Drilling

Drilling: A Machining Process

Drilling is the process of using a drill bit in a drill (machine, either fixed or handheld) to produce cylindrical holes in solid materials. As the drill is twisted against and pressure is applied to the material – chips are removed creating the desired hole size and depth. While drilling, the circular motion works in conjunction with the fluted design of the drill bit to expel excess materials upward along the fluted path of the drill bit.

The quality and finish of the drilled hole are largely determined by the sharpness of the drill bit and the speed and feed rates that are being utilized. When cutting harder materials such as steel, it is a good idea to hydrant the work to reduce the heat produced as the part is being drilled.

The drilling process can produce several types of cuts: drilled holes, counter-bores, countersinking, spot-facing or center drilling. Sometimes a specially designed tool is utilized to create holes with two or more different types of cuts – such as drill and countersink.

CNC Drilling

The addition of Computer Numeric Control (CNC) to drill presses has enabled the drilling process to achieve new heights in productivity and the creation of highly precise parts. CNC drill presses are equipped with a computer consisting of one or more microprocessors and storage units and a user interface for programming. All of this enables a CNC machinist to instruct the CNC drill to execute the exact movements and the tool changes necessary to rapidly drill parts.

CNC drills are the most cost-effective in large production runs or when the parts have a wide variety of holes or other drilling processes to be performed on them.