KUKA KR12 SCARA Operations Essentials

KUKA KR12 SCARA Operations Essentials

KUKA KR 12 SCARA is a four axis articulated robot designed for small high-speed handling, assembly, inspection, and machining scenarios. This product family includes KR 12 R650 Z400、KR 12 R650 Z340 CR、KR 12 R750 Z400、KR 12 R750 Z340 CR、KR 12 R750 Z600、KR 12 R850 Z400  And models such as KR 12 R850 Z340 CR. They are usually paired with KR C5 micro control cabinets and smartPAD-2 handheld programmers, with a body weight of approximately 49 to 53 kg, a rated load of 6 kg, a maximum load of 12 kg, a maximum arm span covering 650 mm, 750 mm, and 850 mm, and Z-axis travel covering 340 mm, 400 mm, and 600 mm. For on-site engineers, the true factors that affect equipment stability are often not single parameters, but the coordination between installation foundation, load data, stopping distance, safety circuit, cable wiring, ball screw spline lubrication, A1 gearbox oil change, and maintenance cycle. The following summarizes the key technical points of this series from the perspective of operation and troubleshooting.

Mechanical structure and shaft configuration

The KR 12 SCARA adopts a four axis SCARA structure, mainly composed of arms, ball screw splines, connecting rod arms, bases, and electrical equipment. A1 is the rotation of the turntable, A2 is the rotation of the connecting rod arm, A3 is the vertical lifting and lowering, and A4 is the end rotation. The ball screw spline is responsible for the composite transmission of Z-axis linear motion and end rotation, and is one of the most important components to pay attention to in maintenance. The rotation range of A1 and A2 is usually ± 145 °, with some models A2 having a range of ± 135 °; The A3 stroke is divided into -400 mm, -340 mm, or -600 mm according to the model; the A4 rotation range is usually ± 355 °. In terms of speed, A1 is about 400 to 450 °/s, A2 is about 645 to 665 °/s, A3 is about 1.1 to 1.3 m/s, and A4 can reach 2700 °/s. The pose repeatability accuracy is XY ± 0.025 mm, Z ± 0.005 mm, and R ± 0.005 °. The standard model has a protection level of IP20, and the CR model has an IP54, suitable for clean rooms or special environments. The controller is KR C5 micro, with a working temperature of 0 to 42 ° C and a storage and transportation temperature of -25 to 55 ° C. When operating at low temperatures, it is necessary to first reduce the speed and acceleration for preheating to avoid condensation and mechanical shock.

Installation foundation and foundation requirements

KR 12 SCARA must be installed on the ground, with a steel base that is at least 20mm thick, has a flatness of no more than 0.4, and a maximum allowable horizontal deviation of 5 °. The base is not within the scope of robot supply and needs to be prepared by the user themselves. The installation hole diagram must be processed strictly according to the size, fixed with four M12 or M14 screws, and centered with two locating pins. The installation surface must be clean, flat, free of rust and adhesives. The robot must be lowered vertically and slowly to avoid damaging the positioning pin. If the locating pin is damaged, it must be replaced. When tightening screws, gradually apply force in diagonal order. After installation, use M4 hex nuts and tapered spring washers for the grounding wire, with a tightening torque of approximately 2.8 Nm. The equipotential connection must be checked according to VDE 0100 and EN 60204-1. If the base is not installed horizontally or fixed firmly, it will cause abnormal force on the A1 gearbox, changes in stopping distance, and a decrease in repeatability accuracy.

Load, flange and process force

The rated load of KR 12 SCARA is 6 kg, with a maximum load of 12 kg. The maximum additional load on the arm is 2 kg, but the additional load on the arm of KR 12 R750 Z600 is 0 kg. The load center of gravity is based on the A4 flange surface, and KUKA. Load must be used to check the load mass and mass moment of inertia. The load diagram shows curves for 2 kg, 4 kg, 6 kg, 7 kg, 8 kg, 9 kg, 10 kg, 11 kg, 12 kg, etc. The farther the load is from the flange, the smaller the allowable mass. Load data must be input into the control cabinet, otherwise trajectory planning, acceleration, and braking distance will deviate from reality. To reduce vibration, the center of gravity shift of the end load should be minimized as much as possible. In terms of flange load, during operation, the axial force F (a) is about 150 N, the radial force F (r) is about 600 N, the tilting torque M (k) is about 30 Nm, and the torque M (g) is about 25 Nm; during emergency stop, F (a) is about 500 N, F (r) is about 600 N, M (k) is about 30 Nm, and M (g) is about 40 Nm. The tool must be calculated according to the actual load to ensure long-term bearing of these forces and torques. The A3 process force is limited to 100 N, exceeding this limit can cause abnormal wear on the ball screw splines and guide rails.

Stop distance and stop time

The stopping distance is the distance or angle that a robot travels from triggering a stop signal to completely stopping, equal to the reaction distance plus the braking distance, and is part of the danger zone. STOP 0 immediately closes the drive and the brake acts simultaneously; STOP 1 is controlled braking along the trajectory, and after a delay, the drive closes and brakes; STOP 2 means not turning off the drive or applying the brake, and stopping on a regular braking ramp. Taking STOP 0 as an example, the A1 stopping distance of KR 12 R650 Z400 is about 59.57 °, A2 is about 83.63 °, and A3 is about 30.21 mm; the A1 stopping distance of KR 12 R650 Z340 CR is about 60.95 °, A2 is about 84.92 °, and A3 is about 19.98 mm; the A1 stopping distance of KR 12 R750 Z400 is about 46.35 °, A2 is about 40.60 °, and A3 is about 16.16 mm; the A1 stopping distance of KR 12 R750 Z340 CR is about 64.64 °, A2 is about 74.50 °, and A3 is about 20.14 mm; the A1 stopping distance of KR 12 R750 Z600 is about 48.09 °, A2 is about 55.41 °, and A3 is about 46.54 mm; and the A1 stopping distance of KR 12 R850 Z400 is about 51.00 °. A2 is about 44.38 °, A3 is about 16.57 mm; KR 12 R850 Z340 CR has A1 of about 66.81 °, A2 of about 61.58 °, A3 of about 16.24 mm. The stopping time varies with POV, elongation, and load mass. The larger the mass and speed in the STOP 1 curve, the longer the stopping time and distance are usually. The superposition of axial motion will further elongate the stopping distance. Brake wear is related to operating mode, application, and STOP 0 times. It is recommended to check the stopping distance at least once a year. If the stopping distance significantly increases, check the brake, load data, POV, and mechanical transmission.

Security integration and personnel protection

KR 12 SCARA belongs to partially complete machinery and must be integrated into a complete system before it can be put into operation. The system integrator is responsible for installation, connection, risk assessment, implementation of safety functions and protective devices, issuance of EC conformity declaration, affixing CE mark, and production of system operation instructions. The robot control cabinet has CE markings that comply with EMC and low-voltage directives. The workspace must be limited to the necessary minimum range, and hazardous areas including the workspace and stopping distance must be physically isolated. The control cabinet supports safety door sensors. If light curtains or sensors are used, a separate risk assessment and certification must be conducted. Mechanical terminal stops are used to limit the range of the axis. After a collision, the robot may not be able to operate safely and must be stopped and consulted with KUKA.

The safety mode includes T1 manual deceleration mode (≤ 250 mm/s) and T2 manual high-speed mode (allows>250 mm/s). T1 is used for jogging, teaching, programming, and program verification; T2 is only allowed to be used when testing at speeds higher than T1, and teaching and programming are not allowed. Automatic mode requires all safety devices to be complete and effective, with no one in the system or meeting EN ISO 10218 collaboration requirements, and clear workflow. If the robotic arm stops without reason, an emergency stop must be triggered before entering the danger zone. During maintenance and repair, it is advisable to work outside the danger zone as much as possible; If it is necessary to be within the danger zone, additional safety measures must be defined. Turn off the robot and lock it to prevent accidental restarts. If it is necessary to work while the control cabinet is connected, only T1 mode is allowed. The homework label must be retained, and the emergency stop device must be effective. Before working on live parts, the main switch must be turned off and the electricity must be tested, and emergency or safety stops cannot be triggered alone. After the control cabinet is turned off, some components may still carry a voltage of 50 V to 780 V for several minutes, and must wait and comply with ESD regulations. Dangerous substances should be avoided from long-term skin contact and inhalation of oil mist, and safety data sheets should be requested regularly.

Transportation and lifting

Before transportation, the robot must be placed in the transport position: A1-90 °, A2-90 °, A3-100 mm, A4 0 °. The robot must maintain the transport position until it is secured. Before transportation, obstacles should be removed, transportation fasteners should be dismantled, and contact surface rust and adhesives should be removed. Avoid vibration and impact during transportation. Forklifts can be used to transport the original packaging boxes, or lifting devices can be used. The lifting device needs to have sufficient load-bearing capacity and a rope length greater than 1500 mm. When installing transportation equipment, use M6x25-12.9 screws with a torque of about 9.5 Nm, M5x25-12.9 screws with a torque of about 5.6 Nm, and M10x17 eyebolts with a torque of about 45 Nm. The rope must be threaded in the specified way, and standing under the robot is prohibited. It is also forbidden to use a crane to lift in other ways. During transportation, the robot may overturn and additional anti tipping measures must be taken.

Start, connect cables and interfaces

Before starting, the robot should be checked for completeness, no external damage, no loose parts, complete safety devices, power matching, correct grounding and equipotential connections, and locked connection cables. The default password for system software must be changed before startup, and only authorized personnel should be notified. The connecting cables include motor cables XD20.1/XD20.2-X30, data cables XF21-X31, and optional grounding wires. The standard length can be selected from 5 m, 10 m, 15 m, and 25 m. When fixed installation, the bending radius of motor cables should not be less than 55 mm, and the bending radius of data cables should not be less than 45 mm. The cables should avoid mechanical stress, and the connectors should not be subjected to tension, only for indoor installation. The fixed installation temperature range is -30 to+80 ° C. Motor cables and data cables should be laid separately in metal cable trays and EMC measures should be taken. A space of at least 200mm should be reserved behind the A1 interface.

The A1 interface is located at the rear of the base, including user connectors X40 and X74, air interfaces AIR1 to AIR3, maximum pressure of 0.7 MPa, vacuum negative pressure of 0.95 bar, MEMD, motor cable X30, data cable X31, additional shaft XP5.1, and grounding terminal. The A2 interface is located on the arm and includes a brake release button, user connector X94, air interface, X41, and motor indicator light. The user connector is a 15 pin D-sub, which can be used for I/O expansion. User cables should not be tied to corrugated pipes, high flexibility cables should be used, signal lines should be shielded, and the entire system should be well grounded. After installation, the stress and working status of cables, corrugated pipes, and other components should be confirmed, and the current working space of the robot should be confirmed.

Maintenance: Ball screw spline lubrication and cable group lubrication

Maintenance table regulation: Check the torque of the four fixing screws on the installation base after 100 hours; Lubricate the ball screw spline every 1500 hours using THK AFB-LF, approximately 10 g; lubricate the cable assembly every 4000 hours or at least annually using Optitemp RB2, approximately 20 g; check the base fixing screws annually; Replace A1 gearbox oil every 20000 hours or at least every 5 years, using Optigear ALR 320 with an initial filling volume of approximately 0.37 L. An emergency stop must be triggered before maintenance to ensure that the robot does not move unexpectedly. If working on an electrified robot, it is only allowed to move in deceleration mode and can be stopped urgently at any time.

When lubricating the ball screw spline of the standard model, press and hold the A2 interface brake release button, slowly move A3 to the upper limit position until it cannot continue to move downwards, and be careful not to damage the limit block. Release the button and trigger the emergency stop, remove the old grease, evenly apply THK AFB-LF with a brush, and wear protective gloves. Then move to the lower limit position and repeat cleaning and greasing. After completion, remove excess grease and move A3/A4 to evenly distribute the grease. The CR model requires the removal of 8 M4x8-8.8 screws to move the corrugated tube down or up, apply grease, and then re fix it with a torque of approximately 2.8 Nm.

When lubricating the cable assembly, remove the A1 and A2 cable box covers: 10 M4x12-8.8 hex screws each, as well as 4 ST3.9x13 pan head self tapping screws and cable protection rings each. Apply approximately 20 g of Optitemp RB2 and then restore the cover plate. When changing the A1 oil, remove the cable box cover, remove the lower M10x1 magnetic plug, install the oil drain pipe, loosen the upper two M10x1 magnetic plugs for ventilation, collect and measure the oil drain volume. If the oil discharge is less than 70% of the specified amount, it needs to be flushed once with the discharged oil; If it is less than 50%, rinse twice and move the entire axis range at a jog speed during the rinsing process. When refueling, inject the same amount of oil from the bottom through the oil drain pipe, clean the magnetic plug, check the seal, torque the upper plug about 7.5 Nm, the lower plug about 7.5 Nm, and the cable box cover screw about 2.8 Nm. After completion, check for leaks, run the program in T1 mode, and observe any abnormalities.

Cleaning, disuse, storage, and disposal

When cleaning robots, only solvent-free and water-soluble cleaning agents are allowed. Flammable and corrosive cleaning agents are not allowed, and steam, refrigerants, or high-pressure cleaning machines are not allowed. Cleaning agents must be prevented from entering electrical and mechanical components. After cleaning, the cleaning agent should be completely removed, the corroded area should be re coated with anti-corrosion layer, and all safety devices and cover plates should be restored. When stopping the robot, first place it in the transport position, close the control cabinet and disconnect it, disconnect the peripheral connections, motor cables, data cables, and grounding wires, and then lift and remove it. The storage environment should be dry and dust-free, avoiding temperature fluctuations, wind, condensation, and direct sunlight. Clean the drying robot, inspect its appearance, remove foreign objects and corrosion, install the cover plate and check the seal, seal the electrical connections and hoses, cover with plastic film and seal the base to prevent dust, and place desiccants if necessary. When discarded, classified by material: cast aluminum components include base, arm, and connecting rod arm; Copper is used for cables and wires; Steel is used for gearboxes, ball screw splines, screws, and washers; Electronic components are treated as electrical waste, and motors are directly discarded without disassembly; Plastic ABS, PC+ABS, NBR, PU, PUR are processed according to their respective categories.

Troubleshooting Path

One of the common problems on site is accidental movement or axis sinking of the robot. Possible reasons include failure to input load data, brake defects, insufficient lubrication of ball screw splines, abnormal oil level in A1 gearbox, loose mounting base, damaged locating pins, or external collisions. The load diagram and KUKA. Load data, brake release button status, gearbox leakage, base screw torque, and locating pin should be checked. The second issue is whether the stopping distance becomes longer or stops abnormally. Should check STOP 0 times POV、 Measure the stopping distance at least annually based on factors such as elongation, load mass, axial motion superposition, and brake wear. The third issue is abnormal noise or wear of the ball screw spline. It is necessary to check the lubrication cycle, type of grease, whether the upper and lower limit positions are properly greased, and whether the bellows are damaged. The fourth issue is cable wear or abnormal signal. The bending radius, metal trunking separation, shielding grounding, connector locking, and cable group lubrication should be checked. The fifth issue is A1 oil leakage or insufficient oil volume. The magnetic plug, oil discharge amount, flushing steps, and oil filling amount should be checked. The sixth issue is condensation or abnormal temperature. Wait for the temperature of the control cabinet to adapt to the ambient temperature, and preheat before running at low temperatures. Problem seven is a safety circuit malfunction. The safety door sensor, emergency stop, T1/T2 mode, password permissions, and protective devices should be checked.

End flange options

KR 12 SCARA optional end flange for connecting tools. The weight of the end flange is about 305 g. When installing, align the end flange hole with the ball screw flower key hole, insert the positioning pin, and install two M5x16-12.9 screws. Tighten diagonally to about 4.5 Nm, then remove the positioning pin and tighten diagonally to about 9 Nm. After completion, test run in T1 mode and observe any abnormalities. The maintenance of end flanges mainly relies on visual inspection, and damaged parts should be replaced in a timely manner. When discarded, they should be classified and recycled according to their materials.

Overall, the stable operation of KUKA KR 12 SCARA relies on standardized installation, correct load data, reliable and safe circuits, reasonable cable routing, ball screw spline lubrication, and A1 gearbox oil change. When a malfunction occurs, the control cabinet should be shut down and locked first, and recorded with a tag. Then, the installation foundation, load, brake, stopping distance, lubrication, oil, cable, and safety functions should be checked item by item. Only by considering mechanical, electrical, control, and safety as a whole can unplanned downtime be reduced and the series of robots maintain a stable rhythm in small high-speed handling, assembly, and inspection scenarios.