# Manufacturing Engineering Questions & Answers – Geometry of Twist Drills-4

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This set of Manufacturing Engineering aptitude tests focuses on “Geometry of Twist Drills”.

1. Which of the following is correct about helix angle for left hand flute drill?
a) Positive
b) Negative
c) Zero
d) None of the mentioned

Explanation: Helix angle have negative value for right handed flute.

2. Which of the following is correct about helix angle for parallel flute drill?
a) Positive
b) Negative
c) Zero
d) None of the mentioned

Explanation: Helix angle have zero value for right handed flute.

3. Which of the following drill is most suitable for softer material?
a) 48 degree helix angle drill
b) 68 degree helix angle drill
c) 58 degree helix angle drill
d) 18 degree helix angle drill

Explanation: Helix angle with lower value is more suitable for soft material. Helix angle have negative value for right handed flute.

4. When the value of helix angle increases in drills, the value of required torque for rotation of drill will
a) Increase
b) Decrease
c) First increase then decrease
d) First decrease then increase

Explanation: Torque required is inversely proportional to helix angle of drill. When the value of helix angle increases in drills, the value of required torque for rotation of drill will increase.

5. Point angle of drill is also known as
a) Taper angle
b) Friction angle
c) Helix angle
d) Cutting angle

Explanation: Point angle of drill is also known as cutting angle. Small point angle drills are favored for brittle material because brittle material has low chip flow. Small point angle makes drill strong. But it reduces the passage area for chip flow.

6. Which of the following drill will be most suitable for drilling of brittle material?
a) Small point angle drill
b) Large point angle drill
c) Zero point angles drill
d) None of the mentioned

Explanation: Small point angle drills are favored for brittle material because brittle material has low chip flow. Small point angle makes drill strong. But it reduces the passage area for chip flow. Point angle of drill is also known as cutting angle.

7. Which of the following drill will be most suitable for drilling of ductile and soft material?
a) Small point angle drill
b) Large point angle drill
c) Zero point angles drill
d) None of the mentioned

Explanation: Large point angle drills are favored for ductile material because ductile material has high chip flow. Large point angle makes drill weak but increases chip flow passage area. Point angle of drill is also known as cutting angle.

8. Clearance in drill is
a) Directly proportional to chisel edge angle
b) Inversely proportional to chisel edge angle
c) Does not depend on chisel edge angle
d) None of the mentioned

Explanation: Greater the chisel edge angle larger will be the clearance.

9. For drilling of brass work piece, most suitable rake angle in degrees for drill will be
a) 12
b) 15
c) 0
d) -9

Explanation: Brass is neither brittle nor ductile and hence zero rake angle is preferred for drilling of brass work piece.

10. Which of the following is most suitable range of lip clearance angel in degrees for drilling of aluminum work piece?
a) 8-12
b) 3-2
c) 50-60
d) None of the mentioned

Explanation: 8 degree to 12 degree is the best range of lip clearance angle for most of the operations.

Sanfoundry Global Education & Learning Series – Manufacturing Engineering.

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