I took a tour of the Celestial Seasonings tea company in Boulder, Colorado many years ago and they had a robot arm for loading pallets very much like this one,

I took a tour of the Celestial Seasonings tea company in Boulder, Colorado many years ago and they had a robot arm for loading pallets very much like this one, except it was fixed to the floor. It had the same suction type mechanism and would grab boxes off a conveyer and stack them on pallets to be shipped out. It was very efficient at it's job and definitely was the highlight of the tour for me, even if it wasn't intended to be. Boxes full of tea are not very heavy, but certainly weigh more than an empty box. The point being is the suction mechanism for picking up boxes has been around for a long time (20+ years?), is tried and tested, and in this very article claims it can handle boxes of up to 50 pounds.