Temperature variations and spark generation from rock contact in hot saws

A study was conducted of the fire ignition potential of high-speed disk cutting saws (hotsaws). Surface temperature increases for the operating saw blade were measured during normal cutting and when stopping the disk using friction against a stump. Observed temperature increases during normal operation were as high as 17◦ C above ambient. Tooth temperatures tended to be highest, but were not observed to be vastly different from global saw disk temperatures. Dynamic increases in temperature at the cutting interface of saw disk and tree tended to be on the order of a few degrees C. Stopping the blade by dropping it on a stump caused much higher temperatures on the stump itself (to the point of charring), but average saw blade temperatures increased by only an additional 10◦ C. An additional test of sparking tendencies of various rocks found that the number of visible sparks thrown varied by rock type, with basalt-type rocks having the highest numbers.