Hobbies And Interests
Punches
Once a form has been extruded, it may require one or a whole series of holes or shapes cut into it. There are many ways to cut a hole. One way for sheet goods is to use a punch. Sheet metal punches are like paper punches, just heavier, harder and sharper. With extruded parts, special jigs may be used to locate the placement of the holes or other shapes created by the punch.
Hydro-jet Cutting
Hydro-jet cutting can do several things, which are hard to do with punches on some extruded forms. A punch requires sheer force, which presses the extruded material against a working base; this pressure may deform the extruded shape. In such a case, a hydro-jet might be used to cut out shapes. The hydro-jet doesn't exert overall force, just concentrated force where the highly focused stream of water is sprayed, cutting through one, or potentially more layers of metal.
CNC
CNC is a computer numeric controlled device. Many fabrication tools can be operated by CNC input. CNC is especially popular with cutting tools that operate on a grid, such as a plotter. Hydro-jet cutting is a good example. A hydro-jet, plasma cutter or laser cutter may be fed a CNC pattern. The CNC-equipped cutting machine can then cut out the precise image with a minimum of mechanical force.
Robotic Welding
Robotic welding -- often called spot welding -- is usually done on complex sheet metal forms for a couple of reasons. First, it's difficult to weld thin-gauge metal, so robotic welding machines increase consistency. The second reason is the difficulty of welding complex shapes that are sometimes produced by the extrusion process. Many car frames or chassis are robotically welded together from multiple pieces of extruded sheet metal.