Chapter 21, Problem 1RQ

Why has the metal-cutting process resisted theoretical solution for so many years?

To determine

The reason that the metal cutting process resisted theoretical solution for so many years.

Explanation of Solution

The zone where the chip is formed is not entirely bounded. For example, where the work piece is deformed in the die, in metal cutting, the work piece has free surfaces. In lathe turning, there are free surfaces at the work piece diameter and on the top of the forming chip. And, the boundaries that do exist (the tool-chip interface and the not well-defined deformation zone boundary in the work material) are challenging to characterize.

Further complications of the process are that the strains are enormous, and the strain rate is very high. Material properties at such conditions are not typically known. There are also a large number of process variables.

The theoretical solutions always need to be validated experimentally. It isn't very easy to obtain reliable, consistent experimental results that quantitatively describe the local deformation in the chip formation zone. The chip formation zone extends into the work piece below what will become the finished surface.