Siemens SINUMERIK 840D sl Programming Manual page 599

Properties and use of the various spline types
Spline type
A spline
NC programming
Programming Manual, 12/2019, 6FC5398-2EP40-0BA0
Properties and use
A spline (akima spline)
P3
P2
P1
P1 to P7: specified coordinates
Properties:
● Passes exactly through the specified intermediate points along the curve.
● The curve characteristic is tangential, but does not have continuous curvature.
● Produces hardly any undesirable oscillations.
● The area of influence of changes to intermediate points along the curve is local.
This means that a change to an intermediate point along the curve only affects
up to max. 6 adjacent intermediate points.
Application:
The A spline is especially suitable for interpolating curves with large changes in the
gradient (e.g. staircase-type curves and characteristics).
3.7 Special motion commands
P6
P7
P4
P5
Work preparation
599