Can Spectar be laser cut? If so, how is it done?

YES! Sheet made from Eastman Spectar™ copolyester can be laser cut. Settings need to be modified from those typically used for acrylic. Typical laser cutting settings for acrylic require higher power (watts), higher frequency (pulses per sec), and less air assist compared to Spectar of similar thickness. See reference table for details.

Processing parameters for laser cutting

Laser cutting of plastic material is accomplished by the absorption of highly focused laser energy by the material whereby the longer wavelength of the laser light is converted into heat. The heat generated through this process produces a localized melting of the material (melt shearing process) and/or vaporizing of the material (sublimation process). A gas/air jet which acts coaxial to the laser beam forces the molten material and/or the vaporized material away from the cutting section.

The laser power and cutting speed need to be adjusted according to the sheet thickness. In general, the power is increased for thicker sheet while reducing the cutting speed at the same time. It is suggested to keep the frequency as high as possible (> 1 kHz), as the pulsing effect will produce striations on the surface (rough surface). Operating at high laser power (> 1000 W) can result in material degradation and yellowing of the sheet when the cutting speed is not optimized. Best cutting quality is achieved by minimizing the output wattage of the laser at a given sheet thickness and maximizing the cutting speed. Examples of CO2 laser settings are given in the table as a reference starting point for various sheet thicknesses.

Spectar Laser Cutting
  PMMA Spectar sheet
 Gauge, mils (inches)90 (3/32)90 (3/32)118 (1/8)177 (3/16)236 (1/4)
 Power, watts8060150150200
 Speed, inches/min2030886050
 Frequency, Hz4,0002,7506,0007,00020,000
 Cut height, inches–0.01–0.01–0.01–0.03–0.01
 Air pressure, psi2550505050

  • Lenses: Laser cutting devices have typical focal lengths of 1.5”, 2.5”, 5”, or 7.5”. Generally, the thicker the sheet, the higher the focal length of the lens. The focal point of the laser beam should be set at the middle of the material thickness to minimize the beam divergence.
  • Assisting gas—The coaxial gas/air jet removes the molten and/or vaporized products generated during the cutting process and protects the lens from being contaminated. The gas pressure needs to be adjusted, depending on the cutting speed and the thickness of the material.

  • Cut with protective masking in place to avoid buildup of vapor on cut surfaces.

  • When designing the path of the laser, avoid the laser beam passing two or more times over the same cut.

  • When cutting shapes with sharp corners, do not start the laser path at the corner, because this will increase the heat-affected zone and therefore the internal stress in the material. The laser starting point should be some distance away from the final cutting edge with the laser following a circular shaped path towards the final cutting edge.

Spectar Laser Cutting

 

 Click here to see laser cutting in action.

Laser cutting video

 

 

The following Spectar projects were created using the laser cutting process.

For additional tips, download our Fabrication Guide.