Hyd-Mech S-20DS, Use And Maintenance Manual, Page: 119 / 138

9--5 110 Cutting speed and choice of tools
Blade types
The blades mounted on the S---20DS are 4500 x 27 x 0,9 mm the length can vary
between 4460 mm. and 4540 mm thanks to the blade tensioner device. The
blades, however, apart from size and tooth pitch, are differentiated by other
geometrical characteristics which determine their specialised uses:
H
tooth cutting angle (rake), can be 0 or positive;
H
the tooth pitch can be constant or variable;
H
the set, i.e. the various teeth alignments, have many possible configurations.
Conventional rake
Cutting angle 0 ˚ , constant pitch.
In general use, for small or medium section cast iron or steels and rolled
materials, for straight or angled cuts.
Positive rake
Positive cutting angle 9---10 ˚ , constant pitch.
Can be used for cutting all types of materials, and is particularly suited to
low---carbon and non---ferrous steels. Used for cutting very large sections and
diameters.
Variable pitch
These blades have groups of teeth having different pitches and, as a consequence,
have various tooth dimensions and differing relief angles. These are also available
in M2 and M42 types with zero and positive rakes. The alternation of the
different types of teeth helps to prevent vibration and noise. Elimination of
vibration increases the useful life of the tool and improves the cut surface finish.
A further advantage in using these types of blades lies in the fact that a wide
range of different material types and dimensions can be cut
with the same blade.