Hi, well I've seen all sorts of things that were not intended for industry used in industrial situations, but they do the job and probably cost less than an industrial dedicated one. As for mass production, not all is done on a 24/7 52 weeks a year basis. In my odd job from years ago, the weeks leading up to the annual shutdown, I very often got the job of making up two new roller conveyors for a palletizing machine. OK, it was done in-between other jobs, but didn't involve a lathe of milling machine, but about 160 long tubes and 160 short tubes had to be cut, de-burred and bearings fitted into each end, plus 240 8mm rods had to be cut and de-burred, half of which had to be shorter than the other half, and every rod had to have a 3/32" hole drilled in from the same distance each end. Once all the rollers and rods were made up, the long rollers had to be assembled between two chains and the short rollers had three chains, the third chain being between the short rollers. There was then four shafts and sprocket sets for each set to be made up for each conveyor. Other guys had other things to make/get ready, so things like the power saw, bench drills etc. were in high demand for those relatively short periods. I've had similar in my other jobs, where a small batch of same things had to be made every so often.
Regards Nick.