The process of custom metal fabrication
Custom metal fabrication starts from design wherein a computer generated 3D drawing will represent the product. The fabricators will have an idea on how the product will look like and which features are important. After all the potential weaknesses of the custom part have been identified, the exact materials will be determined. The raw material can be plate metal, formed and expanded metal or tube stock. Cutting of metal can be done with different tools that may include band saws, laser cutters, water jet cutters or cutting torches. Forging with compressive force is applied to deform and shape metal or uniquely shaped turrets can punch metal to create different indentions and other features. The tools chosen for customizing the metal part will depend on its part geometry and its intended purpose.
Shearing in custom metal fabrication
In shearing, a piece of sheet metal is separated through the application of great force called shearing force that will cause the material to fail and separate at the cut location. Shearing force is applied using two tools, one above and the other below the sheet. These two tools are called the punch and die or upper and lower blades. The tool above the sheet provides the downward blow to the sheet that is on the lower tool. In order to facilitate the fracture of the material, a small clearance is present between the upper and lower tools. The size of clearance is typically 2-10% of material thickness but will also depend on several factors like the specific shearing process, thickness of the sheet and the material itself. The effects of shearing on a material aside from cutting the sheet are visible on the edges of the sheared material where it plastically deforms or rollovers at the edges.
Cutting without shear in custom metal fabrication
The geometric possibilities for common processes depend on the technology used but most are only able to accomplish 2D shapes. Laser cutting makes use of a high powered laser to cut through sheet metal to achieve an external profile or complex features. Simple internal features like holes and slots are usually punched using another type of tool. In plasma cutting, a focused stream of ionized gas or plasma is used to cut through metal and is precisely controlled so that it will follow the desired cutting path. Plasma has the capability to cut through thick sheets and is used for other work pieces aside from sheet metal.