Metalworking

Metalworking is the process of working with metals to create individual parts, assemblies, or large scale structures. The term covers a wide range of work from large ships and bridges to precise engine parts and delicate jewelry. It therefore includes a correspondingly wide range of skills, processes, and tools. Metalworking is a science, art, hobby, industry and trade. Its historical roots span cultures, civilizations, and millennia. Metalworking has evolved from the discovery of smelting various ores, producing malleable and ductile metal useful for tools and adornments. Modern metalworking processes, though diverse and specialized, can be categorized as forming, cutting, or joining processes. Today's machine shop includes a number of machine tools capable of creating a precise, useful workpiece. A metal (from Greek "" – metallon, "mine, quarry, metal") is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable, ductile and shiny. The meaning of the term "metal" differs for various communities (for example, astronomers call for convenience metals everything but hydrogen and helium, see Metallicity). Many elements and compounds that are not normally classified as metals become metallic under high pressures (see nonmetal#Metallic allotropes.) An engine or motor is a machine designed to convert energy into useful mechanical motion. Heat engines, including internal combustion engines and external combustion engines

such as steam engines) burn a fuel to create heat, which then creates motion. Electric motors convert electrical energy into mechanical motion, pneumatic motors use compressed air and others—such as clockwork motors in wind-up toys—use elastic energy. In biological systems, molecular motors, like myosins in muscles, use chemical energy to create motion. Jewellery or jewelry (pron.: /?d?ul?ri/) is a form of personal adornment, such as brooches, rings, necklaces, earrings, and bracelets. With some exceptions, such as medical alert bracelets or military dog tags, jewellery normally differs from other items of personal adornment in that it has no other purpose than to look appealing, but humans have been producing and wearing it for a long time – with 100,000-year-old beads made from Nassarius shells thought to be the oldest known jewellery. Jewellery may be made from a wide range of materials, but gemstones, precious metals, beads and shells have been widely used. Depending on the culture and times jewellery may be appreciated as a status symbol, for its material properties, its patterns, or for meaningful symbols. Jewellery has been made to adorn nearly every body part, from hairpins to toe rings. The word jewellery itself is derived from the word jewel, which was anglicized from the Old French "jouel", and beyond that, to the Latin word "jocale", meaning plaything. In British English the spelling can be written as jewelery or jewellery, while in U.S. English the spelling is jewelry.