CNC Milling: Its Definition, Machines, And Operations

What is CNC milling, and how does it work?

The speed and accuracy of milling machines have significantly increased over the years, making them indispensable tools in many industries.

In this article, we will take a closer look at milling, different types of milling machines, and some operations that can be performed with them. Let’s get started!

what is CNC milling

What Is CNC Milling?

CNC milling is a machining process that uses computer numerical control to guide the movements of a cutting tool. This process can create highly precise parts with complex geometry.

A three-dimensional model is first created in computer-aided design (CAD) software to create complex parts. This model is then converted into instructions for the CNC machine, which controls the movement of the cutting tool.

The process can machine various materials, including metals, plastics, and composites.

CNC milling is an automated process, so it means needing fewer people to monitor and run it. This not only improves efficiency, but also reduces production costs.

CNC milling is often suitable for the aerospace and automotive industries, where components with tight tolerances are required.

What Is The CNC Milling Process

The CNC milling process can create very precise parts with a high degree of repeatability. 

CNC milling machines are typically classified according to their number of axes. Three-axis machines are the most common, but five-axis machines are also used. 

The manufacturing process begins with a computer model of the part to be produced. This model is used to generate a toolpath, which is then followed by the CNC machine to produce the desired shape. 

In some cases, the model may be created directly on the CNC machine itself, using a CAM program. The finished part can then be sanded and polished as necessary.

Types Of CNC Milling Machines

Vertical Mill

A vertical mill is a milling machine designed to remove material from a workpiece by feeding the workpiece against a rotating cutter. The cutter is mounted on a spindle aligned with the workpiece’s axis, and the workpiece is fed into the cutter at a right angle.

The cutting tools are held in place by a chuck that can be rotated to different positions, and an electric motor powers them. Vertical mills are used extensively in the machining of metal parts.

Turret Vertical Mill

Bed vertical mills are specialized CNC milling machines designed for larger workpieces. These machines typically have a large table that can accommodate workpieces of various sizes.

Bed Vertical Mill

Turret vertical milling machines have their spindles oriented vertically, giving them a smaller footprint and more rigid.

Horizontal Mill

A horizontal mill machine removes material from a workpiece by feeding it past a rotating cutter or multiple cutters. The cutter(s) are mounted on a spindle that can be cycled at high speeds, and the workpiece is fed into the moving table of the milling machine.

Horizontal mills are typically suitable for perform end milling, face milling, and slotting operations. They can also create grooves, pockets, and threads.

Knee Mill

A knee mill is a type of vertical milling machine where the spindle is equipped with a knee that sits on and moves along a horizontal track. The knee scans the work area, providing motion in the X- and Y-axes. A knee mill may also have a Z-axis, which provides motion along the Z-axis.

Knee mills are generally more precise than other milling machines and are also more expensive. Consequently, they are typically suitable for more delicate or intricate work.

Multi-Axis Mill

2-axis milling machines

A 2-axis milling machine is a machine that can move a workpiece in two directions–X and Y axes.

The X-axis is horizontal, and the Y-axis is vertical. The workpiece is clamped to the milling machine’s table and fed into the spinning cutter. The cutter removes material from the workpiece when it moves along the X and Y axes.

2-axis milling machines typically create flat surfaces, slots, pockets, and dies. 

3-axis milling machines

3-axis milling machines are computer-controlled machines that can move a workpiece in three directions. The X-axis is the horizontal direction, the Y-axis is the vertical direction, and the Z-axis is the depth.

These machines can cut complex shapes out of metal or other materials. 3-axis milling machines are extremely precise and can create parts with tight tolerances.

4-axis milling machines

A 4-axis milling machine is a type of CNC milling machine. Unlike most milling machines with three axes of movement (x, y, and z), a 4-axis machine has an additional axis (a fourth), allowing for more complex milling operations.

With a 4-axis machine, it is possible to mill beveled edges or contoured surfaces that would otherwise be difficult or impossible to create with a 3-axis machine.

5-axis milling machines

Unlike traditional milling machines, 5-axis milling machines allow for greater control and flexibility, allowing operators to produce more intricate shapes and designs. In addition, 5-axis milling machines have more powerful motors and cutting tools, making them capable of handling tougher materials.

5-axis milling

Types Of CNC Milling Operations

Face Milling

Face milling is a machining process in which a rotating cutter removes material from the surface of a workpiece. The face milling cutter is a circular cutting tool with multiple teeth on its periphery.

The cutting tool can be horizontal or vertical, and the workpiece can be moved in a linear or rotary motion. Face milling is suitable for producing flat surfaces, and the depth of the cut is typically limited to half the diameter of the cutter.

When face milling with a CNC machine, the cutting tool is mounted on a spindle and does not move during the machining operation. The workpiece is mounted on a table and is moved in a linear or circular motion under the cutting tool.

face milling

Plain Milling

Plain milling is a milling operation in which the cutter rotates about a horizontal axis, and the workpiece is moved parallel to the axis of rotation. This type of milling produce flat surfaces on workpieces with irregular shapes. Plain milling can also produce angular surfaces if the workpiece is tilted at an angle.

Angular Milling

Angular milling is a type of CNC milling operation. In angular milling, the cutter is rotated at an angle to the workpiece. This angle can be anything from 0 degrees to 90 degrees.

Angular milling create angular cuts, pockets, and tapers. It is also suitable for drilling and reaming holes.

When using angular milling, keeping the cutter aligned with the workpiece is vital. Otherwise, the cutter could damage the workpiece or cause it to malfunction.

Form Milling

Form milling is the process of unique machining contours composed of angles, curves, and tapers. It is specialized to cut irregular or curved shapes into metal, plastic, or other materials. The cutter used for form milling is a circular cutting tool with teeth on the periphery and sides.

Straddle Milling

Straddle milling is a milling operation in which the cutter straddles the workpiece, cutting both above and below it. This can be done with two separate cutters or a single cutter with two cutting edges.

Straddle milling is often used to rough out large volumes of material quickly and produce slots or other features that require cuts on both sides of the workpiece.

Gang Milling

In a gang milling set-up, multiple cutters are mounted on the same arbor. This enables the machinist to mill several features into a part simultaneously.

When using gang milling, it is crucial to consider the cutting tools, feeds, and speeds. Using the wrong tools or operating at the wrong speeds can damage the workpiece or cause tool breakage.

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Benefits Of CNC Milling

Unlike traditional milling machines, CNC machines can be programmed to perform various operations, making them ideal for complex tasks.

CNC milling machines can achieve high levels of precision, making them ideal for creating small parts and components.

There are numerous benefits to using CNC milling machines, including increased efficiency, improved accuracy, and reduced production costs.

Our Machining Capability

4-axis milling

As a China manufacturer of machining complex parts, we can provide various CNC machining services. Our team has the experience and skills to help you produce your product with milling and turning services.

When an CNC milling machine needs to be programmed to produce a particular product, our machines have multicomponent tool holders that house all of the tools essential for the job. And the machining tools can be exchanged within the tool storage area within the spindle within a few seconds automatically.

We are proficient in using this method and can help ensure that your machined parts are high quality and precisely what you are looking for.

If you are interested in learning more about our services or would like to get a quote, don’t hesitate to get in touch with us today. We would be happy to discuss your project with you and answer any questions you may have.


In conclusion,CNC milling is a versatile and precise machining process that can create a variety of parts and products.

With the right machine, tools, and programming, almost any shape or size of part can be created with CNC milling.

A a provider of CNC machining services, we can manufacture various CNC parts of sizes and shapes for you projects.

Hope this article will help you to understand CNC milling work better. If you require any type of CNC machining operations for your next project, you can get in touch with CNCFIRST.