Dake Model SAR 331 - Manual (Page 15)

15
SAR 331 SA GDS
9.7 - Blade type
They differ essentially in their constructive characteristics, such as:
- shape and cutting angle of tooth
- pitch
- set
Shape and angle of tooth
REGULAR TOOTH: 0° rake and constant pitch.
Most common form for transversal or inclined cutting of solid small
and average cross-sections or pipes, in laminated mild steel and
grey iron or general metal.
POSITIVE RAKE TOOTH: 9° - 10° positive rake and constant pitch.
positive
Particular use for crosswise or inclined cuts in solid sections or large
pipes, but above all harder materials (highly alloyed and stainless
steels, special bronze and forge pig).
COMBO TOOTH: pitch varies between teeth and consequently vary-
ing teeth size and varying gullet depths. Pitch varies between teeth
which ensures a smoother, quieter cut and longer blade life owing to
the lack of vibration.
Another advantage offered in the use of this type of blade in the fact
that with an only blade it is possible to cut a wide range of different
SOLID Ø OR L MM
Z CONTINUOUS
TOOTH DESIGN
Z COMBO
TOOTH DESIGN
TILL 30 8 5/8
FROM 30 TO 60 6 4/6
FROM 40 TO 80 4 4/6
MORE THAN 90 3 3/4
Ø = DIAMETER L = WIDTH
9.4 - Cutting and advance speed
The cutting speed (m/min) and the advance speed (cm 2 /min = area
travelled by the disk teeth when removing shavings) are limited by
the development of heat close to the tips of the teeth.
- The cutting speed is subordinate to the resistance of the material
(R = N/mm 2 ), to its hardness (HRC) and to the dimensions of the
widest section.
- Too high an advance speed (= lowering of the saw frame) tends to
cause the disk to deviate from the ideal cutting path, producing
non rectilinear cuts on both the vertical and the horizontal plane.
The best combination of these two parameters can be seen directly
examining the chips.
Long spiral-shaped chips indicate ideal cutting.
Very fine or pulverized chips indicate lack of
feed and/or cutting pressure.
Thick and/or blue chips indicate overload of
the blade.
9.5 - Blade running-in
When cutting for the first time, it is good practice to run in the
tool making a series of cuts at a low advance speed
(= 30-35 cm
2 /min on material of average dimensions with respect
to the cutting capacity and solid section of normal steel with R =
410-510 N/mm
2 ), generously spraying the cutting area with lu-
bricating coolant.
9.6 - Blade structure
Bi-metal blades are the most commonly used. They consist in a sili-
con-steel blade backing with electron beam or laser welded high speed
steel (HHS) cutting edge. The type of stocks are classified in M2,
M42, M51 and differ from each other because of their major hard-
ness due to the increasing percentage of Cobalt (Co) and molybde-
num (Mo) contained in the metal alloy.
distance between teeth
materials in size and type.
COMBO TOOTH: 9° - 10° positive rake.
positive
This type of blade is the most suitable for the cutting of section bars
and large and thick pipes as well as for the cutting of solid bars at
maximum machine capacity. Available pitches: 3-4/4-6.