Page 581 - 04. Subyek Engineering Materials - Manufacturing, Engineering and Technology SI 6th Edition - Serope Kalpakjian, Stephen Schmid (2009)

Chapter 21 Fundamentals of Machining

A velocity diagram also can be constructed, as shown in Fig. 21.4b, in which,
from trigonometric relationships, we obtain the equation

V VS VL.
= = (21.6a)
cos(q3 A a) Cosa sinfjr
where VS is the velocity at which shearing takes place in the shear plane. Note also that
= L = i.
V
t
f tt V ( 21.6b l
These velocity relationships will be utilized further in Section 21.3 in describing
power requirements in cutting operations.

2l.2.I Types of Chips Produced in Metal Cutting
The types of metal chips commonly observed in practice and their photomicro-
graphs are shown in Fig. 21.5. The four main types are as follows:
i

"Yi Q 4. s
Too Secondary shear zones
Primary

Chi P

To
,_ W
2
‘: ",
`~ ,g

7%Q`\1~
li'j*7f_~
mf? ~~'~;;~~‘#i:>¥§~¢»-,ssc *_
Pi; ~~~ .» Q?
,\ _'§§~..,;"<¢\;.~ >»
“~»,¢§\\~.-zfr{,
./.
,,
‘J
I

Low
High s
shear x -
strain _ Q `» -

(dl (9)

FIGURE 2|.5 Basic types of chips produced in orthogonal metal cutting, their schematic representation, and
photomicrographs of the cutting zone: (al continuous chip with narrow, straight, and primary shear zone;
(b) continuous chip with secondary shear zone at the chip-tool interface; (c) built-up edge; (d) segmented or
nonhomogeneous chip; and (e) discontinuous chip. Source: After M.C. Shaw, P.K. Wright, and S. Kalpakjian.