Milling direction terminology When the milling cutter rotates in the same direction as the feed motion of the workpiece (chip thickness starts maximum and decreases), what is this operation called?

Difficulty: Easy

Correct Answer: Down milling (climb milling)

Explanation:


Introduction / Context:
Milling direction affects chip thickness profile, cutting forces, surface finish, and fixture requirements. Choosing up or down milling is a key process decision, especially on machines with or without backlash compensation.



Given Data / Assumptions:

  • Standard horizontal or vertical milling setup.
  • Properly adjusted machine with minimal backlash (or CNC with compensation).
  • Work and cutter engagements are typical.


Concept / Approach:
In down (climb) milling, the cutter rotation matches the feed direction. Chip thickness starts at a maximum and reduces to nearly zero, often giving better surface finish and tool life, provided backlash is controlled and the work is rigidly clamped. In up (conventional) milling, the cutter rotates against the feed and chip starts from zero thickness, increasing to maximum at exit.



Step-by-Step Solution:

Determine relative directions: cutter rotation and table feed are the same → down milling.Consider benefits: improved finish, lower rubbing at entry, reduced work hardening.State correct name: down milling (climb milling).


Verification / Alternative check:
Process diagrams in machining texts illustrate chip thickness progression for up vs. down milling, matching the stated definition.



Why Other Options Are Wrong:
Up milling: feed opposite rotation; incorrect direction.Face/End milling: describe cutter orientation, not direction of milling.Slotting: a specific operation, not a direction convention.



Common Pitfalls:
Using down milling on worn machines with backlash can cause part “pull-in.” Always ensure rigid clamping and backlash control.



Final Answer:

Down milling (climb milling)

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