HG-KR053 | Mitsubishi MELSERVO J4 AC Servo Motor — 50W / 200V / 22-Bit Absolute Encoder / IP65 / Low Inertia

Compact 50W Servo Motor with High-Resolution Absolute Feedback

The HG-KR053 is Mitsubishi Electric's smallest standard-frame servo motor in the MELSERVO J4 HG-KR series — a 50W, low-inertia AC brushless servo motor purpose-built for compact axis drives in space-constrained machine designs. The 40×40mm flange and IP65 sealed construction make this motor suitable for installation directly on small mechanisms, gripper actuators, and miniature linear stages without an additional protective enclosure.

The defining feature of the HG-KR series is the built-in 22-bit absolute encoder — providing 4,194,304 pulses per revolution of position resolution while retaining absolute position data through power-off events. This eliminates the homing sequence that incremental-encoder motors require at every machine startup.

Key Specifications

22-Bit Absolute Encoder — Position Retention Through Power-Off

The built-in absolute encoder is the central engineering feature of the HG-KR053:

4,194,304 pulses per revolution: The 22-bit resolution (2²²) divides each shaft revolution into over 4 million discrete positions — fine enough resolution for precision positioning applications even at this small motor's compact scale.

Absolute position memory: Unlike incremental encoders that reset to zero on power loss, the absolute encoder retains the motor's exact shaft position through power interruptions — using a small battery in the amplifier or encoder cable assembly to maintain position memory while main power is off.

No homing required at startup: Machines using HG-KR053 motors with absolute encoders skip the reference-point return sequence at every power-up — the controller immediately knows each axis's exact position, reducing cycle startup time and simplifying multi-axis machine sequencing

Applications

Compact pick-and-place mechanisms: Small robotic arms and gripper actuators in electronics assembly and packaging lines where the 40×40mm flange and 50W output match the axis load requirements.

Indexing and rotary tables: Small parts handling, labeling stations, and rotary indexing fixtures requiring precise angular positioning with the absolute encoder eliminating homing delays.

Laboratory and medical automation: Compact dosing systems, sample handling equipment, and diagnostic instrument axes where space constraints demand the smallest practical servo motor frame.

Semiconductor and electronics handling: Small-axis positioning in wafer handling peripherals and PCB assembly equipment requiring high-resolution feedback in a compact footprint.

FAQ

Q1: Can HG-KR053 operate without the absolute encoder battery backup?

Without battery backup, the absolute encoder loses its multi-turn position count on power-off — functioning effectively as a single-turn absolute encoder limited to within-one-revolution position data after a power loss. For full multi-turn absolute position retention through power cycles, the encoder battery (typically housed in the servo amplifier or a dedicated battery unit) must remain charged and connected.

Q2: What MELSERVO amplifiers are compatible with HG-KR053?

The HG-KR053 is compatible with MR-J4-10A, MR-J4-10A-RJ, MR-J4-10B, and MR-J4-10B-RJ servo amplifiers — the 10-series amplifiers matched to the HG-KR053's rated current and power class. Confirm from Mitsubishi's MELSERVO combination table that the specific amplifier model and firmware revision support the HG-KR053's encoder interface before commissioning.

Q3: What is the maximum permissible load inertia for HG-KR053 in a typical application?

Servo system design generally limits the reflected load inertia to a multiple of the motor's own rotor inertia — commonly within 5 to 30 times the motor inertia depending on the required dynamic performance and amplifier gain settings. At 0.0000045 kg·m² rotor inertia, the practical load inertia limit for the HG-KR053 is correspondingly very small — appropriate for light, fast-moving mechanisms rather than heavy load applications. Calculate the actual reflected inertia from the specific mechanism's gear ratio and load mass before motor selection.

Q4: Does HG-KR053 require external cooling for continuous operation?

No — the HG-KR053 is a natural-cooling design, relying on convective heat dissipation from the motor housing without a forced-air cooling fan. This is appropriate for the motor's 50W rated power class. Ensure adequate ambient airflow around the motor housing in the installation — completely enclosed mounting positions without any air circulation can reduce the motor's effective continuous duty rating.