How to Use a Press Brake Light Curtain (Operation & Commissioning)
We’re engineers at DAIDISIKE and we work with press brake safety every day. The notes below come from real commissioning jobs in the field—kept simple, practical, and aligned with standards. Use this as a hands-on checklist when you install or verify 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.
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: Dual-channel monitoring, EDM feedback, manual reset, and restart interlock are standard features.
For press brakes, you may need blanking (to let material pass) or muting during bending. Keep limits tight, restoration automatic, and logs clear—shortcuts here are a common cause of incidents.
Pre-Installation Checklist
- Do a quick 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 = minimum distance (mm); K = approach speed (typically 1600 mm/s for hands/upper limbs); T = total response time (stop time + curtain/ controller delays); C = offset (≈0–20 mm for 14 mm; ≈120– 130 mm for 30 mm). Manufacturer tables, where provided, take precedence.
| 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 = 120 mm |
| Safety distance S | 1600 × 0.115 + 120 = 304 mm Mount ≥ 305 mm |
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; stopping must be immediate.
- 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?
Use floating blanking with a strict limit on adjacent beams. For deeper bypass, configure position/time/part-based muting with time-out and auto-restore.
14 mm vs 30 mm resolution—how to choose?
Pick 14 mm for higher-risk close work (finger detection). Use 30 mm for general hand protection and better robustness. Let the risk assessment drive the choice.
Can I bypass the curtain for set-up?
Only with a key-switch plus hold-to-run/low-speed, with clear indication and logging. Never run production with the safety function defeated.
Do I need to re-calculate after changing tooling or speed?
Yes. Any change that affects stop time or approach paths means you must re-measure T and re-calculate S.