Machining heat generation — which mechanism dominates at the tool–chip interface? In metal cutting, the work–tool contact (chip–tool interface) is a major heat source primarily due to what phenomenon?

Introduction / Context:
During machining, heat is generated in three regions: (1) the primary shear zone (plastic deformation), (2) the secondary deformation zone at the chip–tool interface (friction and some plastic deformation), and (3) the tertiary zone at the tool flank (rubbing/burnishing). Understanding which mechanism dominates at the work–tool contact helps in selecting tool materials and cutting fluids.

Given Data / Assumptions:

• The “work–tool contact zone” here refers to the chip sliding over the rake face.
• Steady cutting, conventional speeds and feeds, typical ductile materials.

Concept / Approach:
At the rake face, the newly formed chip is at high temperature and pressure; it slides (or sticks–slides) over the tool, causing intense frictional heating. Although plastic deformation dominates in the primary zone, the specific zone asked is the tool–chip interface where friction is the principal source.

Step-by-Step Solution:

Verification / Alternative check:
Temperature maps show peak temperatures near the tool–chip interface at high speeds, corroborating frictional origin.

Why Other Options Are Wrong:
Plastic deformation in the primary shear zone occurs ahead of the tool, not at the rake face interface.Burnishing on the machined surface is the flank region and contributes less heat than the rake face.Radiation and shank shear are negligible compared to frictional and plastic work.

Common Pitfalls:
Assuming the primary shear zone is always the hottest; at high speeds, the chip–tool interface often reaches the maximum temperature.

Final Answer:

Friction between the moving chip and the tool face