Laser Engraver Operational Safety Overview

Owned by jr_fackler (Unlicensed)
Last updated: Oct 18, 2023
4 min read

The engraver houses a Class IV CO2 Laser.


It is rendered safe for routine laboratory use--i.e. certified as a Class I system--because of these safety features.

Safety Features

Full enclosure

  • The full enclosure ensures that no scattering of the beam can cause eye damage.

  • The view window is covered with material that absorbs the wavelength of light generated by the laser.

  • The full enclosure contains vapor and particulate until air-flow vents it away.

  • The Keyence ML-Z9500 unit is also self-contained. The unit lasing aperture is shuttered.
    The shutter may be programmatically controlled under routine usage conditions.
    If there are any laser controller PLC errors in play, the device remains shuttered and the laser powered off.

Door safety interlock

When the laser is in operation, ensures the door cannot be opened until the laser is off and the door safety interlock is released. Direct electrical feedback from both the door safety interlock and airflow monitoring determine whether the Keyence controller will allow the laser to be turned on.

Manually overriding the door safety interlock will raise an electrical signal to the laser controller PLC. The error condition will cause the laser aperture to be shuttered, and the laser will be powered off. The error condition may be cleared by restarting the laser controller PLC.

Venting and airflow monitoring

Air-flow is intended to be constant on this system. It is tied to ship air handling systems.

Air-flow is monitored by a flow sensor. If air-flow is outside of expected (configured) thresholds, an electrical signal will be raised to the laser controller PLC. The error condition will cause the laser aperture to be shuttered, and the laser will be powered off.

Physical power abort

Abort. Depressing this switch causes the lasing aperture to be shuttered; cuts electrical power to the laser; and raises an error condition on the laser controller that may only be reset by power cycling the controller.

Release. Once error conditions or safety concerns have been addressed, the physical Abort switch may be released by turning the red knob slightly clockwise. The laser controller PLC must be restarted to clear the error condition.

Status lights

The status lights are reliable indicators of physical system states. Operators should be familiar with expected behavior.

Green 

  • Off. The door is open. The door safety interlock is open--preventing activation of the laser.

  • On. Solid. The door is closed. The door is safe to open.

  • On. Blinking (5x roughly once per second)--ephemeral state. The door is closed and the marking sequence has been activated. The door safety interlock is not yet engaged.
    The blinking state is used by LazerKatjie software when the marking process is started. The Marking Builder software does not employ this intermediate state.

Amber

  • Off. The laser is not activated.

  • On. The laser is activated. The door safety interlock is engaged. Air-flow is within the expected operating range.

When an engraving sequence is engaged by either of LazerKatjie or Marking Builder: the door interlock is engaged, the laser aperture is un-shuttered, laser marking continues until done or aborted.

Red

  • Off. No error state on the laser controller PLC.

  • On. The laser controller PLC indicates an error.

    • Communication with the laser control system is in an error state.

    • The laser is powered off.

    • The door safety interlock is engaged.

A video of light activity for the routine process of engraving sections from the catwalk.

Reflects: door closed (green steady); start marking pressed (green flashing); laser engaged, marking in progress (amber on); laser disabled, door safety interlock freed, door still closed (amber off, green on steady).

Marking one half of 4 sections takes 30 seconds. This clip has been abbreviated for instructional purposes.

Engraver software safety features

LaserKatjie software is used for the routine marking of section halves and thin section plates. Marking Builder is used for marking of other incidentals.

Troubleshooting

Q: LazerKatjie on rare occasions will indicate there is a laser error condition, even though the laser controller PLC shows green lights for both Power and Laser.
A: If the door is not fully seated and latched, the error signal it raises can prevent operation of the marking laser.

Q: The abort switch has been released, but laser marking still will not start.
A: Tripping the abort switch raises a critical error that may only be cleared by restarting the laser controller PLC and re-enabling the laser.

 

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