CNC Machining

CNC Machining A CNC MACHINING CNC stands for computer numerical control. CNC machining is a versatile system that allows you to control the motion of tools and parts through computer programs that use numeric data. CNC machining can be used with nearly any traditional machine. CNC Machining CNC machining starts with a piece of metal, sometimes called a "billet." (Billet: pretentious word for "lump of metal," used by machinests and marketeers to confuse outsiders.) That piece of metal might have been cast, forged, or rolled (squeezed between rollers, sort of a limited forging, only capable of making flat things with straight grain like a board). It is put into a fairly standard machine tool, that has had position sensing and motors on the control knobs installed. This is basically just a robot machinist. You use a rotating cutting tool to cut away all the metal that isn✀t your crank. 3D metal etch-a-sketch, with the computer interpolating so the circles come out looking pretty smooth. The down-side of CNC machining There are a couple of issues. First, it wastes a lot of metal. The stuff removed is just metal shavings, and can only be sold for scrap. By comparison, forging uses almost all of the metal, except for a little bit of "flash" that seeps into the crack between the tool and the die. The process can be time consuming -- you can remove a couple of cubic inches of metal per minute. (limited mostly by your ability to keep the friction of cutting from overheating, and possibly melting things. This is especially important for the cutting tool, which may be severely weakened if you get it too hot, never mind near to melting), A part that is "sprawling" like your right crank, can take 10 minutes or more to make, compared to the small number of seconds that it takes a press to cycle. (A large press can make several parts per squish, providing even higher productivity.)