I was one of two people in the "research department" of Unimation, the company that invented industrial robots.<p>You bought a robot "capable of handling a 400lb load". That means it can do that at maximum reach, reliably, repeatably, and without overload.<p>It also means that in the location you have it the robot can easily punch a hole in the wall, ceiling, or floor. We had special test cells for our robots. There were holes everywhere because, while slinging a 400lb weight, something like the gripper failed and the weight flew into the wall.<p>The Unimate had an emergency stop button that immediately shut it down. We required floor markings and no-one was ever allowed in the boundary while the robot had power.<p>We prototyped spot welding on car lines (the things you see in all the car videos are a task we pioneered). The robot chased a car frame mounted on an 18-foot 2-foot thick I-beam (roughly 8000lbs) carrying a 70lb weld gun. One day the signal wires from all of the position encoders failed and the robot "went to its all-0 position" up and to the right. It moved there in less than 1 second. During that time it PICKED UP the I-beam, tore up the car frame, and trashed the weld gun. Fortunately things broke (not the robot, it was fine) , before the I-beam moved far.<p>I will tell you from experience that if a robot can reliably, repeatedly handle 400lbs at full reach you don't want to be in the same room unless you are in "unreachable areas" like in areas it cannot access. A robot capable of handling such loads will turn you into yogurt without slowing down.