The most common materials that are machinated are primarily metal, however wood and plastic may be done as well. In the past, machinists worked manually, and while this is still possible, the majority of contemporary machinists use CNC machining, or computer numerical control machining.
CNC machining essentially removes the working agent from the equation (at least from the machining equation) by transferring those responsibilities to a computer which is subsequently programmed by the machinist to do the necessary cuts and shaping.
The automated system would then do the load of grunt work while the machinist’s skills would be exemplified in his/her ability to program with the help of a CAD, or computer-aided design.
If an individual wished to do machining manually, there are several facets of the process that should be investigated before beginning. The three main steps of the machining process are turning, milling and lastly, drilling, although there are other miscellaneous categories such as boring, sawing and shaping, among others.
The first step, turning, consists of the initial cutting of the material being used, by feeding it gently through the cutter. This is then followed by milling, which involves rotating the cutter so its edges further sculpt the material being molded. The last step of machining is drilling, which produces the final touches to the piece by creating or refining holes drilled into the outer ends.
There are two ways of milling: the conventional milling method and the climb milling method. Conventional milling entails an “up” direction of milling, whereby the cutter is slid over the material being molded until it begins to gradually shred through it, slow to fast. The cons of this method include the possibility of dulling the machine, and the method may also leave a poor finish on the material.
Climb milling is the “down” direction of milling, and involves the opposite. The material is instantly engaged with the cutter, as the cutter moves downward through it instead of upwards, creating a more defined finish. This method may not be suitable for older machines as it can overload the machine.
Another important facet of machining, is the proper removal of the collection of cut material, or swarf, that accumulates as the material is cut. Swarf may clog the machine, dull the tools involved, and potentially interfere with further cuts on the material (or all of the above) if it is not disposed of periodically. One of the advantages of climb milling is that the chips are emitted behind the cutter, thus leading to easier swarf removal.