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Sheet metal is simply metal formed into thin and flat pieces. It is one of
the fundamental forms used in metalworking, and can be cut and bent into a
variety of different shapes. Countless everyday objects are constructed of the
material. Thicknesses can vary significantly, although extremely thin
thicknesses are considered foil or leaf, and pieces thicker than 6 mm (0.25 in)
are considered plate.
Sheet metal is available as flat pieces or as a coiled strip. The coils are formed by running a continuous sheet of metal through a roll slitter.
The thickness of the sheet metal is called its gauge. The gauge of sheet metal ranges from 30 gauge to about 8 gauge. The higher the gauge, the thinner the metal is.
There are many different metals that can be made into sheet metal, such as: Aluminium, brass, copper, steel, tin, nickel and titanium. For decorative uses, important sheet metals include silver, gold, and platinum.
Sheet metal has applications in car bodies, airplane wings, medical tables, roofs for building and many other things. Historically, an important use of sheet metal was in plate armor worn by cavalry, and sheet metal continues to have many decorative uses, including in horse tack.
Welding is the main focus of
steel fabrication. The formed
and machined parts will be assembled and tack welded into place then re-checked
for accuracy. A fixture may be used to locate parts for welding if multiple
weldments have been ordered.
The welder then completes welding per the engineering drawings, if welding is detailed, or per his own judgment if no welding details are provided.
Special precautions may be needed to prevent warping of the weldment due to heat. These may include; re-designing the weldment to use less weld, welding in a staggered fashion, using a stout fixture, covering the weldment in sand during cooling, and straightening operations after welding.
Straightening of warped steel weldments is done with an Oxy-acetylene torch and is somewhat of an art. Heat is selectively applied to the steel in a slow, linear sweep. The steel will have a net contraction, upon cooling, in the direction of the sweep. A highly skilled welder can remove significant warpage using this technique.
Steel weldments are occasionally annealed in a low temperature oven to relieve residual stresses.
Fabrications, when used
as an industrial term, applies to the building of machines, structures and other
equipment, by cutting, shaping and assembling components made from raw
materials. Small businesses that specialize in metal are called
Steel fabrications shops and machine shops have overlapping capabilities, but fabrication shops generally concentrate on the metal preparation, welding and assembly aspect while the machine shop is more concerned with the machining of parts