Chapter 21

Question 1

what are the 4 common cutting processes?

Answer 1

Turning, in which the workpiece is rotated and a cutting tool removes a layer of material as the tool moves along its length, as shown in Fig. 21.1a.

Cutting off, in which the tool moves radially inward and separates a piece (on the right in Fig. 21.1b) from the blank.

Slab milling, in which a rotating cutting tool removes a layer of material from the surface of the workpiece (Fig. 21.1c).

End milling, in which a rotating cutter travels to a certain depth in the workpiece, producing a cavity (Fig. 21.1d).

Question 2

what is the feed or feed rate?

Answer 2

is the distance the tool travels per revolution of the workpiece (mm/rev or in./rev)

Question 3

what are the independent variables when cutting?

Answer 3

(a) tool material and coatings, if any; (b) tool shape, its surface finish and sharpness; (c) workpiece material and its processing history; (d) cutting speed, feed, and depth of cut; (e) cutting fluids, if any; (f) characteristics of the machine tool; and (g) the type of workholding device and fixturing.

Question 4

what are the dependent variables when cutting?

Answer 4

in machining are those that are influenced by changes made in the independent variables listed above. They include: (a) type of chip produced, (b) force and energy dissipated during cutting, (c) temperature rise in the workpiece, the tool, and the chip, (d) tool wear and failure, and (e) surface finish and surface integrity of the workpiece.

Question 5

cutting ratio or chip thickness ratio?

Answer 5

the depth of the cut (to)/the thickness of the chip(tc)

Question 6

what are the 4 main types of chips?

Answer 6

Continuous

Built-up edge

Serrated or segmented

Discontinuous

Question 7

what are built up edge chips?

Answer 7

A built-up edge (BUE) consists of layers of material from the workpiece that gradually are deposited on the tool tip, hence the term built-up

Question 8

what are the effects of the built up edge?

Answer 8

Ruins surface finish and dulls the cutting edge of the cutter. On the other hand a thin stable BUE is generally reguarded as desirable because it reduces tool wear by protecting its rake face,

Question 9

how can built up edge (BUE) be reduced?

Answer 9

Increase the cutting speed

Decrease the depth of cut

Increase the rake angle

Use a sharper tool

Use a cutting tool that has lower chemical affinity for the workpiece material

Use an effective cutting fluid.