[Trucker47]

I know from using 7075 that it is pretty wear resistant in some circumstances, it is a harder compound and more rigid but it is terrible for being corrosion resistant, where as 6061 is softer but is very corrosion resistant and will not oxidize as fast as 7075.

I can't really help you with the life span but I think it all really depends on many different variables from what i'v learned; how tight your tolerances are with the parts, what type of material you will be running in, the weight of your machine, how much you use it, how hard you run it. Once you put hat all into account you could figure out what material to use.

Personally from what i've researched 7075 will be great once it is anodized for many different machine weights, 6061 is also a good material, doesn't need to be coated but with the thin pieces it could bend easier and create binding which will drastically decrease the life span. Steel would be good but it wears the tooling required to make it much more than aluminum, it rusts the quickest, it may be strong but it is heavy so it will increase the wear on itself.

That's what i've learned so far, out of everything titanium would be the best but I dont have deep pockets hahaha

Hope this helps,
Chris