Milling direction where cutting force starts maximum and ends minimum Identify the milling mode in which the instantaneous chip thickness starts at its maximum value when the tooth first engages the work and reduces toward minimum at exit.

Introduction / Context:
The direction of cutter rotation relative to table feed defines up (conventional) or down (climb) milling. This choice affects chip thickness variation during a tooth’s engagement, which in turn influences force, finish, and tool life.

Given Data / Assumptions:

• Standard slab or face milling engagement.
• Properly controlled backlash (e.g., CNC or well-maintained machine).
• Work is rigidly fixtured.

Concept / Approach:
In down (climb) milling, cutter rotation and feed are in the same direction at the point of contact. The tooth bites into the work with the largest chip thickness at entry and exits with near-zero thickness. This lowers rubbing at entry and can improve finish, provided backlash is managed. In up milling, the chip thickness starts at nearly zero and increases to maximum at exit.

Step-by-Step Solution:

Verification / Alternative check:
Chip thickness sketches from machining texts clearly show the opposite progression for up vs. down milling.

Why Other Options Are Wrong:
Up milling: chip starts at zero and ends at maximum; opposite trend.Face/End milling: refer to cutter orientation, not chip-thickness progression.Slotting: an operation type; does not specify direction relationship.

Common Pitfalls:
Attempting climb milling on worn machines can cause part pull-in. Always minimize backlash and secure the work.

Final Answer:

Down milling (climb milling)