Separating one part from another so that you have two or more pieces is one reason to cut metal and the other would be in the form of sculpting, in as much you are left with one finished object and the part that is taken away is nothing more than swarf. Swarf is the excess metal that tools such as lathes, grinders, saws, drills, milling machines and threading taps or die leave behind.
Burn Baby Burn
The other sort of cutting metal is more of a burning process. For example where you have separated metal into two or more sections by using heat, like with an oxyacetylene torch. Instead of welding two parts together the extreme heat is there to burn away a gap in between. Plasma cutting and laser cutting would fall into this burning away side of the cutting processes.
Basic cutting is performed with hand tools or power hand tools, such as saws or snips. There are also machine tools that will saw shear and snip metal, along with the larger machines you find in engineering facilities such as lathes, milling machines, large drills and grinding tools.
Spin The Metal Clamped In A Chuck
With a lathe the metal is put into a chuck which spins it and the cutters are fed into it with precision controls, taking off small amounts of metal. The cutting tools are affected by friction and there is a substantial amount of heat generated, coolants will often need to be used. Because of the fact that the metal is being rotated, cutting on a lathe is called turning. It produces profiles that are basically cylindrical and the perpendicular surface can be cut and is known as facing.
A lathe will be powered by an electric motor that is able to have a speed that will suit the metal being cut. It is usually faster for softer materials such as aluminium and slower for the harder metals like steel. A cutting tool will be moved in a carriage so that it can cut into the spinning metal. The lathe can also be made to bore into the end of the metal. It can also take a corner off to chamfer an edge.
Computers take over
Complex shapes can be cut on the milling machine now that the control of the cutting tool is handed over to the computer. Computer Numerical Control (CNC) takes care of removing the metal from the starting block of metal. Modern lathes will also be controlled by computers, where before it was the job of highly skilled machine operators.
Taking Abrasive Action
Another way of removing the metal you don’t want is to use a grinder. The materials of the grinding wheels of course have to be harder than the metal to be cut. You will find industrial diamonds are used for this purpose. The CNC grinder machines can be used to produce complex items, including parts that could eventually find their way into jet engines. High precision parts have to be made by even higher precision machine tools.