When you're managing production in aerospace engineering, the automotive industry or along supply chains, especially if you're realising lightweight designs, aluminium takes a load off your hands in more ways than one. As a metal, it has a low specific weight but is still very strong. And aluminium possesses additional beneficial properties – it's resistant to corrosion, has good electrical conductivity and is easy to machine. Compared with other metals, aluminium is also ahead when it comes to recycling. An aspect you shouldn’t take lightly if you're looking out for economic viability and sustainability. Read on to find out how you can use aluminium to produce visually pleasing components and why aluminium is a coveted material for lightweight design. You’ll also learn some nifty tricks for machining aluminium and for getting the best results when grinding and cutting it.
Aluminium is popular not only for its specific properties, but also because its silver sheen makes the metal look great. Besides being used for interior decoration, aluminium – in pure form or as part of new alloys – also really shines in the architecture and building sectors, where it’s a popular choice for anything you want to be both functional and beautiful, like facade cladding for example.
In pure form or alloyed: aluminium is also an excellent material for mechanical and plant engineering. It's used anywhere that low weight means a gain in dynamics and efficiency. This might be large-scale body panels for all kinds of vehicles, but could also be fittings in a car’s interior, engine blocks or cylinder heads. In short: almost every sector benefits from aluminium's low weight and use it to achieve the best-possible efficiency, for example by manufacturing machinery components from it. One of the best examples is one production managers like yourself probably see all over in your day-to-day work – the excellent and reliable combination of light weight and strength in robot components or linear actuators. Properties that are also in high demand in shipyards and train construction.
If you’re a master craftsman in the construction industry, you’ll love aluminium's beneficial properties just as much. Property developers and architects alike use it for a multitude of things, from window and door frames to facade cladding to roof and wall systems all the way down to sturdy fittings, handles and grilles. Aluminium is also great at working ‘behind the scenes’, e.g. as mouldable thin heat insulation. Speaking of thin: aluminium is almost completely indispensable as a packaging material, protecting as it does wrapped food from exposure to surrounding conditions. Because of its electrical and thermal conductivity, aluminium is also among the top choices when it comes to manufacturing electrical cabling or coil windings for transformers and the like.
When it comes to machining, aluminium is your friend. As a material, it’s on the softer side, so you need a good deal less force and can also apply higher cutting speeds.
The simplest way to cut aluminium is to saw it. But be sure to choose the right saw blade to do so – for cutting the soft material aluminium, metal saw blades with zero set are best suited. When using powered saw blades, it’s best to favour slower speeds. Feed rates should also be lower and match the material. This applies in equal measure to synthetic resin bonded cutting discs, abrasive flap discs and grinding discs.
Because aluminium is so soft, you’ll need to watch out for a certain degree of melting smear when grinding it. How much pressure to apply when grinding depends mainly on its quality and the alloy in question. Even when using hard and brittle duraluminium, for example, you’ll need to make sure that you’re applying the right grinding pressure. Whatever the pressure, any grinding process will always compress an aluminium component’s surface. You can use this to your advantage in finish machining, for example for polishing. Its good thermal conductivity means that heat generated by grinding dissipates readily. Some helpful tips:
If it’s your first time working with aluminium, it may make sense to spot-test pressure and speed before you get to work on larger surfaces.
Caution: Never use tools that have been or will be used with any material other than aluminium. The tool could otherwise work other metal particles into the aluminium. This kind of machining defect leads to corrosion or damaged material and in the worst case means scrapping the workpiece.
Perhaps you already know from your daily work – welding aluminium is no easy task thanks to its 660°C melting point. What's more, you need to feed a much higher temperature because aluminium has such excellent thermal conductivity. Once you’ve managed to get a cleanly fused weld seam that's free of gas bubbles, seam finishing is next on the list.
Once you’ve removed all the excess material from your aluminium component and given it its final shape, it's time to choose your options for final polishing. You might choose a polishing machine or an angle grinder with adjustable speed. Even a drill with a classic polishing bit can be the right tool for smaller jobs.
What’s certainly true is that the right tool always depends on how many components regularly need polishing on your production floor.
Manual or machine-driven, correct use of special polishing discs and polishing pastes will lend even the dullest aluminium a sheen you can be proud of.
Untreated and blank freshly pressed or rolled aluminium sheet will tarnish with an oxide layer really fast. This layer will grow depending on how long the (component) surface remains exposed and in contact with the ambient air. In some cases, this process is actually desirable. Starting off bright, then turning grey, this layer steadily turns into an optimal material protector. But as a master craftsman, you might want to buff up your components’ looks again – luckily aluminium is easy to clean up. Remove the soiling in two steps – pre-wash followed by thorough cleaning using brushes, sponges and, where necessary, abrasive paste and cleaning agents. Afterwards, wash off all the residue and apply a preservative, water-repellent cleaner.
Special case: cleaning before welding If you're planning on welding components or surfaces, it’s really important to remove every trace of grease or oil. Note that you’ll always be removing grease and oil first, before tackling the oxide layer. Oil and grease are easily taken care of using organic solvents, for example acetone or a mild cleaning lye.
Scrubbing off oxidation using a stainless steel brush will preserve the material – but make sure the brush is never used on materials other than aluminium! Alternatively, there are a number of sprays you can use to prep surfaces for welding jobs.
We recommend stearate non-stick coating to prevent the grinding media from becoming clogged.
The first thing to look out for is products featuring the Alu pictogram. These products have been specially designed and optimised for working with aluminium.
Use very high rpm settings as this will avoid or at least minimise surface clogging.
You’ll only need that towards the end of stearate grinding medias’ tool life, if at all. Using it earlier will actually reduce performance. Also, keep in mind that grinding grease may contaminate your workpiece, leading to problems with subsequent processing.
If you're using an angle grinder, we recommend the VSM XF 733 fibre disc in various grit sizes. You benefit from shorter grinding times, lower heat and thus less clogging, and from producing far less dust.
If you’re using a linishing belt, you’ll find stearated semi-open or open distribution will serve you best when working with aluminium. Examples include 3M944F, VSMXK870F or KK841F.
Use discs with precision grit and open mesh structure. The open distribution reduces clogging significantly, which means longer tool life and good removal rate.
The best thing to use here are non-wovens, either as pads or pressed into compacted non-woven discs and available in various grades of fineness. Roughing depth decreases with increasing fineness. You’ll also smooth the surface and remove smaller scratches.