Drilling involves the creation of holes that are right circular cylinders. The characteristics of drilling that set it apart from other powered metal cutting operations are: • The chips must exit out of the hole created by the cutting. • Chip exit can cause problems when chips are large and/or continuous. • The drill can wander upon entrance and for deep holes. • For deep holes in large work pieces, coolant may need to be delivered through the drill shaft to the cutting front. • Of the powered metal cutting processes, drilling on a drill press is the most likely to be performed by someone who is not a machinist. | Milling is the most common form of machining, a material removal process, which can create a variety of features on a part by cutting away the unwanted material. The milling process requires a milling machine, workpiece, fixture, and cutter. The workpiece is a piece of pre-shaped material that is secured to the fixture, which itself is attached to a platform inside the milling machine. The cutter is a cutting tool with sharp teeth that is also secured in the milling machine and rotates at high speeds. By feeding the workpiece into the rotating cutter, material is cut away from this workpiece in the form of small chips to create the desired shape. 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. |
