OVERVIEW

Throughout this handbook, there have been dozens of programming examples. They all shared one common feature - they were aimed at the CNC vertical machining centers. There was a reason for this approach. First, there are more vertical machining centers in machines shops overall, and mixing two different types of machines would make all reference material more complex. Second, almost every subject covered so far for vertical models is equally applicable to horizontal models. So what are the differences?

Horizontal machining center mainly differs from a vertical machining center in its general functionality. While a CNC vertical machine is mostly used for only one face type of work, a CNC horizontal machine is used for work on many faces of the same part during a single setup. This feature alone makes a horizontal machining center much more versatile machine - and also more expensive. Figure 46-1 shows comparison of axis orientation.

Figure 46-1: Axis orientation differences between vertical and horizontal machines

From the illustration is clear that the XY plane is used for the primary plane of work and the Z-axis is used to control cutting depth. There is no difference whatsoever between the two machine types in this respect.

Between programming and setup, there are three major differences on a horizontal machining center:

• Presence of a fourth axis, typically an indexing B-axis

• Presence of a pallet changer

• Richer variety of setup and offset settings

First, a brief look at the fourth axis of atypical CNC horizontal machining...