Mitsubishi HC-SFS203B (HCSFS203B) — 2kW AC Servo Motor, Straight Shaft + Brake, 3000 rpm, MELSERVO-J2S Series

Product Identification

Part Number: HC-SFS203B Also Searched As: HCSFS203B, HC-SFS-203B Series: Mitsubishi MELSERVO HC-SFS (J2-Super Generation) Motor Type: AC Brushless Servo Motor — Straight Shaft with Electromagnetic Brake, 3000 rpm Condition: New In Box, Factory Sealed

Overview

The Mitsubishi HC-SFS203B is a 2kW medium-inertia AC brushless servo motor from the MELSERVO-J2S platform, running at a rated speed of 3,000 rpm and fitted with a spring-applied electromagnetic brake on a straight shaft. Within the HC-SFS range, this is the 3000 rpm 2kW variant — a motor that prioritises speed over the higher continuous torque of its 2,000 rpm counterpart, the HC-SFS202B, while sharing the same amplifier class and the same J2-Super encoder technology.

At 6.37 Nm continuous rated torque, the HC-SFS203B generates its 2kW output through higher rotational velocity rather than high shaft force. The 19.1 Nm peak — exactly three times the rated continuous figure — handles the acceleration demand on the axis during rapid traverse and deceleration phases. This 3:1 peak-to-rated ratio is consistent across the HC-SFS range and gives the amplifier the headroom to demand maximum torque for short bursts without the motor exceeding its thermal limits during the working cycle.

The "B" suffix makes this the brake-equipped variant. The spring-applied brake keeps the shaft stationary when 24V DC is removed — on deliberate shutdown, e-stop, or any loss of control power. For axes where the load cannot be left to the amplifier's servo lock between cycles, or where safe machine design requires mechanical hold independent of control system state, the brake is the defining specification difference between this model and the HC-SFS203.

Technical Specifications

3000 rpm at 2kW: When Speed Is the Priority

The HC-SFS203 and HC-SFS202 deliver the same 2kW output — but they trade torque for speed in opposite directions. The HC-SFS202B at 2,000 rpm produces 9.55 Nm continuously. The HC-SFS203B at 3,000 rpm produces 6.37 Nm. The power is the same; the operating point is different.

That difference is deliberate and application-specific. When cycle time is dominated by how fast an axis can traverse to its next position, the higher rated speed of the HC-SFS203B pays off directly. An axis running at 3,000 rpm completes a rapid traverse to a given position 50% faster than the same axis at 2,000 rpm when the load torque is within the 6.37 Nm continuous range. For machines with many short, rapid positioning moves — multi-position indexers, pick-and-place axes, high-cycle transfer systems — that speed advantage accumulates into measurable production throughput improvement.

Conversely, if the duty cycle requires sustained torque close to or above 6.37 Nm at any speed, the HC-SFS202B with its 9.55 Nm continuous rating is the more appropriate specification. The choice between the two comes down to a straightforward question: is this axis limited by axis speed or by load torque during the working portion of its cycle?

The 130 × 130 mm flange keeps the physical footprint compact at 2kW. On machines with multiple closely spaced servo axes — multi-spindle heads, gantry cross-members, rotary indexing stations — the smaller frame size allows tighter axis spacing than the 176 × 176 mm flange motors in the HC-SFS series, without sacrificing any of the J2S platform's control capabilities.

The Electromagnetic Brake: Purpose and Proper Use

A servo motor with no brake holds position through closed-loop servo lock — the amplifier continuously monitors encoder feedback and supplies corrective current to keep the axis where the position command says it should be. This works reliably during normal operation, but it depends entirely on the amplifier being powered, faulted-free, and actively controlling the motor. Remove the power, trip the amplifier, or press e-stop, and servo lock disappears instantly.

The spring-applied brake on the HC-SFS203B exists for exactly those moments. The spring engages the brake disc the instant 24V DC is removed — with no delay, no logic sequence required, no dependency on amplifier state. The axis holds mechanically. For any application where losing servo lock means the load moves in an undesired direction — a vertical axis, a gravity-biased arm, a mechanism with significant friction asymmetry, or simply a production process that must not allow axis drift during an e-stop — the "B" suffix is the necessary specification.

Practical installation points:

The MR-J2S amplifier provides the MBR (electromagnetic brake interlock) output signal precisely to control brake relay timing. The MBR signal delays brake engagement until after the amplifier's deceleration routine has brought the motor to rest. Wiring the brake relay directly to an e-stop contact — without routing through the MBR interlock — forces the spring to engage against a rotating shaft. At 2kW, the resulting impact is sufficient to shorten brake disc life significantly with each incident.

For the brake coil wiring, a surge absorber across the coil terminals is not optional. The brake coil is an inductive load; switching it off without suppression generates a voltage spike that can damage the digital output driving the relay circuit. Mount the absorber as close to the coil terminals as possible for maximum effectiveness.

The brake is rated for static hold, not dynamic stopping. It keeps a stopped axis still — it is not designed to arrest a moving load on its own. The amplifier stops the motor; the brake holds what is already stopped. Using it the other way around dramatically reduces brake service life.

17-Bit Encoder: J2-Super Feedback Quality at 3000 rpm

The MELSERVO-J2S platform upgraded the HC-SF range's 14-bit encoder (16,384 ppr) to 17-bit (131,072 ppr) — an eight-fold resolution increase that carries through to every motor in the HC-SFS family, including the HC-SFS203B.

At 3,000 rpm, the practical effect of higher encoder resolution is most visible in two areas. Velocity estimation quality is the first: the amplifier computes speed from consecutive encoder position samples. More positions per revolution means finer angular increments per sample, which translates directly into a cleaner velocity signal for the speed loop. A cleaner velocity signal allows higher speed loop bandwidth without instability, and higher bandwidth means faster recovery from velocity disturbances — cutting forces, load changes, and transmission compliance effects that push the axis off its commanded velocity profile.

The second benefit appears at low feed rates and during deceleration. When the axis slows toward a position target, the encoder's resolution determines how finely the amplifier can detect position error and apply corrective torque. At 14 bits, the last few encoder counts before the target represent relatively large angular steps. At 17 bits, those final steps are eight times smaller, and the position loop settles more precisely and more consistently.

The absolute function requires no external battery in the motor or encoder. The A6BAT lithium cell in the MR-J2S amplifier maintains the multi-turn position counter indefinitely through any power interruption. Startup after any power event — including alarm trips and overnight shutdowns — restores exact absolute axis position without a reference return cycle. For machines with tight restart protocols or automated production sequences that need to resume immediately after a stop, the absence of a mandatory homing cycle is a practical advantage.

Compatible Amplifiers

The HC-SFS203B pairs with the MR-J2S-200 class amplifier, the same 2kW platform used across the HC-SFS202 and HC-SFS203 motor variants. Three interface types cover the primary system architectures:

MR-J2S-200A accepts analog and pulse-train position commands from CNC systems and PLCs. Position, speed, and torque control modes are all supported. RS-232C interface enables parameter setup and real-time monitoring through MR Configurator software.

MR-J2S-200B connects to Mitsubishi motion controllers through SSCNET fiber-optic serial bus — the standard choice for multi-axis interpolation systems using A-series or Q-series controllers. Trajectory commands arrive over the network; the amplifier executes them locally using motor-shaft encoder feedback.

MR-J2S-200CP incorporates a built-in point table for standalone positioning without an external motion controller. Up to 31 target positions are stored in the amplifier and selected by I/O or CC-Link command. This variant suits simple indexed positioning systems where dedicated controller hardware is unnecessary.

The HC-SFS203B is not compatible with original MR-J2-200 (first-generation) amplifiers, which predate the 17-bit J2S encoder protocol, nor with MR-J3 or MR-J4 amplifiers, which use a different encoder interface. If the machine runs first-generation MR-J2 hardware, the HC-SF203B (J2-generation motor with 14-bit encoder) is the correct sourcing target.

HC-SFS 3000 rpm Family — Capacity in Context

The HC-SFS203B sits at the top of the 130 × 130 mm flange group within the 3000 rpm family. Motors at or above the 3.5kW / 353 capacity step up to the 176 × 176 mm flange. All models in this table use the 17-bit serial absolute encoder, 200V AC class supply, and IP65 protection as standard features.

HC-SFS203B vs HC-SFS202B — Choosing Between Them

Both motors share the same 2kW output power, 130 × 130 mm flange (for 202B) to 176 × 176 mm (for 202B — actually 202 uses 176mm), the same amplifier class, the same 17-bit encoder, and the same IP65 protection. They differ in their operating point.

Choose the HC-SFS203B where axis traverse speed is the cycle-time bottleneck and continuous torque demand stays comfortably within 6.37 Nm. Choose the HC-SFS202B where the axis must sustain higher continuous torque — accepting the larger 176 × 176 mm flange in exchange for the extra torque headroom. Note the flange size difference: these two motors do not share the same mounting bolt pattern and are not directly interchangeable without a mounting plate change.

Typical Applications

High-speed pick-and-place axes. Horizontal translation axes on SCARA and Cartesian pick-and-place systems that move moderate payloads over short distances at high cycle rates benefit from the 3,000 rpm rated speed. The brake holds the end-effector in position between pick and place strokes when the servo transitions to a hold state, preventing any settling drift during the gripping operation.

Packaging machine servo feeds. Film pull, product infeed, and cross-seal station drives on packaging equipment run at high cycle rates with moderate torque loads. The 3,000 rpm rating supports the high axis velocities needed for throughput targets, and the absolute encoder handles the precise web register that product quality depends on.

Multi-position servo indexing tables. Rotary indexing stations cycling rapidly through fixed angular positions — component loading stations, multi-process assembly tables — use 3,000 rpm servo drives on the index axis for fast dwell-to-dwell motion. The brake holds each index position firmly during the process dwell time without relying on servo lock.

Auxiliary axes on CNC machining centres. Tool magazine drive axes, chip conveyor drives, and coolant servo axes on CNC machines are well-matched to the HC-SFS203B's capacity and speed. The IP65 rating with oil seal handles the machine tool environment, and the compact 130 × 130 mm flange fits the confined spaces typical of CNC auxiliary axis installations.

Servo-controlled dispensing and dosing axes. Dispensing systems for adhesive, sealant, or fluid-fill applications use servo drives in speed or torque control mode to regulate flow rate. The 3,000 rpm rated speed provides the necessary dynamic range for precise flow adjustment, and the 17-bit encoder resolution supports smooth, ripple-free velocity at low dispensing rates.

New In Box, Factory Sealed

Factory sealed means original Mitsubishi packaging with all protective covers intact — shaft-end cap, encoder connector seal, and power connector cover all in as-manufactured condition. The motor has never been installed, never powered, and carries no thermal or mechanical history. For a machine waiting on this part, in-stock new-in-box delivers a known-condition unit without the variables of repair or the delay of refurbishment.

Stored correctly — stable temperature, low humidity, away from vibration — factory-sealed stock maintains full specification for several years. Beyond five years in storage, a pre-commissioning slow shaft rotation helps redistribute bearing grease before first power-up.

Frequently Asked Questions

Q1: Which amplifiers are compatible with the HC-SFS203B?

The HC-SFS203B requires a MR-J2S-200 class amplifier from the MELSERVO-J2S platform. The three main variants are the MR-J2S-200A (general-purpose analog/pulse command), MR-J2S-200B (SSCNET fiber-optic bus for Mitsubishi motion controllers), and MR-J2S-200CP (built-in positioning with CC-Link). All three support the 17-bit encoder and the motor's 10.4A rated current. The HC-SFS203B is not compatible with original MR-J2-200 amplifiers or with MR-J3 / MR-J4 amplifiers.

Q2: What is the difference between the HC-SFS203B and the HC-SFS202B?

Both are 2kW motors with electromagnetic brakes and straight shafts, using the same MR-J2S-200 amplifier and 17-bit encoder. The key differences: the HC-SFS203B is rated at 3,000 rpm with 6.37 Nm continuous torque and uses a 130 × 130 mm flange. The HC-SFS202B is rated at 2,000 rpm with 9.55 Nm continuous torque and uses a 176 × 176 mm flange. They use different mounting footprints and are not directly interchangeable without a mounting plate change. Choose based on whether speed or continuous torque is the primary axis requirement.

Q3: What is the difference between the HC-SFS203B and the HC-SFS203 (without the B)?

The two motors are identical in every specification — same 2kW output, 3,000 rpm, 6.37 Nm, 17-bit encoder, straight shaft, 130 × 130 mm flange, and MR-J2S-200 amplifier compatibility. The HC-SFS203B has a spring-applied electromagnetic brake; the HC-SFS203 does not. Choose the "B" variant for any axis where the load must be held mechanically at rest when the servo is de-energised. For axes with no gravitational or unbalanced load, and where servo lock is sufficient during all stop conditions, the standard HC-SFS203 is appropriate.

Q4: How is the electromagnetic brake sequenced correctly with the MR-J2S amplifier?

The MR-J2S amplifier provides the MBR (electromagnetic brake interlock) output signal to control the brake relay. The MBR delays brake engagement until the amplifier has confirmed the motor has decelerated to a stop. Wiring the brake relay directly from an e-stop contact — bypassing the MBR signal — risks engaging the spring against a rotating shaft, causing premature brake wear. Always route brake relay control through the MBR output. Also fit a surge absorber across the brake coil terminals to suppress inductive voltage spikes at switch-off.

Q5: Does the absolute encoder require a battery in the motor itself?

No. The 17-bit serial absolute encoder retains multi-turn position data between power cycles using a Mitsubishi A6BAT lithium battery housed in the MR-J2S servo amplifier — not in the motor body. As long as the A6BAT is healthy, absolute position is preserved through any power interruption, and the machine restarts without a homing cycle. Replace the A6BAT at the first low-battery alarm from the amplifier; waiting for full battery depletion causes loss of stored absolute position and requires a reference return cycle before production can resume.