HEIDENHAIN TNC 360 User Manual - Manual (Page 26)

TNC 360 1-8
1 Introduction
Additional axes
The TNC can control machines which have more than three axes. U, V
and W are secondary linear axes parallel to the main axes X, Y and Z,
respectively (see illustration). Rotary axes are also possible. They are
designated as axes A, B and C.
Polar coordinates
The Cartesian coordinate system is especially
useful for parts whose dimensions are mutually
perpendicular. But when workpieces contain
circular arcs, or when dimensions are given in
degrees, it is often easier to use polar coordinates.
In contrast to Cartesian coordinates, which are
three-dimensional, polar coordinates can only
describe positions in a plane.
The datum for polar coordinates is the circle
center CC. To describe a position in polar coordi-
nates, think of a scale whose datum point is rigidly
connected to the pole but which can be freely
rotated in a plane around the pole.
Positions in this plane are defined by:
• Polar Radius (PR): The distance from circle
center CC to the defined position.
• Polar Angle (PA): The angle between the
reference axis and the scale.
1.2 Fundamentals of NC
Fig. 1.12: Positions on an arc with polar coordinates
Fig. 1.11: Arrangement and designation of
the auxiliary axes
X+
Y+
10
CC
0 °
30
PA
1
PA
2
PA
3
PR
PR
PR
Y
B+
V+
X
Z
C+
A+
W+
U+