machines; and a variety of strengths and flexibilities in between, as in items ranging from golf club shafts to nails. Harris sums up metal properties this way: "Inherent in all of these [characteristics] is the property of metals to be deformed to considerable degrees without fracture and to be rendered soft and ductile or hard and tough by heat treatment processes . . ."
The numerous nonmetallic materials whose strength or flexibility contribute directly to their utility and function(s) include: minerals, cement, ceramics, glass, graphite, plastics, petroleum products, wood, paper, rubber, and leather.
Manufacturers must consider the tolerances or allowances permissible between the dimensions of two supposedly identical parts. How close to 16.000 pounds does every bowling ball, shot-put, or artillery shell have to be? Dimensions given by designers with very close tolerances usually mean that such a part must fit closely with another part, or that each unit of a certain part must be interchangeable with its mates in the same bin. However, it is 16 times as costly to machine a bar of steel to 6.000 + 0.001 in. than to 6.000 + 0.020 in.
In their two volume encyclopedic treatment of the materials and processes of manufacturing, Young and Shane devote the entire first volume to: Materials. Chapters by separate authors discuss metals and their properties, nonferrous metals and alloys, inorganic materials (ceramics), plastics and elastomers (rubber), and other materials ranging from cork to wood. Fundamentally, all the materials from which an infinity of products are concocted have properties, which are knowable, predictable, changeable in desired ways, and directly and importantly connected to the manufactured item's appearance, weight, strength, and function.
Plastic deformation is the most important metal property, characterized by the crystalline structure of each metal and planes along which each will shear, the...