Advice On Aluminium Alloy Grade

[rallysteve 22]

Hi there, a bit of a different topic. But I need to get some Bells and Caliper brackets machined for my Lotus Calipers, designs are all done on CAD (based on BenLily's Designs) and I am at the stage of making enquiries about the machining. I was planning on using 6082 alloy due to the good machinability however after discussing with a friends machining company, they questioned why I was using a 6000 grade alloy instead of a 7000 grade. Now I have looked into 7075 alloy which would be the obvious choice for this sort of application. However I am having trouble reaching a decision and sourcing the material. I have found a source for the 6082 alloy (although around £100 after p&p) but cannot so far find any 7075 is suitable sizes.

Now from what I understood 7075 has a poor corrosion resistance compared with 6082, and is very hard to anodise, thus could be a problem for exposed braking components.

Can anyone advise as to the advantages of either material and suggest a source.

[Rippthrough 98]

7075-T6 is prone to corrosion cracking at elevated temperatures, so you're probably better off with the 6082 for a DIY job, unless you intend to make sure the surfaces are all nicely finished and a decent hard coat applied, even then I'd be going for an overaged version.

Edited April 21, 2011 by Rippthrough

[rallysteve 22]

7075-T6 is prone to corrosion cracking at elevated temperatures, so you're probably better off with the 6082 for a DIY job, unless you intend to make sure the surfaces are all nicely finished and a decent hard coat applied, even then I'd be going for an overaged version.

 

Sounds good advice cheers

 

Steve

[petert 601]

Why not 6061-T6? It is as strong as untreated 7075. One of the reasons cheap bikes are made from 7075 is that they don't have to H/T to reach the same strength as 6061-T6.

Edited April 26, 2011 by petert

[Cameron 16]

Mine were made using 6082 / HE30 and hard anodised.

 

Why are you going to all the trouble of trying to source billets yourself? Unless you have contacts who can get it for you cheap, why don't you let your machining company use their contacts (and discounts) to source it for you? BG Developments made my bells and brackets to my design, at around £80 each for the finished components. They have a lot of experience in making brake components, and recommended the use of HE30.

[rallysteve 22]

Mine were made using 6082 / HE30 and hard anodised.

 

Why are you going to all the trouble of trying to source billets yourself? Unless you have contacts who can get it for you cheap, why don't you let your machining company use their contacts (and discounts) to source it for you? BG Developments made my bells and brackets to my design, at around £80 each for the finished components. They have a lot of experience in making brake components, and recommended the use of HE30.

 

Cheers, I will have a look into 6061-T6.

The only reason im looking to source the billet myself is that the friends company who might be doing the machining for me only work with tool steel so cannot easily source aluminium alloys themselves.

 

Steve

[Rippthrough 98]

6082-T6 is easier to get hold of over here and generally supercedes 6061 in most applications, that's what I use in my floating discs and have no problems even with a direct-drive through the bell rather than bobbins.

[shalmaneser 26]

Cheers, I will have a look into 6061-T6.

The only reason im looking to source the billet myself is that the friends company who might be doing the machining for me only work with tool steel so cannot easily source aluminium alloys themselves.

 

Steve

 

They must have an account with a supplier though, have you asked them? Much easier (and potentially cheaper) to get them to do it.