Tin

Tin is characterized by a low-melting point (450°F), fluidity when molten, readiness to form alloys with other metals, relative softness, and good formability. The metal is nontoxic, solderable, and has a high boiling point. The temperature range between melting and boiling points exceeds that for nearly all other metals (which facilitates casting). Upon severe deformation, tin and tin-rich alloys work soften. Principal uses for tin are as a constituent of solder and as a coating for steel (tinplate, or terneplate). Tin is also used in bronze, pewter, and bearing alloys. Tin and tin alloys can be cast, rolled, extruded, or atomized. Because pure tin is too weak to be used alone for most mechanical applications, it is usually alloyed with elements such as copper, antimony, lead, bismuth, and zinc. Tin and its alloys are cast using most conventional techniques, including gravity die casting, pressure die casting, and centrifugal casting. Tin-alloy castings are sound and dimensionally accurate because little shrinkage occurs on solidification. Essential to the casting of tin-rich alloys is the need to reduce microstructure segregation, which occurs during solidification. Part and mold designs should be such that ample metal is fed to remote regions of the mold cavity. Because of their low-melting points, tin-rich alloys can be cast in carbon-steel or rubber molds. Alloys contain from 1 to 8% antimony and 0.5 to 3% copper, and have excellent castability and workability. For spun pewter products, antimony content is usually below 7%, and pewter casting alloys contain 7.5% antimony and 0.5% copper. Because of the excellent drawing and spinning properties of tin, wrought parts are usually made from pewter that is first cast into slabs, then rolled into sheet. These low-friction materials may contain high percentages of antimony (to 10%), copper (to 10%), or aluminum (to 80%). They include babbitt metal,