Milling practice – why choose climb (down) milling? Select the principal advantage that motivates choosing climb milling in suitable setups.

Introduction / Context:
Climb milling (down milling) feeds the work in the same direction as cutter rotation at the contact zone. It changes chip thickness progression and cutting forces compared with conventional (up) milling. The question targets the main shop-floor benefit.

Given Data / Assumptions:

• Backlash is controlled (CNC or anti-backlash gears/ball screws).
• Work and fixturing are rigid enough for down milling.
• Comparable conditions otherwise (tool, material, width of cut).

Concept / Approach:
In climb milling, chip thickness starts at maximum and falls to nearly zero. This reduces rubbing at entry, often lowers specific cutting energy, and leaves a burnished exit surface. The dominant, widely cited practical reason is superior surface finish on many ductile materials under proper rigidity.

Step-by-Step Solution:

Verification / Alternative check:
Surface roughness measurements (Ra) commonly show better values with climb milling on stiff machines and well-clamped parts.

Why Other Options Are Wrong:

• Chip thickness increases gradually: that describes up milling, not climb.
• Enables cutter to dig in: this is a drawback (risk of pull-in), not a benefit.
• Specific power may reduce, but finish is the main, most consistent advantage; the prompt asks for the key reason.

Common Pitfalls:
Using climb milling on machines with backlash can cause self-feeding; always confirm screw condition and clamp securely.

Final Answer:
Better surface finish can be obtained