KUKA LBR iiwa CR Cleanroom Troubleshooting and Maintenance

KUKA LBR iiwa CR Cleanroom Troubleshooting and Maintenance

Why can't the operation and maintenance of cleanroom robots only focus on "axis movement"

KUKA LBR iiwa CR is a lightweight seven axis articulated robot, with the main models being LBR iiwa 7 R800 CR and LBR iiwa 14 R820 CR. The biggest difference between it and ordinary industrial robots is the "CR" cleanroom version: the robot integrates a fan and a base ring inside, reads the speed signal through the control box, and uses the customer's exhaust pipe to bring particles out of the cleanroom. That is to say, troubleshooting should not only focus on servo, encoder, or program, but also consider safety stop, fan monitoring, exhaust negative pressure, WorkVisual mapping, and mechanical tightening torque. Any mismatch in any link will manifest as "robot immobility," "frequent safety stops," "cleanroom level not meeting standards," or "fan alarm.

The troubleshooting approach for this type of equipment is similar to replacing the shutdown control module or troubleshooting the safety system: first confirm the model and system boundary, then check the safety functions, load, stopping distance, interface, and cleanroom specific components, and finally verify at low speed in T1 mode, gradually scaling up to automatic mode. Jumping operations may cause excessive stopping distance, axis sagging, particle leakage, and even personal injury.

Model and System Boundary

The LBR iiwa CR system consists of a robotic arm, KUKA Sunrise Cabinet controller, KUKA smartPAD teaching pendant, connecting cables, software, options, and accessories. The robotic arm is a seven axis redundant articulated arm, with all drive units and current carrying cables inside the robot. Each joint module contains position, torque, and temperature sensors: the axis range sensor ensures the range of motion, the torque sensor prevents the axis load from exceeding the limit, and the temperature sensor monitors the thermal limit of electronic components. If the temperature is too high, the robot will automatically shut down for protection, and can be restarted after cooling without additional measures.

The CR version also includes the LBR CR base ring and LBR CR control box. The base ring is located under the shielding plate below A1 and has a built-in fan for extracting particles from the shell; The control box controls the operation of the fan and reads the tacho signal. Robot side interface A1 is located at the rear of the base, connecting data cables and power supply. The control box must be installed outside the robot workspace to avoid collisions.

Key technical data: must be verified before selection, replacement, and troubleshooting

LBR iiwa 7 R800 CR: Seven axis, working range of approximately 1.7 m ³, repeatability of ± 0.1 mm, weight of approximately 26.1 kg, rated load of 7 kg, maximum arm span of 800 mm. Protection level IP54, base IP20. LBR iiwa 14 R820 CR: Seven axis, working range of approximately 1.8 m ³, repeatability of ± 0.15 mm, weight of approximately 32.7 kg, rated load of 14 kg, maximum arm span of 820 mm. Both are installed on the ground, with base dimensions of 220 mm × 220 mm and 256 mm × 256 mm, respectively.

Axis motion range: A1 ± 170 °, A2 ± 120 °, A3 ± 170 °, A4 ± 120 °, A5 ± 170 °, A6 ± 120 °, A7 ± 175 °. Speed under rated load: 7 R800 CR is A1 98 °/s, A2 98 °/s, A3 100 °/s, A4 130 °/s, A5 140 °/s, A6 180 °/s, A7 180 °/s; 14 R820 CR is A1 85 °/s, A2 85 °/s, A3 100 °/s, A4 75 °/s, A5 130 °/s, A6 135 °/s, A7 135 °/s.

Environmental conditions: Operating temperature from 5 ° C to 45 ° C, storage and transportation from 0 ° C to 45 ° C. The cleanroom level is ISO 14644-1 Class 3 (80% override, with exhaust system). If there is no exhaust system or insufficient fan speed, the cleanroom level cannot be guaranteed.

In terms of load, the 7 R800 CR has a rated mass inertia of 0.3 kgm ² and a rated total load of 7 kg. No additional load is allowed; 14 R820 CR has a rated mass inertia of 0.3 kgm ² and a rated total load of 14 kg, and no additional load is allowed. The load center of gravity is based on the A7 flange surface. Exceeding the load diagram will shorten the service life and overload the motor and gears. Load data must be written into the controller, and mass inertia must be verified through KUKA. Load.

Exclusive for cleanroom: fan, control box, and exhaust interface

The core of the CR version is particle control. The base ring fan is used to extract particles from the shell, and the control box controls the fan and reads the speed. The technical documentation requires a minimum fan speed of 2200 rpm. If the fan speed drops by 25% or more, the cleanroom level cannot be guaranteed. Therefore, during debugging, the fan controller must be integrated into WorkVisual and programmed to loop background tasks to monitor speed.

WorkVisual integration steps: Import device description file, including bus terminal EL6695-1001, fan controller EM8905-1002, and I/O module EK1100 EtherCAT coupler. Add expansion buses SYS-X44, EK1100, EL6695, and EM8905 under the bus structure. Then create a fan control I/O group in the I/O Mapping, which should include at least three signals: fan on, tacho signal evaluation, and fault evaluation. Usually, Out7.Output is mapped to fan start, and In1.Input is mapped to speed feedback. After saving, export the I/O mapping to Sunrise. Wordbench.

Fan monitoring backend task parameters: Delay of 20 seconds, cycle of 10 ms, speed calculated as "pulse count x 60/4", minimum speed of 2200 rpm. The programming logic is: start the fan during initialization, wait for about 5 seconds, and create an edge observer to count pulses; Calculate the speed per second in the loop, and if it is below the minimum limit, output a signal to the PLC indicating that the fan is not running; Otherwise, output a normal signal. This allows for parallel monitoring of fans while the robot executes applications.

In terms of exhaust interface, a 120mm diameter exhaust hole is required in the center of the LBR CR base ring, and the customer needs to install the exhaust duct themselves. The exhaust duct is not within the scope of supply and must be provided by the customer. If the fan is not connected to the exhaust duct and the rotating fan is exposed, there is a risk of injury. Therefore, LBR iiwa CR must not operate without connecting the exhaust duct. In order to remove particulate matter from the clean room, it is necessary to ensure that the specified airflow is not restricted. It is recommended to connect an active exhaust system to the fan interface.

Installation and transportation: positioning pin, torque and foundation load

The installation adopts a machine frame with centering. LBR iiwa 7 R800 CR uses 4 M8x65-8.8 hex socket screws, and LBR iiwa 14 R820 CR uses 4 M10x70-8.8 hex socket screws. The positioning pin is 6x12, divided into cylindrical pin and flat head pin. Installation sequence: First, drive the positioning pin into the prefabricated hole, lower the LBR CR base ring vertically, insert the positioning pin, then lower the robot vertically onto the base ring, and finally cross tighten the 4 screws. After running for 100 hours, it must be tightened again: 7 R800 CR is 23 Nm, 14 R820 CR is 45 Nm.

The basic load must be designed according to the maximum load. 7 R800 CR: vertical force of 545 N, horizontal force of 240 N, overturning moment of 318 Nm, and torque around A1 of 156 Nm. 14 R820 CR: vertical force of 568 N, horizontal force of 228.4 N, overturning moment of 290 Nm, and torque around A1 of 172.6 Nm. These values include the load and the robot's own weight, and the foundation must be able to safely withstand them. The control box is fixed with 4 M4x8-8.8 screws and must be located outside the robot workspace.

Before transportation, the robot must be placed in the transportation position: A1 0 °, A2+25 °, A3 0 °, A4+90 °, A5 0 °, A6 0 °, A7 0 °. The outer dimensions of the transportation packaging are 1180 mm × 780 mm × 595 mm. When lifting, the force should be applied between A2/A3 and A4/A5, and inappropriate lifting equipment is prohibited. Avoid vibration and impact during transportation, tools must be removed, and connecting cables must be unplugged.

Safety functions and stop categories

The safety functions of LBR iiwa CR are divided into safety oriented functions and non safety oriented functions. The safety oriented function meets EN ISO 13849-1 category 3, performance level d, and EN 62061 SIL 2. The premise is that all safety related machinery and electromechanical components are tested at start-up and at least once every 12 months, unless otherwise specified in the workplace risk assessment. These components include: local emergency stop on the teaching pendant, teaching pendant enable device, manual guidance enable device (if any), external enable device (if any), smartPAD key switch (if used as a teaching pendant), and safety output of discrete safety interface.

The standard safety functions include emergency stop devices and enable devices. The functions that are pre configured and can be integrated into the system security interface include: operator safety signals (used to monitor physical protection such as safety doors), external emergency stop, and external safety stop 1 (path maintenance). External enablement, external safety operation stop, axis specific workspace monitoring, Cartesian workspace monitoring, speed monitoring, stationary monitoring, axis torque monitoring, collision detection, etc. can also be configured.

Stop category: STOP 0 means the driver immediately loses power, the brake is applied, and the robot brakes in the direction of the path. STOP 1 is the path holding brake, and after about 1 second, the power is cut off and the brake is applied. Emergency stop triggers safety stop 1 (path maintenance). Enable switch in three positions: not pressed, middle, fully pressed. Only the middle position can move. Release or fully press to trigger safety stop 1. The operator safety signal is required by default in T2 and automatic mode, and T1 and CRR are not evaluated; Loss of signal triggers safety stop 1. Restoring automatic mode cannot rely solely on closing the door, it must be reset by an additional confirmation button to prevent automatic recovery when personnel are still in the danger zone.

External security stop 1 is triggered through the security interface input. When the signal is False, it remains stopped, and when it is True, it can be moved again without confirmation. External enablement is used for multiple people entering hazardous areas, with a pre configured maximum speed of 250 mm/s for manual guidance. The specific value needs to be determined through risk assessment. External safety operation stop is static monitoring, without stopping the movement, only monitoring whether the axis is stationary.

In terms of modes: T1 manual deceleration, T2 manual high-speed, CRR cooperative mode, AUT automatic. The maximum speed of T1 is 250 mm/s. The speed does not decrease during manual guidance, but is limited by safety speed monitoring. In T1, T2, and CRR, the robot movement can only be initiated by pressing and holding the enable switch. Automatic mode requires all safety equipment and protective devices to be functioning properly, with no one in the system, or to meet the EN ISO 10218 collaboration requirements.

Stop distance: STOP 0 reference value and verification

The technical data provides a reference value for STOP 0. LBR iiwa 7 R800 CR: A1 stopping distance 5.193 °, time 0.182 s; A2 5.092 °, 0.212 s; A3 8.091 °, 0.166 s; A4 7.538 °, 0.114 s. LBR iiwa 14 R820 CR: A1 5.742 °, 0.188 s; A2 5.998 °, 0.200 s; A3 9.323 °, 0.198 s; A4 3.162 °, 0.092 s. These values show a 100% extension POV 100%、 Measured under maximum load conditions, only applicable to single axis motion; The overlapping axis motion may be longer.

The stopping distance is part of the danger zone and must be physically isolated. The actual stopping distance is affected by braking torque, load, and extension POV、 Brake wear affects. It is recommended to check the stopping distance at least once a year. Axis specific or Cartesian workspace monitoring can be triggered through safety monitoring, and measurement data can be evaluated using a Data Recorder. If the stopping distance significantly increases, the brake, load configuration, speed monitoring, and safe stopping category should be checked.

Debugging and Security Testing

Before the first debugging or re debugging, the system must be checked for completeness, safe operation, and no damage. Before starting, the user group password must be changed and transmitted to the controller through the installation program for activation. The password can only be provided to authorized personnel. Functional testing includes: correct installation of the robot, no foreign objects, no loose parts, complete safety equipment, matching power levels, correct grounding and equipotential, and locked connection cables.

Security function testing must cover all security oriented functions. Emergency stop test: Press the emergency stop button, and the teaching pendant will display that the emergency stop has been triggered without displaying any errors in the emergency stop device. Enable switch test: When moving the robot in test mode and releasing the enable, the movement must stop and no enable device errors must be displayed. The full press test must also be stopped. Key switch test: Turn right and return to the correct position without any error. Safety output shutdown capability test: When the controller is powered off and then back on, there must be no safety output errors.

Braking test is used to check whether each axle brake provides sufficient torque. Unless the risk assessment proves that brake failure will not result in unacceptable risks, brake testing must be performed on each axle during start-up and re commissioning; Do it once a day during operation. If the startup is incomplete, alternative measures must be taken and recorded, such as installing safety fences, posting warning signs, and locking the main switch.

Maintenance and Cleaning

Maintenance plan: Check the bolts after 100 hours of operation, with a torque of 23 Nm for 7 R800 CR and 45 Nm for 14 R820 CR, to be executed only after the first installation. Visually inspect and listen to the fan running noise after 1 year. When the ambient temperature is 25 ° C, replace the fan after 3 years. Fan replacement can only be carried out through negotiation between authorized maintenance personnel and KUKA customer service.

Only cleanroom approved cleaning agents and tools, such as cleanroom cloths, can be used for cleaning. Corrosive cleaning agents, steam, refrigerants, and high-pressure cleaning are prohibited. Do not allow cleaning agents to enter electrical or mechanical components. Cleaning steps: Turn off the robot, if necessary, close and lock adjacent systems, clean the robot, thoroughly remove cleaning agents, clean the workspace, dispose of cleaning agents properly, install and inspect safety equipment, replace damaged or unreadable signs and covers, and only resume operation if they are completely normal. The painted surface can only come into contact with cleaning agents for a short period of time.

Common troubleshooting tree

Unable to enable: Check the emergency stop circuit, enable the middle position of the switch, key switch, whether smartPAD is uniquely assigned, safety signal for the safety door operator, external emergency stop, cable locking, and controller diagnostic information.

Frequent safety stops: check if the enable switch is released or fully pressed, if the operator's safety signal is lost, if there is an external safety stop, if there is an error in the safety controller, if there is a mode switch, if there is a manual guide to release the enable, if the speed exceeds 250 mm/s.

Fan alarm or cleanroom level non-compliance: Check if the fan is started, Out7.Output mapping, In1.Input feedback, if the speed is below 2200 rpm, if it has decreased by 25%, if the exhaust duct is connected, if the exhaust system is active, if the fan noise and operating time exceed 3 years.

Robot not moving but no alarm: Check if T1/T2/CRR is holding down the enable button, Start button, if the program is in jog mode, safety door signal, external enable, and if the single point control SPOC parameters have been modified by online tools.

Communication or data cable issues: Check whether the bending radius of the data cable is not less than 45 mm, whether it is in the metal cable tray, whether it is stretched, whether the joint is locked, and whether the control box WX55/X55, WX65/X65, WXE1 connections are connected.

Mechanical looseness or damaged locating pin: Check the torque of 4 screws, locating pin, base ring seal, foundation load, cleanliness of installation surface, and vertical installation to avoid pin damage.

Automatic shutdown when the temperature is too high: check the ambient temperature, duty cycle, continuous high load, heat dissipation conditions, fan operation, and temperature sensor alarm. After cooling, it can be restarted without any additional measures.

Collision or overload: Check whether the torque sensor, load map, mass inertia, tool center of gravity, and additional load exceed the limit. If there is abnormal noise or decreased accuracy after collision, the motor and mechanical structure must be checked.

Dismantling, replacement, and storage

Before dismantling, move the robot to the transport position, turn off the power, unplug the connecting cable, open the control box, remove 4 M4x8 screws, 4 Allen screws and locating pins, protect the joints and hoses from contamination, lift the robot together with the base ring, and place it in the transport box. Reinstall in reverse order: set the positioning pin, lower the base ring, lower the robot, cross tighten the screws, connect the exhaust duct, connect the data cable and grounding, check that the cable is not stretched or rubbed, and finally install the tools and energy supply.

Long term storage requirements: dry, dust-free, avoid temperature fluctuations, avoid wind, avoid condensation, use appropriate coverings, leave no loose parts, avoid direct sunlight, comply with storage temperature, and choose a location that will not damage the packaging. Clean and dry before storage, conduct internal and external inspections, remove foreign objects and corrosion, install cover plates and seals, seal electrical and hose connections, and place them in the transport box.

Classify by material during disposal: aluminum outer structure, base ring, control box shell; Stainless steel shielding plate, screws, washers; Copper cable; Steel screws and pins; Electrical components such as fans, boards, and optocoupler modules shall be treated as electrical scrap, and the motor shall not be disassembled; Plastic ABS terminal box, elastomer seal, PA cable joint, PUR/PVC/rubber cable sheath. The safety data sheet for auxiliary materials should be requested from the manufacturer.