Cast vs. Extruded Acrylic

When shopping for acrylic sheets, you'll encounter two primary manufacturing types: cast and extruded. While both are made from the same base material (PMMA), their production methods create significant differences in performance, appearance, and application suitability.

Manufacturing Process

Cast Acrylic

  • Produced by pouring liquid acrylic into moulds
  • Slowly polymerizes between glass plates
  • More labour-intensive production process
  • Generally more expensive

Extruded Acrylic

  • Produced through a continuous extrusion process
  • Molten acrylic is forced through dies
  • More automated manufacturing
  • Typically less expensive

Key Differences

Laser Cutting & Engraving

  • Cast Acrylic: Superior for laser cutting with clean, polished edges
  • Cast Acrylic: Engraves with a frosted white appearance
  • Extruded Acrylic: More likely to melt at edges when laser cut
  • Extruded Acrylic: Produces less distinct engravings

Physical Properties

  • Cast Acrylic: Higher molecular weight for better chemical resistance
  • Cast Acrylic: Less consistent thickness (±10%)
  • Extruded Acrylic: Lower molecular weight
  • Extruded Acrylic: More precise thickness tolerance (±5%)

Fabrication Characteristics

  • Cast Acrylic: Better for thermoforming with less shrinkage
  • Cast Acrylic: Easier to glue and bond
  • Extruded Acrylic: More flexible and easier to cold-bend
  • Extruded Acrylic: May contain internal stress, making it more prone to cracking

When to Choose Cast Acrylic

Cast acrylic is the preferred choice when:

  • Laser cutting or engraving is planned
  • Chemical resistance matters
  • Optical clarity is paramount
  • Complex thermoforming is needed
  • The project requires premium quality
  • Long-term outdoor applications are intended

When to Choose Extruded Acrylic

Extruded acrylic works best when:

  • Budget constraints are significant
  • Precise thickness tolerance is required
  • Simple bending without heat is needed
  • The application is primarily indoors
  • Large quantities are required at lower cost

How to Identify Cast vs. Extruded

Not sure which type you have? Here's a simple test:

  1. Check the edges - cast typically has slightly rougher edges
  2. Apply acetone to an inconspicuous spot - cast resists longer
  3. Check the price - cast is usually 15-30% more expensive
  4. Examine the protective film - manufacturers often label the type

For laser cutting projects and display work, cast acrylic generally delivers superior results despite the higher price point. However, for many everyday applications where laser cutting isn't involved, extruded acrylic offers an economical alternative with excellent performance.

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