Theres a lot of optimizations you need to be aware of when cutting aluminum (at least, on a production scale, which it looks like your gonna ramp up to).
Your feed rate is a bit too low you want to maintain ~.005-.01 inch per tooth (chipload). If not, you will "rub" the tool and you'll get chip welding (as you've experienced). Once you've got your feed rate you need to do a little bit of testing to figure out a usable depth of cut that your spindle (and frame/steppers) can handle. IIRC, I used to run 18-20k RPM, 60 in/min @ .015" doc, slotting with a 3flute ZrN coated 1/8" EM.
Your 4flute EM can easily cause the chip welding. Most 'aluminum-optimized' EMs are 3flute, and even then I'm having trouble evacuating the chips fast enough. There just isn't enough space for the chips to clear effectively. I've never welded chips with a single flute and with a 2flute I've only welded chips when I don't use air or any lubricant.