Tiger 370 CNC--MR, Use And Maintenance Manual

Page: 157 / 180

9--3 147 Cutting speed and choice of tools
T = tooth pitch in mm.
A larger pitch should be chosen when, as a result of the shape of the piece to be
cut, the cross---section at any given point exceeds the average cross---section given
above.
Types of swarf:
H
Very fine or fragmented swarf indicates that the downstroke speed and/or cutting
pressure is too low.
H
Thick and/or blue swarf indicates that the blade is overloaded.
H
Long coils of swarf indicate ideal cutting conditions.
Cutting and feeding speed
The cutting speed, in m/min, and the head feeding speed, in cm
2
/min, are limited
by the amount of heat generated near to the points of the teeth. If the head
feeding speed is too high, the cut will not be straight in either the vertical or the
horizontal plane. As we have already said, the cutting speed depends on the
strength (kg/mm 2 ) and hardness (HRC) of the material and the dimensions of the
thickest section. The feeding speed depends on the cross---section of the material.
Solid or thick---walled materials (thickness > 5 mm), can therefore be cut at high
speed providing there is sufficient swarf removal by the blade, while thin---walled
materials such as tubes or thin profiles must be cut with a low feeding speed. A
new blade requires a wearing---in period, during which time a feeding speed of
about half normal speed should be used.