When we are asked to quote for a job or have an enquiry from an engineer, architect or designer one key thing that is often misunderstood is the choice or specification of the aluminium alloy. Nothing will quite dishearten an anodiser or surface finisher in general as much as to be total “Aluminium” when asked the question what are you making it from. If you want to have it anodised then 99% of the time it will be an aluminium alloy, this is quite different to an ingot of pure aluminium and is similar to the difference between an ingot of pure iron and 316 stainless steel sheeting. There is a world of aluminium alloys. They are developed for different purposes and have correspondingly different properties. On top of this aluminium alloys are also “aged” to give them different properties, this is called the condition. So you will have an alloy specified as something like “6063 T6”. This gives the alloy 6063 and the condition/temper T6. 6063 is an alloy that is one that is readily anodised in a number of ways with normally good results. Other alloys such as the 2000 series with its higher copper content aren’t so readily anodised due to their higher copper content and have very different mechanical and engineering properties. Cast materials can have high quantities of silicon.
So you are wondering how this all matters to you after all they are all “aluminium”. Well it should from a corrosion resistance, mechanical and especially an aesthetic point of view. Many are the times we have had to talk over why different alloys which look different in their natural state look even more different when they are treated. This is because the anodised or for that matter Alocrom or Iridite coating is composed in part from the alloy itself. Rather than plating which covers the surface, anodising grows out from the surface and what that surface is made of is incorporated into the film. So a 6063 extrusion may anodise with the classical anodised coating as will sheets of 5005 but a block of 2219 will look far less pleasant as would an LM25 castling with it’s silicon content.
It can cost a fortune to remake a facade or even some guttering so before ploughing on with a project call LBParkes and get some advice and a quote for your finishing before you go ahead and make it.