CNC milling (computer numerical control milling)
CNC milling, or computer numerical control milling, is a highly precise machining process utilized in industrial manufacturing to create customized products and components. It operates by using computer-programmed codes that relay instructions to machines, guiding them to remove material from raw workpieces made from materials such as metal, plastic, wood, and glass. The process involves entering numerical data into specialized software, which translates it into Cartesian coordinates that direct the machine in executing tasks with remarkable precision.
Historically, milling has evolved from manual techniques used during the Industrial Revolution to automated systems, beginning with numerical control (NC) technology in the late 1940s. CNC milling emerged in the 1970s, integrating advanced computer-aided design (CAD) software to enhance the complexity and accuracy of machining tasks.
The technology supports various milling processes, including plain, face, angular, and form milling, each producing different types of shapes and finishes. While human operators still play roles in setup and monitoring, ongoing advancements in automation, machine learning, and artificial intelligence are increasingly transforming CNC milling towards full automation, enhancing efficiency in producing precision instruments, furniture, and industrial prototypes.
On this Page
CNC milling (computer numerical control milling)
Computer numerical control milling, commonly known as CNC milling, is a precision process used in industrial machining to create customized products or parts. It uses computer-programmed code to relay instructions to production machines, which then execute the instructions to yield objects with the desired physical and functional characteristics. CNC milling is compatible with numerous commonly used raw materials, including glass, metal, plastic, and wood. By definition, CNC milling alters the raw material, known as “workpieces,” by removing substances from it via machine-powered cutting.
The systems and equipment used to program and control CNC milling machines work through computer interactions. Technicians use specialized software to enter numerical code, which is then relayed to the machine as Cartesian coordinates. The machine then uses those coordinates to carry out the assigned task. CNC milling is one of multiple types of precision computer numerical control machining, with others including CNC lathing, turning, grinding, lasering, waterjet cutting, plasma cutting, sheet metal stamping, and electrical discharging.
Brief History
Milling is an industrial process that deploys rotating cutting equipment to remove material from a workpiece and shape it into a finished product or part. During the early stages of the Industrial Revolution in the 19th century, workers performed milling tasks manually using a technique known as hand-filing. Milling machines first appeared when rudimentary industrial technologies began to evolve during the early nineteenth century. Surveys of machining history note that it is not known exactly when the first milling machines were invented, as many independent industrial manufacturers developed and used their own systems on small scales. Machine-assisted milling became a common feature of industrial production beginning in the 1840s, and the earliest such machines capable of milling materials in three dimensions appeared in 1861 when the Providence, Rhode Island-based Brown & Sharpe company introduced its first Universal Milling Machine. The Universal Milling Machine quickly became a widely used standard, leading competitors to create refined systems capable of more precise movements.
CNC milling was preceded by a noncomputerized technology known as numerical control (NC) milling. NC milling arose to address persistent production errors arising from the high volume of input required of manual machinists. Its invention is credited to the American industrial developer John T. Parsons (1913–2007), who pioneered a system of using punched tape to relay instructions to automated machines in the late 1940s. The punched tape contained numerical data, which was interpreted by specialized tape readers and relayed to machines, which then carried out the assigned task according to the submitted instructions. NC machining was initially limited to the manufacture of aviation and aerospace equipment and products, but slowly expanded into other industries over the course of the 1950s.
During the 1960s, improvements in data storage capabilities propelled significant advancements in emerging computer technologies, and allowed automated tools to replace human workers in many processes. NC machining became computerized when the initial generations of computer-aided design (CAD) software became compatible with three-dimensional objects, an advancement attributed to the French engineer Pierre Bézier (1910–1999), who created an early CAD system known as UNISURF for the Renault automobile company in 1968. As the capabilities of CAD software continued to expand, it became able to interpret complex three-dimensional blueprints and relay specifications to milling machines. CNC milling matured further during the 1970s, becoming a widely used technique in automated industrial production.
Overview
Contemporary CNC milling systems have the capability and data capacity to carry out highly complex and large-scale milling processes with extreme precision. Their basic structure links a computer running CAD software to a production machine with cutting tools affixed to rotating spindles. A technician places a workpiece of raw material into the cutting machine, and the CAD software then relays instructions that tell the machine exactly where, when, and how to cut the workpiece. The machine then carries out the commands, selectively removing material from the workpiece until it matches final specifications. Simple CNC milling systems operate on a single, flat plane, but more complex examples mount workpieces on tables, which then rise, tilt, or rotate at various angles to facilitate cutting on multiple planes.
Manufacturers can use CNC milling in many ways. It has become a common way to cut workpieces into specified shapes, but CNC milling systems also create holes, notches, pockets, slots, and other precision characteristics. Exact manufacturing instructions can be entered in two-dimensional or three-dimensional formats, which CAD software converts into a set of commands readable by the cutting machine. These commands are then exported, and the CNC machine selectively activates its cutting tools as needed to create a product or part that matches the original instructions. In shaping workpieces, the CNC milling machine’s cutting tools spin at extremely fast rates, guiding raw materials into their final forms with great speed and efficiency.
Industrial manufacturers use four main types of CNC milling processes: plain, face, angular, and form milling. Plain milling, sometimes called slab milling or surface milling, brings cutting tools into contact with workpieces at a flat, parallel angle. In face milling, the cutting tool’s rotary axis is perpendicular to the workpiece. Angular milling straddles plain and face milling, positioning the cutting tool’s rotary axis in positions that are neither parallel nor perpendicular. Form milling is the most complex type, yielding curved, concave, or convex products and parts with no flat surfaces. These four primary CNC milling techniques can be deployed to create many different types of manufactured goods, but they are most commonly used to make precision instruments or product components, furniture and cabinetry, sculpted objects, signage, and industrial prototypes.
Human operators still participate in various phases of the process. Some CNC milling machines have removable tools, allowing technicians to choose and place the specific implements necessary to complete the task at hand. Machinists also place and secure the unformed workpieces, then initiate the production process by manually enabling the programmed task with the CNC machine’s interface. However, advancements in machine learning (ML), artificial intelligence (AI), and robotics technologies continue to drive CNC milling processes toward complete automation.
Bibliography
“Different Types of Machining Operations and the Machining Process.” Thomas Publishing Company,2021, www.thomasnet.com/articles/custom-manufacturing-fabricating/machining-processes/. Accessed 16 June 2021.
Gupta, Kapil and J. Paulo Davim. High-Speed Machining.Academic Press, 2020, pp. 164–168.
Jepson, Phil. “The CNC Milling Process Explained.” EGL Vaughan,4 Aug. 2020, eglvaughan.co.uk/cnc-milling-process-explained/. Accessed 16 June 2021.
Kumar, Kaushik, Chikesh Ranjan, and J. Paulo Davim. CNC Programming for Machining,Springer Nature, 2020, pp. 31–41.
“The Complete Engineering Guide: CNC Machining.” Hubs,2021, www.hubs.com/guides/cnc-machining/ Accessed. 16 June 2021.
“The History and Design of Milling Machines.” Plethora,8 Aug. 2017, www.plethora.com/insights/the-history-and-design-of-milling-machines. Accessed 16 June 2021.
“Understanding CNC Milling.” Thomas Publishing Company,2021, www.thomasnet.com/articles/custom-manufacturing-fabricating/understanding-cnc-milling/. Accessed 16 June 2021.
“What Is CNC Machine Milling?” Ardel Engineering,2021, www.ardelengineering.com/what-is-cnc-milling/. Accessed 16 June 2021.
"What Is CNC Machining in Manufacturing?" Goodwin University, 9 July 2024, www.goodwin.edu/enews/what-is-cnc/. Accessed 22 Nov. 2024.