Siemens SINUMERIK 840D sl Programming Manual page 768

Work preparation
3.13 Tool offsets
of the original tool is a negative value. A negative wear value always describes a tool with a
reduced diameter.
Using cylindrical tools
When cylindrical tools are used, infeed is only necessary if the machining surface and the
surface of limitation form an acute angle (less than 90 degrees). If a toroidal miller (end mill with
corner rounding) is used, tool infeed in the longitudinal direction is required for both acute and
obtuse angles.
3D TRC with CUT3DCC: Contour on the machining surface
If CUT3DCC is active with a toroidal miller, the programmed path refers to a fictitious cylindrical
milling tool having the same diameter. The resulting path reference point is shown in the
following diagram for a toroidal miller.
①
②
③
④
R
The angle between the machining and limitation surfaces may change from an acute to an
obtuse angle and vice versa even within the same block.
The tool actually being used may either be larger or smaller than the standard tool. However,
the resulting corner radius must not be negative and the sign of the resulting tool radius must
be kept.
For CUT3DCC, the NC part program refers to the contour on the machining surface. As for
conventional tool radius compensation, the total tool radius is used that comprises the following
components:
● Tool radius (tool parameter $TC_DP6)
● Wear value (tool parameter $TC_DP15)
● A tool offset OFFN programmed to calculate the perpendicular offset to the limitation surface
The position of the limitation surface is defined from the following difference:
Dimensions of the standard tool - tool radius (tool parameter $TC_DP6)
768
Toroidal miller
Limitation surface
Path reference point
Machining surface
Shaft radius (tool radius)
Programming Manual, 12/2019, 6FC5398-2EP40-0BA0
NC programming