Hyd-Mech PH 211, Use And Maintenance Manual

Page: 77 / 98

9--1
Cutting speed and
choice of tools
The cutting speed is determined by the blade speed and the head feed speed.
While the head speed is provided by the downstroke movement of the head, the
blade rotation speed can either be fixed or variable. This chapter describes the
cutting speeds the machine can operate at in the standard version, as well as the
speeds for which the optional electronic speed controller (inverter) is necessary.
When using the PH211 , it is important to select the correct type of blade for the
material to be cut. This chapter explains the limitations and specific applications
of the different types of blades.
Cutting speed
Standard machine
The basic version with 2/4 pole motor, is provided with the following cutting
speeds:
H
1st speed = 40 m/min. (4 pole)
H
2nd speed = 80 m/min. (2 pole)
These speeds are selected using the polarity change switch situated on the control
panel.
Choice of blade
When using band saws to cut metals, an important factor is the choice of pitch,
i.e. the number of teeth per inch (25.4 mm.), which must be suitable for the
workpiece material. The following recommendations may be taken as general
guidelines:
H
thin---walled materials, such as sheet steel, tubes and profiles require a fine
pitch frequency. 3 to 6 teeth should be engaged in the breadth of the material
at any one time;
H
large section cutting requires a coarse pitch to cope with the higher volume of
swarf and optimal tooth penetration;
H
soft materials (aluminium alloys, soft bronze etc.) also require a coarse tooth
pitch.
Saw tooth pitch
The choice of teeth per inch, therefore, depends on various factors:
H
the size of the section;
H
the hardness of the material;
H
workpiece wall breadth.
9