Acrylic Sheet


“Acrylic” is a common term for PMMA, (Polymethyl methacrylate) material, which is a thermoplastic that is usually better known by their trade names such as Acrylite®, Plexiglas®, or Lucite®. All are the same type of material ( acrylic ), just manufactured by different companies. There are some technical differences between the different sheets, and in addition there are different manufacturing methods that all manufacturers utilize that produce sheets with different characteristics that may have an impact on the desirability of the sheet for a particular end use.

Primarily the differences between types of acrylic are “Cell Cast”, and “Extruded”. Cell Cast sheet is manufactured by pouring acrylic monomer (MMA liquid) into molds (cells), generally between sheets of perfect glass that are separated by rubber gaskets which are the same thickness as the required sheets. The mold is then sealed and placed into curing ovens. After curing, the molds are then cooled and disassembled where the sheets are then removed and subjected to an intense inspection for any imperfections that occurred in the process. After passing inspection, sheets are then masked and packaged. This method is very labor intensive, but does produce a generally stress free homogeneous sheet, which is considered superior in terms of molecular weight ( highest ) and optics.

Extruded sheet, in simple terms, is manufactured by automated machinery inputting acrylic PMMA pellets into a large machine, melting the pellets and forcing the melted plastic through a die and rollers (calendars) to get a proper thickness and width.  As the sheet exits from the machinery it is cut to proper width by two opposing saw blades and cut to length by a saw blade that traverses diagonally at the same speed as the exiting sheet to produce a generally square sheet to finish the process. If a patterned sheet is required then a large stainless steel roller with the pattern embedded is added to the process to input the pattern to the sheet while it is still soft enough to imprint, and cured enough to maintain, the pattern.

The extrusion method is utilized to produce large quantities of “commodity” sheet for market use, generally in the neighborhood of 25,000+ pounds of material at a time or more before a change in production is made. Colored sheet can be produced in the same manner, but a strict regimen of specific color sequence must be adhered too, to maintain sheet integrity and quality. For instance, white sheet cannot be produced directly after black sheet, as strains of black would permeate the white for some time. Considering the current colors and products available, it may take 4-6 weeks before a scheduled cycle repeats in this method, and changing the schedule is not something that is ever done lightly.  This process is vastly more economical than cast sheet, but does produce a sheet that requires more exacting tools for cutting, drilling, and general workability; and in addition does create a sheet with very specific differences to the casting process. This production process creates the most widely available sheet that most consumers will readily find on the market today, and it will generally do an excellent job for most consumer uses if proper tooling and working conditions are adhered too.