Did a goggle search on this topic and found this guys response.
Surface preparation is most important and you do have some options. However, the extent to which you invest in surface prepping depends on the number of parts you intend to coat on a daily basis, size and configuration of the parts, whether you will do the surface prep or if you will contract it out, and several other issues.
I'll be more than happy to spend time with you on the phone giving you various options and pointing out the pro's and con's of each. If you want to pursue this then I will also go into equipment needs, oven etc.
Once you have properly prepped the aluminum an epoxy primer will do just fine, and there is a wide range of products that you can use.
Unfortunately I can only spend a few minutes on each Q&A as I perform this service for on a gratis basis. Since it will take more time to give you the information you require, I invite you to retain my services for approximately 1 hour by phone so that we can cover all of the important issues. My fee is $200 per hour and payment can be made by credit card.