Hey there guys, I have been having problems drilling a clean burr free 1/4" hole through 5052 aluminum,

Here is what I am trying to acomplish:
We are designing an automated riveting system that requires a 1/4" hole to be drilled through upto 3 sheets of aluminum or steel, or a combination of the 2, eg 1st sheet alum, 2nd alum 3rd steel. the thickness of the sheets can range anywhere upto 1/8".
There is minimal support behind the hole.
The problems I am getting are swarf between the sheets and burrs on the backside of the sheets.

I have tried all manner of cutters, from drilling to milling to reaming and most things in between, and have been all over the map with my speeds and feeds.
The best sucess I have had is with a square ended cutter, ie end mill, but still seem to get burrs.

Is there any secret to machining / drilling this soft grade of aluminum, that will not create a major burr?

Cheers, Texiwi.