Aluminum CNC Machining For Beginners

Aluminum is a lightweight, highly workable metal that offers an excellent strength-to-weight ratio. Because of these properties, it is widely used in applications where weight reduction and efficiency are important. Most aluminum used in CNC machining processes is not pure but alloyed with elements such as magnesium or manganese. These alloys preserve aluminum’s natural advantages while compensating for its weaknesses. With many alloy types available, manufacturers can choose the right grade for each application.

This guide introduces the characteristics of aluminum, its main alloy series, and common CNC machining considerations. Aluminum has the following characteristics:

• Lightweight

• High specific strength

• High thermal and electrical conductivity.

• Abundant in types (grades)

• Relatively inexpensive

• Versatile

• Resistant to brittle fracture

Characteristics of Aluminum

Lightweight

Aluminum has a specific gravity of 2.7, about one-third that of iron (7.8) or copper (8.9). This lightness improves efficiency in applications such as rotating parts, sliding components, and transport equipment, where reducing weight enhances performance and lowers energy use.

High Specific Strength

While pure aluminum has relatively low tensile strength, alloying it with elements like magnesium and manganese produces aluminum with excellent strength relative to their weight.

Easy to Process

Aluminum is easy to form into thin foils or complex extrusions. It also has excellent machinability, making it a common choice for precision components.

High Thermal Conductivity

With a thermal conductivity of about 240 W/m·K, aluminum heats and cools quickly. This makes it suitable for heat exchangers, fins, sinks, engine parts, and HVAC equipment.

Types of Aluminum Alloys

Almost all aluminum used in machining is alloyed, because pure aluminum is soft and lacks sufficient strength for certain applications. Commonly used alloy metals include manganese, zinc, magnesium, and nickel.

Series numbers indicate the alloying element and properties, classified by a series number starting with "A" followed by four digits.

1000 Series (No Major Additives)

This is nearly pure aluminum (99%+). It offers excellent conductivity and corrosion resistance but low strength.

Its ductility makes machining prone to chip entanglement, leading to scratches or dents. Common grades include: A1100, A1070, A1050. The last two digits indicate aluminum purity: A1100 is specified as 99%+, A1070 as 99.7%+, and A1050 as 99.5%+.

2000 Series (Copper)

This series includes high-strength alloys such as A2017 (duralumin) and A2024 (super duralumin). These are strong, but because copper tends to oxidize easily, they have low corrosion resistance and weldability due to its propensity for hot cracking, so anodizing or other treatments are often required.

3000 Series (Manganese)

These alloys are stronger than pure aluminum but retain corrosion resistance.

They are not typically used for machining stock and are used mainly for forming applications such as aluminum beverage cans. Example: A3003.

4000 Series (Silicon)

The addition of silicon improves heat and wear resistance. Example: A4032.

5000 Series (Magnesium)

Magnesium enhances corrosion resistance, strength, and workability, making this a popularly used alloy. Examples include A5052 for sheet material, and A5056 and A5083 for round bars. A5052 sheet material generally has good dimensional accuracy, so if thickness tolerances are not critical, it can be used with a four-sided finish directly.

6000 Series (Magnesium, Silicon)

These alloys enhance strength and corrosion resistance, even compared to the 5000 series. A6061 (when heat-treated and alloyed with copper), approaches SS400 (a common steel grade) in strength. A6063 has excellent extrudability, so it's widely used for shaped extrusions.

7000 Series (Zinc, Magnesium)

This is the strongest aluminum alloy, hardened through heat treatment. A7075 (ultra-super duralumin) is used in aircrafts and vehicles.

What is Duralumin?

Duralumin refers to aluminum alloys strengthened with copper (Cu) and magnesium (Mg). The most common grades are A2017 (Duralumin), A2024 (Super Duralumin), and A7075 (Ultra-Super Duralumin). Because of their high copper content, Duralumin alloys have low corrosion resistance. When machining parts for corrosive environments, surface treatments or protective coatings are essential.

Super Duralumin

Super Duralumin (A2024)contains more copper and magnesium than standard A2017, giving it greater strength while maintaining good machinability.

Because it has low corrosion resistance, surface treatments such as anodizing are necessary. To improve durability, a composite plate called A2024PC is used, which bonds a pure aluminum layer (A1230) to the surface.

Ultra-Super Duralumin

Ultra-Super Duralumin (A7075) is one of the strongest aluminum alloys available. It contains 1.2–2.0% copper, 2.1–2.9% magnesium, and 5.1–6.1% zinc.

A7075 is valued for its steel-like strength, making it a preferred material for aircraft structures. On the Brinell hardness scale, it measures around 160 HB, compared to 58–63 HB for tool steel SKD11 and about 187 HB for stainless steels SUS303 and SUS304. While stainless steel is harder in absolute terms, A7075 delivers nearly twice the specific strength.

Like other types of Duralumin, A7075 has poor corrosion resistance and is prone to stress corrosion cracking, so careful material selection is critical. Composite versions, such as those bonded with an A7072 surface layer, improve durability.
The only forms standardly available in the market are round bars and plates.

Benefits of Aluminum Processing

Across industries worldwide, robots are increasingly used in manufacturing. What was once made by human hands is now often produced through automation, with industrial robots playing an active role in sectors such as automotive, food, and semiconductors.

Among the materials used for these parts, aluminum has a high utilization rate, as explained below.

Lightweight

Aluminum weighs less than one-third of iron or stainless steel by volume. Its lightness makes it easier to transport, reduces shipping costs, and simplifies processing.

When devices are made from heavier metals, their size and weight can create installation challenges, particularly on upper floors of buildings. Aluminum processing helps reduce part weight, making installation more manageable without sacrificing performance.

High Specific Strength

Aluminum offers a strong strength-to-weight ratio. In particular, the 2000 and 7000 series alloys, often referred to as duralumin, combine light weight with high strength. This makes it possible to design lightweight parts that remain durable.

Suitable for Complex Shape Processing

Aluminum has excellent machinability and reproducibility, allowing for efficient processing and shorter processing time, even with complex shapes.

While magnesium and titanium alloys also provide strong, lightweight properties, they are considered difficult-to-cut materials. They require more time, greater precision, and higher costs in machining.

By contrast, aluminum alloys such as the 5000 series are easy to process and ideal for producing complex, high-precision components.

Strong Against Corrosion

Metals generally corrode in the air. However, aluminum reacts with oxygen to form a thin oxide film that protects against corrosion. Depending on the environment, this natural layer may not be sufficient, which is why anodizing—a process that artificially creates a thicker oxide film—is often applied to enhance durability.

Points to Note When Selecting Aluminum

Aluminum offers many advantages, but it also has some limitations.

Except for high-strength alloys like the 7000 series Ultra-Super Duralumin (A7075), aluminum generally has lower strength compared to other metals. It can dent or scratch easily under strong impacts, and sliding parts may experience wear over time.

Aluminum also has a higher coefficient of linear thermal expansion than most metals, making its dimensions more susceptible to changes from temperature fluctuations.

Aluminum CNC Machining

Aluminum is highly machinable, but it can adhere, or “weld,” to the cutting tool during processing. Despite aluminum’s high thermal conductivity, adhesion may occur depending on the alloy type and workpiece geometry.

When aluminum melts and sticks to the tool, it forms a built-up edge, reducing machining accuracy. In slender tools, this can cause breakage and embed the tool in the workpiece.

Two primary methods prevent adhesion:

• Chip Removal by Air Blow: Regularly removing chips with an air blow can reduce buildup, especially for blind holes or small tapping operations. Adjusting the depth of cut per pass helps ensure effective chip evacuation.

• Use of Cutting Fluid: Using a large flow of cutting fluid prevents chips from floating and sticking to the tool, which is particularly important because aluminum is light (about one-third the density of iron or copper) and its chips are prone to float.

Aluminum CNC Machining Examples

We have manufactured numerous aluminum alloy parts using CNC machining, handling production from single prototypes to mass production of up to 1,000 units.

Key Points

Aluminum is a metal that is light and possesses high strength per unit weight. Its properties improve when alloyed with other metals, with performance varying according to the proportions of added elements. Aluminum’s excellent machinability makes it ideal for complex shapes. Among aluminum alloys, A2017, A2024, and A7075 are particularly strong. However, their corrosion resistance is low, so either the usage environment must be carefully selected or anti-corrosion treatments, such as anodizing, should be applied.

Aluminum CNC Machining FAQ

Yumoto Electric specializes in CNC machining, handling the production of essential components from single prototypes to mass production, including post-processing. We can also support CAD data creation. We also have experience with 3D printing and sheet metal processing, allowing us to adapt to diverse manufacturing needs.

Supported Sizes

For aluminum CNC machining, our maximum processing sizes are:

• Rectangular parts: 700 x 400 x 150mm

• Round parts: Maximum diameter of Φ300, maximum length of 500L

These dimensions may vary slightly depending on machining conditions.

Supported Lot Sizes

We can produce quantities ranging from a single unit to up to 1,000 units for mass production. Our system is optimized for high-mix, low-volume production with short lead times.

Material Requests

In addition to aluminum alloys, we accept consultations for the following materials, and we can also discuss other materials not listed here. Our one-stop service covers everything from material procurement to finished parts.

• Stainless Steel (SUS)

• SC Material (Carbon Steel for Machine Structural Use) - Often refers to SCM/SC materials like S45C, etc. based on context.

• SCM Material (Chromium Molybdenum Steel)

• SS Material (General Structural Rolled Steel - e.g., SS400)

• Copper (Pure Copper - C1100, etc.)

• Brass

• Titanium

• Magnesium

• Molybdenum

• Inconel

What information is required for a quote?

To provide an accurate estimate, we require 3D-CAD or 2D-CAD data, along with material type, quantity, and desired delivery date. Details on surface or heat treatments should also be included. 3D-CAD data allows the fastest estimation, but we can also provide quotes from PDF drawings if CAD data is unavailable.

Step Up Your Project with Yumoto Electric

Yumoto Electric delivers high-quality components fast, worldwide. We provide precision machining for a wide range of metals using milling, turning, and specialized metal processing. We have experience with over 200 materials including aluminum alloys, stainless steel, molybdenum, and titanium. 

If you’re unsure about material selection or machining methods, we offer complimentary consultations to help optimize your design and production. For any questions, please feel free to contact us.