KUKA KR 20 R1810 HO maintenance troubleshooting

KUKA KR 20 R1810 HO maintenance troubleshooting

KUKA KR 20 R1810 HO belongs to the Hygienic Oil food grade version of the KR CYBERTECH series, mainly targeting food grade areas. It adopts special gear oil, enhanced anti-corrosion design and light gray coating, with a rated load of 20 kg, a maximum load of 23.9 kg, a maximum arm span of 1813 mm, a repeat positioning accuracy of about ± 0.04 mm, a body weight of about 250 kg, a working space of about 23.3 m ³, a protection level of IP65, and a wrist part that can reach IP67. It is usually paired with KR C5 S6/S7 or KR C4 controllers. For on-site engineers, the real tricky problem is not "replacing a component", but how to determine the root cause of the malfunction in a food grade environment and complete the replacement, calibration, and cleaning according to specifications. Below, we will discuss several aspects including stopping distance, common faults, planned maintenance, involute teeth, oil change, cable lubrication, food grade cleaning and PURGE, and installation and transportation.

First, consider safety and stopping distance

The danger zone of KR 20 R1810 HO 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, A1 stops at a distance of about 16.27 °, A2 stops at a distance of about 17.61 °, and A3 stops at a distance of about 27.24 °; The corresponding stop times are approximately 0.23 s, 0.19 s, and 0.26 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 Cassida Fluid GL150. 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 PETAMO GHY 133 N 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. In food grade environments, the overflow of lubricating grease may adsorb particles and must be cleaned thoroughly.

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 of this model 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.

Food grade cleaning and PURGE abnormalities

Performance: Arm contamination, dust ingress, residue after cleaning, PURGE gas path blockage.

Reason: Improper cleaning agent, high-pressure water entering the seal, insufficient PURGE pressure, pipeline leakage.

Treatment: Only neutral, solvent-free, water-soluble, non flammable, non strong acid and alkali, and chlorine free cleaning agents can be used for cleaning. Prohibit high-pressure cleaning machines and use compressed air to blow bearings and sealing points, ensuring that cleaning agents do not enter electrical or mechanical components. PURGE option A/B is only used for cleaning and is prohibited from use during operation to prevent particle emissions. The gas source should be oil-free, waterless, and filtered, and the pressure regulator should be set correctly.

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 for the maintenance table of KR 20 R1810 HO:

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 PETAMO GHY 133 N.

2000 hours: 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. Special attention should be paid to the food grade version: cleaning agents, lubricants, and gear oils must be compatible with the food production environment and cannot be replaced arbitrarily.

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: The HO version uses 4 M8x25-A4-80 hex socket screws. Be careful not to tilt when removing the motor; Apply Microlube GL 261 to the teeth; Check the O-ring; Pay attention to the sealing components during installation.

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; The HO version uses 4 M8x20-A4-80 chips; Pay attention to the spacer sleeve and O-ring.

A4/A5: HO version uses 4 M5x14-A4-80s; 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; The HO version uses 4 M3x12-10.9 chips; 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 PETAMO GHY 133 N 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.

Food grade cleaning and PURGE usage boundary

The cleaning of KR 20 R1810 HO must follow special rules: use neutral cleaning agents, solvent-free, water-soluble, non flammable, non strong acid strong alkali, and chlorine free; Do not use high-pressure cleaning machines; Do not use compressed air to clean bearings and sealing points; Ensure that cleaning agents do not enter electrical or mechanical system components. After cleaning, the cleaning agent must be completely removed, and the corroded area must be re protected against corrosion. PURGE option A/B is used for compressed air pretreatment, but only for cleaning work. It is prohibited to use during operation to prevent the emission of foreign particles. The gas source must be free of oil, water, and filtered, and the pressure regulator must be set correctly. The food grade version cannot come into direct contact with food and cannot be used in medical environments.

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. Basic load: floor Fv normal 4038 N、max 4443 N，Fh 2336/2988 N，Mk 3334/4177 Nm，Mr 1965/2361 Nm； Ceiling Fv 4104/4535 N, Fh 2272/2793 N, Mk 3642/4553 Nm, Mr 2017/2314 Nm; Wall Fv 4265/4661 N, Fh 1464/2268 N, Mk 4603/5124 Nm, Mr 1739/2368 Nm. Flange load: operating at F (a) 970 N, F (r) 960 N, M (k) 249 Nm, M (g) 107 Nm; Emergency stop F (a) 1115 N, F (r) 1280 N. The tool must be able to withstand these loads. 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。 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, PURGE air circuit.

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.

Extra recording of batches of cleaning agents, lubricants, and gear oils in food grade environments to ensure traceability.

The reliability of KUKA KR 20 R1810 HO is based on standardized maintenance. By controlling the stopping distance, involute teeth, Cassida Fluid GL150 gear oil, cable lubrication, zero point calibration, base bolts, food grade cleaning, and PURGE, 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.