Specifications

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CONCISE GUIDE FANUC 93

6.0 BACK SPINDLE MACHINING

The back spindle option is an additional spindle opposite and co-axial to the main one, which makes it

possible to machine on the rear part of the workpiece after taking it from the first spindle. The back spindle

is useful when working on parts machined from bars, since in most cases, it is possible to obtain complete

items regarding the turning operations. This option consists of a spindle mounted on a saddle that allows

movement in the direction parallel to the turret axis Z.

6.1 MOST IMPORTANT ADDRESSES USED

The programming of the movements of this axis uses address B (E.g.: N54 G0 X… Z… B0). The B

function can be used together with other movement co-ordinates, and in this case the movement will take

place when all the axes inserted in the block simultaneously reach the programmed position.

Also the back spindle direction of rotation is controlled by special instructions: M203, M204, M205 (E.g.:

N12 S1250 M203)

The block with the spindle rotation instructions is programmed as follows:

N24 G92 S2500 ; Revs limitation

N25 G96 S250 M204 ; Cutting speed

;

N32 G97 S1400 M203 ; Number of fixed revs

N41 G0 X… Z… M205 ; Separation from axes and back spindle stop

- B +

B − ….