Superfinishing uses ultra-fine abrasive grains with randomly shaped cutting edges. Unlike turning or milling, the cutting geometry is not defined. According to DIN 8589 Part 14, the process is therefore classified as “machining with geometrically undefined cutting edges.”

In turning or milling, the tool has a precisely defined cutting geometry with specified rake angle, clearance angle, and wedge angle.
In superfinishing, however:

• many individual abrasive grains are active
• each grain has a random cutting geometry
• material removal occurs through micro-cutting
• multiple cutting edges engage simultaneously

This results in:

• very small chip thickness
• extremely low cutting forces per grain
• controlled material removal in the micrometer (µm) range