Mechanical Engineering - Production Engineering - Discussion

Explanation:

Helix angle of a drill refers to the angle between the leading edge of the flute and the drill axis.

A low helix angle (15°–20°) means the flutes are less twisted.

Material Preferred: Helix Angle - Reason.

Plastics : Low helix angle - Prevents excessive cutting and reduces the tendency to grab or chip the soft material.
Copper/Aluminium (soft, ductile metals) : High helix angle (35°–45°) - Improves chip removal.
Cast steel/Carbon steel (hard materials): Medium helix angle (25°–30°) - Balanced cutting and chip evacuation.

Therefore, low helix angle drills are best for plastics.

(c) is correct answer /as low helix angel preferred for drilling a hole in hard and brittle material as helix angle decreases rake of cutting edge decreases hence cutting edge becomes stronger.

D. carbon steel is correct.

Carbon steel 0.1 to 1.5%.
Cast steel 0.1 to 0.75%.

The helix angle is inversely proportional to strength. CARBON STEEL has the highest strength here.

D is the right answer because low helix angle is 10-13 degree that is called the normal material.

Low helix angle used for Hard & brittle material, so "C "is Right answer.

Low Helix for Soft.

High Helix for Hard material.

So, Option C is correct.

Low helix angle for soft material.

High helix angle for hard material.

Small helix for hard material and large helix for ductile material.

D is correct as per Sadhu Singh. It was of 1992IES.

Yes, correct @Amiya Mishra.