CNC milling, or computer numerical control milling, is a machining process which employs computerized controls and rotating multi-point cutting tools to progressively remove material from the workpiece and produce a custom-designed part or product. This process is suitable for machining a wide range of materials, such as metal, plastic, glass, and wood, and producing a variety of custom-designed parts and products.
Several capabilities are offered under the umbrella of precision CNC machining services, including mechanical, chemical, electrical, and thermal processes. CNC milling is a mechanical machining process along with drilling, turning, and a variety of other machining processes, meaning that material is removed from the workpiece via mechanical means, such as the actions of the milling machine’s cutting tools.
This article focuses on the CNC milling process, outlining the basics of the process, and the components and tooling of the CNC milling machine. Additionally, this article explores the various milling operations and provides alternatives to the CNC milling process with production fixture.
Milling Definition
What is milling? It's is a type of machining that uses cutters to shape a workpiece, often on a moveable tabletop, although some milling machines also feature movable cutters. Milling started out as a manual task performed by humans, but most milling these days is done by a CNC mill, which utilizes a computer to oversee the milling process. CNC milling offers higher precision, accuracy, and production rates, but there are still some situations when manual milling comes in useful. Manual milling, which requires a lot of technical skill and experience, offers shorter turnaround times. It also has the added benefit that manual mills are cheaper and the user doesn’t need to worry about programming the machine.
Overview of CNC Milling Process
Like most conventional mechanical CNC machining processes, the CNC milling process utilizes computerized controls to operate and manipulate machine tools which cut and shape stock material. In addition, the process follows the same basic production stages which all CNC machining processes do, including:
Designing a CAD model
Converting the CAD model into a CNC program
Setting up the CNC milling machine
Executing the milling operation
The CNC milling process begins with the creation of a 2D or 3D CAD part design. Then the completed design is exported to a CNC-compatible file format and converted by CAM software into a CNC machine program which dictates the actions of the machine and the movements of the tooling across the workpiece. Before the operator runs the CNC program, they prepare the CNC milling machine by affixing the workpiece to the machine’s work surface (i.e., worktable) or workholding device (e.g., vise), and attaching the milling tools to the machine spindle. The CNC milling process employs horizontal or vertical CNC-enabled milling machines—depending on the specifications and requirements of the milling application—and rotating multi-point (i.e., multi-toothed) cutting tools, such as mills and drills. When the machine is ready, the operator launches the program via the machine interface prompting the machine to execute the milling operation.
