A Quick Comparison of CNC Machinable Aluminum Alloys
Dec 10, 2019
Although CNC machining is a versatile manufacturing process compatible with a wide range of materials, it is virtually synonymous with aluminum, a widely used metal available in numerous grades. Aluminum is highly machinable and relatively affordable, and its many alloys are suited to myriad machining applications, from rigid architectural components to aerospace parts and beyond.
RapidDirect gives the option of some 20 aluminum alloys for its CNC machining services (see our full material list for details), all of which offer distinct and unique advantages. But while that range of options gives you huge flexibility when embarking on a machining project, it does make it harder to narrow down the best aluminum alloy for the job.
Which aluminum alloys, then, are best for your machining project? Which grade offers the best value? Which is most resistant to chemicals or heat? Which has the highest tensile strength?
This guide attempts to provide a quick comparison of five of the most popular aluminum alloys, highlighting their composition, common applications and the industries in which they are regularly put to use.
What are alloys?
An alloy is a metal mixed with either other metals or non-metallic elements. Aluminum alloys are materials largely consisting of aluminum, but with other elements such as iron, copper and magnesium mixed in.
Depending on their composition, different aluminum alloys are suitable for different applications. The mixture of other elements affects an alloy’s physical properties, including its strength, ductility and corrosion resistance, and these properties can help a company decide whether the material is suitable for a given part.
Aluminum grades can be broken down into three groups: commercially pure aluminum, heat-treatable alloys and non-heat-treatable alloys. Since commercially pure aluminum is less regularly used in CNC machining (we can, however, machine parts using Aluminum 1060), this article focuses on five alloys from the latter two groups.
Aluminum 2024, one of the more widely used of the ‘duralumin’ aluminum alloys in the 2xxx group, is a copper-alloyed material with an excellent strength-to-weight ratio. It is resistant to fatigue but fairly susceptible to corrosion.
Tensile strength: 68,000 psi
Major alloying elements: Copper
Industries: Automotive, aerospace, transportation
Products: Car parts, aircraft parts, transport vehicle parts, structural parts, electronics
Aluminum 6061 is the most widely used alloy in the 6xxx series and one of the most versatile of all machinable alloys. By CNC machining aluminum 6061, it is possible to make a wide range of products, including electronic and aircraft parts.
Tensile strength: 45,000 psi
Major alloying elements: Magnesium, Silicon
Industries: General manufacturing, aerospace, consumer goods, architecture
Products: Structural parts, steps, platforms, covers, truck bodies, valves, pipes, aircraft parts, computer parts, electronics
Commonly used for highly stressed structural applications, Aluminum 7075 is often found in structural aircraft parts, as well as sports equipment, tooling and more. 7075 is heat-treatable, ductile, strong and tough, but can also become brittle.
Tensile strength: 83,000 psi
Major alloying elements: Zinc
Industries: Aerospace, transportation, sporting goods
Products: Aircraft parts, transport vehicle parts, bicycles, golf clubs, weapons
The most widely used aluminum alloy (across all manufacturing processes), Aluminum 3003 is a near-pure aluminum alloyed with Manganese. It is frequently used for household goods like cooking equipment.
Tensile strength: 13,000 psi
Major alloying elements: Manganese
Industries: Household goods, chemicals
Products: Cooking utensils, kitchen equipment, tanks, siding and trim, roofing, chemical equipment
Strong, workable and corrosion-resistant, Aluminum 5052 — made with magnesium and chromium, amongst other components — is widely used in marine applications because of its resistance to salt water. It is also the strongest non-heat-treatable alloy available.
Tensile strength: 33,000 psi
Major alloying elements: Magnesium, chromium
Industries: Marine, aerospace, architecture, electrical, oil and gas
Products: Marine transport parts, heat exchangers, aircraft parts, fuel lines, fuel tanks, panels, household appliances, commercial and heavy-duty cooking equipment
Choosing an aluminum alloy
In addition to the sample of materials mentioned here, RapidDirect offers CNC machining services in several other alloys. When getting a rapid quote from us, you can select one of these alloys drop the drop-down list of materials, or choose one of many non-aluminum materials instead.
If you’re not sure about what kind of aluminum alloy suits your parts or prototypes — or if you think your part should be machined from an alloy not on our list — you can request a manual quote and specify the requirements of the project.
With this information, we can help you decide on the best material for the job, ensuring that your parts get made exactly as you want them.
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