HEIDENHAIN iTNC 530 User Manual page 483

Please note for the configuration of the post
processor

Always set the data output for axis positions to exactly four decimal
places. This way you improve the quality of the NC data and avoid
rounding errors, which can result in defects visible to the naked eye
on the workpiece surface

Always set the data output for the machining of surface normal
vectors (LN blocks, see "Three-dimensional tool compensation
(software option 2)", page 529) to exactly seven decimal places

Set the tolerance in Cycle 32 so that in standard behavior it is at least
twice as large as the chord error defined in the CAM system Also
pay attention to the description of functions for Cycle 32 in the
"Cycles: Special Functions" chapter of the Cycle Programming
User's Manual

If the chord error selected in the CAM program is too large, then,
depending on the respective curvature of a contour, large distances
between NC blocks can result, each with large changes of direction.
During machining this leads to drops in the feed rate at the block
transitions. Recurring and equal accelerations (i.e. force excitation),
caused by feed-rate drops in the heterogeneous NC program, can
lead to undesirable excitation of vibrations in the machine structure.

You can also use arc blocks instead of linear blocks to connect the
path points calculated by the CAM system. The TNC internally
calculates circles more exactly than can be defined via the input
format

Do not output any intermediate points on exactly straight lines.
Intermediate points that are not exactly on a straight line can result
in defects visible to the naked eye on the workpiece surface

There should be exactly one NC data point at curvature transitions
(corners)

Avoid sequences of many short block paths. Short paths between
blocks are generated in the CAM system when there are large
curvature transitions with very small chord errors in effect. Exactly
straight lines do not require such short block paths, which are often
forced by the continuous output of points from the CAM system

Avoid a perfectly even distribution of points over surfaces with a
uniform curvature, since this could result in patterns on the
workpiece surface

For 5-axis simultaneous programs: avoid the duplicated output of
positions if they only differ in the tool's angle of inclination

Avoid the output of the feed rate in every NC block. This would
negatively influence the TNC's velocity profile
HEIDENHAIN iTNC 530
Beispiel: NC blocks with variable feed-rate
definitions
1 Q50 = 7500 ; POSITION FEED RATE
2 Q51 = 750 ; FEED RATE FOR PLUNGING
3 Q52 = 1350 ; FEED RATE FOR MILLING
...
...
25 L Z+250 R0 FMAX
26 L X+235 Y-25 FQ50
27 L Z+35.5
28 L Z+33.2571 FQ51
26 L X+231.7562 Y-24.9573 Z+33.3978 FQ52
...
483