The YASKAWA SGM7G-20AFA61 is a Sigma-7 (SGM7G) rotary AC servomotor designed for industrial motion systems that need stable torque delivery, predictable tuning, and reliable positioning in medium-inertia applications. In the Sigma-7 rotary lineup, SGM7G motors are positioned for medium inertia, low speed, high torque duty—an engineering “sweet spot” for many real machines where loads are not feather-light, yet responsiveness and accuracy still matter.
This particular model is a 200 V-class, 1.8 kW motor with a straight shaft (key and tap) and no extra mechanical options (no brake, no seal). It uses a 24-bit incremental encoder, which is common in high-performance servo systems where the drive/controller handles fast feedback loops and the machine’s homing strategy is based on sensors, marks, or mechanical references.
What you get, practically, is a compact torque-capable motor intended for production equipment that runs long hours: packaging and converting lines, conveyors and transfer modules, indexing mechanisms, general automation axes, and many other machines where repeatability and uptime matter more than flashy peak RPM.
Key Specifications (SGM7G-20AFA61)
| Item | Value |
|---|---|
| Product family | Sigma-7 Rotary Servomotor, SGM7G |
| Input power supply | 200 V |
| Rated output | 1.8 kW |
| Rated torque | 11.5 N·m |
| Instantaneous maximum torque | 28.7 N·m |
| Rated motor speed | 1500 min⁻¹ (rpm) |
| Allowable load inertia guideline | 5 Times (listed as allowable load moment of inertia) |
| Encoder resolution | 24-bit |
| Encoder type | Incremental |
| Shaft end | Straight with key and tap |
| Options | Without options |
| Dimensions (H × W × D) | 169 mm × 130 mm × 229 mm |
| Weight | 8.6 kg |
Why the SGM7G Class Is Useful in Real Machines
Servo motor selection isn’t only about “power.” It’s about how a motor behaves when connected to the messy reality of inertia, friction, compliance (belts/couplings), and variable loads. Yaskawa positions the SGM7G group as medium inertia, low speed, high torque in Sigma-7 rotary servomotors.
That positioning usually maps to machines like:
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Indexing and intermittent motion: tables, feeders, starwheels, diverters
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Material transport: conveyor sections, transfer axes, pusher modules
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Web handling / packaging: rollers, pullers, seal/cut axes (with appropriate mechanics)
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General automation axes: positioning stages where the reflected inertia is not tiny
The big point: an SGM7G motor is typically chosen because it stays stable and controllable when the load is substantial enough to make low-inertia motors feel twitchy or under-torqued.
Encoder Choice: 24-bit Incremental Feedback
The SGM7G-20AFA61 is specified with a 24-bit incremental encoder.
Incremental encoders are widely used in servo systems because they support high-speed feedback loops and consistent motion control once referenced. In many factories, incremental feedback remains standard because:
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It integrates smoothly with many motion controllers and servo drives.
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Homing and referencing can be tailored to the machine (home switch, hard stop, mark sensor).
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Maintenance teams often have established practices for incremental systems.
This model’s high encoder resolution supports smooth low-speed performance and fine velocity control when paired with the correct Sigma-7 drive and properly tuned loop parameters. Sigma-7 documentation and catalogs emphasize the unified Sigma-7 ecosystem across motors and SERVOPACKs for rotary/linear/direct-drive products.
Performance Perspective: Torque Where You Need It
With 11.5 N·m rated torque and 28.7 N·m instantaneous maximum torque, the motor offers a meaningful torque reserve for acceleration events, short-term load peaks, and transient disturbances.
That peak torque headroom is especially valuable in:
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Start/stop indexing cycles
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Short acceleration ramps to meet throughput
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Load changes (product size/weight variations, friction drift, belt tension shifts)
A practical integration note: size couplings, gearboxes, and mechanical linkages for transient torque, not just continuous torque. Peak events are where weak couplers and underspecified keyways tend to fail first.
Mechanical Package: Compact, Straight Shaft with Key and Tap
This motor uses a straight shaft with key and tap, making it a natural match for couplings, pulleys, and gearbox inputs that require positive torque transmission and service-friendly assembly.
It is also relatively compact for its output class, with a listed envelope of 169 × 130 × 229 mm and 8.6 kg mass.
Those numbers matter for machine builders and retrofits because they drive:
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Mounting plate stiffness and resonance behavior
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Cabinet/machine packaging and cable routing
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Installation effort and maintenance handling
Integration Checklist (What to Verify Before You Commit)
| Integration item | What to check | Why it matters |
|---|---|---|
| Drive matching | Sigma-7 SERVOPACK suitable for 200 V and motor capacity | Prevents mismatch, overheating, and performance limits |
| Homing method | Incremental encoder requires a defined referencing strategy | Avoids position ambiguity after power cycles |
| Inertia ratio | Confirm the load and reflected inertia vs motor capability (listed guideline “5 Times”) | Stability, tuning time, and overshoot control |
| Mechanics | Coupling/keyway/gearbox ratings for peak torque | Protects drivetrain reliability |
| Environmental needs | This model is “without options” (no brake/seal) | If you need holding or sealing, choose the correct variant |
Typical Use Cases
The SGM7G-20AFA61 is best described as a general-purpose high-torque servo motor for medium-inertia motion axes where you want stable control and robust acceleration without stepping up into much larger motor frames. It works well for:
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Conveying and transfer axes that must track speed accurately
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Indexing mechanisms that repeat hundreds of thousands of cycles
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Packaging machinery where quick acceleration and settling are required
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General automation modules where torque reserve improves uptime margins
Within the Sigma-7 lineup, that “medium inertia, low speed, high torque” identity is exactly what SGM7G is aimed at.
Summary
The YASKAWA SGM7G-20AFA61 is a 200 V, 1.8 kW Sigma-7 SGM7G rotary servomotor featuring a 24-bit incremental encoder, 11.5 N·m rated torque, 28.7 N·m peak torque, and a compact mechanical package with straight keyed shaft.
For machine builders and maintenance teams, it is a solid choice when the priority is repeatable industrial motion, torque headroom, and stable performance in medium-inertia axes—without the extra complexity of brake or seal options on this specific variant.
