Subtractive manufacturing machines, which create objects by removing material from a larger workpiece through processes such as cutting, grinding, and drilling, originated in ancient times. There is evidence of wood-turning lathes being used in ancient Egyptian and Mycenean Greek cultures more than 3,000 years ago. In China, rotary lathes were used by the 5th century BCE.
However, it was not until the First Industrial Revolution in the 1700s when the power of steam engines enabled precise machining to take off, introducing mass production for metal parts, interchangeable parts, and standardized fasteners.
By the 1940s and 1950s, numerical control was added to manufacturing machines, moving tools, or parts according to data continuously fed from punched paper tape. Machine numerical control evolved rapidly in concert with the development of analog and digital computing. Today’s CNC machines work off of sophisticated files derived from computer-aided manufacturing (CAM) software, which precisely control CNC machine behavior.
Modern advanced precision machining refers almost exclusively to a class of CNC machining that exceeds standard CNC operations to produce complex parts with very tight tolerances. Standard CNC machining produces tolerances—acceptable deviations from the CAD model’s dimensions—of about (0.12 to 0.2mm). Precision machining, on the other hand, can achieve much tighter tolerances, as close as 0.0001 inches (0.0025mm).
Precision machining also frequently makes use of multi-axis machines, which are capable of greater accuracy and detail. A 5-axis CNC machine tool can approach the workpiece from multiple directions with one initial setup, which is more accurate and less prone to errors than 3-axis machinery with multiple fixtures and setups.
Precision machining’s higher standards stem from the demands of high-performance industries such as aerospace, automotive, medical and surgical devices, robotics, electricity generation, electronics, and more. These industries often manufacture intricate parts and assemblies that need to fit and function together with the greatest level of reliability.
Multi-axis CNC machines typically four, five, or more controlled axes, meaning they’re ideally suited for precision machining. They can perform simultaneous processes with less human setup and repositioning, making precision machining operations reliably repeatable at scale.
Precision machined parts usually don’t require additional polishing or finishing, which eliminates costly and inconsistent manual processes. They produce an aesthetic quality free of blemishes and imperfections, which makes them valuable for visible product parts where impeccable appearance matters. Suppliers may be attracted to making precision machined parts because their high quality could fetch a higher price.