Table of Contents

cnc machining services company in china

CNC Milling: The Complete Guide

CNC (Computer Numeric Control) milling is a flexible manufacturing method that helps to produce several different custom components from different materials. This process uses automated controls to command rotating multi-point cutting tools to remove excess material from the workpiece.

CNC milling operations are responsible for many products today, ranging from mobile gadgets to supersonic jets. The technique is suitable for rapid prototyping and high-volume metal and plastic parts manufacturing.

This article guides you through CNC milling, how it works, the differences between the 3-axis, 4-axis, and 5-axis milling machines, and the benefits of using the CNC milling process for your project. Get comfortable as we dive in!

What is CNC milling?

what is cnc milling

CNC milling is computerized process manufacturers use in producing custom-designed components of high quality and precise finishing. A mounted cutting tool rotates around the stationary workpiece to add different features. It rotates along varying axes to machine highly complex designs.

The milling process is different from other manufacturing processes like 3D printing. It removes material from the substrate to form a part precisely per the product specification.

It also offers extraordinary accuracy, consistency, and the ability to improve production and maintain uniformity. Most CNC milling machines are sophisticated and can have 3 to five or more axes of independent motion which can help to produce more complex shapes.

How Does CNC Milling Work?

As mentioned earlier, the CNC milling process is a subtractive manufacturing technique. It removes material from a raw substrate using different cutting tools till it forms the desired shape. The workpiece turns continuously to achieve precise cuts at different angles.

However, it would help to understand that the whole milling process takes a few steps before the workpiece is ready. Here are these steps:

how does cnc milling work

1. Creating CAD Model

The first step involves creating a CAD model blueprint suitable for your desired part geometry. You can make this CAD design/model using Computer-Aided Design software. It helps you to create 2-D or 3-D models for different product ideas.

2. Converting CAD to CNC

The CAD model needs to be changed to a CNC program because the CNC milling machines cannot interpret a CAD model directly. However, converting the CAD model to the CNC program is straightforward. Most CAD software possesses this feature already; you have to follow the instructions closely to get the best results.

3. Setup of CNC Milling Machines

Ensure that the milling machines are appropriately set up and in the right conditions before initiating the program. It is important to note that the setup procedures for different CNC milling machines vary depending on their manufacturers and models. Therefore, endeavor to know about the maker and models before using the machine for your milling operation.

4. Executing the Program

While the machine is correctly set up and ready, the machinist can execute the CNC machine program. The machine automatically performs the whole milling process that follows. Once the program is completed, the machine provides the preferred part with the correct specifications.

What is The Difference between 3-axis, 4-axis, and 5-axis Milling Machines?

CNC milling machines are ideal for drilling operations, boring operations, and creating slots. These machines are broadly categorized into two parts:

  • Horizontal milling machines
  • Vertical milling machines

The complexity and geometry of your parts often determine the type of CNC mill to use for the machining operations. The difference between these milling machines is the complexity of the movement that the cutting tool and the workpiece can undergo relative to each other. However, these milling machines are more efficient and productive based on the number of their axis. Here’s a look at the difference between 3-, 4-, and 5-axis milling.

3-axis CNC Milling

3 axis cnc milling
3 axis cnc milling

It is the simplest machining type where the workpiece remains fixed in a single position. The spindle moves in the X, Y, and Z straight directions. The 3-axis milling machines are commonly used for machining 2D and 2.5D geometry and can allow the machining all six sides of a part. However, each side requires new fixturing which could be costly. A single fixture setup can only machine one side of the part.

You can manufacture many complex and practical shapes with the help of 3-axis CNC mills, especially with a state-of-the-art CNC machining facility. Note that 3-axis machining is ideal for drillings & threaded holes in-line with an axis and producing planar milled profiles. Dovetail milling cutters and T-slot cutters are suitable for machining undercut features.

The features not attainable on the 3-axis milling machine include any features on an angle to the X-Y-Z coordinate system. However, know that there are certain physical features that the 3-axis machine cannot add. These features are sometimes more economical using the 4- or 5-axis machine.

There are two different angled features that you can design for your parts. Nevertheless, understanding their differences is vital to designing parts for the CNC machining process. These are

  • Angled Feature: this is a typical feature added on an angle to one of the three axes (X, Y, or Z).
  • A compound Angle Feature is a feature created on an angle to two axes.

It is important to note that 3-axis CNC milling machines cannot machine both angled and compound angle features.

4-axis CNC Milling

4 axis cnc milling
4 axis cnc milling

You can machine 4 sides of parts in a single fixture setup using the 4-axis machine. A 4-axis milling machine has a different A-axis rotation along the X-axis. These 4-axis machines have a few other arrangements, although they are usually vertical milling operations, whereby the spindle rotates about the Z-axis. The milling spindle possesses 3-linear axes (X-Y-Z) and the A-axis, which occurs by rotating the workpiece. The workpiece is placed on the X-axis and can spin with the fixture on the A-axis.

4-axis machining is a more economical way of machining parts that are probably possible on the 3-axis machine. Using the 4-axis milling machines helps to prevent the cost of running two different fixtures in the 3-axis machining, which costs more. In addition, the 4-axis machining helps avoid fixture change-overs, ensuring tighter tolerances between features on different sides of the workpiece. It prevents loss of accuracy and high cost of production due to fixturing and re-setups.

“Index” and “continuous 4-axis” CNC machining are the two types of 4-axis machining.

In index 4-axis CNC machining, the A-axis rotates while the machine does not cut material from the workpiece. The machine resumes cutting once the correct rotation is selected and a brake is applied. While in continuous 4-axis machining, the milling machine cuts material at the same pace as the A-axis rotations. It allows the machining of complex arcs like the profile of helixes and cam lobes.

4-axis CNC machining offers the ability to create angled features that is not achievable in 3-axis milling machines. However, remember that 4-axis machines permit a single-axis rotation per fixture setup. All angled features must be turned at the same axes, or extra fixtures must be put in place.

5-axis CNC Milling

5 axis cnc milling
5 axis cnc milling

Depending on the type of machine used, 5-axis CNC milling machines commonly use 2 of the 3 possible rotation axes. A CNC machine can rotate the A-axis and C-axis or the B-axis and C-axis. The rotation often occurs by the spindle or the workpiece. In addition, 5-axis machining offers product designers a much higher level of design flexibility, allowing them to develop highly complex 3D geometry.

The two major types of 5-axis CNC machines include fully continuous 5-axis machines and 3+2 machines.

  • Continuous 5-axis machining can create highly complex 3D shapes with complex 3D surfaces. It offers you the ability to create parts that are usually reserved for molding methods.
  • 3+2 axis machining: it comprises two axes operating independently of each other. The milling machine rotates the workpiece to any compound angle to the cutter, adding features to the workpiece. You can create highly complex 3D shapes with 3+2 machining.

However, it is essential to note that fully continuous 5-axis machining can rotate two rotation axes simultaneously while machining and moving the cutting tool linearly in the XYZ coordinates, which the 3+2 machining cannot.

What Are the Advantages of CNC Milling Machining?

what are the advantages of cnc milling machining

There are several reasons why CNC milling technology is commonly considered a versatile and reliable way of machining parts for different applications using various CNC machining materials. Here are some of the notable advantages of CNC milling service:

High Production Rate

CNC milling is an automated machining method which means there are no human limitations to the speed of the milling cutter. As a result, the method provides a high production rate unequaled by other manufacturing methods. This process is a capable and popular option for manufacturing parts in high volume with high-quality features.


CNC milling machines operate on autopilot and do not need much operator supervision. These machines only stop operations whenever there is a need to perform regular maintenance, or there has been an accident. These CNC mills can machine parts without interruptions. They can operate for days, continuously creating parts with exact precision.


The CNC milling uses computerized controls and a simple machine interface which offer excellent consistency irrespective of changes in the personnel managing the operation. Each part matches the previous version perfectly, a feature that is impossible in manual mills even if handled by experts. As long as there is a master file of the design, you can create endless copies that will possess the same quality and accuracy without errors.

Unmatched Precision

unmatched precision

CNC milling machine components have incredible capabilities for accurate and precision machining. As a result, they are common in the medical and aerospace industries due to their requirement for parts with high precision and tighter tolerances. CNC machining relies on using a digital template and autonomous machining, allowing it to prevent manufacturing errors. Thus, it can provide the highest accuracy that is close to the perfection that it does now.

Less Personnel Supervision

The CNC milling process needs a few personnel to oversee the entire operation because it is automated. In addition, the procedure only needs a few skilled specialists to supervise the whole process, which improves the end client’s cost-effectiveness. It helps to save time and reduce the labor involved in the production process. As a result, it helps reduce production costs while increasing efficiency to the highest level.


CNC milling is a very adaptable solution. It is a machining method that various industries of size can adopt. The process continues to evolve as the size of your workshop does. CNC milling machining is suitable for multiple parts regardless of their shapes and sizes.

Advanced Possibilities

advanced possibilities

CNC milling machines surpass the most skilled operators operating manual machines due to their advanced automation software and design software. It uses computer numerical control, which allows you to eliminate human errors and improve consistency and create complex designs with different shapes, sizes, and textures.

Why Outsource CNC Milling Service from China?

The CNC milling process is an efficient process suitable for machining many projects. Although there are several CNC milling companies worldwide, China tops the chart with its state-of-the-art facility and advanced CNC technology. These Chinese companies offer a wide range of custom machining services. Hence, it would help if you had a basic understanding of what your project needs before contacting a potential partner.

Outsourcing CNC milling service from China gives you a better chance at enhancing your production output; achieve uniformity, precision, and high-quality finish. However, to benefit from the numerous advantages of CNC milling services, you must find the right and most reliable China-based manufacturing partner for your projects.


CNC milling is one of the many beneficial contributions of modern technology to parts manufacturing. Its ability to increase production outputs and offer higher quality finishes and accuracy has made it a widely embraced production process across all fields. Also, the process is compatible with various materials, allowing you to use any CNC milling material of your choice for your project.

However, to get the best results, you need to work with a CNC milling company with powerful manufacturing capabilities. Contact AT-Machining today, and let’s help bring your products to life!

photo 2

Hey there, I’m Sam!

From AT-Machining, I’m a CNC Machining Expert in this field for more than 20 years.  We offer cost-effective machining services from China. Ask for a quote for your ongoing or upcoming projects now!

Best Regards, Sam, Co-Founder

AT Machining

On-demand CNC Machining With Custom Finishes. You Design It, We'll Make It.