Basic Metal Cutting Theory

Question 1

What is tangential force? * 2 points *

Answer 1

A force that is tangential to the work surface and is the main power-consuming force.

Question 2

What is axial force?

Answer 2

A force that is
1. parallel to the work axis
2. resists the feed motion that is associated with the feed rate
force is relatively small as compared to the tangential force

Question 3

Which force is bigger, axial or tangential force?

Answer 3

Tangential force.

Question 4

What are the 2 cutting methods?

Answer 4

Orthogonal Cutting & Oblique Cutting

Question 5

At what angle is the tool cutting edge set for orthogonal cutting?

Answer 5

90 degrees.

Question 6

What does the effectiveness of the tool depend on for orthogonal cutting?

Answer 6

the slope of the active surface of the tool

Question 7

How will the tool curl the chip for orthogonal cutting?

Answer 7

1. in the form of a clock spring
2. or a flat spiral

Question 8

Does orthogonal cutting produce the best form of chip for efficient removal?

Answer 8

Nope, the disposal of such chips (in the form of clock spring/flat spiral) present difficulties

Question 9

Why does the disposal of such chips present difficulties?

Answer 9

The chip will stay on top of the tool holder & may damage the workpiece’s surface.

Question 10

How many forces are present most of the time in orthogonal cutting? And what are they?

Answer 10

2 forces : tangential force & axial force

Question 11

What angle is the cutting tool for oblique cutting set at?

Answer 11

other than 90 degrees to the direction of movement or the cutting edge is inclined to the the direction of cut: tending to give the familiar twisted curl chip formation

Question 12

Does oblique cutting improve surface finish of the workpiece? Why or why not?

Answer 12

Yes, the inclined cutting condition does improve the surface finish. Because it allows the chips to move freely away from the area of cutting

Question 13

Which type of cutting improves surface finish?

Answer 13

Oblique cutting.

Question 14

How many forces are present in oblique cutting most of the time? What are they?

Answer 14

3 forces: Tangential force, axial force and radial force

Question 15

Why is the Radial Force present in oblique cutting?

Answer 15

Because the cutting edge used in oblique cutting is not 90 degrees to the direction of movement.
Therefore, the Axial force that is present in orthogonal cutting is divided to Axial force AND Radial Force in Oblique Cutting. [insert picture]

Question 16

How significant is the Radial Force?

Answer 16

It is insignificant as compared to the other 2 forces (axial & tangential).

Question 17

Why is the Radial Force insignificant?

Answer 17

Radial force tends to force the tool out of work

As no motion is associated with Radial force, it does not consume power.
It influences Axial force

Question 18

How many types of cutting chips are there? And what are they?

Answer 18

3 types: Discontinuous Chip, Continuous Chip and Continuous Chip with a Built-Up Edge

Question 19

How many factors influence chips? What are they

Answer 19

4 or 5.
1. Work Material
2. Tool geometry
3. Tool material
4. Cutting Conditions (Speed, Feedrate & Depth of Cut)
5. Presence of Cutting Fluid