Cutting Polyurethane Parts
One of the best machines for cutting urethane parts is a band saw. Long blades of 125 to 175 inches (3,175 to 4,445 mm) are desirable because they stay cooler and keep the urethane from melting. A band type we have found to work well is a 4 tooth per inch with raker set. A raker set blade is one that has its teeth alternating to the left and right of center. This type of blade reduces friction by removing chips from the kerf.
Band speeds in the range of 2,600 feet per minute work well on almost all hardnesses. Feed rate is controlled by hand, so it is operator dependent. Any moderate hand feed will suffice, but do not force the work. Keep hands well to the side of the saw blade; never in front of the saw.
On softer urethane, a faster blade speed helps prevent the urethane from pulling down into the cut, rubbing on the blade, and building up heat. When cutting thin, low durometer sheet stock, the work must have some support. A sheet of cardboard, for example will help prevent the work piece form being pulled through the table slot by the blade.
When cutting 90A durometer and below, use a spray mist of water-soluble oil (50-50 mix) to help keep the heat down and to improve the finish.
