Jet J-FK350-2 Operating Instructions And Parts Manual page 13

Figure 17
Short swarf material such as brass, bronze,
aluminum and hard cast iron require smaller cutting
angles because the swarf becomes crushed
immediately and the rake angle has little effect
during the cutting stage.
Figure 18
The J-FK350 uses discs with positive cutting
angles for cutting solid materials and with negative
cutting angles for cutting hollow profiles. This is
because, as a result of the high cutting speeds
(3400 rpm), even with non-ferrous materials the
tool "strikes" against the wall of the profile to be cut
several times, thus requiring a cutting edge with a
larger resistant section.
Circular saws can also be characterized by other
parameters such as the whine reduction feature,
which cuts down noise at high speeds, or
expansion, which compensates for the pushing of
chips inside the cutting edge, thus reducing the
thrust on the walls of the material to be cut.
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Figure 19
Figure 20