What Are the Advantages of Aluminium for CNC Machined Parts

Aluminium is one of the most popular materials for CNC machined parts. Continue reading to discover six key reasons why.

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1. Quick to Machine

If you ask any CNC machining manufacturer, they will highlight how easy it is to machine aluminium. It is highly dimensionally stable, allowing for significant material removal while keeping residual stress under control. With carbide tooling and modern coolants, you can achieve an excellent finish. Additionally, it can be bead blasted for a matte finish or anodized for a consistent aesthetic finish and increased corrosion resistance.

This machinability can help decrease production costs. However, the selection of material should depend on the specific characteristics required for your parts. So, what other advantages does aluminium offer?

2. Great Strength-to-Weight Ratio

Aluminium is lighter than most metals, making it an excellent option for weight-sensitive applications. While pure aluminium has a tensile strength of under 100 MPa, its strength can be enhanced in several ways:

• Alloying: Mixing with other elements improves the grain structure.
• Heat Treatment: Heating and cooling at specific rates create optimally sized crystals.
• Work Hardening: Deliberately deforming the metal to alter its grain structure, which can be done during heat treatment (e.g., rolling) or afterward (e.g., forging).

A "temper" designation indicates the specific condition or strength of the resulting material, with "H" for "hardened" and "T" for "thermal." Notably, most aluminium alloys exhibit a higher strength-to-weight ratio, or specific strength, than stainless steel 316L.

While titanium may outperform aluminium in specific applications, high-strength aluminium alloys provide an excellent cost-effective alternative when stiffness and weight savings are priorities.

3. Wide Choice of Alloys and Material Properties

Aluminium's versatility stems from the wide variety of available alloys, each offering different properties and used based on specific needs. These alloys are categorized into nine series identified by thousands, further classified by a number. Generally, the closer the numbers are, the more similar the grades are. For instance, 6060 and 6061 are nearly identical.

Some of the most popular aluminium grades include:

• Aerospace Grade: High fatigue strength, trading ultimate tensile strength (UTS) for enhanced ductility/toughness through copper alloying.
• Marine Grade: Exhibits good corrosion resistance due to a higher magnesium content.
• General Purpose and Aerospace Grade: Balances strength, ductility, and corrosion resistance; commonly used and produced by alloying with magnesium and silicon.
• High Strength Aerospace Grade: Offers a good balance of properties for areas with high static loads. It contains more zinc and can be heat treated.

4. High Corrosion Resistance

Corrosion resistance varies among aluminium grades; nonetheless, aluminium is an excellent choice for corrosion-sensitive applications. The metal and its alloys have a natural affinity for oxygen—reactive metals like magnesium oxidize easily, while less reactive metals form a loose oxide layer, like rust on iron and steel.

When exposed to the atmosphere, aluminium generates a passivating layer of aluminium oxide that seals the surface, preventing further oxidation and erosion. This layer is self-repairing, even if scratched, which may reduce the need for painting or surface treatments, leading to cost savings in manufacturing and lifetime service. Anodizing can further enhance this natural resistance.

5. High Conductivity

Although copper is often the preferred material for conductivity, aluminium is frequently used in electrical components due to its lower cost and lighter weight. It is commonly used for busbars, battery cables, and connectors, particularly within automotive and electric vehicle applications.

Additionally, its excellent thermal conductivity makes it suitable for heat sinks and heat dissipation. For more information, please visit aluminum cnc machining service.

6. Recyclable

With sustainability gaining importance, it is worth noting that approximately 75% of all aluminium produced is still in use. Recycling aluminium consumes significantly less energy compared to its initial production, and as long as impurities are managed, it can be recycled repeatedly.

We have already discussed how machining this material yields excellent finishes and the intrinsic corrosion resistance of aluminium. To further improve aesthetics, it can be anodized to achieve a variety of colors.

This surface finishing procedure enhances wear and corrosion resistance while allowing for easy color application. At Protolabs, we provide decorative anodizing (type II) as well as type III, which offers an even thicker layer of 50 μm for extra protection.

This process thickens the passivating oxidized layer using acids and electrolytic treatment. The resulting aluminium oxide creates a hard, durable ceramic finish.

Choosing the right material is critical and should consider the characteristics you need. While aluminium is often an excellent choice for the reasons discussed, numerous other metal and plastic options are available. To help you make informed decisions for CNC machining, we have created a pocket-sized CNC materials selector as a quick reference guide.

What are the Benefits of Aluminum CNC Machining?

Aluminium is one of the most commonly used materials for CNC machining projects due to its favorable physical characteristics. Its oxidized outer layer protects it from weather-related corrosion, and its strength makes it ideal for mechanical parts. As a result, aluminium parts are increasingly employed across various industries, notably in automotive, aerospace, medical, and consumer electronics.

Easily Bendable

One notable advantage of using CNC machining to create aluminium parts is their ease of bending. Unlike steel, aluminium can be processed with ease during machining as its thickness allows for various molding techniques. This is most effectively achieved through pressing and processing, enabling the attainment of diverse shapes for aluminium CNC parts.

Easy Machining

Another significant advantage of aluminium CNC machining is the relative ease of manufacturing various shapes through methods like punching, folding, and drilling. The energy consumed in machining aluminium is considerably lower than that used for steel.

Resistant to Low Temperatures

Aluminium exhibits resistance to low temperatures. It is well-known that steel can become brittle in low-temperature conditions, especially during welding. In contrast, aluminium can be machined effectively even in low temperatures compared to steel.

Custom Finishing

Aluminium can be customized according to client requirements after finishing. Various options are available to achieve the perfect custom look, including plating in different colors such as black, blue, and green.

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