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

Safety standards - CE, OSHA, ISO - what applies to us?

ian_presstech

Got confused by all the safety standards that apply to our servo press installation. CE, OSHA, ISO — what actually applies and what do we need to do?

**Applicable Standards
**
Servo presses must comply with multiple safety standards depending on market:

**Europe (CE marking):**
- Machinery Directive 2006/42/EC
- EN ISO 16090-1: Machine tools safety — Machining centres
- EN ISO 13849-1: Safety of machinery — Safety-related parts of control systems
- EN 62061: Safety of machinery — Functional safety

**North America:**
- OSHA 29 CFR 1910.217: Mechanical power presses
- ANSI B11.3: Safety requirements for power press brakes (also applied to servo presses)
- CSA Z142: Code for power press operation (Canada)

**Safety Performance Level
**
For servo press safety functions (E-stop, two-hand control, light curtain), the required performance level is typically PLe / Category 4 per EN ISO 13849-1.

This means:
- Dual-channel safety circuit
- Cross-monitoring between channels
- Automatic fault detection
- Mean time to dangerous failure (MTTFd) > 100 years per channel

**Required Safety Functions
**
1. Emergency stop (Category 0 or 1 stop)
2. Two-hand control (Type IIIC per EN 574)
3. Light curtain or safety gate (Type 4 per IEC 61496)
4. Safe torque off (STO) on servo drive
5. Safe stop 1 (SS1) — controlled stop before STO

**Annual Safety Inspection**

All safety functions must be tested annually by a qualified person. Test results must be documented and retained for the life of the machine.

jim_apps

The most commonly missed safety requirement: the safety-rated monitored stop (SS1) function. CE requires that when a guard is opened, the press performs a controlled stop (decelerate to zero, then remove power) rather than just cutting power immediately. Most modern servo drives support SS1 but it needs to be configured and tested. I see it misconfigured on about 30% of installations I audit.

carlos_mx

Budget tip: get the safety assessment done BEFORE ordering the press. We ordered a press for a CE-marked line and then discovered we needed additional safety relays, a safety PLC upgrade, and modified guarding. Added $35K and 6 weeks to the project. If we'd done the assessment first, the vendor could have included it in the original package.

mchen_servo

One thing that trips people up — OSHA 1910.217 technically covers mechanical power presses, and servo presses fall into a gray area because they are not purely mechanical. Some AHJs (authorities having jurisdiction) apply it anyway, some don't. Get a written interpretation from your local OSHA area office before assuming you are exempt. We had an inspector cite us under 1910.217 for missing a presence-sensing device on a servo press, and we had to fight it for 4 months before it was withdrawn.

On the CE side, jim_apps is right about SS1. But also check your safety distance calculations per ISO 13855. I have seen shops put light curtains at the right height but too close to the point of operation. The press needs enough stopping distance that the operator's hand cannot reach the die before the slide stops. On a 200T servo that stopping distance can be 150-200mm depending on your decel rate. Get it wrong and the light curtain is just decoration.

ANSI B11.1 and B11.2 are the US equivalents worth reading. B11.2 specifically covers hydraulic and servo presses. Your insurance company will probably ask about these during the annual audit.

anna_plc

Adding to the OSHA gray area — if you're retrofitting an older mechanical press with a servo drive, you absolutely still fall under 1910.217 because the frame and clutch/brake mechanism are mechanical. The servo motor doesn't change the press classification in OSHA's eyes. We went through this with our 400T retrofit and the compliance officer was very clear about it.

Practical tip on the safety PLC side: don't cheap out on the safety controller. We tried using safety relays instead of a proper safety PLC on our first installation to save $4K. Ended up spending $12K six months later ripping it out and installing a Pilz PNOZmulti because the relay logic couldn't handle the muting sequences for our automated loading system. A safety PLC gives you the flexibility to modify muting zones, add light curtains, or change guard configurations without rewiring.

Also — annual validation of safety functions is not optional, even if your local AHJ doesn't explicitly require it. Document everything: SS1 stop times, STO response, light curtain reaction distance calculations. We keep a binder for each press. When the insurance auditor shows up (and they will), having that binder ready saves weeks of back-and-forth.