Aluminum is one of the most machined materials today. In fact, aluminum CNC machining processes are second after steel in terms of frequency of execution. This is mainly due to the excellent machinability.
In its purest form, the chemical element aluminum is soft, ductile, nonmagnetic, and silvery-white in appearance. However, the element is not only used in its pure form. Aluminum is typically alloyed with various elements such as manganese, copper, and magnesium to form hundreds of aluminum alloys with various significantly enhanced properties.
Is Aluminum good for machining?
Aluminum as a material offers some interesting thermal and mechanical properties. Also, aluminum metal is relatively easy to shape, especially in drilling processes like CNC aluminum machining. In fact, we value an aluminum alloy very much compared to other light metals such as magnesium and titanium alloys.
The use of CNC aluminum has increased immensely, the production of CNC automotive parts and other lightweight CNC parts has been intense.
Why is aluminum easier to machine than steel?
Aluminum is easier to cut than steel, allowing for faster machining and shorter lead times. Although aluminum is considered too soft for mass production, this is simply not true.
Some aluminum molds are capable of producing parts after 2 million cycles! Aluminum cools much faster and more evenly than steel. This shortens the cycle time and saves money.
Because aluminum is so light, it can be machined on smaller machines and faster too. Aluminum dissipates heat very evenly, allowing for great dimensional stability through less warping. There is far less scrap because there are far fewer cracks and warps.
Aluminum is often viewed as a weak, soft material that is not good for mass production. However, aluminum can actually be used for high volumes. It can also be machined faster and dissipates heat much faster and more evenly than steel. This often shortens throughput times and saves money.
Which Aluminum Grade is Used for Parts Fabrication?
The final choice of the type of aluminum grade you want to use depends on your machining projects, which allow you to classify each grade according to its characteristics, from the most important to the least important. This allows you to choose aluminum with specific properties and shapes according to your needs.
The following are some types with essential facts about the Aluminum grade;
- Aluminum 6061: This grade has excellent mechanical properties and excellent weldability. Its topical properties make it one of the most extruded strains. This is because of its good toughness, medium and high strength, excellent corrosion resistance under harsh conditions, cold anodizing and bend workability. Aluminum 6061 is commonly used for 5-axis CNC machining.
- Aluminum 7075: Also popular, although not like 6061. This grade is known for its exceptional fatigue strength. This type of aluminum is not suitable for welding; it is expensive. Therefore, it is better suited for heavy-duty parts such as fuselages, bicycle parts, climbing equipment, and airplane wings. This alloy also has better corrosion resistance.
- Aluminum 2024: The alloy is mainly used in the military and aerospace sectors. This is due to its mechanical properties such as high wear resistance and high strength. The 2024 aluminum has terrible corrosion resistance and is not weldable.
Ways to Fabricate Aluminum Parts
The main types of fabrication include cutting, bending and assembling. Cutting is typically accomplished via sawing, shearing or chiseling the metal by hand or machine; or by using hand-held torches or an extremely powerful CNC cutter using a laser, mill bit, plasma jet or water jet. Hammers, press bakes or tube benders are employed when bending metal. Assembling describes the joining of two separate pieces of metal by welding, binding or riveting.
2. Aluminum Extrusion
A powerful ram pushes a heated billet of aluminum through a die with the desired final cross-sectional shape. We can compare this process to the way children play with play-dough, forming a long strand of putty by pushing it through a plastic mold, or squeezing toothpaste out of a circular tube.
The resulting aluminum extrusion has the cross-section of the die, which can have a wide range of shapes including solid, hollow, and semi-hollow. In addition, these profiles can be cut to any length, making extrusion the perfect method to create complex cross-sections with relatively low production costs.
In addition, extrusions have a consistently smooth surface finish that is perfect for further processing to enhance their appearance and prevent corrosion.
3. Aluminum Sheet Metal
The aluminum rolling process involves passing slabs or billets of aluminum alloys through different sets of rolls to reduce their thickness. This process repeats until the aluminum reaches its final form, resulting in a piece that will be considered a plate, sheet, or foil, depending on the thickness.
The aluminum plates, sheets, and foils produced by aluminum rolling have great versatility. Fabricators can further process them, performing operations such as bending, forming, or machining. For example, they can use rolled aluminum to produce beverage and food cans, aluminum roofing and gutters, and household aluminum foil.
4. Aluminum molding and casting.
Casting is a process that is excellent for shaping aluminum into very complex shapes. The technique involves fully melting aluminum alloy ingots and injecting the liquid metal into a mold.
The cast metal completely fills the empty cavity and then solidifies to create a perfect aluminum duplicate of the mold’s internal shape. Casting can be done using several different types of molds including female and permanent molds, clay molds and sand molds.
The parts made by casting often require minimal additional machining. And if you use steel dies, you can repeat the process many times before replacing the die.
One of the main advantages of die casting is the complexity of the parts produced. This complexity is unparalleled in other aluminum forming processes, giving you options for different textures with almost no size limitations.
5. Aluminum Forging
Forging involves forming metal by pressing, pounding, or squeezing it to achieve the desired form. The producer heats a slab of aluminum and uses a press or hammer to change its shape.
Aluminum can be forged using an open or closed die. Closed dies include two halves that reflect the product’s final shape, similar to casting dies. Open dies do not constrain the aluminum slab, so as it is pressed or hammered in one direction, it can expand in the others. Manufacturers generally use open-die forging for very large pieces.
Parts produced by forging have great fatigue and impact resistance thanks to the strengthening imparted by the processing technique.