Correct option is D
A
high feed rate can cause a twist drill to produce a
rough hole because excessive feed leads to increased cutting forces, vibrations, and poor chip evacuation. This can result in rough surfaces, burrs, and even drill bit deflection, making the hole uneven and imprecise. Proper control of feed rate ensures smoother cutting, reduced chatter, and better surface finish.
Feed Rate Definition: The distance the drill bit advances per revolution of the spindle. A high feed rate leads to faster drilling but can compromise accuracy and surface quality.
Effect of High Feed Rate:
· Increases cutting forces, causing deflection and tool vibration.
· Reduces the ability of the drill to clear chips, leading to rough cutting.
Optimal Feed Rate: Dependent on material type, drill diameter, and desired surface finish. Lower feed rates are recommended for precision drilling.
Additional Factors for Rough Holes:
· Worn or dull drill bits can also produce rough holes.
· Inadequate lubrication can lead to excessive friction and poor finish.
