Siemens SINUMERIK 828D Function Manual page 1379

The absolute value of F must be applied to G34 or G35 according to the desired lead increase or lead decrease.
When the thread length l
can be determined as follows by modifying the formula:
• G34 (progressive lead):
• G35 (degressive lead):
Note
If the formula results in a negative root expression, the thread cannot be machined!
In this case, the NC signals alarm 10605 or alarm 22275.
Sample program
Thread cutting G33 with degressive thread lead G35
N1608 M3 S10
N1609 G0 G64 Z40 X216
N1610 G33 Z0 K100 SF=R14
N1611 G35 Z-220 K100 F17.045455
N1612 G33 Z-240 K50
N1613 G0 X218
N1614 G0 Z40
N1616 M17
Suppress special alarms
Any lead changes that would overload the thread axis when G34 is active or would result in an axis standstill
when G35 is active are detected in advance during block preparation.
Alarm 10604 "Thread lead increase too high" or alarm 10605 "Thread lead decrease too high" are output if bit 10
in machine data:
MD11410 SUPPRESS_ALARM_MASK
is not set.
During thread cutting, certain practical applications require a correction of the spindle speed. In this case, the
operator will base his correction on the permissible velocity of the thread axis.
Basic Functions
Function Manual, 09/2011, 6FC5397-0BP40-2BA0
, lead change F and initial lead k
G
; Spindle speed
; Approach starting point
; Thread with constant pitch 100 mm/rev
; Thread lead decrease 17.045455 mm/rev2
; Thread lead at end of block 50 mm/rev
; Traverse thread block without jerk
;
;
;
are known, the lead increase at the end of block k
a
V1: Feedrates
17.2 Path feedrate F
e
1379