KUKA CYBERTECH maintenance troubleshooting

KUKA CYBERTECH maintenance troubleshooting

The KUKA KR CYBERTECH series is a six axis articulated robot designed for medium to high load handling, machining, and casting applications, covering KR 8 R2010、KR 12 R1810、KR 16 R1610、KR 16 R2010、KR 20 R1810、KR 20 R1810 F  And models such as KR 22 R1610. This series is usually paired with KR C4 or KR C5 S6/S7 controllers, with a protection level of IP65, and the wrist part can reach IP67. The cast version KR 20 R1810 F also adds positive pressure, PURGE air path, heat-resistant silver paint, and special anti-corrosion coating inside the arm to adapt to dust, coolant, and water vapor environments. For on-site engineers, the real tricky problem is often not "replacing a component", but how to determine the root cause of the fault within the shutdown window and complete the replacement, calibration, and testing according to specifications. Below, we will discuss several aspects including stopping distance, common faults, planned maintenance, involute teeth, oil change, cable group lubrication, and special maintenance for F variant.

First, consider safety and stopping distance

This series of hazardous areas consists of both workspace and stopping distance. The stopping distance is not a fixed value, it is affected by program magnification, load, extension distance, and brake wear. Taking STOP 0 as an example, the A1 stop distance of KR 8 R2010 is about 29.37 °, A2 is about 25.60 °, A3 is about 21.00 °, corresponding to stop times of about 0.24 s, 0.24 s, 0.19 s; The A1 of KR 12 R1810 is about 26.49 °, A2 is about 29.71 °, A3 is about 28.26 °, and the time is about 0.23 s, 0.28 s, 0.23 s; The A1 of KR 16 R1610 is about 25.36 °, A2 is about 23.81 °, A3 is about 22.84 °, and the time is about 0.22 s, 0.24 s, 0.19 s; The A1 of KR 16 R2010 is about 26.72 °, A2 is about 22.74 °, A3 is about 20.34 °, and the time is about 0.26 s, 0.26 s, 0.38 s; The A1 of KR 20 R1810 and KR 20 R1810 F is about 16.27 °, A2 is about 17.61 °, A3 is about 27.24 °, and the time is about 0.23 s, 0.19 s, 0.26 s; The A1 of KR 22 R1610 is about 18.15 °, A2 is about 19.64 °, A3 is about 24.49 °, and the time is about 0.18 s, 0.22 s, 0.22 s. STOP 1 varies with program magnification and mass, and the corresponding curve needs to be checked. If it is found on site that the robot's sliding after braking has significantly increased, there is abnormal braking noise, and there is repeated positioning drift, the first reaction should not be to change the program, but to check the brake wear and stopping distance. It is recommended to retest the stopping distance at least once a year, especially under frequent triggering of STOP 0, high cycle, and high load conditions.

Strict habits must be formed for safe operation: switch T1 before entering the danger zone, press emergency stop, cut off the main switch and lock it; If it is necessary to debug in the powered on state, it can only run at low speed T1 and ensure emergency stop at any time. After the robot loses power, the power components may still be charged for a short period of time. Wait for at least 5 minutes and verify the power. The motor and brake will generate electromagnetic fields, and personnel wearing active implants such as pacemakers should maintain a distance of at least 300 mm. The surface temperature of the motor is high, and protective gloves must be worn when replacing or inspecting it. When it comes to electrical operations, strictly follow the five safety rules: power off, prevent accidental restart, confirm no power, ground short circuit, and block adjacent live parts; After the work is completed, restore in reverse order.

Common faults and troubleshooting ideas

The stopping distance increases or the braking is abnormal

Performance: Stop position deviation, increased collision risk, and abnormal braking sound in automatic mode.

Reason: Brake wear, incorrect input of load data, high program magnification, external axis stacking motion.

Processing: Verify the load data in the controller, including mass, center of gravity Lx/Ly/Lz, moment of inertia Ix/Iy/Iz, and A/B/C directions; Verify with KUKA Load; Check the brake system; Retest the stopping distance. If there is a change in load or supplementary load, it must be re inputted, not based solely on experience.

Wear of involute teeth or abnormal motor noise

Performance: A1 to A6 motion jitter, increased reverse clearance, and high motor temperature.

Reason: Insufficient lubrication of the teeth, aging of the O-ring, improper installation of the motor, and long-term high load.

Solution: Check the involute teeth according to the maintenance table. Clean the teeth and check for wear and tear; If the teeth are damaged, the input shaft of the motor or gearbox must be replaced, and the replacement of the gearbox input shaft requires contacting KUKA Service. Apply Microlube GL 261 to the teeth, thin and continuous, about 2 g. Check the O-ring and replace it if it is damaged.

Gear oil leakage or abnormal oil level

Performance: There are oil stains near A1, A2, A3, A4, A5/A6, and the temperature is high during operation.

Reason: seal aging, screw plug not tightened according to torque, incorrect oil quantity, installation angle leading to incomplete oil discharge.

Solution: Replace the gear oil according to the shaft. The recommended oil is Optigear Synt. ALR 150. The standard maintenance cycle is 2000 hours; the F variant is 10000 hours or 5 years. Initial filling amount: A1 is about 1.20 L, A2 is about 0.80 L, A3 is about 0.32 L, A4 is about 0.32 L, A5/A6 is about 0.37 L. Oil discharge must be carried out at operating temperature and the discharge amount must be measured. If the discharge volume is less than 70% of the specified amount, it should be rinsed once; If it is less than 50%, rinse twice. The filling amount shall be based on the actual discharge amount. Be aware that the oil chamber may be under pressure, and release the pressure before opening the drain plug. The torque of M18x1.5 magnetic plug is about 20 Nm, M10x1 plug is about 7.5 Nm, and A1 union nut is about 45 Nm.

Cable group A1 is worn or has abnormal noise

Performance: The hose inside the base is worn, dust accumulates, and there is friction noise during movement.

Reason: Insufficient lubrication, aging of hoses, long-term high-frequency exercise.

Solution: Remove the base cover, inspect the hose, clean it, and apply Optitemp RB2 grease to the outer surface of the hose, the contact surface with the base, and the inner side of the cover, weighing approximately 0.3 kg. If the hose is damaged, the cable assembly must be replaced. After reassembly, wipe off excess grease and move A1 to evenly distribute the grease.

Zero point loss or Mastering abnormality

Performance: teaching point offset, program unable to reproduce, abnormal axis angle display.

Reason: Replacement of motor, manual release of brake, loss of encoder data, collision.

Solution: Prioritize using EMD or a dial gauge for standard Mastering. The Mastering positions for this series are: A1 27 °, A2 90 °, A3 90 °, A4 0 °, A5 0 °, A6 0 °. After replacing the motor, checking the involute teeth, and replacing the connecting shaft, the Mastering must be redone.

Connector, grounding, and cable layout faults

Performance: The controller reports motor/data line faults, intermittent shutdowns, and abnormal shielding.

Solution: Check the motor cables, data cables, and grounding conductors. KR C4 uses X20-X30, X21-X31; KR C5 uses XD20.1... XD20.6-XD30, XD10.1/XD10.2-XD30, XF21-XF31. The cross-sectional area of the grounding conductor is 16 mm ², and the torque of the M8 nut is about 15.0 Nm. When the cable bending radius is fixed and laid, the motor cable should not be less than 150 mm, and the data cable should not be less than 60 mm. The maximum length is 50 m, and it can be extended up to once. The cable shall not bear tensile force and shall be laid separately from the power line.

F variant positive pressure loss or PURGE abnormality

Performance: Pollution inside the arm, entry of dust, accelerated wear of bearings and teeth.

Reason: The gas source contains water and oil, insufficient pressure, pipeline leakage, and the pressure regulator is not set.

Solution: Check for an overpressure of 0.01 MPa (0.1 bar) ± 10% inside the arm. The compressed air must be free of oil and water, in accordance with ISO 8573-1 Class 4. PURGE has a maximum pressure of 0.01 MPa, input pressure of 0.1-1.2 MPa, pressure regulator of 0.005-0.07 MPa, and air interface of 6 mm. Pressure loss can cause dust and coolant to enter, and must be repaired in a timely manner.

Wear of connecting shaft or large clearance between A4/A5 movements

Performance: A4/A5 abnormal noise, positioning drift, and increased reverse clearance.

Reason: Tooth wear, insufficient lubrication, and damage to the tooth surface during installation.

Solution: The connecting shafts must be replaced in pairs. Clean the teeth and apply Microlube GL 261 before installation. Pay attention to locking washers and wave springs during installation. A6 replacement requires the dismantling of A4, A5, and the inline hoist, which weighs approximately 23 kg and must be reliably lifted.

Planned maintenance: Block faults before they occur

Core nodes of standard maintenance table:

100 hours: Check the torque of the fixing bolts on the installation base.

2500 hours: Check if the visible hose is damaged.

5000 hours: Lubricate cable group A1 using Optitemp RB2.

2000 hours: Check A1-A6 involute teeth and grease them; Replace A1, A2, A3, A4, A5/A6 gear oil.

F variant maintains the core node of the table:

100 hours: Check the torque of the fixing bolts on the installation base.

2500 hours: Check for visible hoses.

5000 hours: Lubricate cable group A1 using Optitemp RB2 for approximately 200 cm ³.

10000 hours or 5 years: Check A1-A6 involute teeth and grease them; Replace A1, A2, A3, A4, A5/A6 gear oil.

Before maintenance, the maintenance point must be accessible and any obstructing tools and accessories must be removed. If the oil temperature exceeds 60 ° C for a long time, the maintenance interval should be shortened and KUKA should be consulted. All accessories must use approved products, otherwise it may lead to early wear and tear.

Practical replacement of involute teeth and motors

The involute teeth are a critical transmission component between the motor and the input shaft of the gearbox. During inspection, it is necessary to remove the motor, clean the teeth, and check for wear and tear; If the teeth are damaged, the input shaft of the motor or gearbox must be replaced, and the replacement of the gearbox input shaft requires contacting KUKA Service. Operation points:

A1: Standard use 4 M8x22-8.8-A2K hex socket screws, while F and HO versions use M8x25-A4-80. Be careful not to tilt when removing the motor; Apply Microlube GL 261 to the teeth; Check the O-ring.

A2: First, fix the connecting rod arm with a sling to prevent the arm from falling down after disassembling the motor; The screw specifications are the same as A1.

A3: First, fix the robot arm with a sling; Standard use 4 M8x20-8.8, F and HO versions use M8x20-A4-80; Pay attention to the spacer sleeve.

A4/A5: Standard use 4 M5x14-8.8-A2K, F and HO versions use M5x14-A4-80; Pay attention to the connecting shaft, locking washer, and wave spring; Apply Microlube GL 261 to the connecting shaft teeth; After installation, the connecting shaft should have a slight axial clearance.

A6: A4, A5, and inline writer need to be disassembled first; The inline hoist weighs approximately 23 kg and must be reliably lifted; Standard use 4 M3x12-8.8, F and HO versions use M3x12-10.9; Apply Microlube GL 261 to the teeth.

After replacing the motor, it is necessary to perform Mastering on the corresponding shaft and test the program in T1 mode. After replacing A4/A5/A6, it is usually necessary to master A4, A5, and A6 simultaneously.

Details of oil change and cable group lubrication

When changing the oil, A1 uses an oil pump with a union nut torque of about 45.0 Nm and an M18x1.5 plug torque of about 20.0 Nm; A2 uses an M18x1.5 plug torque of about 20.0 Nm; A3 uses an M10x1 plug torque of about 7.5 Nm; A4 uses an M10x1 plug torque of about 7.5 Nm; A5/A6 uses an M10x1 plug torque of about 7.5 Nm. Before draining the oil, release the pressure first, measure the discharge amount after draining, and the filling amount should be based on the actual discharge amount. When lubricating cable group A1, first remove 5 M5x10-10.9 round head screws and 2 M4 hex nuts, remove the cover and brush strip; Use a brush to apply Optitemp RB2 to the outside of the hose, the contact surface with the base, and the inside of the cover; After reassembly, wipe off excess grease and move A1 to evenly distribute the grease.

F variant casting plate special maintenance

The protection focus of KR 20 R1810 F is on positive pressure and PURGE. The overpressure inside the arm is 0.01 MPa (0.1 bar) ± 10%, and the compressed air must be free of oil, water, and filtered, in accordance with ISO 8573-1 Class 4. PURGE has a maximum pressure of 0.01 MPa, an input pressure of 0.1-1.2 MPa, a pressure regulator of 0.005-0.07 MPa, and an air interface of 6 mm. The thermal load is 10 s/min at 180 ° C, and the wrist is coated with heat-resistant silver paint. The entire machine is coated with special paint and protective varnish. If positive pressure is lost, dust and coolant will enter the arm, accelerating the wear of bearings and teeth; Therefore, every maintenance should check for leaks in the air circuit, pressure regulator, and pipelines.

Installation, transportation, and electrical interfaces

Transportation location: A1 0 °, A2-138 °, A3 139 °, A4 0 °, A5 90 °, A6 0 °. Use slings or forklifts, unauthorized lifting is prohibited. Install base S31 weighing approximately 25.4 kg, using 4 M20x55-8.8 bolts and 6 chemical anchor bolts; Machine frame installation 0000-268-113 weighs approximately 1.05 kg and uses 4 M20x55-8.8 bolts. Tighten the base bolts again after 100 hours. Interface A1 is located at the rear of the base and includes X30 motor, X31 data, X32 mastering, XP7.1/XP8.1 external axis PURGE（F variant）。 The grounding conductor is 16 mm ², and the torque of the M8 nut is approximately 15.0 Nm. The connecting cable lengths are 4 m, 7 m, 15 m, 25 m, 35 m, and 50 m, with a maximum of 50 m and a maximum extension of once.

Fault Handling Checklist

Emergency stop, power off, padlock, and power check first.

Check the alarm: motor, brake RDC、 Data cables and safety circuits.

Mechanical inspection: oil level, oil leakage, involute teeth, O-ring, connecting shaft, cable assembly, positive pressure.

Check parameters: load, center of gravity, inertia, installation angle, program magnification.

After replacement: Mastering, T1 testing, stop distance retest.

Record: Fault time, frequency, axle number, temperature, load, maintenance content.

The reliability of the KUKA KR CYBERTECH series is based on standardized maintenance. By controlling the stopping distance, involute teeth, gear oil, cable assembly, zero point calibration, base bolts, and F variant positive pressure, most on-site faults can be detected in advance. For engineers, the true idea of "replacing discontinued modules" is not to wait until they break before replacing them, but to use verifiable parameters and standard steps to turn every maintenance into a traceable quality record.