Soft, lightweight, and virtually maintenance-free, that’s aluminum – a popular choice across all industries, from aerospace to automotive and construction. It is soft enough to be cut by manual tools, yet its precision parts like those in aerospace require precise CNC machining.
Since its characteristics largely differ from other metals, the equipment and methods for CNC machining aluminum also vary. This article highlights all the tools and best practices adopted in the industry for cutting different grades of aluminum.
Tools and Equipment for Cutting Aluminum
Aluminum is used in a wide array of applications, and accordingly, its required grade and level of precision vary. So, do the tools.
There are some tasks that can be done with manual tools, while others demand the accuracy of CNC machines. Based on that we classified the aluminum cutting tools into the following three classes:
1.Manual Tools
Manual tools often treat domestic tasks, especially for working with thin aluminum sheets and making cuts in tight spaces. Common manual tools include hand shear and hacksaw.
Hand shears, also known as tin snips, are similar to pliers but equipped with sharp, scissor-like blades. They are easy to maneuver in tight spaces. However, they can only cut thin Aluminum sheets (up to 1/8 inch).
The hacksaw features fine-toothed blades tensioned in a C-frame. It’s primarily used for cutting through the cross-sections of aluminum pipes and bars. It does cut well in small use cases. But it’s a slower and more labor-intensive option for cutting aluminum.
2.Power Tools
Power tools are mostly the electrically powered version of manual tools. But this segment has some additional tools.
Power shears are the electrically powered counterparts of manual hand shears. They have a motor to drive a pair of blades in a shearing action, which cleanly cuts through metal without producing much waste or distortion. Power shears are effective for cutting straight lines in aluminum sheets.
An angle grinder is a versatile power tool that features a rotating abrasive disc. It can be used to cut, grind, and polish various metals including aluminum. When equipped with a cutting disc, the angle grinder performs slicing actions, ideal for cutting through thicker pieces of aluminum or for making cuts in difficult-to-reach areas.
Metal brake is typically associated with bending, but it can be as a cutting tool. For cutting, you can crease and break metal along a straight line. This tool is handy in fabricating aluminum pieces with consistent, clean bends and minimal effort.
3.Advanced Machining Tools
Advanced machining tools are the ones used in industries, especially aerospace and automotive where the geometry is complex and the tolerance range is very narrow.
CNC Routers
CNC routers use computer-controlled drills to cut aluminum. They can cut out detailed and complex designs in aluminum sheets and blocks. Being computer-controlled, they offer precise cuts, but the thickness is limited to 5 – 6 mm, in most cases.
CNC Milling
CNC milling machines, similar to CNC routers, use computer-controlled rotary cutters to shape aluminum into precise components. Their use case is making complex, thick aluminum parts – especially large batches of identical parts during production runs.
Plasma Cutter
Plasma cutters use a high-velocity jet of ionized gas to melt aluminum at the cutting point. They are not as precise as other ones, but quite suitable for cutting thick Aluminum. Some cutters can be aluminum up to 160 mm thick.
Water jet Cutters
Waterjet machines cut by directing a high-pressure, high-speed stream of water mixed with abrasives onto aluminum. Compared to other machines, they don’t induce stress onto the material, preserving its inherent characteristics.
Water Jet machines produce clean, smooth edges and can multiply other materials with high precision. However, cutting is slow and costly.
Turrets
Turret presses punch out shapes from aluminum sheets with high precision, usually within 0.01 millimeters. They are best in industries that require high volumes of uniform parts.
Best Practices for Cutting Aluminum
Aluminum is largely different from other metals machined in the industry; one needs to be carefully when handling such soft materials.
lClamp Carefully
Clamping is necessary so the materials doesn’t shift or slip away during the cutting operation. At the same time, one needs to remember how soft the Aluminum is. Since it can bend or warp under excessive pressure, we need clamps that distribute the force evenly.
lUse the right blade
Toughness is usually a parameter for tool selection. However, in this case, we prefer hardness over toughness since Aluminum is comparatively soft and easier to cut. The harder the tool the sharper the edge you receive.
High-speed Steel is not a choice here. Instead, carbide tools are ideal for Aluminum cutting. Both coated and uncoated work fine in this case.
For CNCs, use flute end mills. Single-flute end mills work fine, however, 2 to 3-flute end mills can also be used. Since Aluminum makes large chips, with one flute, they have an easier escape path. But, if there are more than three flutes, the chips can jam the flutes and fracture the cutting tool.
lOptimize the Feed and Cutting Speed
Aluminum has a small sweet spot between optimal feed and cutting speed. If the speed is too low (and the feed rate is high), the tool rubs against the material and wears out early. At high speed and feed rate, the material removal rate also jumps off exponentially.
But for cutting metals, high speed (above 10,000 rpm) is a viable option, subject that you deal with the excess removal quickly.
lLubricate Thoroughly with Cutting Oil
Aluminum has a comparatively lower melting point (660 C) – it melts due to the machining heat and sticks to the tool bit. This stickiness factor requires constant lubrication to achieve the desired results.
For CNCs, a mister that provides air or coolant blast can be used. When working with small power tools, you can use the common lubricant spray like WD – 40.
Conclusion
Aluminum is different from other metals, it’s lightweight, soft, and melts early. Most of these properties don’t pose a challenge for machining but demand care and attention.
Its thin sheets can be cut with manual hand tools but when precision and accuracy are requirements, only CNCs are required for the job.
