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

Writing an RFQ for a servo press - what to include?

sam_automation

Writing an RFQ for a new servo press and I want to make sure I'm asking the right questions. What should be in there?

**Why Specification Matters
**
A poorly specified servo press RFQ results in quotes that are not comparable, and a press that may not meet your production needs. Use this checklist to write a complete specification.

**Required Specifications
**
**Tonnage:** State nominal tonnage AND the position at which it is rated. Example: 200T at 6mm above BDC. Some manufacturers rate tonnage at BDC (optimistic) vs. 6mm above BDC (conservative).

**Stroke:** Maximum stroke length in mm. For deep drawing, you need stroke = draw depth x 2.5 minimum.

**Shut height:** Distance from slide bottom to bolster top at BDC. Must accommodate your die height.

**Bolster size:** Length x width in mm. Must be larger than your die footprint.

**SPM range:** Minimum and maximum SPM. State your production target SPM.

**BDC repeatability:** State required value. Typical: 0.01mm for general forming, 0.005mm for precision.

**Motion profile:** State if you need programmable speed profiles, dwell at BDC, pendulum motion.

**Drive and Control Specifications
**
- Control system brand preference (Siemens, Fanuc, Yaskawa, Mitsubishi)
- Safety category required (typically Category 4 / PLe for press applications)
- Network protocol (PROFINET, EtherNet/IP, EtherCAT)
- Data logging requirements (strokes per shift, tonnage history, fault log)

**Delivery and Support**

- Required delivery date
- Installation and commissioning support required
- Spare parts package
- Training requirements
- Warranty terms

carlos_mx

Add to the RFQ: require the vendor to run your actual part (or a representative test part) during the acceptance test. Paper specs are meaningless if the press can't make your part. We specify a 500-piece acceptance run with CPK > 1.33 on critical dimensions. If the press can't pass, we don't accept delivery.

jim_apps

From the vendor side: the more detail you put in the RFQ, the more accurate the quote. Vague RFQs get padded prices because we have to assume worst case. Include: material specs, part drawings, annual volume, target SPM, die weight, and shut height range. A good RFQ saves both sides time and money.

anna_plc

Biggest thing missing from most RFQs I see -- energy specs. Ask for the rated energy in kJ at the tonnage you actually need, not just peak tonnage. A 200-ton servo press with 30 kJ of energy is a very different machine than a 200-ton with 60 kJ. If you are doing deep draws or thick material you will hit the energy wall before you hit the tonnage limit and the press will just slow down or fault out.

Also ask about service response time in your region. We bought a press from a manufacturer with no local service and waited 11 days for a tech when the main drive faulted. Now every RFQ includes a requirement for 48-hour on-site response. If they cannot commit to that in writing we move on.

raj_pm

One more RFQ item that bites people later — servo motor cooling method. Air-cooled vs liquid-cooled is a huge difference in sustained tonnage capability. Air-cooled motors derate 15-25% in continuous operation above 20 SPM on heavy jobs. We had a 300T air-cooled press that could only sustain 220T at 30 SPM because the motor hit thermal limits. The vendor spec sheet said 300T — technically true, but only for intermittent duty.

Also specify the drive manufacturer and model in the RFQ, not just "servo drive included." There's a massive difference between a Yaskawa Sigma-7, a Mitsubishi MR-J4, and whatever off-brand drive some builders use. The drive determines your tuning flexibility, diagnostic capability, and spare parts availability for the next 15 years. We standardized on Yaskawa across our plant — one set of spare drives, one training program, one set of parameter backup tools.

And don't forget to ask about the HMI software licensing model. Some builders charge $5-8K for the press control software license, then another $2-3K/year for "support" that's really just keeping the license active. Get that in writing before you sign. We got burned on this with our first servo press — the annual software fee wasn't in the quote.