Programming principles
1.5 Special turning functions
Turning Part 2: Programming (Siemens instructions)
66 Programming and Operating Manual, 05/2012, 6FC5398-5DP10-0BA0
Upper speed limit LIMS=
During machining from large to small diameters, the spindle speed can increase significantly.
In this case, it is recommended to program the upper spindle speed limitation LIMS=... .
LIMS is only effective with G96 and G97.
By programming LIMS=..., the value entered into the setting data (SD 43230:
SPIND_MAX_VELO_LIMS) is overwritten. This SD takes effect when LIMS is not written.
The upper limit speed programmed with G26 or defined via machine data cannot be
overwritten with LIMS=.
Deactivate constant cutting rate: G97
The function "Constant cutting rate" is deactivated by G97. If G97 is active, a programmed S
word is given in RPM as the spindle speed .
If no new S word is programmed, the spindle turns at the last defined speed with G96
function active.
Programming example
N10 M3 S1000 ; Spindle's direction of rotation
N20 G96 S120 LIMS=2500 ; Activate constant cutting speed, 120 m/min, speed
limit 2,500 r.p.m.
N30 G0 X150 ; no change in speed, because block N31 with G0
N40 X50 Z20 ; no change in speed, because block N32 with G0
N50 X40 ; Approach on contour, new speed is automatically set as
is required for the beginning of block N40
N60 G1 F0.2 X32 Z25 ; Feedrate 0.2 mm/revolution
N70 X50 Z50
N80 G97 X10 Z20 ; Deactivating constant cutting rate
N90 S600 ; new spindle speed, r.p.m.
N100 M30
Information
The G96 function can also be deactivated with G94 or G95 (same G group). In this case, the
last p
rogrammed spindle speed S is active for the remaining machining sequence if no new
S word is programmed.
The programmable offset TRANS or ATRANS (see Section “Programmable work offset:
TRANS, ATRANS (Page 30)”) should not be used on the transverse axis X or used only with
low values. The work piece zero point should be located at the turning center. Only then is the
exact function of G96 guaranteed.
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