type metal
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type metal
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.