Beginner's Guide
Aluminum CNC Machining
Aluminum CNC machining is one of the most prevalent manufacturing techniques due to its ability to produce complex yet lightweight parts quickly and cost-effectively. Read our complete guide to understand the elements, alloy types, and processes.
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Aluminum Machining Guide
Introduction to Aluminum CNC Machining
Very few substances can match the incredible versatility of aluminum. Aluminum is highly machinable and relatively inexpensive, making it perfect for CNC machining. Manufacturers can machine it three or even four times faster than other common machining materials such as steel and titanium.
Its flexibility and impressive strength-to-weight ratio make it ideal for use as the exterior skin panels of all forms of transportation, from automobiles and trains to aircraft and boats. Greater emphasis on fuel efficiency and "lightweighting" has seen aluminum replace the heavier metals traditionally used to make components and internal structures. Its high corrosion resistance also avoids the need for heavy and expensive anti-corrosion coatings often required by other materials.
Additionally, aluminum is non-toxic, malleable and 100% recyclable. Thanks to its sleek, silver surface finish, it is also well-suited for electronic devices like smartphones, laptops, tablets, and flatscreen TVs.
Where does aluminum come from?
Aluminum is the most abundant metal element in the Earth’s crust. The metal industry smelts more than 40 million tons each year, and manufacturers use it in numerous applications.
Like most metals, aluminum is present in rocks throughout the Earth’s crust as an ore. Mining companies extract almost all aluminum metal from bauxite ore, which typically contains 30% to 60% aluminum oxide (or alumina). The rest is a mixture of silica, various iron oxides and titanium dioxide.
A two-step process transforms alumina into aluminum metal:
- Bayer Process: Refines bauxite ore to obtain pure aluminum oxide (alumina).
- Hall-Héroult Process: Smelts the alumina using electrolysis to separate pure liquid aluminum.
What is CNC machining?
Computer Numerical Control (CNC) machining is a subtractive manufacturing technology. It uses pre-programmed computer software to dictate the movement of factory tools and machinery.
The process can be used to control a range of complex machinery, from grates and mills to lathes and routers. With CNC machining, three-dimensional cutting tasks can be accomplished in a single set of prompts. The computer program is written in standard G-code, which tells the machine exactly how to move, cut, and shape the material to match the digital CAD design model.
What types of aluminum are used in CNC machining?
In its pure form, aluminum is malleable, resistant to most forms of corrosion, non-magnetic and an excellent conductor of heat and electricity. However, it is too weak for most commercial applications. Greater strength is achieved by combining molten aluminum with other elements to form alloys.
Cast Alloys
Affordable, versatile, lightweight, durable, and perform well under high temperatures. Formed by pouring molten aluminum into molds. Widely used for engine blocks and machinery housings.
Al-Li Alloys
Alloyed with lithium to achieve extremely low density and high fatigue resistance. Widely used in the aerospace industry for aircraft fuselage parts, lower wing skins, and space rocket structures.
Wrought Alloys
Shaped while in a solid state through rolling, forging, or extrusion. They have superior mechanical properties and structural integrity compared to cast alloys, making them the most popular choice for CNC machining.
Steel Versus Aluminum CNC Machining
Aluminum and steel are the most widely used metals in CNC machining. Choosing which is the right one for a particular application comes down to five main factors:
Steel
Mild steels and carbon steels are generally cheaper than aluminum alloy equivalents. However, stainless steel tends to be more expensive.
Aluminum
Higher raw material costs, but mitigated by faster machining speeds which reduces labor and run time costs.
Steel
Other than stainless steel, most steels must be painted, treated or coated to protect them from rust, adding extra weight and maintenance cost.
Aluminum
Naturally forms a protective oxide layer, offering high corrosion resistance without the need for additional surface treatments.
Steel
Two to three times heavier and denser than aluminum. Unsuitable for components where lightweight design is critical.
Aluminum
Extremely lightweight (about 1/3 the weight of steel). Ideal for fuel efficiency and modern lightweight structures.
Steel
Incredibly strong and durable. Highly unlikely to warp, bend or deform under heavy load, high heat, or mechanical force.
Aluminum
Soft and more prone to scratches and dents compared to steel under high stress or sharp contact forces.
Steel
Dense and hard. Requires lower cutting speeds and higher force, leading to faster tool wear and longer cycle times.
Aluminum
Outstanding machinability. Can be machined three to four times faster than steel, cooling down quickly and extending cutting tool lifespan.
What are the most common aluminum CNC machining processes?
Depending on the geometry and tolerances of your part, we utilize various CNC cutting techniques to manufacture aluminum components:
CNC Milling
Uses rotating cutting tools to precisely carve material away from a stationary block of aluminum. Excellent for complex shapes, pockets, and precision flat surfaces.
CNC Turning
Holds and rotates a cylindrical workpiece while a stationary toolhead cuts it. Essential for producing precision round parts, spindles, fasteners, and shafts.
CNC Laser Cutting
Uses a high-power laser beam to melt or vaporize sheet metal. Offers incredible precision and clean edges, particularly suited for thin aluminum sheet parts.
CNC Water Cutting
Uses high-pressure water jets mixed with abrasives to slice through thick metals. Avoids thermal warping since no heat is generated during the cutting process.
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