Wuhan Huazhong Numerical Control Co., Ltd HNC-18iT, Programming Manual

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1. General
8
1.4.2
1.4.2 1.4.2
1.4.2 Machine
Machine Machine
Machine Coordinate
Coordinate Coordinate
Coordinate System
System System
System
The coordinate system is set on a CNC machine tool. Figure 1.8 is a machine coordinate
system of turning machine, and shows the direction of axes:
Figure 1.8 Machine Coordinate System
In general, three basic linear coordinate axes of motion are X, Y, Z. Moreover, X, Y, Z axis
of rotation is named as A, B, C correspondently. Due to different types of turning machine,
the axis direction can be decided by following the rule – “three finger rule” of the right
hand.
+ X
+ X
+ Y
＇
+ Z
+ Y
+ Z
+ Y
+ C
+
Z
＇
+
A
+
B
+ C
+X + Y + Z
+ A
+ B
+
X
＇
Figure 1.9 “three finger rule”
- The thumb points the X axis. X axis controls the cross motion of the cutting tool.
“+X” means that the tool is away from the spindle centerline
- The index points the Y axis. Y axis is usually a virtual axis.
- The middle finger points the Z axis. Z axis controls the motion of the cutting tool.
“+Z” means that the tool is away from the spindle.