Brass works can range from inexpensive castings to high-end, hand-hammered, gallery-quality art. Working with brass is a skill that has been honed since the accidental discovery of brass centuries ago. Brass is an alloy that consists of zinc and copper. Most fittings created in brass are cast, forged, or extruded. A casting is what you would most commonly recognize as brass figurines or knobs. The differences between forged and extruded fittings, however, can be more difficult to identify unless you understand each process.
What is Extrusion?
Extrusion is a machining process that forces softened brass through a die. A die is a piece or pieces of steel configured for a specific end product. If you have ever seen noodles made, extrusion is the same idea. The dough is forced through a die, and, depending on the design of the die, a specific pasta shape is formed. However, with brass, the process is somewhat more complicated due to the precise temperatures involved and the additives required to keep the brass from bonding with the steel of the die.
Just like the pasta mentioned above, once brass is extruded through a die, it is cooled and cut to length from its bar form (the continuous length that has been extruded through the die). In relation to fittings, each time the blade drops, a new fitting is created. Once cut to size, there is a refining process that smooths rough edges and perfects the brass piece for distribution.
What is Forging?
Forging is the process of pressing, hammering, or compressing metal into a desired form. This process creates metal that is exceedingly strong. Unlike castings, metal that is forged is never melted. It is softened so it can be manipulated. The forging of metal results in creating products that are stronger and more resilient than any other process of metalworking.
A majority of the confusion between forged fittings and extruded fittings comes from the fact that the forging process begins with extrusion. The brass is extruded into round bars that are straightened and cut to the desired length. The straightening process strengthens the brass and actually changes the metal composition. The extruded bars are then cut into plugs (short pieces from the bar), reheated to make them pliable, then pressed into fitting dies.
Choosing Forged or Extruded Fittings
The confusion between forged and extruded fittings spills over into their uses, considering that you can find the same fitting shapes made by both processes. The real difference lies in the strength of the product. Forged fittings are much stronger than extruded fittings. Extruded fittings are more than adequate for low pressure, low vibration purposes like hinges and railings. Forged fittings are more appropriate for industrial purposes like plumbing and electrical components.