Milling machines have been around since Eli Whitney invented the first version in 1818. This milling machine was small and used a sort of file which allowed designs of equal standard to be made by people from varying skill levels. Since then, there have been various versions which have evolved with technological advancements and ended up with the machines we use today – CNC machines.
CNC milling is a development of traditional milling machines into appliances which are directed by computer numerical control (CNC). Computer numerical control works by inputting a design blueprint for a project into CAD (computer aided design) software, then translating the design information into a code which can be read by the machine – this is referred to as g-code. G-code transcribes the CAD design to the milling machine which is then able to follow these instructions with no further human input.
There are myriad forms of milling machines with different functions but here are a few examples;
The horizontal mill is named as such due to the direction of the axis upon which the cutters are mounted which is, of course, horizontal. On a horizontal mill there are cutters referred to as side and face mills which are comparable to a circular saw in terms of their cross section. Horizontal mills tend to be used to cut slots and grooves.
Again, the name references the orientation of the spindle axis in the machine which, in this case, is vertical, so that it is perpendicular to the table. The cutters spin on the vertical axis making it useful for plunge cuts, drilling, boring or cutting gears.
Bed mills have mobile spindles which move along their own axes and the table can only be moved perpendicularly to the spindle. This is a type of vertical mill, where the table is on the bed of the machine, rather than on top.
Another type of vertical mill, turret mills have a stationary spindle and a moving table and function much like a drill press. Unlike the bed mill, the table can be moved both perpendicularly and parallel in relation to the axis.
Column and Knee Type
Here, the worktable is mounted on the knee-casting of the machine which is mounted on vertical slides upon which the table height can be varied.
With some machines having various potential applications, milling machines have unbounded versatility. Some have swivelling or fixed spindles, others have rotating, fixed or adjustable tables. Each have their own strong points so consult a professional who can guide you as to which machine is best for your project.