What lands in the panel when you specify this code
The Siemens 1FL2105-4AF11-0SB0 is a SIMOTICS S-1FL2 low-inertia servo from the 1FL2 family, built to drop into a SINAMICS S200 drive cabinet — the drive pairing is fixed in the catalog entry, so the motor's encoder protocol and power stage are sized for that specific drive platform rather than the wider SINAMICS line. Supply is 400 V three-phase, continuous rated power Pn=2 kW at a rated speed Nn=3000 rpm, with a stall torque M0=8 Nm and rated torque Mn=6.6 Nm — that torque margin is what gives the velocity loop headroom during acceleration transients before the current saturates. Shaft height is 52 mm and the unit ships with a holding brake, an AS21bit absolute encoder, and IP65 sealing with an oil seal at the shaft exit for installations where coolant or cutting fluid is present. Group Code R220 and Product Group X0DK are the internal Siemens classification fields for this line.
Tuning-room read on the dynamic envelope
The AS21bit absolute encoder on this variant delivers the feedback resolution the SINAMICS S200 expects for its auto-tuning pass — coarse feedback on a low-inertia frame is the usual reason a servo sings at a specific RPM, because the current loop is closing on a position estimate that's too slow to catch the mechanical resonance. With 21-bit feedback the loop sees the shaft position to within arc-minutes, and the auto-tuner can place the notch filter correctly the first time rather than after an afternoon on the scope. The 3000 V AC supply class and three-phase 400 V input put this on a standard industrial three-phase feed — no transformer tap dance required. IP65 with oil seal at the shaft is the spec you want for a machine-tool or wet-line environment, because standard IP65 alone does not stop oil migration along the shaft; the seal lip is what keeps cutting fluid out of the bearing cavity over time.
Compliance and packaging on record
Compliance posture is straightforward: RoHS conformity since 01-01-18, REACH Art. 33 duty-to-inform on the current candidate list, and export classification AL:N / ECCN:N — no special export license is required for routine shipment. Product class C on the line item means each unit is built per order and is not returnable against credit, which is the normal Siemens posture for a configured servo and is worth flagging on the PO before commit. Catalog packaging is a single-piece shipper at 432 x 222 x 240 mm — useful for the panel-builder sizing the goods-in bay and the MRO planner checking whether a replacement motor will clear the maintenance aisle. Quantity unit is one piece per order code.