HEIDENHAIN TNC 640, User Manual, Page: 633 / 948

Multiple-Axis Machining | Three-dimensional tool compensation (option 9)
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HEIDENHAIN | TNC 640 | Conversational Programming User's Manual | 10/2017
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Definition of a normalized vector
A normalized vector is a mathematical quantity with a value of
1 and any direction. The control requires up to two normalized
vectors for LN blocks, one to determine the direction of the
surface-normal vector, and another (optional) to determine the
direction of the tool orientation. The direction of a surface-normal
vector is determined by the components NX, NY and NZ. For end
mills and spherical cutters, it points from the workpiece surface
in perpendicular direction to the tool reference point PT, for toroid
cutters, it goes through PT’ or PT (see figure). The direction of tool
orientation is determined by the components TX, TY and TZ.
Programming notes:
In the NC syntax, the order must be X,Y, Z for the
position and NX, NY, NZ as well as TX, TY, TZ for the
vectors.
Always indicate all coordinates and all surface-
normal vectors in the NC syntax for an LN block,
even though the values have not changed from the
previous block.
Calculate the normal vectors as exactly as possible
and specify them with a sufficient number of decimal
places (recommended: at least 7), in order to avoid
drastic feed rate decreases during machining. LN
blocks are always calculated with a high accuracy,
regardless of the setting of Option 23.
The 3-D tool compensation using surface normal
vectors is effective for the coordinate data specified
for the main axes X, Y, Z.
If you load a tool with oversize (positive delta value),
the control generates an error message. You can
suppress the error message with the
M107
function.
The control will not warn you if there is a danger of
contour damage due to tool oversizes.