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A summary of Information provided by CYRO Industries and reprinted by permission.
Cutting Acrylic with a Circular Saw
Acrylic sheet is generally cut with overhead panel saws, below table panel saws and table saws. The saws should have minimal vibration and be powerful enough to make the required cuts. The run out (wobble) of the saw arbor and blade collar should be no greater than 0.002 inches, as typically supplied by most equipment manufacturers. A simple dial indicator maybe used to measure the run out.
The saw arbor, the saw table and the table fence must be properly aligned to prevent back cutting.
The width of the throat plate gap (table kerf) must be kept to a minimum.
| Blades
There are several blades on the market today which can effectively cut acrylic sheet. Carbide tipped blades are recommended for longer life of the cutting edge. The number of teeth per blade can vary depending on the blade size and application, such as gang or single sheet cutting. A 10 inch, 80 tooth blade is recommended for all‑purpose cutting. The blade's teeth should be the triple chip design, where every other tooth has a beveled cutting edge to help clear away saw chips. |
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Best results are achieved when the teeth have a clearance angle of 100 to 150. To prevent chipping, saw blade teeth must have a constant height and must all be in the same plane, i.e., one tooth cannot extend to one side more than the others.
Avoid impact shocks such as dropping or hitting the saw blades, as the carbide tips are brittle and chip easily. Also, an impact shock may slightly bend a blade, creating melting and chipping as it moves through a cut. |
For gang cutting of stacked sheets, a saw blade whose teeth have increased radial clearance is recommended. This clearance will reduce carbide/ plastic contact and therefore willreduce heat generated by friction. Use polyethylene masked sheets where possible when gang cutting; the polyethylene masking acts as a lubricant.
Dampeners/stiffeners placed tightly against the blade will greatly reduce vibration and unwanted runout. Best results are obtained by installing a stiffener 1/2 to 2/3 the saw blade diameter and mounting it against the outside of the blade.
Be sure to follow all manufacturer's safety recommendations for equipment and materials.
On table type saws or panel saws with the blade mounted underneath, the blade should protrude approximately 1/8 inch to 1/2 inch above the work pieces. On overhead blade mounted panel saws, the blade should protrude 1/32 inch through the material. These settings generally yield a smooth cut and minimize edge chipping because of the more favorable cutting angle. The proper blade angle allows the material to be scraped away, not chipped away.
Every effort should be made to clamp stacked sheets tightly. Vibration of sheets can cause chipping. Taping the edges of stacked sheets together helps to limit individual vibration.
Feed the material evenly through the saw. Uneven feed rates will produce melted spots or chipping on the plastic. A relatively fast rate of cutting, e.g., 50 ft./min., minimizes the frictional heat build up between the acrylic sheet and the saw blade.
The use of a saw blade mist cooling system will yield a much cleaner, smoother edge and greatly increase the life of the saw blade. A mist cooling system removes heat from the blade and plastic sheet as fast as it is generated. An air/water mist should be lightly sprayed on the blade before it enters the plastic, Thoroughly dry the sheet edges before flame polishing.
Fire Precautions
Acrylic sheet is a combustible thermoplastic. Precautions should be taken to protect this material from flames and high heat sources. Acrylic sheet usually burns rapidly to completion if not extinguished. The products of combustion, if sufficient air is present, are carbon dioxide and water. However, in many fires sufficient air will not be available and toxic carbon monoxide will be formed, as it will when other common combustible materials are burned.
Compatibility
Like other plastic materials, acrylic sheet is subject to crazing, cracking, or discoloration if brought into contact with incompatible materials. These materials may include cleaners, polishes, adhesives, sealant, gasketing or packaging materials, cutting emulsions, etc.
All thermoplastic materials will gradually lose tensile strength as the temperature approaches the maximum recommended for continuous service 160'F. (71'C.).
Plastic sheet will expand and contract from 3 to 8 times as much as glass or metals. The designer should be aware of its coefficient of expansion and make appropriate provisions. A 48" panel will expand and contract approximately .002" for each degree F. change in temperature.
Plastic Sheets also absorb water when exposed to high relative humidity, resulting in expansion of the sheet. At a relative humidity of 100%, 80%, and 60%, the dimensional changes are 0.5%, 0.3% and 0.2%, respectively.
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