We used to use screwguns that ran about 400 rpm. After years and years, the bean counters were able to show that they ran way too fast for our operation. The cost to us and the customer for replacing hardware and gun tips that were either damaged during installation or during removal for routine or irregular maintenance was more expensive than adding manhours to drive the fasteners by hand. There were days that I would install a couple of thousand screws and wear out a dozen or more tips. I was lucky if I didn't have to change more than a couple of dozen screws on days like that.
Part of the damage was due to the high rpms heating the fasteners as they went in or out and burning the corrosion protection and lubrication off. That induced more galling and subsequently more screws and bolts to have to be drilled out and nutplates replaced, along with the high possibility of damage to the covers or structure during drilling.
The engineering and ergonomics people worked with some suppliers and set guns up with as low as 50 rpm speeds and we still had burning problems. The final solution has ended up being that we are back to speed handles and torque wrenches, with way less hassles than before.
BTW...the difference in time for driving a standard MS/AN short thread screw or bolt, between an 850 rpm and a 200 rpm gun is about 1 to 2 seconds total.
