Precision machining involves the process of machining a component to the precise finish tolerances. This is usually the last step of the machining process and it requires: an accurate machining tool, the correct cutting tools, components of the right amount of allowance, reliable measuring instruments, and most importantly, skilled manpower to use all of them. All types of steels and alloys, along with formulated plastics, glass, stone, wood, and composites, can go through the precision machining process to reach precise tolerances.
The preciseness of precision machining is often measured in microns, which may be a critical factor for many finished items. Precision machining can produce holes in the tolerance of +- 0.0025mm and distances of +-0.002 mm or less. Precision machining is usually done for items such as: jigs/fixtures, dies, master components, to finish the machining of bores, components, etc. The processes that make up precision machining include milling, turning, sharpening, deburring and grinding.
Some of the tools that are used in precision machining include: reamers, fine boring tools, and precision ground milling cutters, etc. There are various types of tools used in the process which may apply pressure, employ cutting, impact on, create electrical current, or combine any of these processes to achieve a final product. These machines are controlled by a CNC (computer numerical controlled) machine or an EDM (electrical discharge machining) machine. Milling centers are the most common type of precision machining equipment as these machines can accept an assortment of tooling and also possess programmable indexes which help to make products in an accurate and high-speed fashion.
The machine tools that are used are: jig boring, precision milling, boring machine tools or machines with a reliable digital readout. With these machine tools, the spindle run out and play in the slides is almost zero, with very little backlash. Machining is done with reference to a master dowel. Measurement is done by using precision ring gauges, three point internal gauges, air gauges, three coordinate measuring machines, etc. The allowance made for precision machining is less and the productivity is lower, when compared to other types of machining operations.