Cast Acrylic

Posted by Laird Plastics on 3rd Feb 2022

WHAT IS CAST ACRYLIC?

When liquid acrylic, or PMMA (polymethyl methacrylate), is poured between two glass sheets that form a mold, cast acrylic is created. Gaskets divide the sheets of glass, which define the thickness of each sheet. The molds are then immersed in hot water to allow for polymerization, which is the chemical reaction in which monomers combine to produce polymers. The sheets are then placed in an autoclave to cure (essentially a gigantic steam oven). They are examined for optical clarity and quality after cooling.

How Cast Acrylic is Made

Acrylic is a synthetic plastic made from a chemical reaction between a catalyst and a monomer that produces a lightweight, transparent plastic. Acrylic is 10 times more shatter-resistant than glass and has a greater optical clarity than glass. Acrylic is also resistant to the sun's rays.

There are several types of acrylic sheets available, with cast acrylic being the highest grade. The liquid materials are poured into a glass mold, where they harden into a sturdy sheet. Extrusion, on the other hand, pushes the liquid through an extruder and rollers to produce a comparable sheet. Casting produces a plastic sheet that is strong, robust, and uniform.

Common Uses of Cast Acrylic

Cast Acrylic is utilized in a variety of applications where both transparency and strength are required. Here are a few examples:

● Signage

● Building and construction

● Bullet-resistant windows

● Manufacturing

● Trade shows and exhibit spaces

● Machine shops

● Recreation

● Hospitals

● Prisons and detention centers

Cast acrylic can be used almost anyplace you require a sturdy, impact-resistant clear plastic or a more durable alternative to glass.

Benefits of Cast Acrylic

For starters, cast acrylic is more resistant to solvents than other varieties of acrylic, making it a desirable choice for environments with harsh chemicals. This form of acrylic is also somewhat more thermally stable, making it ideal for high-temperature applications.

Cast acrylic alternatives might be thicker than extruded acrylic thanks to the casting process. As a result, cast acrylic is the chosen material for impact-resistant applications such as bullet-proofing and security. It has the finest optical clarity of any acrylic and comes in a variety of colors.

Buyers can place custom orders with much lower minimums because cast acrylic is created sheet by sheet rather than extruding numerous sheets at once. Because of the material's strength, it can be machined and laser cut without causing damage to the sheet.

Disadvantages of Cast Acrylic

Cast acrylic, like any plastic materials, has some disadvantages. The expense is the most significant disadvantage. It costs more to make than other related items, such as extruded acrylic. When enhanced strength and durability are required, however, it is the best option.

Cast & Extruded Acrylic

Cast and extruded acrylic are the two most common types of acrylic. Cast acrylic is made by combining liquid acrylic materials in molds.

Extruded acrylic is made by continually forcing acrylic substance through a shape while a chemical reaction occurs. As a result, extruded acrylic is heterogeneous, having characteristics that change depending on the direction of extrusion. For acrylic sheets, we call it the extrusion direction.

Even though cast acrylic and extruded acrylic are two different materials with their own set of benefits and drawbacks.

Extruded acrylic, like cast acrylic, has a number of advantages to consider. The first is the price. Extrusion reduces the overall cost of extruded acrylic sheets since it is faster and easier than casting. If cost is a big consideration, this could be the acrylic sheet for you.

Extruded acrylic, like cast acrylic, has outstanding optical qualities, with optical clarity that is clearer than glass but is much lighter. Because of its transparency, extruded acrylic can easily replace glass in virtually any application, and it is significantly more impact resistant than glass. It also has a high resistance to electrical current and UV radiation.

The melting point of extruded acrylic is lower than that of cast acrylic. This makes it thermoformable, which can help you create a better finished product. Because extruded sheet is more malleable than cast acrylic, it bends and molds better, allowing you to more easily mold it into the shape you choose. It's also good at bonding and flame polishing. Because little surface scratches may be sanded or wiped away, your final product will be more durable.

There are a few minor but significant variations between the various production methods:

● Laser Cutting: There will be a burr on one side of the part when laser cutting extruded acrylic. There are almost no burrs on the cast acrylic. Depending on the direction of the acrylic extrusion, the edges of extruded acrylic parts can seem a little different.

● Chemical Resistance: Cast acrylic is more resistant to some solvents.

● Heat Bending and Thermoforming: Because of the acrylic extrusion position, a sheet of extruded acrylic can react differently depending on the bending direction relative to the extrusion. It makes no difference with cast acrylic. The color of cast colored acrylic can change when heated for thermoforming or heat bending. Transparent surfaces can become matt, while matt surfaces can become clear. In addition, the color shade can shift. Cast acrylic is more difficult to bend and form.

● Thickness Tolerance: Cast acrylic sheets come in a wider range of thicknesses. A cast 3 mm acrylic sheet might vary by 15%. While an extruded sheet only varies by 5%. Extruded sheets also appear to have less dispersion within the tolerance. Designers are frequently surprised by the high tolerance of cast acrylic sheets, which leads to numerous building blunders.

● Colors: Cast acrylic comes in a variety of colors and thicknesses. The color selection for extruded acrylic is somewhat limited. If a customer requests a specific color, it will almost always be cast acrylic.

● Tension: Extruded acrylic has a higher tensile strength.

● Scratch-resistant: Extruded acrylic is less scratch-resistant than cast acrylic.

Disadvantages of Extruded Acrylic Vs Cast

The thickness of extruded acrylic is its biggest drawback. Because of the extrusion method, its thickness is limited, and very thick sheets are not conceivable with this acrylic. For security or bullet-resistant applications, it does not perform as well as cast acrylic.