8 Cycles
L-
8.6
Cycles for Multipass Milling
\
RULED SURFACE (Cycle 231)
* From the cufrenr position, the fbdC positions
the tool with
a 30 stFa$$lt tine mawnent to the starting paint
of
the first machining operation. Pre-position the tool in such a way that there is
no danger of collision
wirh
the
urorkpiece or
fixtures.
* T’h? TNC positians
the
t~bl with radius compensation RQ to
the programmed
positions.
* ff necessary, use a center-cut end mill (ISO 1641 f.
Process
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From the current position, the TNC positions
the tool with a 3D straight line movement to
starting point 0.
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The tool subsequently moves at the pro-
grammed feed rate for milling to stopping point
0.
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Here, the TNC moves the tool at rapid traverse
by the tool diameter in the positive tool axis
direction and afterwards back to starting point
0
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At starting point 0 the TNC moves the tool
back to the Z value last used.
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The TNC subsequently offsets the tool in all
three axes from point @ in the direction of point
@ to the next pass.
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After this, the TNC moves the tool to the end of
this pass. The TNC calculates the stopping
Fig. 8.64: Sequence of RULED SURFACE cycle
point from point @ and an offset in the direction
of point 0.
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Multipass milling is repeated until the pro-
grammed surface has been completely ma-
chined.
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At the end the TNC positions the tool above the
highest programmed point in the tool axis,
offset by the tool diameter.
Cutting motion
You can freely choose the starting point and thus the milling direction
since the TNC always performs the individual cuts from point @I to point
0. The process sequence is executed from points a/@ to points @/@.
You can position point @ at any corner of the surface to be machined.
If you are using an end mill for the machining operation, you can opti-
mize the surface finish by programming:
Fig. 8.65:
Cutting motion of an end mill with
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a shaping cut (tool axis coordinate of point 0 greater than tool axis
steep surfaces
coordinate of point 0) for slightly inclined surfaces, or
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a drawing cut (tool axis coordinate of point @I less than tool axis
coordinate of point 0) for steep surfaces.
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When milling skew surfaces, program the main cutting direction (from
point @ to point 0) parallel to the direction of the steepest inclination
(Fig. 8.65).
If you are using a spherical cutter for the machining operation, you can
optimize the surface finish by programming:
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When milling skew surfaces, program the main cutting direction (from
point 0 to point 0) perpendicular to the direction of the steepest
inclination (Fig. 8.66).
Fig. 8.66:
Cutting motion of a sphencal cutter
with steep surfaces
TNC 370
8-57
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