The tool’s length-to-diameter ratio is significant in any milling process. The larger the ratio, the less rigid the setup. However, the difference in performance between different levels of L:D becomes even more pronounced when tools are particularly small.

This video shows machining footage involving tools as small as 0.008 inch in diameter. It defines the maximum practical limit of L:D for milling processes involving such small tools, and it analyzes how much cutting parameters need to change as the L:D ratio changes.