Acrylic is a versatile and widely used material known for its transparency, durability, and versatility in various applications. When it comes to acrylic sheets, two popular manufacturing methods are employed: casting and extrusion. While both techniques produce high-quality acrylic products, there are some differences between cast and extruded acrylic. In this article, we will delve into the characteristics, manufacturing processes, and applications of these two variants, shedding light on their unique attributes
1. Manufacturing Processes:
Cast Acrylic: Cast acrylic is created through a process known as cell casting. This method involves pouring liquid acrylic polymer into a mold, followed by curing it under controlled temperature and pressure conditions. This slow and meticulous process ensures uniform thickness and minimizes internal stress, resulting in a high-quality sheet with excellent optical clarity.
Extruded Acrylic: Extruded acrylic is manufactured by pushing melted acrylic resin through a die, forming a continuous sheet. The extrusion process offers greater efficiency and speed compared to casting. However, the rapid cooling during extrusion can lead to internal stress, which affects the optical properties and overall quality of the sheet.
2. Optical Clarity and Quality:
Cast Acrylic: Cast acrylic exhibits superior optical clarity, making it ideal for applications where transparency is critical, such as displays and optical lenses. The casting process eliminates impurities and bubbles, resulting in a pristine and visually appealing sheet. Cast acrylic also boasts excellent light transmission, ensuring minimal distortion and maximum visual impact.
Extruded Acrylic: While extruded acrylic also offers excellent optical clarity, it may not match the pristine quality of cast acrylic in certain applications. The extrusion process introduces inherent stress, which can cause minor imperfections like ripples or lines on the surface. Although these imperfections are generally not visible to the naked eye, they may become noticeable when used in precision optical applications. There is no noticeable difference for glazing or everyday applications.
3. Physical Properties:
All acrylic sheets exhibit excellent weatherability, withstanding UV radiation and outdoor exposure without significant degradation. It has low water absorption, ensuring dimensional stability over time. Our PLEXIGLAS range of sheets have a 30 year guarantee of not yellowing.
CAST Acrylic sheets tend to have a greater variance on thickness tolerance (as much as + / – 30% on thickness). This is compensated by the surface finish (as smooth as glass, since it was CAST, or molded, between two sheet of glass). Furthermore, the ability to colour the clear MMA monomer by using master batch pigments allows for numerous colours to be obtained in relatively small production batches, in most cases as few as 20# sheets 3030 x 2030mm can be obtained.
CAST acrylic sheets lend themselves to ease of fabrication. Cutting, whether with conventional saws produce a cleaner cut and the sheets when stacked (cut in multiples) tend not to fuse or weld together. In addition CAST acrylic when laser cut produce a highly polished edge, thus reducing finishing times when fabricating. Furthermore, when hot wire line bending, drape or vacuum forming CAST acrylic sheets are more malleable / pliable than Extruded acrylic sheet.
Extruded acrylic sheets have a better tolerance on thickness, typically + or – 10% , however, tighter tolerances can be achieved by prior agreement with the extrusion mill. Because of the continuous nature of production short production runs are of the order of 3 – 5 Tonne per size and gauge and colour. Clear, Opal and black are amongst the more standard colours produced.
4. Availability and Cost:
Cast Acrylic: Due to its more intricate manufacturing process, cast acrylic tends to be more expensive than its extruded counterpart. However, the price variation depends on factors like thickness, size, and specific requirements. Cast acrylic sheets are readily available in various sizes and thicknesses, catering to a wide range of applications.
Extruded Acrylic: Extruded acrylic is generally more cost-effective compared to cast acrylic, making it a popular choice for budget-conscious projects. It is widely available in standard sizes and thicknesses, making it easily accessible for a variety of applications.
4. Applications
Cast Acrylic: Cast acrylic’s superior optical properties and durability make it suitable for applications requiring premium clarity and impact resistance. It is commonly used in industries such as architecture, automotive, aerospace, marine, and healthcare. Cast acrylic sheets are utilized for signage, skylights, aquariums, retail displays, lenses, and artistic installations, where visual appeal and long-term performance are paramount.
Extruded Acrylic: Extruded acrylic finds its application in various industries, including construction, retail, advertising, and interior design. It is commonly used for glazing, protective barriers, point-of-purchase displays, shelves, lighting fixtures, and DIY projects. While extruded acrylic may not be suitable for precision optical applications, it offers a cost-effective solution for projects that prioritize affordability without compromising transparency and durability.
Both cast and extruded acrylic sheets have their distinct advantages and applications. Cast acrylic stands out with its superior optical clarity, making it the preferred choice for high-end projects and precision optical applications. On the other hand, extruded acrylic offers affordability, ease of availability, and versatility, making it a practical option for a wide range of applications. Understanding these differences will enable you to choose the most suitable acrylic variant based on your specific requirements, budget, and desired performance. Learn more about our Acrylic Perspex Plexiglas Sheet and shop acrylic sheets through our online store 365Plastics.ie
