CNC milling is a precision machining process that removes material by rotating a tool. CNC milling is automatically controlled by a computer numerical control system, making the machining process more efficient and accurate. Aluminum is one of the common materials used in CNC milling. It is widely used in many industries due to its easy machining and excellent performance.
How CNC milling works
The working principle of CNC milling is to gradually remove the surface of the material to form the desired shape through the contact between the high-speed rotating tool and the material. The cutting tool usually moves along multiple axes and processes the material from different directions to achieve accurate machining of complex geometric shapes. The CNC milling machining path is controlled by a computer to ensure high machining accuracy and small errors.
Processing steps of aluminum CNC milling
Preparation before machining
In the preparation stage of aluminum CNC milling, you first need to create an accurate 3D CAD model to ensure that the part design can be effectively machined by the CNC machine. The model contains all geometric information, dimensions and specific machining features. Special care should be taken to avoid designing too many complex undercuts (deep or recessed features) because these areas are difficult to machine with standard CNC milling machines and may require the use of special tools or multi-axis milling machines, which increases costs.
Next, the CAD model is converted into a CNC program through CAM software to generate numerical control codes (usually G-code or M-code), which instruct the machine tool how to operate. G-code controls the tool’s motion path, spindle speed and cutting depth, while M-code handles other functions such as tool changes and machine operation. After writing the program, the simulator in the CAM software is used to verify that the machining path is correct to ensure that the subsequent machining process goes smoothly.
Finally, the machine tool is set up and the workpiece is clamped. The prepared aluminum blank is fixed to the worktable of the CNC machine tool and equipped with tools, fixtures and auxiliary equipment.
Milling stage
Aluminum CNC milling is divided into two stages: roughing and finishing:
- Roughing: In the roughing stage, the focus is on quickly removing excess material. At this time, large-sized tools and higher cutting speeds can be used to improve efficiency. Roughing does not focus on surface finish, but focuses on machining the workpiece to a near-finished size, leaving a small amount of material for finishing.
- Finishing: In the finishing stage, smaller tools and lower cutting speeds are used to improve surface quality and accuracy. Finishing focuses on achieving the desired tolerance requirements and surface finish.
To optimize the machining path, accurate programming can reduce unnecessary tool movement and non-cutting time. By reducing the number of tool changes and maintaining continuous machining operations as much as possible, production efficiency can be significantly improved.
Cooling and lubrication
In aluminum CNC milling, cooling and lubrication are crucial to machining quality and tool life. Coolant can effectively reduce the high temperature generated during cutting, prevent workpiece deformation, and reduce tool wear. In addition, lubricants can help remove chips, keep the tool cutting surface clean, and improve the surface finish of the part. Appropriate cooling and lubrication measures can improve machining accuracy and extend tool life.
Tool selection
Tools suitable for aluminum are usually made of cemented carbide, which has high wear resistance and sharp cutting edges, and can maintain good cutting efficiency. In addition, aluminum milling often uses tools with special coatings, such as titanium nitride coating or carbide coating, to reduce friction, extend tool life, and improve the discharge of aluminum chips.
Popular CNC milling methods
CNC milling has many different operating forms, each with unique advantages. Here are some common CNC milling methods:
- General milling: The tool cuts parallel to the workpiece, suitable for machining planes and large surfaces, and is the most basic form of milling.
- Face milling: The tool is perpendicular to the surface of the workpiece, suitable for machining high-quality planes and contours. Face milling is often used to create fine and smooth surfaces for parts.
- Angle milling: Using a single-angle milling cutter to remove material from the plane of the workpiece at a specific angle, suitable for machining grooves or geometric shapes at a specific angle.
- Forming milling: This method is used to process irregular surfaces, such as curved surfaces, and special tools (such as fillet tools) can cope with complex curved structures.
- Group milling: By using multiple tools to process the workpiece at the same time to improve production efficiency, it is suitable for mass production or large-area material removal.
- End milling: Use a toothed cutting tool to process the end and periphery of a workpiece, usually used for milling grooves, slots and complex contours.
- Thread milling: Used for machining threads, it is fast and flexible and can accommodate a variety of thread sizes.
- Gear milling: Specialized in the manufacture of precision gears, high-precision gear machining is achieved through form milling or involute gear milling cutters.
Comparison of CNC Milling Methods
| Milling Type | Characteristics | Suitable for | Advantages |
| Face Milling | Tool is perpendicular to the workpiece | Flat surfaces and contours | Excellent surface finish |
| End Milling | Tool has teeth on the end and periphery | Grooves, slots, and contours | Versatile for various shapes |
| Angle Milling | Removes material at a specific angle | Parts requiring angled features | Great for angled designs |
| Form Milling | Handles irregular surfaces | Curved surfaces or complex shapes | High flexibility |
Comparison of aluminum CNC milling with other materials
Compared with steel and stainless steel, aluminum is more efficient in CNC milling because it is softer and has less tool wear. Although plastic is easier to process, its strength and rigidity are not as good as aluminum. Therefore, aluminum has an advantage in situations where both easy processing and mechanical properties are required.
Equipment used for CNC milling
The NC milling process relies on a variety of equipment working together to ensure the accuracy and stability of the processing. The following are the key equipment commonly used in CNC milling:
Workbench: used to stably fix the workpiece to ensure that the workpiece does not move during the processing process and maintain the processing accuracy.
Saddle: located under the workbench, providing additional support and ensuring that the movement of the workbench remains parallel to the tool rotation axis, making the processing process more stable.
Support: supports the saddle and workbench, and the position can be adjusted vertically to accommodate workpieces of different thicknesses and enhance processing flexibility.
Spindle: used to fix the cutting tool and guide the tool to rotate and move to ensure precise cutting.
Spindle: The fixed axis of the tool, assembled through the spindle, is used to ensure the stability and accuracy of the tool.
Ram: An optional component on a vertical milling machine or an angular milling machine that provides additional support for the spindle and improves machining stability.
Cutting tools: Commonly used tools include end mills, which are responsible for cutting materials to achieve the desired shape.
Operation interface: The operator enters instructions through a computer interface (usually including a screen and keyboard) to control the operation and operation of the CNC machine tool.
CNC Milling Equipment and Functions
| Equipment Name | Function Description |
| Worktable | Holds the workpiece steady during machining |
| Spindle | Secures the cutting tool, guiding its rotation and movement |
| Cutting Tools | Remove material to achieve desired shapes |
| Interface | Allows the operator to communicate with the CNC machine, typically via screen and keyboard |
What is the difference between CNC milling and CNC turning?
CNC milling and CNC turning are two common CNC machining methods. Milling is the removal of material by rotating the tool, while turning is machining by rotating the workpiece and using a fixed tool. Milling is suitable for machining complex planes and curved surfaces, while turning is more suitable for machining cylindrical parts. For more detailed differences, please refer to this blog.
Types of milling machines
CNC milling machines can be classified differently according to the spindle direction and operating capabilities. Common types include vertical milling machines, horizontal milling machines, universal milling machines, turret milling machines, and CNC bed milling machines. Milling machines can also be classified by the number of axes, such as three-axis, four-axis and five-axis milling machines, each type has different advantages when processing parts of different complexity.
- Vertical milling machine：Vertical milling machines have a spindle that is perpendicular to the table and are suitable for drilling, grooving and other operations. The spindle directly contacts the workpiece from above, providing better visibility, especially suitable for processing fine and complex parts.
- Horizontal milling machine：Horizontal milling machines have a spindle parallel to the table and are suitable for heavy cutting tasks. Because the workpiece is well supported on the table, horizontal milling machines can process large and heavy workpieces and are often used for milling complex shapes such as gears.
- Universal milling machine：Universal milling machines combine the functions of vertical and horizontal milling machines, and the spindle can be rotated to different angles to adapt to a variety of processing tasks. This flexibility allows universal milling machines to quickly switch processing modes, which is very suitable for workshops that need a variety of processing operations.
- Turret milling machine：Turret milling machines (Bridgeport type) are known for their fixed spindle and movable table design, which is suitable for precision processing.
- CNC bed milling machine：The table of a CNC bed milling machine can only move vertically, while the spindle moves in a parallel direction, making it suitable for heavy-duty cutting tasks. Due to CNC control, this type of milling machine can perform complex machining operations with high precision and efficiency, and is particularly suitable for mass production environments.
Advantages and Disadvantages of CNC Milling
Advantages
- High Precision: CNC milling can achieve high-precision part manufacturing, suitable for parts with strict size and shape requirements.
- High Flexibility: CNC Milling can process a variety of geometric shapes to meet different processing needs.
- High Degree of Automation: Once the processing parameters are set, the machine can run automatically, improving production efficiency.
Disadvantages
- High Initial Cost: The initial investment in CNC equipment and programming is large, especially for complex parts.
- Programming Time: The programming of complex parts may take a long time.
Common Grades of Aluminum CNC Milling
6061 Aluminum Alloy
6061 Aluminum Alloy is one of the most commonly used materials for CNC milling. It has good strength and machinability and is suitable for the production of a variety of structural parts. This material is widely used in aerospace, automotive parts, building profiles and other fields.
7075 aluminum alloy
7075 aluminum alloy is a high-strength aluminum alloy, often used in fields with high strength requirements, such as aerospace and military applications.
6063 aluminum alloy
6063 aluminum alloy is mainly used for milling of building profiles. It has good extrusion and surface treatment properties and is often used in building applications such as door and window frames and pipes.
Common Aluminum Alloys for CNC Milling
| Aluminum Alloy Grades | Key Features | Application |
| 6061 | Moderate Strength, Easy to Process | Aerospace, Automotive Parts |
| 7075 | High Strength, Corrosion Resistance | Aerospace, High Stress Applications |
| 6063 | Good Surface Treatment Performance | Building profiles, Door and Window Frames |
Cost factors of aluminum CNC milling
Material cost
The cost of aluminum varies depending on the alloy type and market supply. 6061 aluminum alloy is relatively cheap, while high-strength 7075 aluminum alloy is more expensive.
Tool and equipment cost
Tool life is a key cost factor in CNC milling. Aluminum has moderate hardness and usually causes less wear on the tool, so the tool replacement frequency is low. But for processing high-strength aluminum alloys such as 7075 aluminum, the tool wear will be faster and the cost will increase relatively. In addition, the maintenance and operating costs of high-end CNC machines also need to be considered.
CNC Milling Cost Factors
| Aluminum Grade | Material Cost (per kg) | Tool Wear | Relative Machining Time |
| 6061 | Moderate | Low | Fast |
| 7075 | High | Medium | Slow |
| 6063 | Low | Low | Fast |
Processing time
The processing path, cutting speed and feed rate are the key factors affecting the processing time. Reasonable processing path design can reduce unnecessary movement and optimize processing efficiency. The balance of cutting speed and feed rate is very important for aluminum processing. Too high feed rate may cause faster tool wear, while too low speed will prolong processing time.
What types of parts can be manufactured by aluminum CNC milling?
Aluminum CNC milling can manufacture a variety of parts, ranging from structural parts to high-precision mechanical parts. Common aluminum CNC milling parts include:
- Aerospace components
- Automotive parts
- Electronic equipment housings
- Medical device parts
- Brackets and supports in industrial equipment
These parts usually require high precision and durability. Aluminum CNC milling can meet the needs of different industries for customized parts through flexible processing methods.
Conclusion
Aluminum CNC milling has become the mainstream method for aluminum parts processing with its high precision, flexibility and efficiency. For your needs of CNC Milling aluminum custom parts, please contact us and we will provide fast quotes and competitive prices.
