HEIDENHAIN iTNC 530 (340 422) ISO programming - Manual (Page 300)

300 8 Programming: Cycles
8.4 Cy
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POCKET MILLING (Cycles G75, G76)
1 The tool penetrates the workpiece at the starting position (pocket
center) and advances to the first plunging depth.
2 The cutter begins milling in the positive axis direction of the longer
side (on square pockets, always starting in the positive Y direction)
and then roughs out the pocket from the inside out.
3 This process (1 to 2) is repeated until the depth is reached.
4 At the end of the cycle, the TNC retracts the tool to the starting
position.
Direction of rotation during rough-out
n In clockwise direction: G75 (DR-)
n In counterclockwise direction: G76 (DR+)
U U U U Set-up clearance 1 (incremental value): Distance
between tool tip (at starting position) and workpiece
surface.
U U U U Milling depth 2 (incremental value): Distance
between workpiece surface and bottom of pocket
U U U U Plunging depth 3 (incremental value): Infeed per cut
The TNC will go to depth in one movement if:
n the plunging depth is equal to the depth
n the plunging depth is greater than the depth
U U U U Feed rate for plunging: Traversing speed of the tool
during penetration
U U U U First side length 4 (incremental value): Pocket
length, parallel to the reference axis of the working
plane
Example: NC blocks
N27 G75 P01 2 P02 -20 P03 5 P04 100
P05 X+80 P06 Y+40 P07 275 P08 5 *
...
N35 G76 P01 2 P02 -20 P03 5 P04 100
P05 X+80 P06 Y+40 P07 275 P08 5 *
X
Z
11
12
13
14
15
Before programming, note the following:
This cycle requires a center-cut end mill (ISO 1641), or pilot
drilling at the pocket center.
Pre-position over the pocket center with radius
compensation G40.
Program a positioning block for the starting point in the
tool axis (set-up clearance above the workpiece surface).
The algebraic sign for the cycle parameter DEPTH
determines the working direction. If you program
DEPTH = 0, the cycle will not be executed.
The following prerequisite applies for the 2nd side length:
2nd side length greater than [(2 x rounding radius) +
stepover factor k].