I've ground the surface of AL blocks a couple of times when I had no other means of ensuring precision greater than a BP could offer. It was 6061 and I had several AO wheels to choose from as well as a SC wheel. Nothing I tried worked very well, the wheels loaded up rather quickly and required frequent dressing. Heat and thermal expansion was another issue as well. I ended the experiment using flood coolant, a coarse SC (green) wheel, and only taking about .0005 total for finishing to dimension. Although doable it was not much of a success in my opinion. I'd enjoy reading about methods others have tried with better/worse results as I still have other projects in mind that would allow me the option when needed.
Hey, so an Ao wheel glass bonded and 46 grit size is what we use and we have a minor problem with the grit size. We produce blow molds and as a company rule the parts need to look pretty when they leave the shop, so when we have a coarse dress it looks bad but I like it because the wheel behaves predictably.
So, when we cut it's an infeed of 2 to 4 tenths, for precision grinding, we have to learn the behavior of our particular wheel. For example we get a good finish with a fine dress and with a single point, I can remove stock regularly at a 1:1 ratio with a .0002 infeed no problem, meaning what I program it to remove is what it takes.
Now when I step it up to .0004 infeed, the wheel has a harder time cutting, so when I tell it to remove four tenths at a time with a medium to fine dress on my wheel I know it's bound to disappoint. It's going to take less in the beginning of a run and by the end, it's going to dull and cut more.
So say in the beginning I tell it to remove .004, well when I indicate it, its reading .0037. Then at the end of a run, I will find, it will take .0035. so when I compensate the .0005 the damn thing takes the original .004 plus the .0005. wtf! Well what happens is the wheel gets dull and does something called burnishing. It won't cut small numbers like a tenth. it will apply a lot of wheel pressure to your part and polish it until the pressure causes it to break and redresses the wheel.
So to counter the problem we are getting a finer grit wheel, so we can dress the wheel at a fast pace, make me happy, and keep a smooth finish, making management happy. So that was a bit of rambling but it's a challenge we are facing.