemical composition and additive properties of single-column hydraulic presses and hydraulic oils cause various physical and chemical changes. Hydraulic oil gradually deteriorated.

PBH Section Bending Machine hydraulic oil in the use of the process, because of mechanical, physical and chemical effects, is always to quickly or slowly aging deterioration. When the quality of the working medium is reduced to meet the requirements of the index, it must be replaced in time.

  • Determined by visual inspection on schedule, whether the maintenance staff sampled on time, or whether to change the oil after doing a simple analysis, is also dependent on personal experience.
  • Change oil according to schedule. This is a common method used by factories. However, it is not in line with the actual conditions of aging and deterioration of hydraulic oil in use, nor does it take into consideration the fact that the use of hydraulic presses is frequent and other actual operating conditions. Therefore, it is biased in experience and not scientific enough.
  • Demarcate the oil change index, and determine whether to change the oil according to the oil sample test results, in the most scientific and fairest way. However, the same oil change indicator has not yet been designated.

Maintenance for Hydraulic Cylinders of PBH Section Bender

The damage to the hydraulic bending machine’s oil cylinder is usually manifested in forms such as pulling scratches, electrical scratches, fatigue wear, etc. The presence of damage affects the sealing of the hydraulic cylinder, usually resulting in oil leakage. Failure to repair it promptly will inevitably affect the efficiency of the hydraulic cylinder’s operation, and in severe cases, may lead to operational failure or even production accidents.

6 Major Maintenance Points for Hydraulic Cylinders

  1. To prevent bending or deformation of slender parts such as piston rods, they should be supported evenly with wooden blocks when placed. When disassembling hydraulic cylinders, care should be taken to avoid damaging the piston rod threads, oil port threads, piston rod surfaces, cylinder liner inner walls, etc.
  2. Disassembly of hydraulic cylinders should be done in sequence. Due to the different structures and sizes of hydraulic cylinders, the disassembly sequence may vary slightly. Generally, the oil in both chambers of the cylinder should be drained first, then the cylinder head should be removed, followed by the piston and piston rod. When disassembling the cylinder head of a hydraulic cylinder, special tools should be used for internal key-type connections or circlips, and flat shovels should be prohibited; for flange-type end covers, they should be pushed out with screws, and hammering or hard levering is not allowed. When it is difficult to pull out the piston and piston rod in the bending machine, do not force them out, but first identify the cause before disassembly.
  3. Efforts should be made before and after disassembling hydraulic cylinders to prevent the cylinder components from being contaminated by surrounding dust and impurities. For example, disassembly should be carried out in a clean environment as much as possible; after disassembly, all parts should be covered with plastic sheets, and not with cotton or other work cloths.
  4. After disassembling the hydraulic cylinder, careful inspection should be carried out to determine which parts can continue to be used, which parts can be repaired and reused, and which parts need replacement.
  5. Thoroughly clean each part before assembling the hydraulic cylinder.
  6. When installing the hydraulic cylinder onto the mainframe, seal rings should be added and tightened between the oil inlet and outlet joints to prevent oil leakage.
  7. After the hydraulic bending machine’s oil cylinder is assembled as required, it should undergo several reciprocating movements under low pressure to eliminate gas inside the cylinder.