Precision machining describes a variety of subtractive manufacturing processes performed with specialized tools and computer numerical control (CNC) machines to create complex parts with the tightest tolerances that the most demanding industries need.
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.
While there is a cost associated with precision advanced machining, industries such as aerospace, robotics, and automotive, along with surgical device manufacturers, require complex parts fitting and functioning together flawlessly.
Tight tolerances are the name of the precision machining game. With specialized tools and processes, precision machining can achieve tolerances as close as ±0.0001 inch (0.0025mm) from a 3D model’s ideal dimensions.
Besides achieving the industry’s tightest tolerances, precision machining can also reliably replicate those results at scale, making each part in a run as close to identical as possible.
While precision machining is used for prototypes and custom, small-batch parts, it can also fulfill high-volume orders to the same exacting specifications.
Precision machining works with a wide range of materials—many types of metals, plastics, and composites, as well as wood and glass—on a variety of milling, turning, grinding, drilling, laser, and multi-axis CNC machines.
Thanks to highly automated and accurate processes, precision machining contributes to a factory’s productivity with high production speeds, efficient use of the workforce, and low defect rates.
With highly automated, computer-controlled precision machining, workers stay clear of dangerous cutting and grinding operations and can focus on valuable higher-level skills like CNC programming.
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NERC PRECISION ENGINEERING LTD
This precision component manufacturer invested in Fusion 360 to drive its range of three- and five-axis CNC machines and helping the business to shorten project delivery time and win more business.
ODICO
Odico created its six-axis Drill Mate robot for the advanced precision machining needed to fix 12-ton aluminum blades to the massive wind turbines vital to Denmark’s electricity generation.
Image courtesy of Odico
PEMBREE
UK-based Pembree uses precision machining and automation within Fusion 360 to design and make a range of mountain bike components.
This industry-recognized course teaches the practical skills for 2.5-axis precision machining using Fusion 360 CAD/CAM software.
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CNC machining and precise machining are related advanced manufacturing techniques, but they are not exactly the same. The key difference comes down to tolerances—the maximum amount that a produced part’s dimensions can vary from the design specs and still be viable.
With standard CNC machining, the tolerances vary from about 0.005 to 0.008 inches (0.12 to 0.2mm). However, for precision machining, which is crucial to performances industries such as aerospace, automotive, and medical, the tighter tolerances are as close as 0.0001 inches (0.0025mm). Precision machining usually uses CNC (computer numerical control) machines, but its tighter tolerances distinguish it from standard CNC machining.
Many processes fall under the banner of precision machining, and all of them are designed for extremely high accuracy and tight tolerances as close as 0.0001 inch (0.0025mm).
Advanced precision machining processes include CNC milling and turning using cutting tools, grinding and honing using abrasive tools, drilling, and laser cutting. Waterjet cutting is also a very accurate process, but its tolerances of around ±0.002 inch (0.05mm) arguably do not qualify it for the “precision CNC machining” category.
Precision machining can use a large selection of materials, including metals (aluminum, brass, bronze, copper, titanium and other alloys, carbon steel, stainless steel, tool steel), plastics (acrylic, nylon, polycarbonate, PVC), ceramics (alumina, silicon carbide, zirconia), composites (carbon fiber-reinforced polymers, glass fiber-reinforced polymers), and certain hardwoods and softwoods.
