The thickness of sheet metal is called gauge and it ranges from 8 to 30 gauge. The higher the gauge number, the thinner the metal. Beyond thickness, precisionsheet metal is categorized by type, of which there are many components. Some measurable components of sheet metal are hardness, tensile strength, alloy composition and quality. Long, thin precision sheet metal parts are made by pressing, similar to pressing it into different forms or shapes. The machine that bends the metal into various shapes is called a brake press.