KUKA LBR iiwa CR Operations and Troubleshooting

KUKA LBR iiwa CR Operations and Troubleshooting

Model positioning and system composition

KUKA LBR iiwa CR is a seven axis lightweight articulated robot designed for cleanroom environments. CR stands for Clean Room, emphasizing its ability to control particulate matter pollution. This model is suitable for handling tools, fixtures, workpieces, or products, but the operating environment must be a clean room contaminated with monitored particles and meet the specified environmental conditions. It is not a universal outdoor robot and is not allowed to be used in potential explosive environments, medical or food technology, manned and animal carrying, climbing assistance, and other scenarios.

A complete LBR iiwa CR system typically includes: robotic arm, KUKA Sunrise Cabinet robot controller, KUKA smartPAD handheld control panel, connecting cables, control box, LBR CR base ring kit, software, options, and accessories. The mechanical arm body is a seven axis redundant structure, and all drive units and current carrying cables are arranged inside the robot. Each axis is equipped with position, torque, and temperature sensors for position control, impedance control, and protection functions. If the axis range, axis load, or electronic component temperature exceeds the allowable value, the system will trigger protection and automatically shut down; After cooling, it can usually be restarted without additional measures.

The LBR CR base ring is located below axis 1 and below the shielding plate. The base ring integrates a fan, which is used to extract particles from the shell and then discharge them through the clean room exhaust duct. The control box is responsible for controlling the operation of the fan and reading the speed measurement signal. If the exhaust duct is not connected, the rotating fan will be exposed, posing a risk of injury. Therefore, LBR iiwa CR must not operate without connecting the exhaust duct.

Quick search of main technical data

There are two main specifications for LBR iiwa CR: LBR iiwa 7 R800 CR and LBR iiwa 14 R820 CR.

Project LBR iiwa 7 R800 CR LBR iiwa 14 R820 CR

Number of axes/number of control axes 7/7 7/7

The work envelope volume is about 1.7 m ³ and about 1.8 m ³

Position repeatability accuracy ISO 9283 ± 0.1 mm ± 0.15 mm

Weight approximately 26.1 kg, approximately 32.7 kg

Rated load 7 kg 14 kg

Maximum arm span 800 mm 820 mm

Protection level IP54; Base IP20 IP54; Base IP20

Installation location: Ground level

Controller KUKA Sunrise Cabinet KUKA Sunrise Cabinet

Cleanroom Class ISO 14644-1 Class 3, 80% override, with exhaust system as on the left

Operating at an ambient temperature of 5-45 ℃; Storage/Transportation: 0-45 ℃ Same as Left

Fan power supply 24 VDC, approximately 0.3 A, minimum 2200 rpm, same as left

Control box fuse 2 A 2 A

In terms of axial motion range, A1 is ± 170 °, A2 is ± 120 °, A3 is ± 170 °, A4 is ± 120 °, A5 is ± 170 °, A6 is ± 120 °, and A7 is ± 175 °. The speed varies with the rated load, for example, A1/A2 of 7 R800 is about 98 °/s, A3 is about 100 °/s, A4 is about 130 °/s, A5 is about 140 °/s, A6/A7 is about 180 °/s. A1/A2 of 14 R820 is about 85 °/s, A3 is about 100 °/s.

Special attention should be paid: The LBR CR base ring kit will raise the robot position by 35 mm in the positive Z direction. When using the "Robot Base Coordinate System" and "World Coordinate System", this height increase will not be automatically incorporated. When displaying the actual position of Descartes or using a "world" base, a deviation of+35 mm must be considered.

Safety function and stop reaction

The safety function of LBR iiwa CR is oriented towards personnel protection and meets the requirements of EN ISO 13849-1 Category 3, Performance Level d, and EN 62061 SIL 2. But the prerequisite is that all safety related machinery and electromechanical components undergo functional testing at start-up and at least once every 12 months, unless otherwise specified in the risk assessment. The test objects include local emergency stop, enabling devices, manual guidance enabling devices, external enabling devices, key switches, and safety outputs of discrete safety interfaces on smartPAD.

Common security features include:

Local emergency stop: The standard configuration is an emergency stop on smartPAD. After pressing, the robotic arm stops with a safe stop 1 (path maintenance). Reset before continuing.

Enabling device: There are three enabling switches on the smartPAD, namely, not pressed, middle, and fully pressed (panic position). In T1, T2, and CRR modes, movement is only possible by maintaining the middle position. Release or full press both trigger safety stop 1.

Operation safety signal: used to monitor physical protection such as safety doors. By default, T2 and automatic modes cannot operate without this signal. Trigger safety stop 1 when signal loss occurs.

External emergency stop: Every operating station that may cause robot movement or danger must be equipped. By connecting through a secure interface, security stop 1 is triggered by default.

External security stop 1: Triggered through a security interface input, the signal remains stopped when it is false, and can be moved again when it is true without confirmation.

External enabling device: used when multiple people are needed in a hazardous area. Can connect multiple external enabling devices. When manually guided, the robot can only move at a reduced speed, with a pre configured maximum allowable speed of 250 mm/s.

External safety operation stop: used for stationary monitoring, does not stop movement, only monitors whether the axis is stationary.

The permanently defined stop triggers include: switching modes during operation, releasing the enable switch, fully pressing the enable switch, pressing the local emergency stop, and safety controller error, all of which trigger safety stop 1. User specific triggers may include opening of safety doors, pressing of external emergency stop, external safety stop, etc.

T1 is the manual speed reduction mode, with a speed not exceeding 250 mm/s; T2 is in manual high-speed mode, allowing for speeds exceeding 250 mm/s. Automatic mode must be used when all safety equipment and protective devices are complete, there is no one in the system, or when EN ISO 10218 cooperation requirements are met. If the robotic arm stops without reason, it must not directly enter the danger zone and must first trigger an emergency stop.

Braking testing is an important maintenance project. Unless the risk assessment proves that mechanical brake failure will not result in unacceptable risks, brake tests should be performed on each axis during start-up and re commissioning, and daily during daily operation. Check the stopping distance and stopping time at least once a year. The stopping distance will be affected by braking torque, wear, load, speed, extension distance, etc. In practical applications, it should be measured under real conditions.

Installation, transportation, and electrical connections

Before transportation, the robot must be in the transport position: A1 0 °, A2+25 °, A3 0 °, A4+90 °, A5 0 °, A6 0 °, A7 0 °. The outer dimensions of the transport packaging are approximately 1180 mm in length, 780 mm in width, and 595 mm in height. During handling, it can only be lifted between A2 and A3, A4 and A5. Authorized handling equipment with sufficient load-bearing capacity must be used to avoid vibration and impact.

Installation adopts rack installation with positioning method. The preparation work includes: machining positioning pin holes, threaded holes, and exhaust holes on the base. LBR iiwa 7 R800 CR uses M8 thread, LBR iiwa 14 R820 CR uses M10 thread. When installing, first drive the positioning pin into the hole, lower the LBR CR base ring vertically, then insert the positioning pin, and then lower the robot vertically onto the base ring. It must be kept completely vertical to prevent damage to the positioning pin.

Tighten with 4 hexagon socket bolts and washers: 7 R800 is M8 × 65-8.8, 14 R820 is M10 × 70-8.8. Tighten gradually in diagonal order to the specified torque. After running for 100 hours, it needs to be re tightened. Torque reference: 7 R800 is about 23 Nm, 14 R820 is about 45 Nm. The control box is installed near the robot controller with 4 M4 × 8-8.8 hex bolts and must be located outside the robot workspace.

The electrical connections include: WX55 connected to controller X55, WX65 connected to controller X65, WXE1 connected to LBR iiwa CR base ring. When the bending radius of the connecting cable is fixed and laid, the data cable should not be less than 45 mm; avoid mechanical stress and tensile force; Indoor installation only; Fixed installation temperature range -10 ℃ to+70 ℃; Suggest using metal cable trays and taking EMC measures if necessary. Cable layout should prevent tripping risks.

The exhaust duct is not within the scope of supply and will be installed by the customer. It is necessary to ensure that the specified airflow is not restricted, and it is recommended to connect an active exhaust system. After installation, the control box must be closed and the exhaust outlet must be connected to the exhaust duct.

Fan monitoring and WorkVisual integration

Cleanroom compliance relies on the fan running at 2200 rpm. If the fan speed decreases by 25% or more, the cleanroom level cannot be guaranteed. Therefore, it is necessary to write periodic background tasks to monitor the fan speed in parallel during the operation of the robot application. If it deviates from the specified range, the program must trigger the corresponding response.

Integrating a fan controller in WorkVisual: Start FHIR figuration-wvs, close the project, and import the device description file. Need to import Bus terminal EL6695（KRC4 primary EL6695-1001）、Fan controller EM8905-1002 I/O module、Beckhoff bus coupler EK1100 EtherCAT coupler。 Then add the expansion bus SYS-X44, EK1100, EL6695, and EM8905-1002 to the controller bus structure. Next, create a fan controller I/O group in I/O Mapping, which includes three signals: fan start, speed signal evaluation, and fault evaluation. Map Out7.Output to fan start and In1.Input to speed evaluation. Save the project and export the I/O mapping to Sunrise Workbench if necessary.

Sunrise backend task parameters can refer to: delay of 20 seconds, cycle of 10 ms, speed calculation (pulses * 60)/4, minimum fan speed of 2200 rpm. The example logic is to create process data during initialization, start the fan, wait for about 5 seconds, create an edge observer to count pulses, and initialize the cycle task. Read the minimum speed during periodic operation, calculate the actual speed, reset the counter, and update the smartPAD display; If the actual speed is less than or equal to the minimum limit, output a signal to the PLC or upper system that the fan is not running, such as setting fanIO and run to false; Otherwise, set it to true. This logic can help engineers quickly detect fan aging, blockage, abnormal power supply, or obstructed exhaust.

Maintenance plan and cleaning requirements

The maintenance interval is based on the operating conditions in the technical data. If the operating conditions deviate, KUKA should be consulted. Typical maintenance table:

Interval activity

Check the bolts after 100 hours of operation. 7 R800 torque is about 23 Nm; 14 R820 torque is about 45 Nm

Tighten all at once after startup/installation according to the above instructions

1 year visual inspection and check for fan operating noise

Replace the fan within 3 years (25 ℃ environment)

Fans can only be replaced by authorized maintenance personnel after consultation with KUKA customer support. When cleaning robots, only cleanroom approved cleaning agents and tools, such as cleanroom cloths, can be used. Do not use corrosive cleaning agents, steam, refrigerants, or high-pressure cleaning machines. Cleaning agents must be prevented from entering electrical or mechanical components. After cleaning, thoroughly remove the cleaning agent, clean the workspace, dispose of the cleaning agent properly, restore safety equipment and check its function, replace damaged or unreadable signs and covers. Only fully functioning robots and systems can be put back into operation.

Common troubleshooting ideas

1. Robot automatically shuts down

The common reason is triggered by temperature monitoring. Continuous high load, high ambient temperature, poor heat dissipation, or abnormal fan can all cause it. Environmental temperature, load cycle, fan speed, and exhaust duct should be checked. After cooling, it can be restarted, but the root cause needs to be investigated.

2. Safety stop 1 frequently triggered

Check if the enable switch is released or fully pressed; Whether to switch the operating mode; Has the local/external emergency stop been pressed; Is the safety door open; Whether the operation safety signal is lost; Is there any error in the safety controller. After resetting the emergency stop, the automatic mode cannot be restored solely by closing the safety door. Additional devices such as confirmation buttons must first reset the operation safety signal and confirm that there are no people in the danger zone.

3. Low fan speed or clean room alarm

Check if the WorkVisual I/O mapping is correct: Out7.Output, In1.Input. Check the control box 2A fuse, 24 VDC power supply, fan connector, exhaust duct for blockage, and fan for dust accumulation. If the speed is below 2200 rpm or decreases by more than 25%, the fan should be replaced. Abnormal fan operating noise should also be included in the annual inspection.

4. Emergency stop cannot be reset or the enable is invalid

Confirm that the smartPAD connection is reliable. If smartPAD is configured as pluggable, the system may not have a local emergency stop, and at least one external emergency stop must be accessible at any time. Check external emergency stop, external safety stop, safety output, and key switch. If the enable switch is stuck in the middle position, you can press another enable switch to the bottom or press emergency stop.

5. Abnormal stopping distance or braking

Perform brake testing and check the braking torque of each axle. Abnormal stopping distance may be caused by brake wear, overheating, contamination, damage, load changes, or excessive speed. Trigger axis specific or Cartesian workspace monitoring through safety monitoring and evaluate measurement data using a Data Recorder. Stop checking the distance at least once a year.

6. Communication or cable issues

Check if WX55, WX65, WXE1 are connected correctly and locked; Whether the cable can withstand tension and friction; Is the bending radius sufficient; Is it inside the metal conduit; Are shielding and EMC measures in place. The robot controller must not be plugged or unplugged during operation.

7. Coordinate display deviation of 35 mm

This is caused by the lifting of the base ring. When using the world base and displaying the actual position of Descartes, a deviation of 35 mm needs to be considered in the positive Z direction.

Replacing robots, disabling and storing them

Before replacing the robot, ensure that the installation/removal position is freely accessible and there are no system component hazards. Removal steps: Fix the robot, remove tools and equipment, power on and move to the transport position, fix again, close the controller, loosen and unplug the connecting cable, remove 4 hexagon socket bolts and locating pins, protect the connector and hose from contamination, lift the robot together with the LBR CR base ring, and place it in the transport container.

The installation steps are consistent with the previous installation: insert the positioning pin, place the base ring, insert the positioning pin, lower the robot vertically, install 4 bolts and gradually tighten them diagonally. After 100 hours, tighten them again, connect the exhaust duct, data cable, grounding conductor, installation tools, check the cables, and connect the energy supply.

Shutdown storage requirements: Choose a dry, dust-free, temperature fluctuation free, wind and airflow free, and condensation free location. Use coverings that will not detach on their own and can withstand environmental conditions. Loose parts must not be left on the robot. Avoid direct sunlight. Comply with the allowed storage temperature. Store in transportation location, clean and dry, inspect inside and outside, remove foreign objects and corrosion, install cover plate and check sealing, seal electrical connections and hose connections, and place in transportation container. 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 are treated as electronic waste; The motor is not disassembled; Plastic ABS, elastomers, PA, PUR/PVC/rubber, etc. should be disposed of according to the labeling.

Tightening torque and maintenance precautions

The general tightening torque is applicable to screws and nuts that are not specifically specified, and the values are for light oil black or coated screws. Commonly used 8.8 levels: M8 about 23 Nm, M10 about 45 Nm, M12 about 78 Nm, M14 about 125 Nm, M16 about 195 Nm. The torque of 10.9 and 12.9 levels is higher. There are dedicated tables for hexagon socket screws ISO 7991, half round heads, etc. M5 cap nut is approximately 4.2 Nm. Screws of grade 10.9 or above or with test certification can only be tightened once with the rated torque; Once released, new parts must be replaced.

During maintenance, if the robot is still able to move, it must be fixed by emergency stop. If it is necessary to work in the controller on state, only T1 mode can be used, and additional safety measures should be taken. After maintenance or repair, it is necessary to check the safety level and test all safety functions. New or modified programs should be tested under T1 first. When there is a malfunction, turn off the controller and lock and tag it, record the fault, troubleshoot and perform functional testing. If the safety function or protective device is disabled, it must be restored immediately after the work is completed.

Engineer Inspection Checklist

Is the transportation location correct?

Has the positioning pin, 4 bolts, torque, and 100 hour re tightening been completed?

Is the exhaust duct connected and is the fan running at 2200 rpm?

Is the mapping of EL6695, EM8905-1002, EK1100, and SYS-X44 correct in WorkVisual?

Does Out7. Output and In1. Input correspond to fan startup and speed measurement?

Does the backend task periodically monitor the speed and output faults?

Is the emergency stop, enable, safe operation, and external emergency stop functioning properly?

Is the braking test performed daily, and is the stopping distance checked annually?

Cable bending radius, stress EMC、 Is the grounding compliant?

Does the coordinate display consider a base ring of+35 mm?

Have maintenance schedules, cleaning standards, and fan replacement cycles been implemented?

Does the shutdown storage meet the requirements of dryness, dust-free, and non condensing?