Which is the possible cause when a twist drill produces a rough hole on the job?

Question

Question

This question was previously asked in

ALP CBT 2 Fitter Official Paper: Held on 21 Jan 2019 Shift 2

Answer 1

Explanation:

The common defects in drilling are listed below:

Oversized holes	The unequal length of the cutting edges The unequal angle of the cutting edges The unequal thinning of the point The spindle running out of the center The drill point not being in the center
Overheated drills	Cutting speed is too high Feed rate is too high Clearance angle is incorrect Cooling is ineffective Point angle is incorrect The drill is not sharp
Rough holes	Feed rate is too much Drill cutting edges are not sharp Cooling is ineffective
An unequal flow of chips	An unequal flow of chips is caused if the cutting edges are not equal and the point angle is not in the center of the drill
Broken drill or split web	Cutting speed is too high Feed rate is too high Work is not held rigidly The drill is not held correctly The drill is not sharp Point angle is incorrect Cooling is insufficient Flutes are clogged with chips