Laser Cutting Head Vibrates: Troubleshooting with the DIF Reading

Read the DIF value first

Watch the BCS display while cutting and first determine whether the issue may be electrical interference. With the head about 2–3 mm above the sheet, press 5 on the height-controller main screen and observe the DIF reading. The source uses a maximum DIF of 30 to separate two cases: DIF ≤30 and DIF >30.

If DIF is 30 or lower

The source treats a DIF reading at or below 30 as indicating that capacitive-sensor interference is unlikely to be the cause. Recalibrate the height controller with a sheet under the head, enable tracking and see whether the head vibrates.

• If the head does not vibrate after tracking is enabled, close the laser shutter and run the machine’s approved no-gas simulation. If it remains stable, consider whether the job is cutting thick sheet (>6 mm) or thin sheet (<3 mm). For a thick-sheet job on FSCUT8000, the source suggests trying thick-plate mode. For thin sheet, it suggests reducing the height-controller following gain gradually.
• The source also describes enabling the controller’s vibration-suppression function under F2 → 8 advanced parameters and adjusting its suppression time; longer time is described as stronger suppression. Use only settings approved for the controller and machine.
• If the head vibrates during the no-gas simulation, the sensor may be damaged or installed incorrectly. Reinstall it or replace the relevant component after checking the model.
• If vibration starts only when tracking is enabled, check whether servo-drive stiffness/gain is set too low or too high, and whether the Z-axis screw-module coupling is slipping. Have a qualified technician inspect these settings and mechanics.

If DIF is above 30

The source associates a reading above 30 with possible electromagnetic interference. It suggests isolating likely sources one at a time and watching the DIF value. Power isolation and electrical checks should be performed by qualified personnel using the machine maker’s procedure.

• If the DIF value stays high with little change, the source suggests checking the height-controller switching power supply.
• If DIF falls below 30 after a suspected source is isolated, inspect grounding on the servo or external electrical equipment. The source also mentions a ferrite ring on the servo power cable, grounding the controller power-input FG terminal, and using a star-ground arrangement rather than daisy-chain wiring.

Need technical help?

Controller menus and thresholds vary by machine. Do not change electrical wiring or servo settings unless qualified. Send PK LASER the controller model, alarm and a short video. Business / Zalo: 0394 552 839. Technical support: 0394 542 839.