Milling 
Milling is typically used to produce parts that are not axially symmetric and have many features, such as holes, slots, pockets, and even three dimensional surface contours. Parts that are fabricated completely through milling often include components that are used in limited quantities, perhaps for prototypes, such as custom designed fasteners or brackets. Another application of milling is the fabrication of tooling for other processes. Milling is also commonly used as a secondary process to add or refine features on parts that were manufactured using a different process. Due to the high tolerances and surface finishes that milling can offer, it is ideal for adding precision features to a part whose basic shape has already been formed.
End milling operation (Pocket milling)
End milling – An end mill makes either peripheral or slot cuts, determined by the step-over distance, across the work-piece in order to machine a specified feature, such as a profile, slot, pocket, or even a complex surface contour. The depth of the feature may be machined in a single pass or may be reached by machining at a smaller axial depth of cut and making multiple passes.
Chamfer milling operation
Chamfer milling – A chamfer end mill makes a peripheral cut along an edge of the work-piece or a feature to create an angled surface, known as a chamfer. This chamfer, typically with a 45 degree angle, can be machined on either the exterior or interior of a part and can follow either a straight or curved path
Face milling operation
Face milling – A face mill machines a flat surface of the work-piece in order to provide a smooth finish. The depth of the face, typically very small, may be machined in a single pass or may be reached by machining at a smaller axial depth of cut and making multiple passes.