What is a servo press?

A servo press uses servo motors for precise force and position control during forming operations.

How do I calculate servo press tonnage?

Use our free tonnage calculator at servopress.club/tonnage-calculator.html

Siemens S120 vs Yaskawa Sigma-7 - which drive do you prefer?

ryan_ops

We're standardizing on one servo drive platform and it's down to Siemens S120 vs Yaskawa Sigma-7. Anyone run both and have a preference?

**Application Context
**
Both Siemens SINAMICS S120 and Yaskawa Sigma-7 are used in servo press applications. Here is a technical comparison for engineers specifying or maintaining servo press drives.

**Siemens SINAMICS S120
**
**Strengths:**
- Centralized multi-axis architecture: one CU320-2 controls multiple axes
- PROFINET/PROFIBUS integration: easy connection to Siemens PLCs
- Advanced safety functions: STO, SS1, SLS, SOS built-in
- Strong in European and Chinese press manufacturers

**Weaknesses:**
- Higher cost per axis
- More complex commissioning (STARTER/TIA Portal required)
- Larger cabinet footprint

**Yaskawa Sigma-7
**
**Strengths:**
- Simpler commissioning: SigmaWin+ auto-tuning works well for press loads
- Lower cost per axis
- 23-bit encoder: 8,388,608 pulses/rev (excellent resolution)
- Strong in Japanese and North American press manufacturers (Aida uses Yaskawa)

**Weaknesses:**
- Distributed architecture: each axis needs its own drive
- EtherCAT or MECHATROLINK-III required for multi-axis sync
- Less integrated safety compared to S120

**Key Specs Comparison**

| Feature | S120 | Sigma-7 |
|---------|------|----------|
| Max current | Up to 1200A | Up to 400A |
| Encoder | 20-bit | 23-bit |
| Bus | PROFINET | MECHATROLINK-III |
| Auto-tune | Manual | Automatic |

**Recommendation
**
S120: choose if your press uses Siemens PLC, you need centralized multi-axis control, or you are in Europe.

Sigma-7: choose if you need simpler maintenance, lower cost, or your press is Aida/Komatsu brand.

anna_plc

I've tuned both extensively. Yaskawa is easier to set up out of the box —the auto-tuning works well for press applications. Siemens S120 has more parameters and more flexibility but takes longer to optimize. For a shop without a dedicated controls engineer, Yaskawa. For a shop with controls expertise that wants maximum performance, Siemens.

raj_pm

From a maintenance perspective: Yaskawa spare parts are cheaper and more available. A replacement Sigma-7 amplifier is about 60% the cost of an equivalent S120 module. Siemens has better remote diagnostic tools though —TIA Portal's online monitoring is excellent for troubleshooting without being at the press.

carlos_mx

Run both in production, S120 on two Komatsu presses and Sigma-7 on an Aida. My take after 5+ years with each:

Siemens S120 wins on deterministic cycle time. The SINAMICS Integrated safety (STO/SS1/SLS all on the drive) means you do not need a separate safety relay for most press applications, which simplifies the cabinet. The downside is commissioning time. Expect 2-3 days of parameter tuning with STARTER or TIA Portal to get the torque loop response right for press duty. The default auto-tune is optimized for machine tools, not the high-inertia impact loads of a press.

Yaskawa Sigma-7 wins on ease of setup and cost of ownership. The press-specific auto-tune mode (Pn170=3) gets you 90% of optimal performance in 20 minutes. Spare parts are cheaper and the amplifier swap procedure is simpler because the parameters store on the encoder battery backup, not just the amplifier EEPROM. When a drive fails at 2am, your maintenance guy can swap it and be running in 30 minutes without a laptop.

One thing people overlook: the Sigma-7 has a 3.2kHz current loop vs 1.25kHz on the S120 CU320. For press applications where you need fast torque response during the forming stroke, that matters. The S120 compensates with better feedforward algorithms but you have to tune them manually.

If I were standardizing a new shop today with 5+ presses: Yaskawa for the maintenance simplicity. If I had one critical press doing exotic forming profiles: S120 for the flexibility.

toolndye_dave

We switched from S120 to Sigma-7 on our last press purchase and honestly regret it a little. The Yaskawa is easier to set up out of the box, but when something goes wrong the diagnostic tools are nowhere near as good as Siemens. The S120 trace function is incredible for catching intermittent faults — you can log 8 channels simultaneously at 125 microsecond resolution. Yaskawa's SigmaWin+ gives you maybe 2 channels at 1ms. When you're chasing a vibration issue at 200Hz, that resolution matters.

That said, the Sigma-7 auto-tuning actually works on presses, which surprised me. The S120 auto-tune is basically useless for anything with variable load — you always end up tuning manually. So it depends on whether you value ease of setup or depth of diagnostics.

carlos_mx

Coming back to this thread after another year of running both side-by-side on similar tonnage classes.

Where I've landed: **S120** when the customer already has TIA Portal in the plant and the maintenance crew speaks Siemens. The integration with safety (F-CPU, FSoE) and the diagnostics buffer make commissioning faster on complex line projects. Drive-CLiQ is a love/hate relationship ??clean when it works, brutal when a connector goes intermittent.

**Sigma-7** when it's a standalone press cell or a job-shop environment. Tuning is more forgiving for people who don't live in drive parameters every week, the encoder battery story is simpler, and the regen sizing rules are honest. Spare parts pricing is also noticeably better for small shops.

Neither is wrong. The expensive mistake is picking based on the press OEM's preferred relationship rather than who's going to maintain it for the next 15 years.