Aluminium is used across practically every industry on the planet. Unlike most metals that are difficult to manipulate, aluminium can be returned back to its original shape after being dented or bent due to its elasticity and flexibility. Despite this malleability, aluminium is still strong and durable, and can absorb more energy per unit of weight than steel, making it the perfect material for even the most extreme conditions or situations.
When a product is still in the design stage, it makes sense that engineers might simply choose the most cost effective aluminium alloy available – but as you move forward with your project you’ll soon find that is a mistake; you must choose the best material for the project – not simply the cheapest.
The advantages of using aluminium – it’s high strength to weight ratio, natural resistance to corrosion, its malleability, and the fact that it’s cost-effective and sustainable – make this metal the number one choice for most manufacturers. However, it’s important to consider things such as how the material reacts to extruding as well as the surface finishing, as it could jeopardise your final product!
As an engineer you’ll need to work closely with your aluminium extruders during the design stage in order to understand the variations of each alloy so that you can choose the one that is going to offer you just the right combination of weight and strength – as well as being cost-effective – for the project in hand.
The physical advantages and properties of using aluminium as an engineering material of choice are clear, and include:
- High strength-to-weight ratio
- Corrosion resistant
- Heat conducting
- Electrically conducting
- Ductile at low temperatures
- Comes in a wide range of finishes
- Virtually seamless
- Attractive appearance
- Easy to fabricate
- Can form complex, integral shapes
- Cost effective
- Joinable by various methods
Aluminium is roughly ⅓ of the weight of iron, steel, copper or brass – a huge advantage – if not crucial – in the manufacture of some products. This also results in a reduction in shipping and handling costs.
Aluminium behaves elastically under both static and dynamic loading conditions, having the ability to resume shape and size. This flexible strength is why masts and spars of racing yachts are made from aluminium, allowing them to withstand the stress of wind and waves. Because aluminium remains strong at low temperatures, there’s no risk of fracturing. Aluminium alloys are ideal for low temperature applications as they increase in strength as temperatures decrease – without the quality of the metal diminishing. In fact, an aluminium moon buggy was constructed to withstand the deep cold of outer space.
Corrosion resistance is another huge plus of this incredible metal. When exposed to the air, an oxidised film forms on the surface and protects the aluminium from corrosion. This film quickly reforms when scratched, which is why aluminium is a popular material for use in everything from the construction of the largest buildings, to household utensils. Being non-toxic and odourless is another reason you’ll find plenty of aluminium in your kitchen; not just your utensils, but also in drinks cans and food packaging. It’s also widely used in the fishing and dairy industries. This popularity is due in part to aluminium’s smooth surface that is washable and hygienic, as no germs can grow on it.
Other qualities, including being non-sparking (petrol pump nozzles are made from aluminium), its heat-conducting properties – aluminium is approximately three times as thermally conductive as steel – and the fact that it is non-combustible and doesn’t emit anything hazardous when exposed to heat, is why you’ll find aluminium alloys used in industries across the board, from the food industry to the aircraft industry.
And let’s not forget the wide range of finishes that are available. The metallic surface of aluminium can be coloured by chemical or anodising processes, as well as with paint, lacquer, enamel or electroplating, and different textures can be created – from rough, to matte, to smooth as a mirror. Aluminium is an incredibly joinable metal – not just to other aluminium products, but to a variety of materials and by all major methods, including welding, riveting, bolting, brazing, cinching, crimping, clipping, adhesive bonding and slide-on, snap together or interlocking joints.
With the construction industry constantly on the lookout for greener solutions, the use of aluminium over other metals holds another distinct advantage. Aluminium extrusions can be recycled – a process which only requires 5% of the energy needed to produce new aluminium. A huge plus when it comes to reducing carbon emissions.
This series is the most popular type of aluminium alloys for extrusion because they are easy to form, machine and finish. They also withstand corrosion well, making them a firm favourite for outdoor structural applications.
The issue with the 6000 series seems to be that as the tensile strength, corrosion resistance and weldability increase, the appearance of the finish starts to suffer, as does the ability to extrude the alloy. Despite this, one of 6000 the series – 6063 – is one of the most cost-effective alloys available, and therefore one of the most popular – in fact this alloy makes up over 70% of all aluminium extrusions. Used primarily for window and door frames and tubing, this type of aluminium alloy has a high heat tolerance, strength and smooth surface that make it a popular choice.
For products that require a highly reflective, mirror-like finish, 6463 is the go-to option. This alloy, although similar in most characteristics to the 6063, accepts bright-dip anodizing – making it ideal for objects such as reflectors, shower doors, or decorative trims.
Another alloy that’s popular for aluminium extrusion is the 6060, due to its strong corrosion resistance, as well as being easy to form and weld..but if we’re talking about the highest mechanical properties in the 6000 series, alloys 6061 and 6005A are king.
The 6061 alloy joins the 6063 in making up over 70% of all extrusions, and is incredibly common for use in boat components, medical equipment and firearms, thanks to it being highly weldable and having a combination of strength and corrosion resistance.
6005A is a medium strength alloy that shares similar characteristics, but has the added bonus of having better extrudability and surface appearance, and can be formed by extrusion, forging or rolling. It is closely related to 6005 aluminium alloy, but is more heavily alloyed and can be used to produce thin-wall or complicated extrusions, unlike the 6005 alloy, which has a higher strength than alloys 6063 and 606, but is harder to extrude.
Selecting the right aluminium alloy for the job will optimise your product’s design and function, so make sure you take into account more than just cost when deciding which extrusion is right for your project.