type metal

type metal,

alloy of lead with antimony, tin, and sometimes copper, so named because of its one time extensive use for making printing type. Expanding upon solidification, the alloy takes a fine and clear impression of the mold in which it hardens. It has a low melting point. Once used extensively for type, it is also employed in making the metal parts of various musical instruments and for ornaments of intricate design and pattern. The percentages of the metals in the alloy vary, according to the use to which it is to be put.

Type Metal

 

an alloy of nonferrous metals used to make cast stereotypes and printing elements, such as letters, spaces, and slugs. Type metals consist of 75–85 percent lead, 8–23 percent antimony, which decreases shrinkage and increases the hardness of the alloy, and 2–7 percent tin, which improves the casting properties, raises the melting point, and prevents excessive brittleness. Type metals have a low melting point (240°–350°C) and good casting properties (approximately 0.7 shrinkage), and they give castings a fine grain structure; however, they are also toxic, relatively expensive, and insufficiently hard. They may therefore be replaced in some cases by plastics. Type metals based on zinc are not widely used because of their high melting point and harmful effect on casting equipment.

REFERENCE

Berezin, B. I. Materialovedenie poligraficheskogo proizvodstva, 2nd ed. Moscow, 1972.

type metal

[′tīp ‚med·əl]

(metallurgy)

Any of various low-melting-point alloys, composed mainly of lead (50-90%), antimony (2-30%), and tin (2-20%), used for casting printers' type.