YASKAWA UGFMED-B9MMG21 MINERTIA CORELESS DC SERVO MOTOR SPECIFICATION

UGFMED-B9MMG21 belongs to Yaskawa classic F-series Minertia coreless DC servo motor lineup, a high-response low-inertia direct current servo unit tailored for precision industrial automation and high-speed positioning equipment. This motor adopts unique cup-type coreless rotor design without laminated iron core inside winding, delivering ultra-low rotor inertia, near-zero cogging torque and ultra-smooth low-speed rotation; it applies full natural convection cooling structure without auxiliary cooling fan. The prefix B stands for factory pre-installed fail-safe DC electromagnetic power-off brake for vertical-axis anti-drop protection; suffix MMG21 is exclusive OEM customized incremental rotary encoder specification with dedicated pin definition, distinct rear connector wiring layout and fixed cable configuration compared to MMG11 variant, including different pulse resolution and terminal assignment designed to match specified original Yaskawa legacy DC servo drives only. The size code 9 defines fixed frame dimension and rated power tier for this model.

UGFMED = base model code of Yaskawa coreless Minertia DC servo motor; B = integrated built-in DC power-off electromagnetic brake assembly; digit 9 = fixed frame size and 0.9kW rated power grade; MMG = customized incremental encoder family with proprietary wiring standard; numeral 21 = factory internal variant code specifying unique encoder resolution, outgoing cable length and connector pinout differing from MMG11 version.

The motor is designed for rated 144VDC armature input voltage and exclusively matched with Yaskawa old-generation dedicated Minertia DC servo amplifier systems. Its continuous rated output power reaches 0.9kW, nominal full-load rated armature current is approximately 7.2A under steady-state rated operation condition, standard rated rotational speed is set at 1750rpm with stable continuous rated torque output; instantaneous peak overload torque can reach up to 3.5 times continuous rated torque to satisfy instant heavy startup and abrupt acceleration for short-time impact loads. The independent built-in brake coil requires separate 24VDC auxiliary control supply: brake releases when auxiliary power is energized and instantly locks output shaft once auxiliary power cuts off to prevent free fall of vertically mounted loads during unexpected power outage. The customized MMG21 differential line-drive incremental encoder follows exclusive factory pin assignment rule with different pulse count specification versus MMG11, requiring paired original driver without arbitrary rewiring or parameter modification for normal closed-loop feedback. Internal stator winding is manufactured per Class F insulation standard, equipped with embedded temperature sensing component that transmits overheat warning signal to matched servo controller to trigger automatic overload shutdown and avoid winding thermal burnout under long-term overloading. Internal wiring cavity is pre-fitted with surge suppression components to restrain industrial field impulse voltage and surrounding inverter electromagnetic interference effectively.

Full enclosed motor housing carries IP54 ingress protection rating and fully relies on shell natural heat dissipation without extra cooling fan structure. Front driving end features standard solid output shaft with integrated flat keyway for rigid coupling with precision reducers, miniature ball screws and timing wheel transmission parts; due to rear-end embedded brake module layout, overall axial body length is longer than non-brake same-frame coreless servo counterparts, and complete unit net weight stands roughly 4.1kg with unified standard flange mounting dimension for direct installation on equipment frames without additional transition fixtures.

Permissible continuous working ambient temperature ranges from 0°C to +40°C; long-term spare part storage temperature covers -20°C up to +70°C; applicable operating relative humidity is controlled within 5%RH~80%RH under non-condensing status to prevent dew-caused internal circuit short-circuit failure. If installation altitude exceeds 1000 meters above sea level, users must properly derate continuous running load to compensate degraded heat dissipation efficiency under thin air environment. The motor can withstand standard industrial vibration ranging 10Hz to 55Hz; installation sites with corrosive chemical vapors, continuous liquid splashing and heavy conductive dust accumulation are prohibited to extend service life of front bearing, brake friction disc and internal winding components.

UGFMED-B9MMG21 is originally compatible with Yaskawa vintage dedicated DC servo drive modules, supporting two mainstream external command input modes including ±10VDC analog voltage speed instruction and differential pulse position command transmitted from upper PLC or compact CNC controller. The matched servo control system supports seamless switching among position closed-loop control, speed closed-loop control and torque closed-loop control to adapt varied production process requirements. Benefiting from factory-built power-off brake structure, vertical mounted machinery eliminates the need for additional external mechanical locking device against gravity sliding after power failure. As incremental-type MMG21 feedback encoder is configured, full mechanical origin homing procedure has to be executed after complete system power cut before formal equipment startup to restore accurate mechanical zero point for subsequent precision positioning motions.

Cooperating with matched servo amplifier, the motor implements comprehensive multi-layer safety protection functions. Winding over-temperature signal triggers servo overload shutdown to protect coreless winding against overheat damage; open circuit or poor contact of MMG21 customized encoder cable activates independent encoder fault alert displayed on servo operation panel; internal winding short-circuit and abnormal overcurrent input trigger driver hardware overcurrent protection with immediate main power cutoff; brake coil open or short-circuit fault outputs corresponding auxiliary fault prompt on paired drive terminal. All internal feedback signal circuits are equipped with noise filtering components to suppress complex on-site electromagnetic interference and guarantee stable position feedback signal transmission.

Field on-site replacement must adopt identical original UGFMED-B9MMG21 spare motor; non-brake variant or MMG11 encoder version motors cannot realize direct substitution unless full connector rewiring and complete servo parameter reset are finished after replacement operation. Before disassembling motor for bearing inspection, brake maintenance or encoder overhaul work, maintenance personnel need to fully disconnect main 144VDC armature power supply and 24VDC brake auxiliary power, then wait no less than 15 minutes for full discharge of servo internal DC bus capacitance to eliminate residual high voltage and avoid electric shock hazards. Standard periodic maintenance items include tightening rear connector fixing screws every three months, supplementing high-temperature resistant bearing grease after accumulating over 8000 continuous running hours and cleaning casing surface dust every six months to retain original natural heat dissipation performance. Random modification to MMG21 exclusive encoder pin definition and internal brake wiring layout will lead to unexpected motor runaway or permanent servo driver locking fault.

This low-inertia coreless DC servo motor is widely deployed for precision feed axes of bench-type high-precision micro processing equipment, indexing positioning turntable of tiny component automated assembly lines, micro drive unit of optical inspection and testing machinery and compact precision packaging automation devices, especially suitable for vertical installation working conditions requiring frequent start-stop operation, ultra-fast dynamic response and mandatory power-off anti-drop positioning constraints.