Siemens SINUMERIK 808D ADVANCED - Fixed Point Approach; Fixed Point Approach: G75

Programming and Operating Manual (Milling)
82 6FC5398-4DP10-0BA1, 01/2014
Right-hand or left-hand thread
The
sign of the
thread lead determines the direction of spindle rotation:
Positive: right-hand (as with M3)
Negative: left-hand (as with M4)
Note
A complete thread tapping cycle with thread interpolation is provided with the standard cycle CYCLE84.
See the following illustration for tapping using G331/G332:
Axis velocity
For G331/G332, the velocity of the axis for the thread length results from the spindle speed and the thread lead. The
feedrate F is not relevant
. It is, however, stored. However, the maximum axis velocity (rapid traverse) defined in the machine
data can not be exceeded. This will result in an alarm.
Programming example
metric thread 5,
lead as per table: 0.8 mm/rev., hole already
premachined:
N5 G54 G0 G90 X10 Y10 Z5
; Approach starting point
N10 SPOS=0
; Spindle in position control
N20 G331 Z-25 K0.8 S600
; Tapping, K positive = clockwise
of the spindle, end point Z=-25 mm
N40 G332 Z5 K0.8
; Retraction
N50 G0 X30 Y30 Z20
N60 M30
8.6
Fixed point approach
8.6.1
Fixed point approach: G75
Functionality
By using G75, a fixed point on the machine, e.g. tool change point, can be approached. The position is stored permanently
in the machine data for all axes. A maximum of four fixed points can be defined for each axis.
No offset is effective. The speed of each axis is its rapid traverse.
G75 requires a separate block and is non-modal. The machine axis identifier must be programmed!
In the block after G75, the previous G command of the "Interpolation type" group (G0, G1,G2, ...) is active again.