Page 380 - 04. Subyek Engineering Materials - Manufacturing, Engineering and Technology SI 6th Edition - Serope Kalpakjian, Stephen Schmid (2009)

Metal Extrusion and

Drawing Processes

and Equipment

l5.| Introduction 360 ° Extrusion and drawing involve, respectively, pushing or pulling a material
l5.2 The Extrusion
Process 362 through a die basically for the purpose of reducing or changing its cross-
I5.3 Hot Extrusion 364 sectional area.
|5.4 Cold Extrusion 368 ° This chapter examines the fundamentals of these processes and their applications.
I5.5 Extrusion Defects 37|
l5.6 Extrusion Equipment 373 ° The chapter starts by discussing the basic types of extrusion processes, namely,
l5.7 The Drawing Process 373 direct, indirect, and hydrostatic extrusion, and explains how the extrusion
l5.8 Drawing Practice 375 force can be estimated from material and processing parameters.
|5.9 Drawing Defects and
Residual Stresses 377 ° Hot and cold extrusion are then discussed; cold extrusion is often done in
l5.|0 Drawing Equipment 377 combination with forging to produce specific parts.
EXAMPLES: ° Extrusion practices and die designs that avoid common defects are also
l5.l Calculation of Force in resented.
P
Hot Extrusion 363
|5.2 Manufacture of Aluminum ° The drawing of rod, wire, and tubing is then examined in a similar manner,
along with die design.
Heat Sinks 368
I5.3 Cold-extruded Part 369 ' The equipment characteristics for these processes are also described.
Typical parts made by extrusion and drawing: Long pieces having a wide variety
of constant cross sections, rods, shafts, bars for machinery and automotive
power-train applications, aluminum ladders, collapsible tubes, wire for numerous
electrical and mechanical applications and musical instruments.
Alternative processes: Machining, powder metallurgy, shape rolling, roll forming,
pultrusion, and continuous casting.

l5.l Introduction

Extrusion and drawing have numerous applications in the manufacture of continuous
as well as discrete products from a wide variety of metals and alloys. Plastics also are
extruded extensively, as described in Section 19.2. In extrusion, a cylindrical billet is
forced through a die (Fig. l5.1) in a manner similar to squeezing toothpaste from a tube
or extruding Play-Doh® in various cross sections in a toy press. A wide variety of solid
or hollow cross sections may be produced by extrusion, which essentially are semifin-
ished parts. A characteristic of extrusion (from the Latin extrudere, meaning “to force
out”) is that large deformations can take place without fracture (see Section 2.2.8),

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