HEIDENHAIN TNC 320 (340 551-01) - Manual (Page 206)

206 8 Programming: Cycles
8.2 Cy
cles f
o
r Dr
illing,
T
apping and Thr
ead Milling
8 Nominal diameter Q335: Nominal thread diameter.
8 Thread pitch Q239: Pitch of the thread. The algebraic
sign differentiates between right-hand and left-hand
threads:
+ = right-hand thread
– = left-hand thread
8 Thread depth Q201 (incremental value): Distance
between workpiece surface and root of thread.
8 Threads per step Q355: Number of thread
revolutions by which the tool is offset, (see figure at
lower right):
0 = one 360° helical path to the depth of thread.
1 = continuous helical path over the entire length of
the thread
>1 = several helical paths with approach and
departure; between them, the TNC offsets the tool by
Q355, multiplied by the pitch.
8 Feed rate for pre-positioning Q253: Traversing
speed of the tool when moving in and out of the
workpiece, in mm/min.
8 Climb or up-cut Q351: Type of milling operation with
M03.
+1 = climb milling
–1 = up-cut milling
8 Set-up clearance Q200 (incremental value): Distance
between tool tip and workpiece surface.
8 Workpiece surface coordinate Q203 (absolute
value): Coordinate of the workpiece surface.
8 2nd set-up clearance Q204 (incremental value):
Coordinate in the tool axis at which no collision
between tool and workpiece (clamping devices) can
occur.
8 Feed rate for milling Q207: Traversing speed of the
tool in mm/min while milling.
Example: NC blocks
25 CYCL DEF 262 THREAD MILLING
Q335=10 ;NOMINAL DIAMETER
Q239=+1.5 ;PITCH
Q201=-20 ;THREAD DEPTH
Q355=0 ;THREADS PER STEP
Q253=750 ;F PRE-POSITIONING
Q351=+1 ;CLIMB OR UP-CUT
Q200=2 ;SET-UP CLEARANCE
Q203=+30 ;SURFACE COORDINATE
Q204=50 ;2ND SET-UP CLEARANCE
Q207=500 ;FEED RATE FOR MILLING