Flattened expanded metal is defined by Type, Class and Grade per ASTM F1267. Type and Class are required when specifying and ordering.
Type I—Expanded
Type II—Expanded and flattened
Class 1—Uncoated.
Class 2—Hot-dip zinc-coated (galvanized).
Class 3—Corrosion-resisting steel.
Grade A—0.0025 in. (0.06 mm) minimum coating thickness.
Grade B—0.0012 in. (0.03 mm) minimum coating thickness.
The illustration to the right shows that the strands and bonds form a sharp angle to the original plane of the solid sheet.
Sheets are expanded in the regular form and then passed through a cold rolled reducing mill. This process elongates the length of the sheet about 5%. The width of the sheet remains the same. The sheet is then sent through a leveler to maintain its flatness.