How to Use a Press Brake Light Curtain (Operation & Commissioning)
Use this planning checklist to prepare a qualified commissioning assessment for a press brake light curtain. Important: always follow your machine manual, local regulations, and a thorough risk assessment. For a step-by-step walk-through, see: Steps for Installing Laser Protection Devices on Bending Machines Article.
The press photoelectric protection guide provides the wider press-safeguarding context; a press brake and a mechanical punch press do not automatically share the same machine-specific rules. See ISO 13855:2024 for positioning scope and the exact machine/device manuals for the approved application.
Safety & Compliance
Start with a safe architecture. Use a dual-channel safety light curtain and a safety relay/controller capable of ISO 13849-1 PL d/e (Category 3/4). This isn’t just a paperwork target—it’s what gives you diagnostics, fault tolerance, and predictable stopping behavior. Our DAIDISIKE products are designed to integrate cleanly into such systems.
How It Works & Key Terms
- Tx/Rx beams: Break a beam and the OSSD outputs switch off within about 10–30 ms, commanding a stop.
- Resolution: 14 mm (finger detection) or 30 mm (hand protection) are common on press brakes.
- Protective height: The beam field must cover the whole hazardous opening across the working range.
- Safety controller: verify compatible dual-channel evaluation and the reset/EDM functions required by the validated design. Do not assume those functions from a relay model name.
Blanking or muting is permissible only within the machine manufacturer's documented safeguarding mode. Evaluate changed detection capability, any residual access route, limits and fault behaviour before use; do not enable either simply because a workpiece interrupts the field.
Pre-Installation Checklist
- Complete a documented risk assessment: confirm resolution and protective height for the job.
- Prepare rigid brackets, a clean 24 VDC supply, shielded cabling, and a stop-time meter.
- Have Ø14 mm and Ø30 mm test rods on hand—don’t skip the rod tests.
- Check the foot pedal / start logic is dual-channel and free of unsafe latching.
Mounting Distance — The Safety Distance (ISO 13855)
Position the curtain so motion reaches a full stop before hands can reach the danger zone. Measure—don’t guess.
S is separation distance; T includes all sensor, qualified safety logic and final stopping delays. For the conventional perpendicular hand-detection method, begin with K = 2000 mm/s and C = 8 × (d − 14) for 14 mm ≤ d ≤ 40 mm. Reaching-over and other geometries require separate checks. The 1600 mm/s recalculation is conditional, not a universal hand speed; manufacturer instructions cannot waive applicable requirements.
| Parameter | Value |
|---|---|
| Machine stop time | 0.090 s |
| System delay (curtain+controller) | 0.025 s |
| Total T | 0.115 s |
| Resolution & C | 30 mm → C = 128 mm |
| Safety distance S | 2000 × 0.115 + 128 = 358 mm Historical arithmetic only; not a complete ISO 13855:2024 or press-brake approval |
Re-check T and S whenever you change speed, tonnage, tooling, or the blanking/muting setup. Validate under the actual production conditions you intend to run. For background, see our Sensor FAQ.
Wiring & Control Logic (Typical Cat.4 / PL e)
- Feed a stable 24 VDC supply.
- Land OSSD1/OSSD2 on two independent safety inputs—no merging.
- Use EDM to monitor contactors/actuators and catch welded contacts.
- Prefer manual reset and confirm restart interlock behavior.
- Include E-stops and guard switches in the same safety function where appropriate.
- Never bypass any part of the safety chain during production.
Alignment & Commissioning
- Align: Set Tx/Rx until the full-height indicators read steady green.
- Test: Use Ø14/Ø30 mm rods across multiple heights and positions; verify the full protective response and validated stopping time.
- Measure stop time: Record the worst case at maximum speed/tonnage and keep the reading.
- Check logic: Verify manual reset and restart interlock perform as intended.
- Configure blanking/muting: Keep limits tight (beams, position, timeout). Any fault must restore full protection.
- Document: File the wiring diagram, stop-time data, S-distance sheet, and inspection checklist. Label the work area.
Routine Inspection & Maintenance
- Daily: Visual check; run a few quick interruptions.
- Weekly: Verify stopping time with the meter.
- Monthly: Interrupt every beam zone and review the logs.
Keep an eye on lens contamination, reflections, vibration drift, poor shielding/grounding, and overly generous blanking/muting settings.
FAQ
Workpiece blocks the beams while bending—what should I do?
Do not enable blanking or muting merely to stop production trips. First check the machine manufacturer's approved safeguarding modes. If a documented function is permitted, assess the changed detection capability and access paths, recalculate separation distance and validate its limits and fault response.
14 mm vs 30 mm resolution—how to choose?
Use the documented detected-object capability required for the actual finger or hand hazard and approved press-brake safeguarding mode. A coarser device is not inherently safer or more robust for the task. Include its detection capability in the complete positioning calculation before choosing 14 mm, 30 mm or another permitted option.
Can I bypass the curtain for set-up?
A key switch alone does not authorize bypass. Use only a documented, validated setup mode with the protective measures required by the machine manufacturer and risk assessment. For servicing, follow the applicable hazardous-energy isolation procedure; do not run production with protection defeated.
Do I need to re-calculate after changing tooling or speed?
Reassess stopping performance and safeguard positioning whenever tooling, speed, load or the safeguarding configuration changes in a way that can affect the function. Use the applicable ISO 13855:2024 and press-specific method, not only the historical S = K × T + C expression.