Cast vs. Extruded Acrylic

Posted by Trevor Wanamaker on

When I first started using acrylic in my projects, there was a lot to learn. The first thing is the difference between cast and extruded acrylic. For me personally, it took a few tests and mistakes to learn how to work with each type.

I usually research new materials to find out more about them and how to work with them, but had trouble finding all of the information that I needed in one place.I decided to share the information that I've found in the hopes of helping others.

Cast and extruded acrylic are very popular in laser and CNC machining. In my experience, cast acrylic is the one that I use most often. If I plan to engrave and cut the acrylic, I will buy cast. If I plan on only cutting it, I buy extruded as it has a lower cost. This summary will help you figure out which type to use.

HOW ARE THEY MADE

  • CAST ACRYLIC
    • MMA (Methyl Methacrylate monomer) liquid is pumped into a mold made from two sheets of glass. This is then submerged in warm water and the process of polymerization takes place. Once this process is complete, the result is the acrylic sheet.
  • EXTRUDED ACRYLIC
    • Acrylic or PMMA pellets are fed into a system that heats them until they bond together into a molten form. This molten form is then pushed through a series of machinery into a die until the desired shape is achieved.

DIFFERENCES

  • Cost
    • Extruded acrylic is less expensive than cast
  • Heat Bending
    • In my experience, cast acrylic is easier to heat bend and form than extruded. It is best to use thin sheets 1/8" thick or thinner
  • Color Options
    • Cast typically has more color options. Cast acrylic can be run in smaller quantities which allows for more one off colors. Extruded acrylic is usually run in higher quantities and colors have to be popular to warrant making the color.
  • Laser Engraving
    • Cast gives a better engraving result. Cast typically gives a frosty white engraving where as extruded gives a dingy grey color.
  • Laser Cutting
    • Both can be laser cut. Cast gives a better edge finish and smells sweeter when cut, whereas extruded acrylic typically smells bad and may have small burrs on the edges.
  • CNC Engraving and Cutting
    • Cast acrylic is better for CNC machining due to its higher melting point. Extruded acrylic tends to melt and bind into the bit which may ruin the tool.

LASER MACHINE SETTINGS

  • Laser specs: 60 watt Epilog Fusion M2 40
  • Vector Engraving: 60% speed, 40% power
  • Vector Cutting: 10% speed, 100% power, 2500 frequency (100%)
  • Engraving time: 7.5 minutes per side

SUPPLIES USED IN THIS PROJECT (May contain affiliate links)

 


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