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Selecting the right aluminum alloy for CNC machining can produce reliable, low-cost, high-performance CNC-machined parts for industrial and household use. Each alloy has its own properties, including strength, machinability, and cost. The alloys behave differently depending on the tools used, the heat applied, etc., during machining.
This alloy selection guide provides an overview of selecting the best aluminum for CNC machining, explaining the alloys and the best grades for several applications.
Key Factors Affecting Aluminum Machinability
Aluminum alloys have different properties depending on their composition, which affect the CNC machining process. Various factors that affect the machining process of aluminum alloys are given below:
Hardness and Tool Wear
Hardness is one of the factors that affect the machining process of aluminum alloys. The higher hardness of the aluminum alloys increased cutting forces and generated greater heat at the cutting edge of the tools. It directly influences the cutting tool wear.
Alloys like 5083, which are softer, can be easily cut and do not place greater stress on the cutting tools during machining. But alloys with higher hardening properties, like 7075-T6, increase tool wear. Selecting an aluminum alloy with optimal hardness can improve dimensional stability under highly variable loads. To avoid tool wear, carbide tool coating, the right coolant, and optimized cutting parameters must be used during CNC machining of aluminum alloys.
Thermal Conductivity
The thermal conductivity of any material helps dissipate heat from the material’s working zone. It is very important in the CNC machining of aluminum alloys because it reduces the risk of thermal expansion and chipping. It can also prevent the tool edge softening during the cutting process of aluminum alloys.
But poor heat management can affect the tolerance to cutting inconsistencies and result in poor surface finish. The tools used in CNC machining of aluminum alloys can have shorter tool life. Selecting alloys with good thermal conductivity is essential for machining aluminum alloys, providing a stable cutting process.
Chip Formation
In any machining process, chip formation is a critical aspect. It is often overlooked in the CNC machining of the aluminum alloys. Long, continuous chips can wrap around the tool and clog the CNC machine. A gummy chip formed during the machining process can increase friction on the job piece’s surface and increase heat retention in the cutting tools. This behavior can degrade surface finish quality and increase tolerance errors in aluminum products produced by CNC machining.
To minimize the chip formation issues in CNC machining of the aluminum alloys, the following techniques can be used, as presented below:
- Use sharp tools specifically designed for aluminum with an optimized rake angle to reduce cutting forces.
- Apply high-pressure coolant to effectively clear chips and prevent built-up edge (BUE).
- Optimize feed rate and depth of cut to ensure proper chip breaking and easy removal.
Alloy Comparison for CNC Machining
There are several aluminum alloys suitable for CNC machining into aluminum products. Each alloy has its own roles or benefits in the machining process. The major aluminum alloys that are selected for the CNC machining process are explained below:
General-Purpose Aluminum Alloys
In most CNC machining processes, 6061 aluminum alloy is used to produce aluminum products. These alloys have several benefits, which are given below:
- This has excellent strength and is available everywhere at a suitable cost
- This alloy is easily amenable and has good corrosion resistance for outdoor applications.
- This alloy is widely available in plates, bars, and even extrusion form that could be used to make several components like frames, slots, etc.
- This alloy is easily weldable and accepts surface finishes like powder coating and painting.
High-Strength Aluminum Alloys
High-strength aluminum alloys are widely used in aerospace and high-performance component systems. 7075 aluminum alloy is one of the most popular aluminum alloys, often machined to produce aluminum products. The key benefits of the 7075 alloy are given below:
- It has very high strength compared to other steels
- It has very good machinability
- It has high fatigue resistance
Corrosion-Resistant Alloys
There are several aluminum alloys, such as 5083 and 5052, that are designed for corrosion resistance. These aluminum alloys are used in applications that prioritize corrosion resistance, such as marine and outdoor environments. The properties of 5083 alloy are given below:
- It has excellent corrosion resistance, which is used for marine environments, outdoor structures, and in chemical environments
- This alloy has good machinability, but it is softer than alloys like 6061 and 7075.
- It has high strength among the non-heat-treatable aluminum alloys
Choosing the Right Alloy by Application
In CNC machining of aluminum alloys, it is crucial to select the right alloy for each application. The selection of alloy depends on the application, and the same alloy might not be used for different applications, such as marine environments, frames, etc. Here is a practical breakdown of selecting the best aluminum for CNC machining, as given below:
Structural Components
The component used to make the structures must have high strength and fatigue resistance to withstand high loads. Alloys such as 7075 and 6061 could be selected for this type of work.
7075 alloy is ideal for aerospace and high-performance components that resist high loads. It also has an excellent weight-to-strength ratio, which helps it perform well under high loads.
However, Alloy 6061 is the best choice for general structural components such as equipment casing, frames, and brackets. It also reduces material costs and eases the manufacturing process compared to alloy 7075.
Precision Parts
Alloys such as 6061 and 6082 are recommended for CNC machining to get a precise, high-quality finish on manufactured components. These components require very high tolerances and very good surface finishes. It must have the dimensional stability of its components. Both alloys exhibit consistent machining behavior and minimal thermal deformation.
Components made from these alloys are suitable for electronic casings, custom-machined prototypes, and small medical devices that require very high precision and a high surface finish.
Lightweight Designs
Aluminum is widely used in the aerospace, automotive, and robotics industries due to its lighter weight than stainless steel. Choosing the right aluminum alloys that balance strength and light weight helps to achieve good performance of the manufactured systems.
7075 and 5052 alloys are recommended for machining, depending on the application. 7075 has very high strength and low weight, making it well-suited for weight-reduction applications. 5052 is widely used for lightweight panels, where corrosion resistance is also very important.
Conclusion: Optimizing Alloy Selection for CNC Machining
A detailed understanding of the material properties, machining behaviors, and its uses in applications is needed to select the best aluminum alloy for CNC machining. The material properties, such as Hardness and thermal conductivity of the alloy, significantly affect surface quality and the overall machining process. Chip formation is another key factor that affects tool wear and overall CNC machining efficiency. These factors also affect the lifespan of the cutting tool and the machining efficiency of the CNC machining process.
Alloy 6061 is used for general-purpose applications, which provide excellent machinability and versatility for component fabrication. 7075 alloy is used in aerospace and high-performance structures due to its high strength and low weight. On the other hand, alloy 5083 has corrosion-resistant properties that ensure its durability in outdoor structures and marine environments. The selection of the alloy is very important for achieving a good surface finish, extending the lifespan of the cutting tools, and ensuring excellent performance of the parts produced by CNC machining.
Partner with Conglin Aluminum when optimizing alloy selection for CNC machining.
