Motorsport Fabrication Fundamentals: Aluminium
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Aluminium
05.50
| 00:00 | - The most widely used non ferrous metal you'll come across in motorsport fabrication is aluminium. |
| 00:06 | This is for a variety of reasons but one of its most attractive properties is that it's most lighter than steel due to its density being around a third. |
| 00:14 | Aluminium also has excellent corrosion resistance due to its passivation which is a reaction that occurs on the surface of aluminium when exposed to the elements. |
| 00:23 | Known as aluminium oxide, it can be seen as a white powder on the surface of the material and is effectively protecting the aluminium beneath it and preventing any further corrosion. |
| 00:32 | Since the production of aluminium started in the early 1800s, 75% of it is said to still be in use today. |
| 00:40 | This is because this material is infinitely recyclable, without losing any of its purity. |
| 00:45 | Like steel, aluminium benefits from being alloyed with other elements to improve its mechanical properties. |
| 00:51 | Pure aluminium is exceptionally soft and ductile and has a very low yield strength of around 7 to 11 megapascals. |
| 00:59 | But once alloyed with other elements the yield strength can be greatly improved to match some steels with close to 600 mega pascals being achievable. |
| 01:07 | Aluminium also has a low melting point of around 660°C which makes it ideal for casting components like cylinder heads, engine blocks and cases as well as gearbox housings and many other smaller components. |
| 01:21 | You often hear the term forged aluminium in motorsport, particularly when it comes to wheels, pistons and brake components. |
| 01:29 | This is the process of compressing the aluminium under great force and high temperature into a die to shape and profile the part prior to machining which hugely improves its strength and grain structure. |
| 01:40 | These forged parts are superior to cast parts due to the grain structure that's created during the forging process, coupled with the increased material density. |
| 01:50 | Aluminium is available in sheet, bar, plate and square and round tube as well as extrusions and thick billet blocks. |
| 01:58 | Extrusions are specially formed lengths of aluminium forced into a specific shape through a die and billet aluminium is another common term that we'll hear in motorsport, it's simply a term for a solid aluminium block that's then machined into a part. |
| 02:12 | This for example is how the modern crop of billet engine blocks start life. |
| 02:16 | Machining components from large billets can be made easier by using special free machining aluminium or FMA for short. |
| 02:24 | As with other metals, aluminium is available in many different grades to suit the requirements that we need from the part that we're building. |
| 02:31 | These range from super soft, pure aluminium known as grade 1100, to extremely strong alloys like 7075 which is ideal for highly stressed lightweight parts. |
| 02:42 | Now let's look at some of the more widely used grades available, starting with 2011. |
| 02:46 | This offers machinists the ability to machine at extremely high feeds and speeds because the material has been developed to produce fine chips off the cutter. |
| 02:55 | Grade 3003 on the other hand, offers increased strength due to it being alloyed with manganese which gives the aluminium workability and is ideal for deep drawn or spun applications. |
| 03:06 | Grade 5052 is alloyed with magnesium and chromium and is widely used in marine applications due to its higher resistance to corrosion while grade 6061 contains magnesium and silicon and is the most versatile and popular form of aluminium in motorsport due to its excellent corrosion resistance, appearance, weldability, strength and availability. |
| 03:29 | Due to its popularity, 6061 can be further broken down into 3 sub categories. |
| 03:35 | 6061O is annealed through the process of heating and gradually cooling to improve formability for complex shape components. |
| 03:43 | 6061T4 is tempered by solution heat treating for greater tensile strength and 6061T6 is also tempered but has additionally been taken through the process of precipitation hardening to produce the highest strength in the 6061 aluminium family. |
| 04:01 | Lastly, grade 7075 is one of the highest strengths of aluminium available, thanks to it being alloyed with zinc and magnesium, making it ideal for high strength parts. |
| 04:11 | 7075 has an excellent strength to weight ratio and like 6061 is available in a number of different annealed and tempered states for various applications. |
| 04:21 | Although aluminium has excellent resistance to corrosion, it's commonly coated through anosdising when used in motorsport applications. |
| 04:28 | This is something you've most likely seen before, particularly in the popular blue and red AN fittings we see delivering fluids to high performance engines. |
| 04:37 | The vast majority of anodised aluiminium parts aren't actually coloured at all though, anodising is simply the process of speeding up the natural passivation we discussed earlier, by submerging the parts in a controlled acid bath. |
| 04:50 | Aluminium oxide is formed through low voltage being applied to the part which creates an outer layer of naturally occurring protective oxide. |
| 04:58 | This aluminium oxide layer can then be tinted and sealed, giving the aluminium a strong, durable and attractive finish. |
| 05:05 | Like corroded steel, anodised parts don't weld very nicely at all so if we need to repair or modify them we first need to remove this oxidised layer before welding. |
| 05:14 | Speaking of welding, aluminium is one of the most weldable materials out there but before stacking dimes, we need to understand that it's extremely thermally conductive. |
| 05:26 | This means that aluminium can be difficult to work with because it's a great conductor of heat, meaning that it heats up and cools down extremely fast. |
| 05:33 | Both MIG and TIG welding methods are effective here but for motorsport applications an AC TIG welder is the preferred choice. |
| 05:41 | Again, this is something that you can learn more about in detail in our Practical TIG Welding course. |
