Feedrate For Thread Cutting (G33, G34, G35, G335, G336); Feedrate With G33 - Siemens SINUMERIK 840D sl Function Manual

17.2.3

Feedrate for thread cutting (G33, G34, G35, G335, G336)

17.2.3.1

Feedrate with G33

G33
The function G33 can be used to machine threads with constant pitch of the following type:
Speed S, feedrate F, thread pitch
A revolutional feedrate [mm/revolution] is used for G33 threads. The revolutional feedrate is
defined by programming the thread pitch [mm/revolution].
The speed of the axes for the thread length is calculated from the programmed spindle speed
S and the thread pitch.
Feedrate F [mm/min] = speed S [rev/min] * pitch [mm/rev]
At the end of the acceleration ramp, the position coupling between the spindle actual value
(spindle setpoint with SPCON on master spindle) and the axis setpoint is established. At this
moment, the position of the axis in relation to the zero mark of the spindle (including zero mark
offsets) is as if the axis had accelerated abruptly at the start of the block when the thread start
position (zero mark plus SF) was crossed. Compensation is made for the following error of the
axis.
Minimum spindle speed
In order to ensure smooth rotation at low speeds, the spindle speed is not permitted to fall
below a minimum level.
This speed can be set:
● With the setting data:
SD43210 $SA_SPIND_MIN_VELO_G25 (minimum spindle speed)
● For each gear stage with the machine data:
MD35140 $MA_GEAR _STEP_MIN_VELO_LIMIT (minimum speed for gear stage
change)
The minimum spindle speed can be changed in the part program with G25.
NC stop, single block
NC stop and single block (even at the block boundary) are only active after completion of thread
chaining. All successive G33 blocks and the first following non-G33 block are traversed as a
block.
Premature abortion without destruction
Thread cutting can be aborted without destruction before the end point is reached. This can
be done by activating a retraction motion.
Basic Functions
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
V1: Feedrates
17.2 Path feedrate F
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