【正文】 附錄 1：英文資料 MetalCasting Processes AbstractFollowing a description of the fundamentals of solidification of metals in the preceding chapter and the roles of fluid flow and heat transfer in molds, we now describe in detail: ? Characteristics of expendablemold and permanentmold processes. Applications advantages, and limitations of mon casting processes. ? Casting of single crystals. ? Inspection techniques for castings. ? Brief review of foundries and their automation. Typical products made by casting: engine blocks, crankshafts, hubcaps, power tools, turbine blades, plumbing, zipper teeth, dies and molds, gears, railroad wheels, propellers, office equipment, statues, and housings. Alternative processes: fing, powder metallurgy, machining, and fabrication. Introduction The first metal castings were made during the period from 4000 to 3000 ., using stone and metal molds for casting copper. Various casting processes have been developed over time, each with its own characteristics and applications (see also Fig. ), to meet specific engineering and service requirements (Table ). A large variety of parts and ponents are made by casting, such as engine blocks, crankshafts, automotive ponents and power trains (Fig. ), agricultural and railroad equipment, pipes and plumbing fixtures, power tools, gun barrels, frying pans, office equipment, and very large ponents 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 processcontrol systems have replaced traditional methods of casting. The second major trend has been the increasing demand for highquality castings with close dimensional tolerances. This chapter is anized around the major classifications of casting practices (see Fig.Ⅱ .2 in the Introduction to Part Ⅱ ). These classifications are related to mold materials, molding processes, and methods of feeding the mold with molten metal. The major categories are as follows: 1. Expendable molds, which typically are made of sand, plaster, ceramics, and similar materials and generally are mixed with various binders (bonding agents) for improved properties. A typical sand mold consists of 90% sand, 7% clay, and 3% water. As described in Chapter 8, these materials are refractories (that is, they are capable of withstanding the high temperatures of molten metals). After the casting has solidified, the mold is broken up to remove the casting. 2. Permanent molds, which are made of metals that maintain their strength at high temperatures. As the name implies, they are used repeatedly and are designed in such a way that the casting can be removed easily and the mold used for the next casting. Metal molds are better heat conductors than expendable nonmetallic molds (see Table )。 hence, the solidifying casting is subjected to a higher rate of cooling, which in turn affects the microstructure and grain size within the casting. 3. Composite molds, which are made of two or more different materials (such as sand, graphite, and metal) bining the advantages of each material. These molds have a permanent and an expendable portion and ate used in various casting processes to improve mold strength, control the cooling rates, and optimize the overall economics of the casting process. The general characteristics of sand casting and other casting processes are given in Table . Almost all mercially used metals can be cast. The surface finish obtained is largely a function of the mold material。 although, as expected, sand castings generally have rough, grainy surfaces. Dimensional tolerances generally are not as good as those in machining and other shape processes. However, intricate shapes can be made by casting, such as castiron engine blocks and very large propellers for ocean liners. Because of their unique characteristics and applications, particularly in manufacturing microelectronic devices (PartⅤ ), basic crystalgrowing techniques also are described in this chapter, which concludes with a brief overview of modern foundries. ExpendableMold Casting Processes The major categories of expendablemold casting are sand, shell mold, plaster mold, ceramic mold, evaporative pattern, and investment casting. Sand casting The traditional method of casting metals is in sand molds and has been used for millennia. Sand casting is still the most prevalent form of casting。 in the United States alone, about 15 million tons of metal are cast by this method each year. Typical applications of sand casting include machine bases, large turbine impellers, propellers, plumbing fixtures, and numerous ponents for agricultural and railroad equipment. The capabilities of