Acrylic sheets are widely used in various industries due to their transparency, durability, and versatility. However, there are two main types of acrylic sheets: cast acrylic sheet and extruded acrylic sheet. Understanding their differences helps in choosing the right material for specific applications.
1. Manufacturing Process
Cast Acrylic Sheet:
● Made by pouring liquid acrylic (PMMA) into a mold (between two glass plates), where it undergoes a controlled polymerization process.
● This results in a homogeneous material with consistent properties in all directions.
Extruded Acrylic Sheet:
● Produced by continuously pushing molten acrylic mass through a die while the chemical process occurs.
● This process creates a heterogeneous material where properties can vary depending on the extrusion direction.
2. Quality & Properties
|
Feature |
Cast Acrylic Sheet |
Extruded Acrylic Sheet |
|
Molecular Weight |
High, making itstronger and more durable |
Lower, making itsofter and more flexible |
|
Optical Clarity |
Excellent,free from impurities and distortions |
Good, butmay contain slight imperfections |
|
Surface Hardness |
More scratch-resistant |
Softer, more prone to scratches |
|
Chemical Resistance |
Better resistance to solvents and chemicals |
Less resistant to chemicals |
|
Machinability |
Suitable forCNC cutting, laser cutting, and polishing |
Easier tothermoform and bend due to lower melting point |
|
Laser Cutting |
Produces clean edges with minimal burrs |
Leaves burrs on one side due to internal stress |
|
Laser Engraving |
Engraving appears matte white |
Engraving appears matte gray |
|
Heat Bending & Thermoforming |
No directional behavior, bends uniformly |
Bending behavior depends on extrusion direction |
|
Color Stability in Heat Bending |
Color and finish may change (matt can become glossy and vice versa) |
More stable in heat bending |
|
Thickness Tolerance |
Varies more (e.g., a 3mm sheet may vary by ±0.2mm) |
More consistent (typically ±0.1mm) |
|
Flame Polishing |
Harder to flame polish |
Easier to flame polish |
|
Scratch Resistance |
More resistant to scratches |
Less resistant, scratches more easily |
|
Color Options |
Available in a wide range of colors and thicknesses |
Limited color options |
|
Tension & Stress |
Lower internal stress, more stable |
Higher internal stress, prone to warping in some applications |
|
Minimum Thickness |
1.8mm |
1mm |
|
Cost |
Higher due to complex production process |
Lower due to mass production efficiency |
3. Applications
Because of their different properties, cast acrylic and extruded acrylic serve different purposes.
Cast Acrylic Sheet is Ideal for:
✔ High-end signage and displays
✔ Optical lenses and aquariums (superior clarity)
✔ Laser engraving and precision machining
✔ Medical and laboratory equipment (better chemical resistance)
✔ Decorative and artistic applications
Extruded Acrylic Sheet is Preferred for:
✔ Mass-produced signage and lightboxes
✔ Protective barriers and glazing
✔ POP (Point of Purchase) displays
✔ Furniture and home décor
✔ Thermoforming applications (better bending behavior)
4. Conclusion
Both cast and extruded acrylic sheets have their advantages and disadvantages.
● Extruded acrylic is more cost-effective, easier to thermoform, and has a more consistent thickness. However, it has higher internal tension, limited color options, and a lower molecular weight, making it less durable than cast acrylic.
Additionally, extruded acrylic sheets can be made as thin as 1mm, whereas cast acrylic sheets have a minimum thickness of 1.8mm. This makes extruded acrylic a better option for ultra-thin applications.
When selecting the right acrylic sheet for your project, consider factors such as budget, durability, clarity, chemical resistance, and processing requirements to ensure the best results.