Face Milling (A4, B4, C4, A5, B5, C5) - Siemens SINUMERIK 840D sl Programming Manual

3.9.2.5

Face milling (A4, B4, C4, A5, B5, C5)

Face milling is used to machine curved surfaces of any kind.
For this type of 3D milling, you will require the line-by-line description of the 3D paths on the
workpiece surface.
The tool shape and dimensions are taken into account in the calculations, which are normally
performed in CAM. The fully calculated NC blocks are then read into the control via
postprocessors.
Programming the path curvature
Surface description
The path curvature is described by surface normal vectors with the following components:
A4, B4, C4 Start vector at block start
A5, B5, C5 End vector at block end
If a block only contains the start vector, the surface normal vector will remain constant
throughout the block. If a block only contains the end vector, interpolation will run from the end
value of the previous block via large-circle interpolation to the programmed end value.
If the start and end vectors are programmed, interpolation runs between the two directions, also
via large-circle interpolation. This allows continuously smooth paths to be created.
Regardless of the active G17 to G19 level, in the initial setting, surface normal vectors point in
the Z direction.
The length of a vector is meaningless.
Vector components that have not been programmed are set to zero.
NC programming
Programming Manual, 12/2019, 6FC5398-2EP40-0BA0
A4
B4
A5
C4
B5
C5
Work preparation
3.9 Transformations
673