The YASKAWA SGM7G-30A7A6E is a Sigma-7 (SGM7G) rotary AC servomotor built for motion systems that need high torque at lower rated speed with medium inertia behavior—exactly the “heavy but precise” zone where large indexing tables, conveyors, packaging axes, and general machinery tend to live. In the Sigma-7 lineup, the SGM7G family sits in the “medium inertia, low speed, high torque” category, balancing responsiveness with load-handling stability.
What makes this model practical in real builds isn’t just the headline torque. It’s the combination of:
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a 24-bit absolute encoder (fine position feedback and repeatable homing behavior)
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high efficiency / low heat generation (less thermal drama inside cabinets and end-effectors)
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and a mechanical package designed to ease retrofits, including flange compatibility with Sigma-5 and a compact footprint trend (Yaskawa cites downsizing potential).
This specific variant is listed with oil seal + holding brake (24 VDC), a common requirement when the axis must resist gravity back-driving, hold position during E-stop, or maintain load without continuous servo current.
Key Specifications (SGM7G-30A7A6E)
| Item | Value |
|---|---|
| Product family | Yaskawa Sigma-7 SGM7G rotary servomotor |
| Input power supply class | 200 V |
| Rated output | 2.9 kW |
| Rated torque | 18.6 N·m |
| Instantaneous max torque | 54 N·m |
| Encoder | 24-bit, Absolute |
| Shaft end | Straight shaft with key and tap |
| Options on this model | Oil seal + holding brake (24 VDC) |
| Dimensions (H × W × D) | 225 mm × 180 mm × 287 mm |
| Net Weight | 19.5 kg |
| Allowable load inertia guideline | “5 Times” (as listed on product page) |
Performance Character: Why SGM7G Exists
Servo sizing is usually a three-way trade: inertia match, torque margin, and control stability. The SGM7G series targets applications where the load inertia is not tiny (so ultra-high-speed “low inertia” motors aren’t ideal), yet you still want tight velocity and position control. Yaskawa positions SGM7G as medium inertia and high torque within Sigma-7 rotary motors.
In practice, that means this motor class tends to feel “calm under load.” With the right Sigma-7 drive (SERVOPACK), you can push strong acceleration without turning tuning into a long weekend. If your mechanism has gear reduction, belt transmission, or a large rotating mass (tables, rollers, spindles for positioning rather than cutting), the SGM7G profile often lands in a comfortable control region.
Feedback and Repeatability: 24-bit Absolute Encoder
The 24-bit absolute encoder is a core differentiator in modern servo systems because it supports high-resolution position feedback and more predictable recovery behaviors after power cycles. On the Yaskawa product listing, the encoder is specified as 24-bit and absolute for this model.
Why it matters:
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Smoother low-speed motion: better velocity estimation at crawl speeds.
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Cleaner indexing: tighter repeatability for rotary indexing and pick-and-place axes.
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Simplified homing strategy: absolute feedback can reduce homing travel and cycle time (implementation depends on system design and battery/encoder type in the full Sigma-7 ecosystem).
Brake + Oil Seal: Real-World Machine Requirements
This model’s configuration includes a holding brake (24 VDC) and an oil seal.
These are not “nice-to-have” in many machines—they’re how you avoid unpleasant physics.
Typical reasons to specify a brake:
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Vertical axes where gravity is the uninvited coworker.
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Safety requirements where the axis must hold position at power loss.
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Systems where you want a mechanical holding function so the servo doesn’t need continuous current to resist load torque during idle.
Typical reasons to specify an oil seal:
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Environments with mist, splash, or lubricant presence near the motor shaft.
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Gearbox-coupled systems where sealing helps protect internal bearings and encoder-side contamination paths.
Integration Notes: What to Check in a Build
| Topic | What to verify | Why it matters |
|---|---|---|
| Drive matching | Sigma-7 200 V class SERVOPACK suitable for ~3 kW | Prevents under-sizing and thermal trips |
| Brake wiring | 24 VDC brake supply, correct interlock logic | Safe stop behavior and reliable release |
| Encoder interface | Confirm compatible feedback interface for the chosen drive/controller | Avoids “it powers up but won’t run” headaches |
| Mechanics | Coupling/gearbox rated for peak torque (54 N·m) | Peak torque events break cheap couplers first |
| Mounting & space | 225×180×287 mm envelope and cable bend radius | Cabinet and machine layout reality |
| Handling | 19.5 kg motor mass, mounting orientation and lifting | Field install practicality |
Where SGM7G-30A7A6E Fits Best
This motor is a strong fit when your application wants high torque density and stable control behavior rather than extreme RPM. Common use cases include:
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Rotary indexing tables and dial machines
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Packaging and converting equipment (rollers, feeders, cut-to-length axes)
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Material handling axes (conveyors, diverters, transfer units)
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General automation with moderate reflected inertia and the need for “no drama” torque reserves
Yaskawa’s own Sigma-7 rotary motor positioning emphasizes the SGM7G class for medium inertia, low speed, high torque roles.
Summary
The YASKAWA SGM7G-30A7A6E is a 200 V, 2.9 kW Sigma-7 rotary servomotor engineered for high torque motion axes that benefit from medium inertia stability and high-resolution absolute feedback. With 18.6 N·m rated torque, 54 N·m peak torque, 24-bit absolute encoder, and integrated oil seal + 24 VDC holding brake, it’s built for serious machine duty where loads are real and repeatability is not negotiable.
