Siemens 1FK7042-2AF71-1CH0 Servo Motor – SIMOTICS S-1FK7

Siemens 1FK7042-2AF71-1CH0 — Permanent-Magnet Synchronous Servo Motor for High-Precision Motion Control

The Siemens 1FK7042-2AF71-1CH0 belongs to the SIMOTICS S-1FK7 Compact family, a line of permanent-magnet synchronous servo motors designed for closed-loop motion control in machine tools, packaging lines, and general-purpose industrial automation. The motor operates at a rated speed of 2,000 rpm with a continuous stall torque of 4.0 Nm and a rated shaft power of approximately 0.84 kW. Its flange size 42 mm form factor allows integration into mechanically constrained drive trains without compromising torque density.

The suffix structure of the part number encodes the motor’s configuration precisely: 1FK7 identifies the SIMOTICS S compact series; 042 denotes the 42 mm flange (shaft height); 2AF71 specifies the winding variant for 2,000 rpm rated speed with a 400 V AC supply; 1CH0 indicates a smooth shaft with keyway, natural convection cooling, and an absolute single-turn encoder. This encoder variant eliminates the need for a homing reference run after each power cycle, a critical advantage in applications where axis position must be retained across control system restarts.

The motor is designed for direct integration with the SINAMICS S120 and SINAMICS S210 drive platforms via DRIVE-CLiQ, Siemens’ proprietary digital motor interface. DRIVE-CLiQ transmits encoder position data, motor nameplate parameters, and thermal status over a single cable, removing the need for manual motor data entry during commissioning and enabling automatic motor identification (AMI) within STARTER or TIA Portal Drive Configurator.

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Technical Parameters

Hardware Logical Analysis

The 1FK7042-2AF71-1CH0 employs a surface-mounted permanent-magnet rotor topology with sintered NdFeB magnets arranged in a 6-pole configuration. This geometry produces a low rotor inertia-to-torque ratio, which directly shortens the mechanical time constant (τ_mech) and allows the drive to achieve high acceleration rates without overshooting the position setpoint. The low cogging torque — a result of skewed stator laminations — ensures smooth velocity regulation at speeds below 10 rpm, a requirement in grinding and honing applications where surface finish depends on constant peripheral velocity.

The stator winding uses a distributed lap configuration with Class F insulation impregnated under vacuum pressure (VPI process). This construction eliminates air pockets within the winding, improving thermal conductivity between conductors and the stator core. The KTY84-130 temperature sensor embedded in the winding end-turn provides continuous thermal monitoring; the SINAMICS drive reads this resistance value and applies a derating curve if winding temperature approaches the 155 °C insulation limit, preventing thermal runaway without requiring an external PTC relay circuit.

The IP64 shaft seal on the drive end uses a radial lip seal pressed against the shaft shoulder, rated for continuous operation in environments with coolant mist and metal dust — conditions typical of CNC machining centers. The non-drive end bearing is preloaded with a wave spring washer to eliminate axial play under reversing loads, which would otherwise introduce position error in ball-screw-driven linear axes.

From an EMC perspective, the motor housing is die-cast aluminum with a conductive chromate surface treatment on all mating flanges. This provides a low-impedance ground path between the motor frame and the machine bed, suppressing common-mode currents that would otherwise couple into encoder signal lines. The DRIVE-CLiQ encoder cable uses a twisted-pair differential signal architecture with 100 Ω characteristic impedance, immune to the high dV/dt switching transients generated by the IGBT inverter stage of the SINAMICS S120 Motor Module.

The absolute single-turn encoder (2048 pulses/rev, 23-bit interpolated resolution) retains position data within one motor revolution without battery backup. On power restoration, the drive reads the encoder position within the first DRIVE-CLiQ communication cycle (125 µs), making the axis immediately available for motion commands without a reference traverse. For multi-turn absolute position retention across power cycles, the 1FK7042-2AF71-1CH0 can be paired with an external EnDat 2.2 multi-turn encoder module, though the standard suffix -1CH0 ships with the single-turn variant.

System Integration Benefits

• Zero-homing commissioning: The absolute encoder eliminates reference run sequences at machine startup, reducing cycle time loss on shift changes and after emergency stops by an average of 15–45 seconds per axis.
• Automatic motor identification via DRIVE-CLiQ: Motor nameplate data (rated current, torque constant, encoder resolution, thermal model parameters) is stored in the encoder EEPROM and transferred to the SINAMICS drive automatically at first power-up, eliminating manual parameter entry errors during commissioning.
• Deterministic torque response: The SINAMICS S120 current controller operates at a 62.5 µs sampling rate when paired with this motor, achieving a torque rise time of under 1 ms from setpoint change to 90% of target torque — sufficient for high-dynamic positioning tasks in electronic cam and gantry applications.
• Thermal derating transparency: The KTY84 sensor provides a continuous resistance-temperature curve readable by the drive’s thermal model. The SIMATIC S7-1500 can read the motor winding temperature via the SINAMICS telegram (e.g., Telegram 105) and log it to a process historian, enabling predictive maintenance scheduling based on thermal load history.
• Compact footprint for multi-axis configurations: The 42 mm flange allows four-axis servo clusters to be mounted on a 200 mm × 200 mm machine column face, a geometry not achievable with 63 mm or 80 mm frame motors. This is particularly relevant in multi-spindle drilling heads and rotary indexing tables.
• Plug-and-play cable ecosystem: Siemens 6FX series pre-assembled power and encoder cables are available in standard lengths from 1.5 m to 50 m, with pre-fitted M23 connectors on the motor end. This eliminates field crimping and reduces wiring errors during machine assembly.
• Integrated safety readiness: When connected to a SINAMICS S120 with Safety Integrated firmware, the 1FK7042-2AF71-1CH0 supports STO (Safe Torque Off), SS1 (Safe Stop 1), and SLS (Safely Limited Speed) functions without external safety relays, compliant with IEC 62061 SIL 2 and ISO 13849-1 PLd.
• Scalable within the 1FK7 family: The 1FK7 series spans flange sizes from 28 mm to 100 mm with identical electrical interface conventions. A machine design validated with the 1FK7042 can be scaled to higher torque requirements (e.g., 1FK7063 or 1FK7080) without redesigning the control cabinet or cable routing.

Quality Assurance & Global Logistics

Every Siemens 1FK7042-2AF71-1CH0 unit dispatched from our Xiamen, China facility is a genuine factory-original component sourced through verified industrial supply channels. Each unit carries a traceable Siemens serial number that can be cross-referenced against the Siemens Industry Online Support (SIOS) portal. Prior to dispatch, our technical team performs a physical inspection covering nameplate integrity, shaft runout, encoder connector condition, and housing seal continuity.

Packaging follows anti-static and shock-absorption protocols: the motor is wrapped in ESD-safe foam, placed in a rigid corrugated carton with corner protectors, and sealed with tamper-evident tape. For international shipments, we prepare a full export documentation package including commercial invoice, packing list, certificate of origin (CO), and customs HS code declaration (HS 8501.53 — AC synchronous motors, output > 750 W).

Logistics options from Xiamen include DHL Express (3–5 business days to EU/USA), FedEx International Priority (4–6 business days), and sea freight LCL consolidation for bulk orders exceeding 50 kg. In-stock units ship within 1–2 business days of order confirmation. A 12-month warranty against manufacturing defects is included with every unit; DOA claims are processed within 72 hours of receipt notification.

Contact Information

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