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1 Metal-Casting

Processes and

Equipment

° Building upon the fundamentals of solidification, fluid flow, and heat transfer
discussed in Chapter 10, this chapter presents the principles of casting processes.
° Casting processes are generally categorized as permanent-mold and expendable-
mold processes; expendable-mold processes are further categorized as
permanent-mold and expendable-pattern processes.
° The characteristics of each process are described, together with typical applica-
tions, advantages, and limitation.
° Special casting processes that produce single-crystal components as well as
amorphous alloys are then described.
° The chapter ends with a discussion of inspection techniques for castings.

Typical products made by casting: engine blocks, crankshafts, hubcaps, power
tool housings, turbine blades, plumbing parts, zipper teeth, dies and molds, gears,
railroad wheels, propellers, office equipment, and statues.
Alternative processes: forging, powder metallurgy, machining, and fabrication.

Superalloy Components I |.l Introduction
for Gas Turbines 274
CASE STUDIES:
The first metal castings were made during the period from 4000 to 3000 B.C., using
ll.l Lost-foam Casting of stone and metal molds for casting copper. Various casting processes have been devel-
Engine Blocks 272 oped over time, each with its own characteristics and applications (see also Fig. I.6a),
|I.2 Investment Casting
of Total Knee to meet specific design requirements (Table 11.1). A large variety of parts and com-
Replacements 275 ponents are made by casting, such as engine blocks, crankshafts, automotive compo-
nents and powertrains (Fig. 11.1), agricultural and railroad equipment, pipes and
plumbing fixtures, power-tool housings, gun barrels, frying pans, jewelry, orthopedic
implants, and very large components for hydraulic turbines.
Two trends have had a major impact on the casting industry. The first is the
mechanization and automation of the casting process, which has led to significant
changes in the use of equipment and labor. Advanced machinery and automated
process-control systems have replaced traditional methods of casting. The second
major trend has been the increasing demand for high-quality castings with close
dimensional tolerances.
This chapter is organized around the major classifications of casting practices
(see Fig. IL3 in the Introduction to Part II). These classifications are related to mold
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