Specifications

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CONCISE GUIDE FANUC 99
Description:
The sub-program is run as follows:
The spindles start to rotate in synchronism (M70) at approx. 50 rpm in the direction defined by variable
“M”, the parting off tool defined in variable “T” is brought to working position.
The origin used is that which was active before entering the sub-program
The machine opens the back spindle jaws, in rapid traverse it positions X at the dimension specified in the
“X” variable, Z at zero and B (back spindle) at the value for approach to the workpiece defined in
variable “V” (this value requires verification by manually bringing the back spindle near to the workpiece
on the main spindle leaving a space between the two spindles equivalent to the length of a finished
workpiece, reading the value of the current position of axis B on the monitor. This value is then inserted in
variable “V”). A further reduced feed (“E”= feed in mm/min) of the back spindle is made, to the part holder
value defined in variable “B”. This variable is defined in two different ways according to whether the back
spindle is positioned on a mechanical stop or not.
If the rest on mechanical stop is not used (parameter “Z” at zero) the value is to be found by manually
bringing the back spindle on the gripping point, reading the value of axis B current position on the
monitor. This value is to be entered in variable “B”. If the rest on mechanical stop is used the value found
(using the same method as described above – bringing the back spindle manually onto the mechanical
stop) must be increased by 1 or 2 mm before being inserted in variable “B” (E.g.: Value read on monitor
B-255.5; Value inserted in variable “B”=-254.5). The back spindle makes an exploratory stroke of the
value set in parameter “Z” (negative value) within which it should rest on the stop (at the torque set in
parameter “Y”, min. value 20, max. 50) Otherwise the machine will cut off with an operating error.
Variable “A” sets a de-phasing in degrees between the main spindle and the back spindle (used, for
example, to work on hexagonal bars).
The displacement between spindle 1 and spindle 2 refers to function M19 and is obtained by bringing
spindle 1 to M19 S0 and spindle 2 to M219 S.. (desired value); value M219 S.. for spindle 2 is to be
inserted in variable “A”
The part is gripped by the back spindle, released from the main spindle and extracted by a length that
depends on variables “W”, “I” and “K”.
The main spindle jaws close and the parting off of the workpiece takes place, starting from the diameter
defined in variable “D”, finishing at the value defined in variable “U” at a feed in mm/rev. defined in variable
“F” with Vt in m/min defined in variable “S”. For axis Z , the parting off takes place leaving the value of
machining allowance for facing “K” on both the main spindle and the back spindle.
Chip breakage can be performed during the parting off, using depth of cut parameters “C” and radial
separation “Q” . If this possibility is not used , it is sufficient to insert a higher value than the radial parting
off depth in “C”.