Expanded metal sheets come in various forms and may therefore be utilized in many applications in marine, automotive, refrigeration, heating and cooling, food and chemical processing, electronics and other industries. The use of expanded metal products as floors, grills, guards, filters and enclosures keeps items secure while allowing the free passage of light, air and liquids. In addition to these benefits, expanded metal is stronger, more rigid and more light weight than the pre-processed solid sheets or plates.
Metal expansion is not only an improvement over solid sheet metal, but other metal cutting processes as well, such as perforation and welding. Because the metal is only cut and stretched, the waste from punching is eliminated. A sheet of metal can be stretched to cover up to ten times its original size, which also reduces the amount of raw materials necessary for a project from the beginning. Additionally, the solid construction of expanded metal sheets means that there are no welds, seams or joints that may catch or work loose over time.
The two main types of expanded metal are standard and flattened. The manufacturing process for standard metal expansion begins with feeding a metal sheet or plate into an expansion machine or press. A specially shaped die then cuts hundreds or even thousands of uniform slits into the stock metal creating an offset alternating pattern.
Most often a triangular pyramid shaped die is used to produce a diamond shaped aperture, but custom dies can make virtually any pattern. While the die slits the metal, it is simultaneously drawn through the machine. Heat and pressing techniques stretch the metal causing the holes to swell. The process for flattened expanded metal is the same, but sheets undergo an additional step. Cold-rolling the sheet in a reducing mill reduces the raised texture of standard processing in order to create a smoother flatter surface.
Both standard and flattened sheets are available in a number of different materials such as steel, copper, aluminum and titanium. In addition to material, it is important to consider the overall dimensions of the sheet, weight capacity, and the percentage of open area or size of the expanded holes as this will determine what can pass through the sheet.