KUKA KR 500 MT FORTEC Maintenance and Inspection

KUKA KR 500 MT FORTEC Maintenance and Inspection

KUKA KR 500 MT FORTEC belongs to a six axis heavy-duty articulated arm robot, mainly covering models such as KR 500 R2830 MT, KR 500 R2830 MT-F, KR 480 R3330 MT, KR 480 R3330 MT-F. MT stands for Machine Tooling, targeting machine tool loading and unloading, heavy-duty handling, casting, and high cycle automation scenarios. For on-site engineers, the real concern is not a single parameter, but how to quickly locate the problem at the system level and restore operation without compromising safety integrity when the robot experiences abnormal balance system pressure, wrist noise, excessive transmission shaft clearance, gear oil leakage, input stage damage, motor overheating, or safety circuit shutdown.

Product positioning and core structure

The KR 500 MT FORTEC adopts a six axis articulated arm structure, with main components including a linear wrist, arm, connecting rod, rotating column, base, balance system, electrical installation, and connecting cables. KR 500 R2830 MT has a rated load of 500 kg, a maximum load of 611 kg, a maximum arm span of 2826 mm, a body weight of approximately 2440 kg, a working space of approximately 68 m ³, a repeatability accuracy of ± 0.08 mm, a protection level of IP65, and the F-variant wrist can reach IP67, with noise levels below 75 dB (A). KR 480 R3330 MT has a rated load of 480 kg, a maximum load of 568 kg, a maximum arm span of 3326 mm, a body weight of approximately 2475 kg, and a workspace of approximately 114.5 m ³. The controller can be equipped with KR C5 L6/L7 or KR C4.

The linear wrist consists of three axes A4, A5, and A6, which are driven by three AC servo motors installed at the rear end of the arm through transmission shafts. The motor unit integrates brushless AC servo motor, permanent magnet single disc brake, and hollow shaft rotary transformer. The holding brake plays a holding role when the motor is stationary and participates in braking during short-circuit braking, but short-circuit braking cannot be used as a normal stopping method. The wrist gearbox is supplied with oil from three independent oil chambers. The rotation range of A5 is limited by the mechanical end stop. The F variant is designed for higher mechanical and thermal loads, with pressure applied inside the arm to prevent moisture and dust from entering.

The arm is connected to a straight wrist and a connecting rod, and A3 to A6 motors and transmission shafts are installed internally. The connecting rod is located between the arm and the rotating column, installed on one side of the rotating column through a gearbox, and driven by a motor through the input stage. A1 and A2 motors are installed inside the rotating column, and each main motor unit is equipped with a front gear stage. The base is connected to the installation base, and the internal layout includes electrical installation and energy supply system interfaces. The balancing system is installed between the rotating column and the connecting rod, using a closed hydraulic pneumatic system consisting of two accumulators, hydraulic cylinders, pressure gauges, and accumulator safety valves, used to balance the A2 axis load torque. The accumulator belongs to Class III of the Pressure Equipment Directive and Fluid Group 2.

The electrical installation includes power and control cables from A1 to A6, and all motor connections are plug-in. The cable assembly, multifunctional housing, and RDC box form an electrical installation assembly. The connection cable interface is located at the rear of the base, and the motor cable and data cable are connected through a plug.

Technical data and load foundation

The axis motion range of KR 500 R2830 MT is A1 ± 185 °, A2-130 °/20 °, A3-100 °/144 °, A4 ± 350 °, A5 ± 120 °, A6 ± 350 °. Speed under rated load: A1 45 °/s, A2 45 °/s, A3 45 °/s, A4 90 °/s, A5 83 °/s, A6 130 °/s. The axis data of KR 480 R3330 MT is similar, but the maximum arm span is longer.

In terms of flange load, during normal operation, the axial force F (a) is about 9200 N, the radial force F (r) is about 7900 N, the tilting torque M (k) is about 4200 Nm, and the flange torque M (g) is about 2310 Nm. Under emergency stop conditions, F (a) is about 10500 N, F (r) is about 12500 N, M (k) is about 9000 Nm, and M (g) is about 5600 Nm. Tools and loads must be able to withstand these forces and torques for a long time. The load data must be input into the robot controller, and path planning will consider the load. The mass inertia must be verified by KUKA Load. Exceeding the load curve will shorten the lifespan of the robot and overload the motor and gearbox. In this case, KUKA Service must be consulted.

The installation flange standard is ISO 9409-1-200-11-M12, with a hole diameter of 335 mm, threaded M12, a minimum depth of 14 mm and a maximum depth of 18 mm, 12 threads, screw grade 12.9, and positioning element 12 H7. Supplementary loads can be installed on arms, connecting rods, and rotating columns, but must comply with the maximum allowable total load. The installation dimensions of the arm support bracket, connecting rod, and rotating column need to be confirmed according to the diagram.

In terms of foundation load, the normal vertical force F (v) is about 37000 N, with a maximum of 40500 N; the horizontal force F (h) is normal at 15900 N, with a maximum of 23500 N; the tilting moment M (k) is normal at 58900 Nm, with a maximum of 84500 Nm; and the moment M (r) around A1 is normal at 18500 Nm, with a maximum of 45500 Nm. The foundation must withstand these loads for a long time. The supplementary loads on A1 and A2 are not included in the calculation of foundation loads and must be taken into account as vertical forces.

Installation foundation and transportation

The installation methods mainly include 175mm installation base, 200mm installation base, machine frame installation, and ground installation. The concrete foundation strength shall be at least C20/25, and there shall be no insulation layer or mortar layer between the base and the concrete. When using resin anchor bolts, the drilling diameter should be 18 mm. Diamond tools or coring drills must not be used, and setting tools approved by the anchor bolt manufacturer must be used. The installation surface must be flat and filled with leveling material if necessary, but the area where the robot tightens the bolts must not be covered by leveling material. The 175mm base weighs approximately 302 kg, the 200mm base weighs approximately 155 kg, and the machine frame installation weighs approximately 3.695 kg.

The robot must be moved to the transport position before transportation. The standard transportation positions are A1 0 °, A2-130 °, A3 130 °, A4 0 °, A5 90 °, A6 0 °. If the A2 buffer needs to be removed due to the minimum transportation height requirement, the transportation positions are A2-136.5 °, A3 136.5 °, but a clear warning must be attached. The buffer should be restored immediately after transportation. When transporting by forklift, there are two fork slots on the base, and the minimum load capacity of the forklift is 3500 kg. Three M20 DIN 580 lifting rings and three legged lifting devices are used for lifting, arranged along the direction of the robot. During transportation, vibration and impact should be avoided, and tools and additional equipment should be removed to prevent the center of gravity from shifting.

The standard lengths of connecting cables are 7 m, 10 m, 15 m, 20 m, 25 m, 35 m, and 50 m, with a maximum of 50 m and a maximum of one expansion allowed. The bending radius for the fixed laying of motor cables shall not be less than 150 mm, and for data cables shall not be less than 60 mm. Motor cables and data cables shall be laid separately, and EMC measures shall be taken if necessary. The grounding conductor must be connected with low resistance, with a cross-sectional area of 16 mm ² and M8 ring terminals at both ends. The F variant also needs to be connected to compressed air, and the pressure regulator is initially set to 0.01 MPa. Connecting cables is limited to indoor installation, with a fixed installation temperature range of -10 ° C to+55 ° C. Cable routing must prevent tripping hazards and be marked where necessary.

Safety and Debugging Inspection

The danger zone of KR 500 MT FORTEC consists of workspace and stopping distance. Mechanical end stop and optional mechanical axis limit are used to restrict the working range of A1 to A3. Before debugging, all safety functions must be checked, including emergency stop, enable switch, mode selection, safety door, external safety stop, and safety output. T1 is in manual deceleration mode, with a speed not exceeding 250 mm/s; T2 is manual high-speed mode; AUT is in automatic mode. New or modified programs must be tested under T1 first.

Five safety rules must be followed during maintenance and repair: power off, prevent accidental restart, confirm that the system is out of power, ground and short-circuit, cover or isolate adjacent live parts. Even if the controller is turned off, some components may still be charged. The robot system must be disconnected from the main power supply and cannot rely solely on emergency stop or safe stop. Hot surfaces, oil pressure, nitrogen pressure, and extrusion risks should all be prevented. The motor and brake will generate electromagnetic fields, and personnel wearing implants should maintain a distance of 300 mm from the motor and brake. Unauthorized modifications may render warranty and liability invalid.

Before starting, the default password must be changed, and the robot installation, fastening, cable connection, grounding conductor, and equipotential connection must be checked. If there is a significant difference between the internal temperature of the controller and the ambient temperature, it is necessary to wait for temperature equilibrium to prevent condensation. If the robot is subjected to external forces such as collisions or impacts, it may cause invisible damage and the motor and balance system must be checked. Security features must be tested. The brake test must be performed regularly and the system will force it to be carried out, and it cannot be turned off.

Maintenance cycle and oil management

The maintenance cycle is based on technical data and operating conditions. Check the torque of the fastening bolts and nuts 100 hours after startup. O-rings A4 and A5 require regular lubrication: the standard robot takes about 10000 hours, the F variant takes about 5000 hours, and Microlube GL 261 is used. Balance system bearing lubrication: 5000 hours or at least once a year; If A2 frequently has a short stroke of less than 40 ° and the interval is shortened to 3000 hours, use LGEV2/5, with each lubrication point approximately 10 cm ³.

Balance system pressure check: Manually move A2 to -90 ° and wait for 1 minute. The pressure of the ground robot should be 140 bar ± 15 bar (20 ° C). If there is abnormal pressure or deviation in application, a dedicated pressure gauge should be used for measurement and KUKA Service should be consulted. Check for leaks in the bellows, fittings, accumulator, and hoses. The replacement cycle for the ground robot balance system is 10 years.

Inspection of drive shafts A4 to A6: first at 15000 hours or 6 years, and annually thereafter. Remove the installation cover and O-ring, visually inspect for wear and bluing. Apply a tensile force of 20 N to the universal joint and check the axial and rotational clearances. If the gap is greater than 0.8 mm, the drive shaft must be stopped and replaced. The rotational clearance of connecting shaft A5 shall also not exceed 0.8 mm.

Gear oil replacement: standard robot 20000 hours or 5 years; F variant 10000 hours or 5 years. The oil is Optigear Synt. ALR 150. Capacity: A1 10.0 L, A2 10.0 L, A3 3.5 L, A4 2.2 L, A5 2.5 L, A6 5.2 L. The input level A1, A2, A3 gear oil capacity is about 0.4 L, standard robot 20000 h or 5 years, F variant 10000 h or 5 years. Oil discharge must be carried out at operating temperature, first release pressure. Measure the amount of discharged oil. If it is less than 70% of the specified amount, rinse it once with discharged oil; If it is less than 50%, rinse twice and move the entire axis range at a jog speed during the rinsing process. Torque after filling: A1 oil pipe nut 40 Nm, magnetic plug 25 Nm; A2 magnetic plug 25 Nm; A3 to A6 magnetic plug 20 Nm; input stage screw plug 30 Nm. The lubrication cycle of the cable assembly is 20000 hours or 5 years, using Optitemp RB2 for approximately 200 cm ³.

Balance system inspection and replacement

The balance system inspection includes pressure, leakage, bellows, joints, and bearings. When replacing ground robots, the robot should be in mechanical zero position, A2 should be movable, and firmly fixed on the ground. First, fix the piston rod between the hydraulic cylinder and the hinge joint with a clamping sleeve, and then lift the balance system with a crane. Remove 6 Allen screws and retaining plate, remove M10x35 screws, insert pin locator, use M16 puller to pull out the pin by about 25 mm, and then remove the balance system.

Remove corrosion protection before installing the new balance system and move A2 to approximately -85 °. Align the pin on the rotating column during installation, apply Drei Bond 1342, and tighten M10x35 and 6 M8x20 Allen screws to the torque. When replacing the ceiling robot, it is necessary to first remove it from the ceiling and fix it on the ground. The weight of the balancing system is about 97 kg. First, release the pressure, and then follow similar steps for disassembly and installation. After replacement, the pressure must be checked and a functional test must be conducted. Before disposing of the balance system, pressure must be released, and only pressure free balance systems are allowed to be scrapped.

Motor, transmission shaft, and input stage replacement

A1 to A3 motor replacement: Power off and lock, remove XM/XP connector, fix connecting rod or arm with lifting device, remove 4 Allen screws, and take out the motor. Clean the motor and gearbox teeth, apply Microlube GL 261, check the O-ring, install a new seal, tighten the M12x25-8.8 or M12x30-8.8 Allen screws in diagonal order, reconnect the plug, and finally perform mastering.

A4 to A6 motor and drive shaft replacement: arm in horizontal position, wrist axis at zero position. Remove the installation cover and O-ring, remove the XM4 to XM6 and XP4 to XP6 connectors, remove 4 M10x30-8.8 Allen screws from each motor, and take out the motor and drive shaft. The transmission shaft is divided into setscrew type and O-ring type. The Setscrew type needs to be cleaned and coated with Drei Bond 1342. After tightening, loosen it back 45 degrees to allow the Setscrew to fit into the V-shaped groove. The O-ring type requires the installation of axial retainers, washers, M8x20 screws, spacers, and O-rings. Perform mastering and braking tests after installation.

Replacement of input stages A1, A2, A3: First remove the motor, then remove the four M12x100-10.9 Allen screws and locking washers, and take out the input stage. Clean the gear shaft and input shaft during installation, apply Microlube GL 261, install the spacer ring and O-ring, and tighten the M12x100-10.9 screws in diagonal order. After replacing the input stage, it is necessary to master and conduct a trial run under T1 to check for leaks.

Common troubleshooting ideas

Unexpected shutdown or safety stop: Check the emergency stop, enable switch, safety door, mode selection, external safety stop, safety configuration, and brake status.

Low or fluctuating pressure in the balance cylinder: Check the pressure gauge, accumulator, hoses, fittings, and leaks. When the ground pressure is 140 bar and there is a large deviation, consult KUKA Service.

A2 abnormal noise, sinking or vibration: Check the balance system bearings, pressure, mechanical limit and connecting rod fixation.

Wrist abnormal noise or positioning drift: Check the axial clearance of the transmission shaft and replace it if it exceeds 0.8 mm; Check the teeth and O-ring.

Gear oil leakage: Check O-ring A4/A5, magnetic plug, oil pipe, oil pan nut, and gearbox seal.

Motor overheating: Check the load, duty cycle, ambient temperature, cooling, brake and motor current.

Cable wear or interference: Check the cable group, bending radius, shielding, separate laying, and lubrication.

Zero point loss: Mastering A1 to A6 again.

Abnormal braking: Conduct a braking test to check the parameters of the brake, motor, and controller.

Automatic mode cannot start: check safety door, operate safety signal, external emergency stop, confirm button, and mode selection.

Input stage abnormal noise or oil leakage: Check the input stage gear shaft, spacer ring, O-ring, and tightening torque.

After replacing the balance system, the pressure is unstable: check the hydraulic oil filling amount, accumulator pre charging pressure, and exhaust.

After maintenance, functional testing must be conducted to ensure that all safety functions are effective. The replaced components must use original parts or equivalent approved parts. Screws with a rating of 10.9 or above or certified by testing can only be tightened once to the rated torque, and must be replaced after loosening. Tighten the torque according to the appendix, and follow the marked values for special positions. Common auxiliary materials include Drei Bond 1342、Drei Bond 1354、Optigear Synt. ALR 150、Castrol Hyspin ZZ 46、LGEV 2、Microlube GL 261  And Optitemp RB2.

Key points of standards and compliance

KR 500 MT FORTEC is involved in the Machinery Directive 2006/42/EC, EMC Directive 2014/30/EU, Pressure Equipment Directive 2014/68/EU, and EN ISO 10218-1、EN ISO 12100、EN ISO 13849-1/-2、EN ISO 13850、ANSI/RIA R15.6  Waiting for standards. The F variant has higher dust, lubricant, coolant, and water vapor resistance, and adopts a special paint surface and transparent protective coating. If used for other environmental conditions, KUKA Deutschland GmbH must be consulted. The balance system contains nitrogen and hydraulic oil, which may involve UN 3164 during transportation, and must be depressurized before disposal. Industrial robots must be integrated into a complete system and undergo compliance assessment before they can operate.

Overall, the reliability of KUKA KR 500 MT FORTEC depends on the installation foundation, balance system, gear oil, transmission shaft, input stage, and safety circuit. Regularly checking pressure, oil level, clearance, and torque can detect abnormalities in the early stages of faults. When encountering abnormal pressure, abnormal noise, leakage or shutdown, first lock it safely, and then investigate according to the levels of power supply, safety circuit, balance system, transmission shaft, input stage, gear oil and motor. This can reduce unplanned downtime and maintain stable operation of heavy-duty robots under harsh working conditions.