Siemens 1FK706 Series

Siemens 1FK706 Compact Synchronous Servo Motor

The 1FK706 is a three-phase AC synchronous servo motor in Siemens SIMOTICS S product line — purpose-built for closed-loop motion control in packaging, printing, robotics, and CNC machine tools. It delivers high dynamic response (short rotor inertia, 300% peak torque headroom) and nests into the SINAMICS S120 drive ecosystem without extra engineering. If you are coming from an induction-motor open-loop setup, the 1FK7 family replaces the need for a separate encoder kit and drive tuning marathon; the electronic nameplate auto-configures the drive on plug-in.

Typical applications:

• Packaging machinery — cartoners, flow-wrappers, and pick-and-place delta robots where axis cycle times run under 200 ms.
• CNC auxiliary axes — tool changers, pallet loaders, and spindle orienting on VMCs and turning centers.
• Printing & converting — register correction rollers and tension control in flexo and digital web presses.
• General automation — rotary indexing tables, flying shears, and filling/dosing stations in food and pharma lines.

Key specifications (1FK706 frame):

How to select a variant within 1FK706:

Start with the continuous torque your load profile demands — size for the RMS torque of the duty cycle, not the peak. Then confirm the moment of inertia ratio (load inertia ÷ motor rotor inertia) stays under 5:1 for high-dynamics applications or under 10:1 if you can tolerate softer acceleration. If the axis must hold position unpowered (vertical axes, safety-relevant stops), spec the integrated holding brake; it adds about 40 mm to overall length and roughly 0.1 × 10⁻³ kg·m² to rotor inertia.

When picking the encoder, absolute multiturn saves you a homing cycle after power loss — worth the roughly 15% price delta on multi-station machines where re-homing wastes cycle time. Compare against the 1FK701/1FK703 frames if your torque requirement is lower (those top out around 1.5 N·m continuous) and you can save on frame size; conversely, 1FK708 gives you the next torque step without jumping to the 1FT7 series.

Flange and mounting dimensions are IEC 72-1 compliant; bolt patterns interchange with comparable Bosch Rexroth MSK and Indramat MKD frames of the same size code, though the resolver pinout differs.

Procurement notes:

The 1FK706 stays in active production through Siemens Digital Industries. Standard shaft-height configurations ship in 2–4 weeks; motors with non-stock options — IP65 sealing, reinforced bearings for high radial load, or special winding insulation for 480 V operation — can stretch to 8–10 weeks. Order codes follow the 1FK706x-xxxxx-x format where the suffix block encodes frame length, winding, brake, encoder, and shaft variant. Crossing to a third-party servo drive is technically possible but you lose the electronic nameplate benefit and must manually commission the current loop; most integrators stay within SINAMICS for that reason.