Mitsubishi HC-SFS152K (HCSFS152K) — 1.5kW AC Servo Motor, Keyed Shaft, No Brake, 2000 rpm, MELSERVO J2-Super Series

Product Overview

Part Number: HC-SFS152K

Also Searched As: HCSFS152K, HC SFS 152K, HC-SFS-152K

Series: Mitsubishi MELSERVO HC-SFS (J2-Super Generation)

Classification: Medium-Inertia AC Brushless Servo Motor — 1.5 kW, 200V class, 2000 rpm, Keyed Shaft, No Brake

The Motor and Its Defining Feature

The Mitsubishi HC-SFS152K is a 1.5kW, 2000 rpm servo motor from the J2-Super HC-SFS compact family. Its performance specifications — 7.16 Nm continuous torque, 21.6 Nm peak, 17-bit absolute encoder at 131,072 ppr, 130 × 130 mm flange, IP65 — are shared with its straight-shaft sibling, the HC-SFS152. What sets it apart is the single letter at the end: K.

That letter means a machined keyway on the shaft. Not a friction-clamp interface. Not a set-screw coupling seat. A proper machined keyway that provides a positive, mechanically locked torque path between motor shaft and driven hub — one that transmits torque through the key's shear cross-section rather than through contact force, and one that does not depend on clamping geometry remaining intact across years of production service.

At 1.5kW on a 130 × 130 mm frame, the HC-SFS152K fits a specific category of machine axis: compact in frame size, meaningful in torque output, and connected to a driven component through a mechanical interface that genuinely benefits from the key. Timing belt drives with keyed pulleys. Worm gear input shafts. Chain sprocket hubs. Gear hubs on compact reduction gearboxes. These are the applications the HC-SFS152K was designed for.

Technical Specifications

7.16 Nm at 2000 rpm: The Torque Capacity in Practice

Seven point one six Newton-metres of continuous torque positions the HC-SFS152K at a useful working point within the compact 130 × 130 mm frame category. It is the highest continuous torque available in the HC-SFS 2000 rpm range before the flange size steps up to 176 × 176 mm at the HC-SFS202. That makes it the top of the compact range — the choice when the machine structure accommodates only the 130 × 130 mm footprint but the axis torque demand exceeds what the 1kW HC-SFS102 can sustain.

What does 7.16 Nm continuous look like in mechanical terms? On a 5mm pitch ball screw with 90% efficiency, this torque sustains approximately 8.1 kN of axial force — a meaningful feed force for compact CNC machines, small press feeders, and medium-duty material handling mechanisms. On a winding drive in torque control mode, 7.16 Nm covers the working tension range of a light-to-medium winding station across a practical roll diameter range. On a belt-coupled axis with a 2:1 reduction, the effective torque at the driven shaft doubles to approximately 14 Nm, at half the output shaft speed.

The 21.6 Nm peak — exactly three times the continuous rating — handles the acceleration and deceleration transients of each positioning cycle. A 1.5kW axis completing rapid point-to-point moves draws on peak torque for the brief velocity ramp phases and settles to rated torque or below during constant-velocity motion. The MR-J2S-200 amplifier's electronic thermal model tracks this pattern and alarms before the winding temperature approaches a damaging level under any production duty cycle.

Why the Keyed Shaft at 1.5kW

The choice between a straight shaft and a keyed shaft at 1.5kW deserves a direct explanation, because the reasoning is practical rather than theoretical.

A friction-clamp coupling on a straight shaft transmits torque through the contact force between hub bore and shaft OD. That force is established at installation and must remain high enough to resist the full peak torque — 21.6 Nm in this case — throughout the motor's service life. Under ideal conditions, with regular inspection intervals and a clean stable environment, this works reliably. Under production conditions — vibration from adjacent machinery, thermal cycling between machine-on and machine-off states, periodic loosening of fasteners that the maintenance team does not catch because the slip is subtle — the safety margin can erode. A coupling that resisted 21.6 Nm on the day it was installed may slip at 15 Nm after two years of service. The slip is intermittent. The following error is small. The alarm may never trip. But position repeatability degrades, and the cause is not obvious.

The keyway eliminates this degradation mechanism entirely. The key transmits torque through its shear cross-section — a geometry that does not change with service hours, does not loosen under vibration, and does not depend on any installation variable remaining constant. Cyclic loading, reversal torque, the 21.6 Nm peak on every acceleration, shock inputs from chain engagement or gear tooth contact — the keyed joint handles all of these without the accumulating wear that a friction interface experiences.

For the applications the HC-SFS152K typically serves — chains and sprockets, worm gear inputs, keyed timing pulleys, gear hubs on precision reduction gearboxes — the hub has a keyway bore either as a catalogue standard or as a design requirement, and the keyed shaft motor is simply the natural and correct specification. There is no performance cost. The 7.16 Nm rated torque and 21.6 Nm peak are identical to the straight-shaft HC-SFS152.

The Highest Compact-Frame Torque in the 2000 rpm Range

The 130 × 130 mm flange is the compact frame size across the HC-SFS 2000 rpm family. Three motors share it:

Above the HC-SFS152K, the next step in the HC-SFS 2000 rpm keyed-shaft family is the HC-SFS202K at 2kW — which steps up to the larger 176 × 176 mm flange and uses the same MR-J2S-200 amplifier. This is a significant mechanical transition: the 130 × 130 mm mounting cannot accommodate the HC-SFS202K without modifying the motor mount. For machine designs constrained to the 130 × 130 mm footprint, the HC-SFS152K is the maximum torque option available.

Conversely, the HC-SFS102K below it uses a different amplifier class — MR-J2S-100 instead of MR-J2S-200. Upgrading from HC-SFS102K to HC-SFS152K keeps the flange unchanged but requires an amplifier change. The mounting stays identical; only the motor and amplifier need to change.

No Brake: The Right Default for Keyed-Shaft Applications

The HC-SFS152K carries no electromagnetic brake. Position at rest is maintained by the MR-J2S-200 amplifier's servo lock — the position loop active, 17-bit encoder monitoring shaft angle at 131,072 counts per revolution, and corrective current supplied to hold zero following error.

For the types of applications the keyed shaft serves, this is the appropriate and sufficient configuration the overwhelming majority of the time. Chain-coupled conveyors on horizontal planes. Gear-driven rotary indexers on horizontal axes. Belt-coupled feed drives where the load has no vertical component. Worm gear input drives on horizontal mechanisms. These are all horizontal or symmetrically loaded — there is no gravitational force acting along the shaft rotation direction when the servo is inactive. Servo lock holds position cleanly, reliably, and without additional hardware.

The no-brake configuration saves panel circuit resources — no 24V brake circuit, no relay, no surge suppressor, no MBR interlock in the PLC — that would add cost and complexity on every axis that genuinely does not need them.

The boundary condition is worth applying deliberately. If the axis carries a load that would move under gravity when servo current drops to zero — a vertical keyed-shaft axis, an inclined drive, a gravity-loaded mechanism — the correct motor is the HC-SFS152BK (keyed shaft plus spring-applied brake). On a machine with several keyed-shaft axes at this capacity, identifying the vertical and inclined ones and specifying the BK variant only for those axes, and the HC-SFS152K for the rest, produces both a safer machine and a simpler panel design.

17-Bit Absolute Encoder: The Precision Behind the Keyway

The mechanical interface of the HC-SFS152K is built for positive, reliable torque transmission through the keyway. The feedback behind the shaft is built for precision: 131,072 positions per revolution, multi-turn absolute count maintained through power-off by the A6BAT battery in the MR-J2S-200 amplifier.

On keyed-shaft applications specifically, the absolute encoder adds a practical value that is easy to overlook at the design stage. A chain drive or gear-coupled axis does not simply park at the same shaft angle every time the machine stops. Tool changes, E-stops, shift changes, and maintenance stops can leave the axis at any position in its travel range. With an absolute encoder, the controller knows the exact shaft position immediately on restart — no movement required. The keyed coupling holds the mechanical relationship between motor and driven component with zero slip, and the absolute encoder reports the exact angular position of that component relative to the machine's coordinate frame.

For indexed mechanisms in particular — rotary tables, indexed transfer conveyors, multi-station assembly fixtures — the combination of a positive keyed torque path and an absolute encoder means the index position is held exactly through any power-off event and reported accurately on restart. No homing, no index verification movement, no production delay.

Battery care. The A6BAT in the MR-J2S-200 amplifier maintains the multi-turn counter through all power-off periods. Replace it at the first low-battery alarm. Full depletion resets the counter and requires a reference-return cycle on the next startup.

Compatible Amplifiers

The HC-SFS152K pairs with the MR-J2S-200 amplifier family — the 2kW J2-Super platform. Three variants:

MR-J2S-200A accepts pulse-train position commands from CNC controllers and PLCs, plus analog speed and torque references. All control modes — position, speed, torque, and switched combinations P/S, S/T, T/P — are available. RS-232C connects to MR Configurator. This is the standard choice for machine tool auxiliary axes, conveyor drives, and general industrial positioning applications.

MR-J2S-200B connects to Mitsubishi A-series and Q-series motion controllers via SSCNET fiber-optic serial bus. All axis commands and feedback travel over the fiber network. For multi-axis machines where the keyed-shaft axis must coordinate in real-time with other axes — a conveyor section synchronised with a robot arm, an indexed table coordinated with a machining spindle — the SSCNET bus provides the tight axis coupling that pulse and analog interfaces cannot achieve.

MR-J2S-200CP provides built-in single-axis positioning with up to 31 stored point-table positions, activated by digital I/O or CC-Link command. For standalone indexed positioning axes — a rotary table with defined station positions, an indexed conveyor section with fixed pitch — the CP eliminates the need for a dedicated motion controller.

Compatibility notes. The HC-SFS152K requires an MR-J2S-200 amplifier. It is not compatible with the first-generation MR-J2-200, which cannot read the 17-bit J2-Super encoder protocol. For machines on original MR-J2-200 hardware, the HC-SF152K (keyed shaft, 14-bit encoder, same mechanical dimensions) is the correct motor. Not compatible with MR-J3 or MR-J4 amplifiers without a renewal adapter kit.

Typical Applications

Chain and sprocket drive systems. Servo-driven conveyor chains, indexing mechanisms, and transfer systems where the motor sprocket is keyed to the motor shaft. Chain engagement creates cyclic torque transients at each link — the keyed interface handles these reliably over millions of cycles where a friction clamp would be progressively stressed. The 7.16 Nm continuous and 21.6 Nm peak provide practical force capacity for medium-duty chain-driven mechanisms on the compact 130 × 130 mm frame.

Worm gear input drives on compact indexing tables. Rotary indexing tables, servo-driven turrets, and angular positioning fixtures using worm or helical gear reduction between the motor and the output shaft. The worm gear input typically uses a keyed bore coupling to the motor shaft, and the gear's resistance to back-driving means position is maintained largely through the gear reduction rather than servo lock during dwell periods. The HC-SFS152K provides the keyed motor-side connection and the torque budget for these mechanisms at the compact frame size.

Timing belt primary drive axes. Machine axes using a timing belt and sprocket reduction where the motor-side pulley is keyed to the motor shaft. Belt tension pre-loads the pulley radially, creating a combined radial and tangential load on the shaft interface. Keyed pulleys handle this loading pattern reliably without the risk of the pulley rotating on the shaft under combined belt tension and drive torque — a risk that friction clamping must be carefully designed to resist.

CNC auxiliary axis drives with gear-coupled mechanisms. Pallet changer rotation drives, rotary tool magazine primary drives, and chip conveyor primary drives on CNC machining centres where the motor connects through a gear or chain mechanism to the driven component. These axes cycle frequently under defined loads, and the keyed shaft ensures the drive connection remains positive across the full life of the mechanism.

Compact pressing and forming machine feed drives. Light-duty press feeders, coil straightener outputs, and servo-driven material advance mechanisms on compact stamping and forming machines. The cyclic nature of press feeding — acceleration, constant-speed feed, deceleration, dwell, repeat — cycles through the full peak-to-continuous torque range on every stroke. The keyed interface sustains this duty indefinitely; the 21.6 Nm peak handles the acceleration transient at the start of each feed stroke.

Frequently Asked Questions

Q1: What is the practical difference between the HC-SFS152K (keyed) and HC-SFS152 (straight shaft)?

The performance specifications are identical — same 7.16 Nm rated torque, same 21.6 Nm peak, same 17-bit encoder, same amplifier, same flange. The only difference is the shaft-to-hub torque interface. The HC-SFS152K transmits torque through a machined keyway — a mechanically positive connection that does not depend on clamping force and does not degrade with service hours. The HC-SFS152 relies on friction clamping from the hub. For driven components with keyway bores (gear hubs, sprockets, keyed pulleys), the HC-SFS152K is the natural match. For smooth-bore precision coupling on horizontal axes with clean, stable load conditions, the HC-SFS152 is simpler. The choice is determined by the driven component's hub design.

Q2: Why does the HC-SFS152K use the MR-J2S-200 amplifier when it is only 1.5kW?

The amplifier class is determined by the motor's current demand at its operating point, not purely by nameplate wattage. At 2,000 rpm and 1.5kW, the HC-SFS152K draws current that exceeds the MR-J2S-100's rated output. Mitsubishi's compatibility tables confirm MR-J2S-200 for the HC-SFS152 at 2000 rpm. This has a useful practical consequence: both the HC-SFS152K and the HC-SFS202K (2kW, 2000 rpm, keyed shaft) use the MR-J2S-200, so upgrading from 1.5kW to 2kW requires only a motor swap — the amplifier and panel remain unchanged.

Q3: Can the HC-SFS152K be used with a first-generation MR-J2-200 amplifier?

No. The HC-SFS152K uses the 17-bit J2-Super encoder serial protocol, which the original MR-J2-200 amplifier cannot decode. Connecting this motor to a first-generation MR-J2-200 will produce an encoder communication fault on startup. For machines running original MR-J2-200 hardware, the correct keyed-shaft motor is the HC-SF152K — mechanically identical dimensions, 14-bit encoder, compatible with both MR-J2-200 and MR-J2S-200 amplifiers.

Q4: Where is the absolute encoder backup battery, and what happens when it fully depletes?

The Mitsubishi A6BAT lithium cell is inside the MR-J2S-200 servo amplifier, not in the motor. It maintains the multi-turn absolute counter through all power-off periods. Replace it at the first low-battery alarm from the amplifier. A fully depleted battery resets the multi-turn counter — the absolute position data is lost. On the next startup, the controller does not know the axis position, and a reference-return cycle must be completed before production can resume. On chain-driven or gear-coupled axes where homing requires coordinating the mechanism to a reference position, this can be a non-trivial restart procedure. Treating the low-battery alarm as an immediate maintenance item prevents it from becoming an unplanned production interruption.

Q5: The HC-SFS152K is discontinued. Is it still obtainable, and what is the upgrade path?

The HC-SFS152K remains available through industrial automation surplus dealers and Mitsubishi servo specialist suppliers as new old stock and tested refurbished units — a practical and well-established sourcing path for machines committed to J2-Super hardware. For new machine designs or full platform upgrades, the current-generation equivalent would draw from the HF-SP or HG-SR series at the 1.5kW 2000 rpm capacity with an MR-J4 amplifier — but note that current-generation 1.5kW motors in Mitsubishi's lineup tend toward smaller frames than the HC-SFS152K's 130 × 130 mm footprint, so mechanical adaptation is needed when transitioning to current hardware. Both motor and amplifier must be replaced together as the encoder protocols are incompatible across generations.