Siemens 1FK7022-5AK71-1LG5 Servo Motor – SIMOTICS S-1FK7

Siemens 1FK7022-5AK71-1LG5 — Permanent-Magnet Synchronous Servo Motor in the SIMOTICS S-1FK7 Compact Frame

The 1FK7022-5AK71-1LG5 is a shaft-height 20 (SH20) permanent-magnet synchronous servo motor (PMSM) belonging to Siemens’ SIMOTICS S-1FK7 platform. Within a motion-control loop, this motor functions as the final actuator that converts drive-side current commands into precisely regulated mechanical torque and angular displacement. Its rated output of 0.56 kW at 6,000 rpm, combined with a stall torque of 1.0 N·m, positions it for high-cycle, low-inertia axes where settling time and position repeatability are the governing design constraints.

The suffix structure encodes the mechanical and electrical configuration without ambiguity: 5AK71 designates a smooth (plain) shaft without keyway, and 1LG5 specifies the absence of a holding brake paired with a DRIVE-CLiQ absolute encoder interface. This encoder variant transmits position data, temperature, and motor nameplate parameters over a single digital cable to the SINAMICS drive, eliminating the resolver-to-digital conversion stage and the associated latency that degrades velocity-loop bandwidth in legacy architectures.

In a closed-loop servo topology, the 1FK7022-5AK71-1LG5 operates as follows: the SINAMICS S120 or S210 Motor Module receives a torque setpoint from the Control Unit (CU320-2 or CU310-2) at a current-controller cycle time of 62.5 µs. The Motor Module synthesizes a PWM voltage vector applied to the motor’s three-phase stator windings. The rotor’s permanent-magnet field — neodymium-iron-boron (NdFeB) grade — interacts with the rotating stator field to produce torque. The DRIVE-CLiQ encoder feeds back absolute rotor position at each control cycle, closing the position and velocity loops with sub-arc-minute resolution. This deterministic signal chain is what enables the 1FK7 series to achieve dynamic stiffness figures suitable for contouring and synchronization tasks.

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Technical Parameters

Hardware Logical Analysis

The SH20 frame of the 1FK7022-5AK71-1LG5 is not simply a scaled-down version of larger 1FK7 variants — it is a purpose-engineered assembly optimized for low-inertia, high-speed operation. Several hardware design decisions are worth examining in detail.

Rotor Construction and Cogging Suppression: The rotor uses surface-mounted NdFeB magnets with a skewed pole arrangement. Skewing distributes the reluctance variation across the electrical cycle, attenuating cogging torque to levels below 1% of rated torque. This is measurable in velocity-loop performance: at speeds below 10 rpm, the motor maintains smooth rotation without the micro-jitter that characterizes motors with non-skewed rotors — a requirement for precision dispensing, laser cutting, and optical alignment axes.

DRIVE-CLiQ Encoder Architecture: The integrated DRIVE-CLiQ encoder is not a passive transducer. It contains an embedded microcontroller that stores the motor’s electronic nameplate (rated current, pole pair count, thermal model coefficients, encoder resolution) in non-volatile memory. On power-up, the SINAMICS drive reads this data automatically via the DRIVE-CLiQ protocol (100 Mbit/s, deterministic), eliminating manual parameter entry and the risk of motor-drive mismatch. The encoder also transmits motor winding temperature in real time, enabling the drive’s thermal model to adjust current limits dynamically rather than relying on fixed derating curves.

EMC Design and Shielding: The motor housing is die-cast aluminum with a continuous conductive path from the motor flange to the connector backshell. This provides a low-impedance ground reference for the cable shield, suppressing common-mode noise injection into the encoder signal lines. The bayonet connector’s 360° shield termination — as opposed to a pigtail drain wire — reduces shield impedance at frequencies above 1 MHz, where switching-frequency harmonics from the IGBT inverter are most problematic. Compliance with EN 61800-3 Category C2 EMC limits is achievable without additional external filtering when the motor is installed with Siemens-specified shielded motor cables.

Thermal Management: The stator lamination stack is pressed directly into the aluminum housing with an interference fit, maximizing thermal conductance from winding to housing surface. At rated continuous operation, the housing surface temperature stabilizes below 60 °C in a 40 °C ambient with natural convection — within safe-touch limits per IEC 60204-1. The Class F insulation system provides a 35 °C thermal margin above the Class B limit, extending winding life under cyclic overload conditions.

Bearing and Shaft Integrity: The smooth shaft (AK71) is ground to h6 tolerance, compatible with standard coupling hubs and timing pulleys without additional machining. Deep-groove ball bearings are pre-lubricated with high-temperature grease rated for the motor’s maximum speed, with a calculated L10 bearing life exceeding 20,000 hours at rated load and speed.

System Integration Benefits

• Automatic Motor Identification: DRIVE-CLiQ electronic nameplate upload at power-on eliminates manual drive parameterization, reducing commissioning time from hours to minutes and preventing configuration errors that cause nuisance trips.
• Single-Cable Wiring: Power and feedback share a combined cable harness, reducing cable tray fill, connector count, and potential failure points — particularly valuable in multi-axis gantry and robot installations where cable management is a recurring maintenance burden.
• Deterministic Real-Time Response: The 62.5 µs current-controller cycle of SINAMICS S120, combined with the DRIVE-CLiQ feedback latency of less than one cycle, yields a total closed-loop delay below 125 µs — sufficient for velocity bandwidths exceeding 1,000 rad/s on low-inertia loads.
• Integrated Thermal Monitoring: Real-time KTY84 or PTC thermistor data transmitted via DRIVE-CLiQ enables the drive to execute predictive derating rather than hard shutdown, maintaining production continuity during thermal transients.
• Safe Torque Off (STO) Compatibility: The motor’s drive interface supports STO (SIL 2 / PLd per IEC 62061 / ISO 13849-1) without additional hardware, simplifying safety circuit design and reducing panel wiring for CE-marked machinery.
• Diagnostic Transparency via TIA Portal: SINAMICS Startdrive integrates the motor’s operating data — torque utilization, thermal load, encoder status, fault history — directly into the TIA Portal engineering environment, enabling condition-based maintenance scheduling without third-party diagnostic tools.
• Scalable Multi-Axis Architecture: The 1FK7022-5AK71-1LG5 shares the SINAMICS S120 DC bus with other Motor Modules, enabling regenerative energy exchange between axes. Deceleration energy from one axis charges the DC bus and powers an accelerating axis, reducing net energy consumption by up to 30% in coordinated multi-axis systems.
• Interchangeability within 1FK7 Family: Mechanical mounting dimensions (flange, shaft diameter, bolt circle) are standardized across the 1FK7 compact series. A 1FK7022 can be replaced with a higher-torque 1FK7032 or 1FK7040 without modifying the machine structure, providing a clear upgrade path as production requirements evolve.

Quality Assurance & Global Logistics

Every 1FK7022-5AK71-1LG5 unit dispatched from our Xiamen facility is a genuine Siemens OEM component sourced through verified supply channels. Prior to shipment, each unit undergoes a structured pre-delivery inspection: insulation resistance measurement (≥100 MΩ at 500 V DC), encoder signal integrity verification via DRIVE-CLiQ handshake test, shaft runout check (≤0.02 mm TIR), and visual inspection of connector pins and housing integrity. The original Siemens packaging, serial number label, and CE/UL markings are preserved intact.

Counterfeit risk is mitigated through holographic label verification cross-referenced against Siemens’ product authentication database before each unit is released for dispatch. A 12-month replacement warranty covers manufacturing defects from the date of invoice.

Logistics from Xiamen, China: DHL Express and FedEx International Priority are the standard carriers for single-unit and small-batch orders, with typical transit times of 3–5 business days to Europe and North America. For volume orders, EXW and FOB Xiamen Incoterms are available with full export documentation — commercial invoice, packing list, certificate of origin, and MSDS where applicable. Customs HS code 8501.52 applies to this motor category for import duty calculation.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
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