Sinton:Protocols/Laser cutter

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Contents

Description

A laser cutter can be used cut complex and repeatable patterns into plastic for a wide variety of uses. This procedure describes the laser setup and cutting process.

Safety

  • Be prepared for a fire - when the cutter is active, always be present in the lab and monitor the cutting process
  • Use the minimum power setting to achieve the desired cut or etch
  • Ensure the fan is turned on and will stay on for the duration of the cutting process
  • After finishing a cut leave the laser cutter lid closed for 5 minutes in order to exhaust any fumes from the chamber

Responses to fires occurring in the laser cutter are categorized by intensity:

1. Small flare-ups the size, area and intensity of a candle flame: Open the hood and simply blow out the flame with air (do not use liquids).

Flare-ups are fires which are not self-sustaining (typically existing for less than 10 seconds in the laser cutter) and are most common. They are well-contained by the machine housing, and may be extinguished without the aid of a fire extinguisher. The laser cutting head and its optical components are resilient against damage from this level of heat and soot, though the lens on the bottom of the cutting head should be cleaned afterwards with lens paper (only!). Lens paper is found in the left-hand shelves above the sink as you enter MC222.

2. Medium fires the size and area less than a closed fist, and which do not reach the PMMA window of the hood in height: Get the fire extinguisher ready in-hand for use. Open the hood and wait ~2 seconds for the cutting head to retract to its start position. Unplug the laser power cable. Keep garments and hair well away from the flame. If a first attempt to blow out the fire with air fails (do not use liquids!), then use the fire extinguisher.

Fires of this size may quickly become self-sustaining to cover the entire material being cut or etched – this has included PMMA sheets in the past. Such fires are typically well-contained by the laser cutter housing, but have an intensity that threatens the cutting head (the red metal piece), breaching of the PMMA window in the hood, and personnel.

3. Large fires bigger than a fist, or which contact the PMMA window of the hood: Get the fire extinguisher ready in-hand for use. Unplug the laser cutter. Open the hood, keep garments and hair well away from the flame, and use the fire extinguisher. If the fire is not immediately extinguished, the fire alarm may be pulled and the lab evacuated according to U of T procedures, at the user’s discretion and common sense.

If a fire extinguisher is used, the incident must be reported within 24 hours using the “Online Workplace Accident/Incident Report for Employees” at http://www.ehs.utoronto.ca/resources/wcbproc/employee.htm. By submitting this form, U of T’s Fire Prevention Services (http://www.fs.utoronto.ca/utfp.htm) will investigate the incident and deliver a fully charged fire extinguisher to the lab.

Materials and Equipment

  • Universal CO2 Laser Cutter
  • AutoCAD Design Program
  • Material(s) compatible with laser cutting, listed in the laser cutter manual. Do not cut with materials that may release toxic gases, such as Teflon.

Cutting Procedure

  • Creating and sending a drawing to the cutter

Before cutting a sample a drawing must be sent to the laser cutter. Once an AutoCAD file has been created the following steps should be done before trying to cut the features using the laser.

  • Change the line colour to correspond to the order you want the features cut. The order of cutting by colour is: black, red, green, yellow, blue, magenta, cyan and orange.
  • Ensure all lines are set to a 'linetype' of continuous with a 'lineweight' of zero
  • Select 'Print' and change printer to 'MC-360.pc3'
  • Select 'Properties' and change the 'pen mode' to 'VECT' for the colours you wish to cut
  • Adjust the power, speed and ppi of colours to cut and select 'Set'
  • Now choose 'Plot Area' in the 'Plot' settings and select 'Window' in what to print. Ensure that your drawing is selected for this setting. Note: by selecting plot window the upper left portion of the window selection corresponds to (0,0)
  • Using the offset values decide where is the working area of the laser cutter your AutoCAD drawing will be cut (i.e. by default the cutter will cut at the top-left corner)

Print options screen Properties window showing cutting colours and settings

  • Laser Setup
  • Turn the exhaust fan on and ensure it is on for the duration of the cutting process
  • Open the hood and place the material to be cut on four metal spacers
  • To properly align the cutter height select the 'Z' button on the laser cutter and use the X-Y arrows to move the cutter to where you expect to cut
  • Place the alignment tool underneath the cutter and above your material so that the notch on the alignment tool is below the cutter
  • Adjust the 'Z' height with the up and down arrows till the alignment tool just touches the cutter
  • Now toggle the file name on the cutter to locate your file
  • Press start with the lid open to watch the cutter trace out the features, ensure that the cutter stays on the material
  • Cutting
  • Once ready close the lid and hit start again to begin cutting
  • If the first cut didn't go through your material the start button can be pressed again for another pass. Be careful not to shift the material between passes
  • After cutting is finished leave the lid closed with the fan on for 5 minutes to exhaust excess fumes
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