I have heard a lot of good things concerning plunge roughing in general and am interested in trying it on blind pockets. Has anyone had experience with such machining? I am most curious about cutter size and chip evacuation. I often rough pockets that are approx 12 by 18 by 3 to 6" deep in QC7 alum.
For chip evacuation, would make a lot of difference if you were on a vertical or horizontal.
I've used plunging to advantage a number of times in place of extra long end mills, but seldom with blind pockets. There aren't too many good ways to mill pockets 6" deep like some of yours, so it would be worth a try. Drill a start hole, then work out the largest stepover value that works for your cutter and leaves a tolerable scallop height for your finish tool to handle.
Don't be surprised if the cycle times are long. It can take a lot of plunges to eat out a large pocket. The benefits are very application-dependent.