The process for creating expanded metal was first developed and patented in the 1880’s in Hartlepool, UK. Despite technological advancements, the modern process for expanding metal remains similar to the original technique.
Expanding metal is plate or sheet that has been cut and stretched into a mesh. Stretching the metal results in a mesh with diamond-shaped spaces – although many other patterns can be created. Many types of metal can be expanded, including: stainless steel, black steel, bright steel, aluminium and more.
The pattern of the mesh can either be staggered (providing the most open area) or in a straight pattern with all rows and columns aligned. The proportion of open area determines the amount of space for the passage of air, water and light, and will vary according to the intended application of the expanding metal.
There are several benefits to using expanding metal:
Expanding metal is produced by an expanding machine, which turns solid metal sheets and coils into an expanding metal mesh. The expanding machine is fitted with a knife which determines pattern for the mesh. As the metal is fed through the expanding machine, it is cut and stretched simultaneously using a pressured slitting and stretching process. The slits created by the knife allow the metal to be stretched, which produces uniform holes. To ensure a consistent pattern, the expanding machine is programmed or operated manually as the metal is fed through. The finished expanding metal is then wound into coils or cut into sheets.
Depending on the intended application, different thicknesses of metal can be used and different mesh patterns can be chosen. L.W.D (Long Way Diamond) and S.W.D. (Short Way Diamond) are commonly used to indicate the desired length and width of the diamond shaped mesh holes.
The most common types of expanding metal are: