High-Speed Machining

The term “high-speed machining” (HSM) is a relative one from a materials viewpoint because of the vastly different speeds at which different materials can be machined with acceptable tool life. For example, it is easier to machine aluminum at 6000 surface feet per minute (sfm) than titanium at 600 sfm. Because of this difference, and the fact that speed determines to a significant degree whether a material will form continuous chips or segmented, shear- localized chips, one way of defining high-speed machining is to relate it to the chip formation process. Localized shear occurs when the negative effect on strength of increasing temperature due to intense plastic deformation is equal to or greater than the positive effect of strain hardening. In this context, high-speed machining for a given material can be defined as that speed above which shear-localization develops completely in the primary shear zone.