MILLING MACHINE
Ergonomics
The milling machine consists of two main elements: the head, which holds the spindle, and the table, arranged perpendicularly, where the material to be machined is fixed. The rotating spindle holds the cutting tool (the mill). Unlike a lathe, it is the tool that rotates while the material remains stationary.
Spindle Axes
Depending on the machine’s complexity, the spindle of a milling machine may operate along 3 to 5 axes simultaneously. In all instances, the spindle can move along three linear axes (X, Y, and Z) and, occasionally, along one or two of the three rotational axes (A, B, and C), which are perpendicular to each other.
Cutting Tools
The shape of the milling cutter can vary depending on the machining operation to be performed. It can be cylindrical, conical, spherical, toroidal, or much more specialised (for gear cutting, for example).
Spindle Rotation and Movement
The rotation speed of the cutter is determined and adjusted according to its diameter and the nature of the material being machined. These two criteria also govern the speed of the tool’s axial movements.
Versatility
Highly versatile, the milling machine can also perform drilling or tapping operations by replacing the cutter with a drill bit or a tap.
The simple machines considered here do not have automation. The spindles of such milling machines are moved manually by cranks operated by the user. Some machines combine a lathe and a milling machine, known as combined lathes. Like lathes, milling machines began to be automated in the early 20th century, first with mechanical cam controls and later with numerical controls starting in 1980. Most milling machines used in watchmaking today are integrated into versatile machining centres controlled digitally.