The Yaskawa SGM7A-10A6A21 is a Sigma-7 (SGM7A) brushless rotary AC servo motor engineered for industrial motion systems that must be fast, repeatable, and stable under real production duty cycles. In the Sigma-7 lineup, SGM7A is positioned as the general-purpose “workhorse”: a wide range of low-inertia motors covering low to medium power, designed to deliver high power density and high torque performance when required.
This specific model is a 200 V class, 1.0 kW servomotor equipped with a 24-bit batteryless absolute encoder and configured without additional options (no holding brake, no shaft seal options in this code). It uses a straight shaft without key, which is typically chosen for clamp-style couplings and precision hubs where concentricity, repeatability, and clean assembly matter.
Why 1 kW is a useful “platform size” in automation
Many machines hit a turning point around the 1 kW class: loads are large enough that small-axis motors begin to run warm or feel underdamped, but not so large that you want a higher inertia motor family or a much larger frame. The SGM7A-10A6A21 is built to sit right in that middle ground—supporting high response and fast cycle times while staying compact enough for dense machine layouts.
Yaskawa’s published torque and speed ratings show a motor meant for both continuous work and aggressive short bursts:
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Rated torque: 3.18 N·m
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Instantaneous maximum torque: 11.1 N·m
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Rated speed: 3000 min⁻¹
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Maximum speed: 6000 min⁻¹
That peak-to-rated torque headroom is what lets a properly tuned axis accelerate hard, absorb transient disturbances, and still settle cleanly—without oversizing the motor purely “for safety.” It also gives you flexibility in transmission choices (belt reduction, gear reduction, screw pitch) because you have room to trade speed for torque, or vice versa, without immediately running into thermal limits.
Motion quality starts with inertia (and the numbers matter)
Servo behavior is not only a motor spec sheet; it is a system interaction between motor inertia, reflected load inertia, stiffness, friction, and controller gains. For this model, Yaskawa lists:
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Motor moment of inertia: 0.972 × 10⁻⁴ kg·m²
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Allowable load moment of inertia: 20×
This is a practical design signal. A 20× allowable inertia ratio suggests the motor/drive ecosystem is intended to handle a fairly wide range of loads, as long as mechanical design is sane and tuning is done with discipline. In applications like indexing conveyors, rotary tooling, or belt-driven slides, the low-inertia philosophy of SGM7A helps shorten settling time and makes the axis feel “snappy” when the structure is stiff and backlash is controlled.
Batteryless absolute 24-bit encoder: precision without battery maintenance
The SGM7A-10A6A21 uses a 24-bit batteryless absolute encoder. High-resolution feedback improves fine positioning, low-speed smoothness, and disturbance rejection. The “batteryless absolute” aspect can also reduce service friction compared with battery-backed schemes, because it avoids periodic battery replacement cycles and the operational risk of battery alarms appearing mid-production.
At the platform level, Yaskawa’s Sigma-7 materials emphasize 24-bit high-resolution encoder installation as a defining SGM7A characteristic, targeting precision positioning across the range.
Mechanical integration: compact 80 mm flange class, keyless shaft
Mechanically, this motor is designed for modern compact machine frames and standardized mounting patterns:
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Flange dimension (LC): 80 mm; Flange diameter (LA): 90 mm
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Shaft diameter (S): 19 mm; Shaft length (Q): 40 mm
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Overall dimensions (H × W × D): 94.7 × 80 × 170 mm
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Weight: 3.1 kg
The straight shaft without key configuration is commonly paired with clamp couplings or precision hubs. The upside is clean assembly and good concentricity potential; the responsibility is coupling selection, tightening method, and alignment control. If your axis sees frequent reversing or shock loading and you prefer keyed hubs, SGM7A also exists in keyed/tapped shaft variants—but this specific model is optimized for keyless coupling strategies.
Efficiency, heat, and cabinet density: Sigma-7 system thinking
Servo motor selection has “hidden” benefits when it reduces heat and simplifies cabinet design. Sigma-7 materials highlight high efficiency and low heat generation, and the Sigma-7 brochure describes improved motor efficiency reducing heat generation by around 20% (system-level claim) and enabling dense installation.
The brochure also notes that DC power coupling of axes can allow energy sharing and potential energy savings (system-level feature), which is relevant on multi-axis machines where some axes frequently regenerate energy during deceleration. Even if you do not design for energy recovery explicitly, this “system efficiency” mindset tends to show up as lower cabinet temperature and more stable performance over long shifts.
Commissioning and uptime: performance is also “time to stable motion”
In production environments, the most valuable servo feature is often not the absolute peak torque, but how quickly the axis can be commissioned, tuned, and kept stable over time. The Sigma-7 brochure highlights commissioning aids such as presets, “tuning-less” operation concepts, and auto-tuning intended to speed setup. For OEMs building repeat machines, or for maintenance teams doing standardized replacements, that shortens ramp-up time and reduces the chance of “it runs, but it vibrates” outcomes.
Where SGM7A-10A6A21 fits best
Because this motor is 1 kW, batteryless absolute, keyless shaft, and without holding brake, it is commonly suited to:
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High-throughput indexing and transfer systems (conveyors, shuttles, rotary indexers)
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Packaging and converting machinery with short cycles and frequent accelerations
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Assembly automation axes where repeatable positioning and fast settling are critical
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Test and inspection stages requiring smooth low-speed control and repeatability
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Retrofit and modernization projects where a compact 80 mm flange class motor is preferred
If your axis must hold a vertical load safely when power is removed, you would typically select a brake-equipped variant in the same SGM7A family rather than relying on the servo loop alone, since this model is explicitly listed as “without options.”
Technical Specifications Table — Yaskawa SGM7A-10A6A21
| Parameter | Specification |
|---|---|
| Manufacturer / Series | Yaskawa Sigma-7, SGM7A Rotary Servomotor |
| Model | SGM7A-10A6A21 |
| Input power supply | 200 V |
| Rated output | 1.0 kW |
| Rated torque | 3.18 N·m |
| Instantaneous maximum torque | 11.1 N·m |
| Rated speed | 3000 min⁻¹ |
| Maximum speed | 6000 min⁻¹ |
| Encoder resolution | 24-bit |
| Encoder type | Batteryless absolute |
| Options | Without options |
| Shaft end | Straight without key |
| Motor moment of inertia | 0.972 × 10⁻⁴ kg·m² |
| Allowable load moment of inertia | 20× |
| Flange dimension / diameter | 80 mm / 90 mm |
| Shaft diameter / length | 19 mm / 40 mm |
| Dimensions (H × W × D) | 94.7 × 80 × 170 mm |
| Weight | 3.1 kg |
Summary
The Yaskawa SGM7A-10A6A21 is a compact, production-oriented 1 kW Sigma-7 rotary servo motor that combines a 24-bit batteryless absolute encoder, high peak torque capability, and a mechanical package suited to modern machine frames and clamp-coupling shaft strategies. Backed by Sigma-7 system features emphasizing commissioning speed, efficiency, and dense cabinet integration, it is a strong choice for mid-size axes where fast motion response and repeatable positioning directly translate into throughput and stability on the factory floor.
