Two of the most common manufacturing techniques are cast and extruded acrylic, while both have similarities, they also have differences. However, in many cases, the differences do not particularly matter for many intended applications. It is generally difficult to differentiate between either type, especially with clear acrylic. Within this blog, we are going to discuss the differences between cast and extruded acrylic sheets.
What is Cast Acrylic?
Cast acrylic is made when the original hot liquid is pumped into a glass mould and then submerged in warm water. The change in temperature results in polymerization, creating a sheet of rigid acrylic.
What is Extruded Acrylic?
Extruded Acrylic is made from PMMA pellets being put into an extrusion barrel. The temperature is gradually increased, which melts the pellets. The liquid is then pushed into a die, and increased pressure pushes it into a molten sheet. Finally, it is passed through cooling rollers until it can be subject to finishing treatments.
Visual Clarity
Both cast and extruded acrylic have fantastic visual clarity, and the naked eye would struggle to find a difference between the two. Under a microscope, cast acrylic would have the best visual clarity.
Durability & Resistance
Cast acrylic has a better chemical resistance, whereas extruded acrylic is more liable to a ‘stress craze’. Extruded acrylic has a narrow elastic range, however, when heated the shrinkage is not bi-linear. Cast acrylic has a wider elastic range, however, it shrinks up to 2% when heated. Cast acrylic is better suited for laser cutting.
Thickness
Extruded acrylic has a consistent thickness throughout the sheet with a tolerance of just +/-5%. Cast acrylic has a poor thickness tolerance at over +/- 10%, which varies over the sheet.
Pricing
We typically see that cast acrylic is more expensive than extruded acrylic mainly due to the manufacturing process and the end result of the acrylic’s characteristics. So, if you are looking for a cheaper option, you may want to opt for extruded acrylic.
The decision as to which material is best for you is based on what you are planning to do with the material. For example, if you plan to laser cut, we would recommend cast acrylic, if it is used as a replacement shed window, the type doesn’t matter, so we would recommend extruded as the most cost-effective.
If you are still unsure, feel free to get in touch and let us know your intended use, and we will do our best to suggest which would be most suitable.
