FANUC Series 16/18/160/180-Model C Machining Center Operators Manual

To machine (grind/cut) a gear, the rotation of the workpiece axis
connected to a servo motor is synchronized with the rotation of the tool
axis (grinding wheel/hob) connected to the spindle motor. To
synchronize the tool axis with the workpiece axis, an electric gear box
(EGB) function is used for direct control using a digital servo system.
With the EGB function, the workpiece axis can trace tool axis speed
variations without causing an error, thus machining gears with great
Some conditions must be satisfied for setting the workpiece axis and tool
axis. For details, refer to the relevant manual provided by the machine
tool builder.
G81 T _ L _ Q _ P _ ; Starts synchronization.
S_ M03 (or M04) ; Starts tool axis rotation.
M05 ; Stops tool axis rotation.
G80 ; Cancels synchronization.
T : Number of teeth (Specifiable range: 1 to 1000)
L : Number of hob threads
(Specifiable range: –21 to +21 with 0 excluded)
Q: Module or diametral pitch
Specify a module in the case of metric input.
(Unit: 0.00001 mm, Specifiable range: 0.01 to 25.0 mm)
Specify a diametral pitch in the case of inch input.
(Unit: 0.00001 inch
, Specifiable range: 0.01 to 25.0 inch
P : Gear helix angle
(Unit: 0.0001 deg, Specifiable range: –90.0 to 90.0 deg.)
* When specifying Q and P, the user can use a decimal point.
1 Start of synchronization
When synchronization mode is set with G81, the synchronization
switch of the EGB function is closed, and synchronization between the
tool axis and workpiece axis starts. At this time, synchronization
mode signal SYNMOD is turned on. During synchronization, the
rotation of the tool axis and workpiece axis is controlled so that the
relationship between T (number of teeth) and L (number of hob
threads) can be maintained. Moreover, the synchronous relationship
is maintained regardless of whether the operation is automatic or
manual during synchronization.
G81 cannot be specified again during synchronization. Moreover, the
specification of T, L, Q, and P cannot be modified during
2 Start of tool axis rotation
When the rotation of the tool axis starts, the rotation of the workpiece
starts so that the synchronous relationship specified in the G81 block
can be maintained.
GEAR BOX (G80, G81)
D Synchronization control

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