TABLE OF CONTENTS There is a quite good chance that the majority of programs for CNC machining centers include machining of at least one hole, probably more. From a simple spot drill to reaming, tapping and a complex backboring, the field of hole machining is very large. In this chapter, we look at many available programming methods for holes machining, and learn a number of techniques used. Various drilling and boring operations, as well as reaming, tapping and single point boring will be covered.
The most common type of hole machining on CNC machining centers is in the area of drilling, tapping, reaming and single point boring. A typical machining procedure may be to center drill or spot drill a series of holes, then drill them, then tap or bore them. Machining even a single hole will benefit from using the fixed cycles - G81 to G89, G73, G74 and G76, all described in Chapter 25.
Before machining even a single hole on a machine, all required tool paths have to be programmed. Before that, cutting tools have to be selected, speeds and feeds applied, the best setup determined and many other related issues must be resolved. Regardless of the exact approach, always start with a thorough evaluation of the given hole.
The first step relates to the drawing data. That will usually define the material to be machined, the hole location and its dimensional values. Holes are often described, rather than dimensioned and the programmer has...
