Types of circular saw blades used for cutting acrylic sheet

There are several saw blades on the market that can effectively cut ACRYLITE® extruded (FF) sheet. Sharp teeth are essential for achieving good results. Carbide tipped saw blades are recommended for superior cuts and longer life of the cutting edge. It is also important to dedicate saw blades for cutting acrylic only. Cutting other materials on saw blades intended for acrylic will dull or damage the blade and lead to poor cutting performance when the blade is used again to cut acrylic.

The optimum number of teeth per blade can vary depending on the blade size, blade rotation speed and application, such as gang or single sheet cutting. Common blade diameters and tooth selections used for cutting acrylic sheet include:

• 10" diameter, 60 & 80 tooth
• 12" diameter, 60, 80 & 100 tooth
• 14" diameter 60, 80 & 100 tooth

Proper selection of the saw blade size can be guided by considering the surface feet/minute (SFM) of the blade in the saw. The SFM of the blade is the actual speed at which the teeth are moving. For acrylic, it should be between 6,000 - 14,000 ft/min. To determine the SFM of the blade use the following formula:

SFM = Diameter (inches) x RPM x 0.262

Example: 10" diameter blade rotating at 3450 RPM

SFM = 10 x 3,450 x 0.263 = 9,000

The 10" blade size is suitable because the SFM is between 6,000 and 14,000.

The number of teeth on the saw blade should be selected to give proper tooth engagement. Between 2 -6 teeth should be engaged with the material during cutting. Engagement of three teeth is considered to be optimum (one tooth entering the material, one tooth fully engaged, one tooth leaving the material). A 10-inch diameter, 80-tooth blade is recommended for all-purpose cutting on a table saw. For recommended saw blade size and tooth selections, see Table 1.

Table 1: Recommendations for Saw Blade Size, Tooth Selection, and Operating Clearance when Cutting Acrylic Sheet

* Table saws or below table panel saws only.

For cutting acrylic, the teeth of the saw blade should have the triple-chip design, where the cutting edge of every other tooth is beveled. The beveled tooth, or crown tooth, removes the material in the center of the cut while the flat-top raker tooth follows behind, removing material from the edges of the cut. This results in the production of three separate "chips" - center, left side and right side - and hence, the term triple-chip design. On some designs, the flat-top raker tooth also has very slight bevels along the top side-edges of the tooth. This helps to reduce chipping by reducing the notching affect caused by a square cutting edge.

Best results are achieved when the teeth have a clearance angle (top clearance) of 10 to 15 degrees. This minimizes contact between the teeth and the material - reducing friction and resulting in less melting. The proper rake or "hook" angle, 0 to 10 degrees positive, ensures the teeth do not strike the material too aggressively. Higher angles can lead to chipping due to poor blade stability and poor control of material feed rates.

For gang cutting of stacked sheets, a saw blade whose teeth have increased radial clearance is recommended. This clearance will reduce carbide/plastic contact on the sides of the teeth and, therefore, reduce heat generated by friction. Use ACRYLITE® extruded (FF) sheet masked with polyethylene masking where possible when gang cutting; the polyethylene masking acts as a lubricant.

The quality of construction of the saw blade significantly affects how well it will cut. Quality considerations when evaluating a saw blade include:

• Run out, which should be less than 0.002".
• Teeth height, which needs to be nearly constant. Any variations must be gradual and not abrupt - the blade should have good concentricity.
• Teeth positioning, which must all be in the same radial plane, i.e. one tooth cannot extend to one side more than the others or chipping will result.
• Blade plate quality, which should be tempered to a hardness of C42 - C 46 giving it greater rigidity and resulting in reduced vibration during operation.

Saw blades should be handled carefully with cut resistant gloves. Avoid impact shocks such as dropping or hitting the saw blades, as the carbide tips are brittle and can chip easily. Also, impact shock may slightly bend a blade, creating melting and chipping as it moves through a cut. When not in use, blades should be stored on a properly designed wooden fixture that will protect the blade from accidental impacts and prevent accidental contact with its sharp tips.

Saw blades have a maximum rating for rotation speed. Be sure to verify that the saw being used will not exceed the limitations of the saw blade that has been selected. Carbide tipped saw blades should never be operated in excess of 18,000 SFM.