HEIDENHAIN TNC 640, User Manual, Page: 681 / 948

Turning | Basic functions (option 50)
16
HEIDENHAIN | TNC 640 | Conversational Programming User's Manual | 10/2017
681
Feed rate
With turning, feed rates are often specified in millimeters per
revolution. The control thus moves the tool at a defined value
for every spindle rotation. The resulting contouring feed rate is
thus dependent on the speed of the turning spindle. The control
increases the feed rate at high spindle speeds and reduces it at
low spindle speeds. This enables you to machine with uniform
cutting depth and constant cutting force, thus achieving constant
chip thickness
During many turning operations, it is not possible
to maintain constant surface speeds (
VCONST: ON
)
because the maximum spindle speed is reached first.
Use the machine parameter
facMinFeedTurnSMAX
(no.
201009) to define the behavior of the control after the
maximum speed has been reached.
By default, the control interprets the programmed feed rate in
millimeters per minute (mm/min). If you want to define the feed
rate in millimeters per revolution (mm/1), you have to program
M136
. The control then interprets all subsequent feed rate
specifications in mm/1 until
M136
is canceled.
M136
is effective modally at the beginning of the block and can be
canceled with
M137
.
Example
10 L X+102 Z+2 R0 FMAX
Movement at rapid traverse
...
15 L Z-10 F200
Movement at a feed rate of 200 mm/min
...
19 M136
Feed rate in millimeters per revolution
20 L X+154 F0.2
Movement at a feed rate of 0.2 mm/1
...