Chip thickness profile in milling — down (climb) milling In down milling (climb milling), how does the instantaneous chip thickness vary from entry to exit of the cut?

Introduction / Context:
Milling chip load distribution affects surface finish, tool wear, and machine dynamics. Understanding how chip thickness evolves during the tooth engagement helps in selecting feeds, cutter geometry, and climb versus conventional strategies.

Given Data / Assumptions:

• Peripheral milling with a standard helical end mill or slab mill.
• Down (climb) milling configuration: cutter rotation assists the feed direction.
• Rigid setup and proper backlash control.

Concept / Approach:
In down milling, the cutting tooth first meets the work at maximum uncut chip thickness and exits at near-zero thickness. This reduces rubbing at the exit and can improve surface finish and tool life, provided machine backlash and workholding are adequate. Conventional (up) milling has the opposite profile.

Step-by-Step Solution:
Define chip thickness h(theta) based on entry/exit angles.For down milling, entry angle corresponds to maximum h; exit angle tends to zero h.Conclude that chip thickness decreases from maximum at entry to minimum at exit.

Verification / Alternative check:
Cutting force measurements show peak forces near entry in climb milling, tapering off toward exit as h diminishes.

Why Other Options Are Wrong:
Option (a) describes up milling; uniform thickness does not occur in peripheral milling; randomness is not a defining feature and depends on dynamics, not geometry.

Common Pitfalls:
Attempting climb milling on machines with significant backlash can cause work pull-in; modern CNCs mitigate this with preloaded screws.

Final Answer:
Maximum at the beginning and minimum at the end