Axes Designation - Y-Axis

It is perpendicular to both X- and Z-axes and the direction is identified by the right hand Cartesian co-ordinate system.In the case of several spindles and slide ways, one of the spindles, preferably the one perpendicular to the work-holding surface may be chosen as the principal spindle and associated with the Z-axis. The motions of other spindles or slides, may be treated as secondary and tertiary motions and accordingly designated like U, V, W and P, Q, R respectively.

The designation of Z-axis is demonstrated in Figure 6 for a vertical axis milling machine. In Figure 7 is shown a turning centre.

Figure 6 : Vertical Axis Milling Machine or Machining Centre

As already discussed, most of the machine tool manufacturers adhere to the standard to a very great extent. However, some deviations may be present in some cases because of the historical reasons or specific convenience in operation or programming of the machine tool.

Figure 7 : Axes Designation for CNC Turning Centre

A, B and C are defined as the primary rotary motions and are assigned about the axis parallel to X, Y and Z respectively. Additional rotary motions if present are designated as D or E regardless of whether they are parallel or not to A, B and C.