Fundamentals Of Thread Milling; Prerequisites - HEIDENHAIN TNC 640 User Manual

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4.5

Fundamentals of Thread Milling

Prerequisites

Your machine tool features internal spindle cooling (cooling
lubricant at least 30 bars, compressed air supply at least 6 bars).
Thread milling usually leads to distortions of the thread profile.
To correct this effect, you need tool-specific compensation
values which are given in the tool catalog or are available from
the tool manufacturer. You program the compensation with the
delta value for the tool radius DR in the TOOL CALL
The Cycles 262, 263, 264 and 267 can only be used with
rightward rotating tools. For Cycle 265 you can use rightward
and leftward rotating tools.
The working direction is determined by the following input
parameters: Algebraic sign Q239 (+ = right-hand thread / – =
left-hand thread) and milling method Q351 (+1 = climb / –1 =
up-cut). The table below illustrates the interrelation between the
individual input parameters for rightward rotating tools.
Internal thread
Right-handed
Left-handed
Right-handed
Left-handed
External thread
Right-handed
Left-handed
Right-handed
Left-handed
Danger of collision!
If you program the plunging depth values with different algebraic
signs a collision may occur.
Always program the depths with identical algebraic signs.
Example: If you program parameter Q356 COUNTERSINKING
DEPTH with a negative algebraic sign then also program
parameter Q201 DEPTH OF THREAD with a negative
algebraic sign
If for example you wish to repeat a cycle only with
countersinking, it is also possible to enter 0 with the DEPTH
OF THREAD. In this case the work direction is determined via
COUNTERSINKING DEPTH
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Fixed Cycles: Tapping / Thread Milling | Fundamentals of Thread Milling
Pitch Climb/
Up-cut
+ +1(RL)
– –1(RR)
+ –1(RR)
– +1(RL)
Pitch Climb/
Up-cut
+ +1(RL)
– –1(RR)
+ –1(RR)
– +1(RL)
NOTICE
Work direction
Z+
Z+
Z–
Z–
Work direction
Z–
Z–
Z+
Z+
HEIDENHAIN | User's manual for cycle programming | 10/2017