Milling machines are very versatile. They are usually used to machine flat surfaces, but can also produce irregular surfaces. They can also be used to drill, bore, cut gears, and produce slots. The type of milling machine most commonly found in student shops is a vertical spindle machine with a swivelling head. The milling technique is used to machine and produce work pieces made of free- cutting material. The milling technique is used to produce, mainly on prismatic components, flat, curved, parallel, stepped, square and inclined faces as well as slots, grooves, threads and tooth systems.
There are two basic milling methods: plain (or cylindrical) milling and face (or end) milling. Either method may be up-cut (or conventional) milling or down-cut (or climb-cut) milling. Milling machines are very versatile. They are usually used to machine flat surfaces, but can also produce irregular surfaces. They can also be used to drill, bore, cut gears, and produce slots. A milling machine removes metal by rotating a multi-toothed cutter that is fed into the moving work piece. Most milling machines are equipped with power feed for one or more axes. Power feed is smoother than manual feed and, therefore, can produce a better surface finish. Power feed also reduces operator fatigue on long cuts. On some machines, the power feed is controlled by a forward reverse lever and a speed control knob.
When milling, one should be aware of the difference between conventional, and climb milling. In conventional milling, the work piece is fed into the rotation of the cutter. This type of cut requires lower forces and is preferred for roughing cuts. In climb milling, the work moves with the rotation of the cutter. This produces a better finish. It is not recommended if the work piece cannot be held securely or cannot support high forces.
Basically the CNC milling machine can complete the work on their own as per the programme, the machine not stop until the entire programme has been run and the product ready.