Siemens CNC Turning | CYCLE96 | Thread Undercut

In this article, we described how to use CYCLE96 for thread undercut in Siemens CNC controlled turning (lathe) machines with all details and examples.


CYCLE96 Introduction

This cycle (CYCLE96) is for machining thread undercuts in accordance with DIN 76 on parts with a metric ISO thread.

CYCLE96 Format



DIATH = Nominal diameter of the thread
SPL = Starting point on the contour of the longitudinal axis
FORM = Definition of the form ; Values:
A (for form A)
B (for form B)
C (for form C)
D (for form D)
_VARI = Specification of undercut position ; Values:
0: Corresponding to tool point direction
1 to 4: Define position
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“Siemens CNC Turning | CYCLE95 | Stock Removal Cycle”


CYCLE96 CNC Program Example – 1 – Thread Undercut

This program can be used to program a thread undercut of form A.

Siemens CNC Turning CYCLE96 Program Example

N10 D3 T1 S300 M3 G95 F0.3 ; Specification of technology values
N20 G0 G18 G90 Z100 X50 ; Selection of starting position
N30 CYCLE96 (10, 60, “A”) ; Cycle call
N40 G90 G0 X30 Z100 ; Approach next position
N50 M30 ; End of program

FORM Parameter Explanation

Thread undercuts of the forms A and B are defined for external threads, form A for standard run-outs of threads, and form B for short run-outs of threads. Thread undercuts of the forms C and D are used for internal threads, form C for a standard run-out of the thread, and form D for a short run-out.

Siemens CNC Turning CYCLE96 FORM Parameter Explanation

If the parameter has a value other than A … D, the cycle aborts and creates alarm 61609 “Form defined incorrectly”.

Internally in the cycle, the tool radius compensation is selected automatically.

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