HEIDENHAIN TNC 426 (280 476) - Manual (Page 259)

232 8 Programming: Cycles
8.3 Cy
cles f
o
r Dr
illing, T
a
pping and Thr
ead Milling
THREAD CUTTING (Cycle 18)
Cycle 18 THREAD CUTTING is performed by means of spindle control.
The tool moves with the active spindle speed from its current position
to the entered depth. As soon as it reaches the end of thread, spindle
rotation is stopped. Tool approach and departure must be
programmed separately. The most convenient way to do this is by
using OEM cycles. The machine tool builder can give you further
information.
7 7 7 7 Total hole depth 1 : Distance between current tool
position and end of thread
The algebraic sign for the total hole depth determines
the working direction (a negative value means a
negative working direction in the tool axis)
7 7 7 7 Pitch 2 :
Pitch of the thread. The algebraic sign differentiates
between right-hand and left-hand threads:
+= right-hand thread (M3 with negative depth)
– = left-hand thread (M4 with negative depth)
Example: NC blocks
22 CYCL DEF 18.0 THREAD CUTTING
23 CYCL DEF 18.1 DEPTH -20
24 CYCL DEF 18.2 PITCH +1
X
Z
11
12
Machine and control must be specially prepared by the
machine tool builder for use of this cycle.
Before programming, note the following:
The TNC calculates the feed rate from the spindle speed.
If the spindle speed override is used during thread cutting,
the feed rate is automatically adjusted.
The feed-rate override knob is disabled.
The TNC automatically activates and deactivates spindle
rotation. Do not program M3 or M4 before cycle call.