For the third installment in our series, familiarizing ourselves with the technical and environmental aspects of light gauge metal framing, we'll examine the process by which coils of sheet steel are transformed into LGMF shapes via the "cold-forming" process. We'll also discuss the galvanizing process and the troubled relationship between pressure-treated lumber and steel.
A "slitter" is used to reduce the large coils to a proper, precisely measured width for the intended production run. The steel's surface is then "pickled" in a bath of sulfuric or hydrochloric acid. Allowed to cool, the resulting strips or "ribbons" are then fed into a roll forming machine, whereby it passes through a series of dies (rollers) that bend the steel to the desired profile. This entire process is computerized and will hold a tolerance of within 1/8 inch for any predetermined length. Typically, 40 feet is the maximum length for LGMF members since a flatbed trailer is 40-feet long-but longer lengths are possible. The computer controls the number and length of members, and the dies in the roll forming machine are set to roll the size and shape desired.