Type Of Feedrate G96, G961, G962, G97, G971 - Siemens SINUMERIK 840D Function Manual

5.2.2

Type of feedrate G96, G961, G962, G97, G971

Constant cutting rate (G96, G961)
The constant cutting rate is used on turning machines to keep the cutting conditions constant,
independently of the work diameter of the workpiece. This allows the tool to be operated in the
optimum cutting performance range and therefore increases its service life.
Selection of G96, G961:
When programming G96, G961, the corresponding S value is interpreted as the cutting rate in
m/min or ft/min along the transverse axis. If the workpiece diameter decreases during
machining, the speed is increased until the constant cutting speed is reached.
When G96, G961 is first selected in the part program, a constant cutting rate must be entered
in mm/min or ft/min.
With G96, the control system will automatically switch to revolutional feedrate (as with G95), i.e.
the programmed feedrate F is interpreted in mm/rev or inch/rev.
When programming G961, linear feedrate is selected automatically (as with G94). A
programmed feedrate F is interpreted in mm/min or inch/min.
Determining the spindle speed
Based on the programmed cutting rate (either S
the transverse axis (radius), the control system calculates the spindle speed at the TCP using
the following formula:
n:
S
Speed
π
r:
The following is assumed when determining the radius:
● The transverse axis position 0 in the WCS represents the center of rotation.
● Position offsets (such as online tool offset, external zero offset, $AA_OFF, DRF offset and
compile cycles) and position components through couplings (e.g. following axis for TRAIL)
are not taken into account when determining the radius.
Frames (e.g. programmable frames such as SCALE, TRANS or ROT) are taken into account
in the calculation of the spindle speed and can bring about a change in speed, if the effective
diameter at the TCP changes.
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA
Spindle speed
: Programmed cutting rate
Circle constant
Radius (distance, center of rotation to TCP)
or S ) and the actual cartesian position of
G96 G961
V1: Feedrates
5.2 Path feedrate F
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