Siemens SINUMERIK 840D sl Programming Manual page 601

Spline type
C spline
NC programming
Programming Manual, 12/2019, 6FC5398-2EP40-0BA0
Properties and use
C spline (cubic 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 with continuous curvature.
● Frequently generates undesirable oscillations, especially at positions where
the gradient changes significantly.
● The area of influence of changes to the intermediate points is global. This
means that if an intermediate point is changed then this influences the com‐
plete curved characteristic.
Application:
The C spline can be well used when the intermediate points lie on a curve defined
analytically (circle, parabola, hyperbola).
3.7 Special motion commands
P7
P6
P4
P5
Work preparation
601