Page 575 - 04. Subyek Engineering Materials - Manufacturing, Engineering and Technology SI 6th Edition - Serope Kalpakjian, Stephen Schmid (2009)

Fundamentals

of Machining

° This chapter is an introduction to the fundamentals of the machining processes
to be covered in subsequent chapters and, as such, presents the basic concepts
relevant to all machining operations.
° The chapter opens with a discussion of the mechanics of chip formation in
machining and the model typically used for orthogonal cutting operations; the
model and its oblique-cutting extensions allow the calculation of force and
power in machining.
0 Temperature rise in chip and cutting tool are then discussed.
* Mechanisms of tool wear and failure follow, with flank Wear characterized by
the Taylor tool-life equation.
° Crater wear, nose wear, and other forms of wear are also described.
~ The chapter ends with a discussion of surface finish, the integrity of parts
produced by machining, and the factors involved in the machinability of
various metallic and nonmetallic materials.
Material Removal 578
2 l.l Introduction

Cutting processes remove material from the surface of a workpiece by producing
chips. Some of the more common cutting processes, illustrated in Fig. 21.1 (see also
Fig. I.6e), are as follows:

° Turning, in which the workpiece is rotated and a cutting tool removes a layer
of material as the tool moves to the left, as in Fig. 21.1a.
° Cutting off, in which the cutting tool moves radially inward and separates the
right piece from the bulk of the blank.
° Slab milling, in which a rotating cutting tool removes a layer of material from the
surface of the workpiece.
° End milling, in which a rotating cutter travels along a certain depth in the work-
piece and produces a cavity.

In the turning process, illustrated in greater detail in Fig. 21.2, the cutting tool
is set at a certain dept/0 of cut (mm) and travels to the left with a certain velocity as
the workpiece rotates. The feed, or feed rate, is the distance the tool travels
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