Indeed, the company says the system is smart enough to diagnose and fix problems, as well as optimizing its own processes to "evolve by itself."

The 80,000-square-meter (860,000-sq-ft) facility, located in the Changping district on the northeast outskirts of Beijing, follows a pilot smart factory in Yizhuang, which produced about a million units a year of the company's Mix Fold smartphone.

"There are 11 production lines," says Xiaomi Founder and CEO Lei Jun in a short video, embedded below. "100% of the key processes are automated. We developed our entire production and manufacturing software to achieve this."

The new factory will produce Xiaomi's upcoming foldable phones, the MIX Fold 4 and the MIX Flip – to be released later this month – spitting them out at a rate of about one every three seconds, 24/7.

According to GizmoChina, it maintains a totally clean manufacturing environment, with micron-level dust removal – which would explain the operating-theater-style gowns and caps worn by the small number of humans working in the 'war room' of the Smart Factory in a second video, shown below.

Totally automated "lights out" factories, of course, have been around a little while. Japanese robotics company Fanuc Ltd, for example, opened its first fully automated line back in 2001, and according to CNN Money, by 2003 it had a factory near Mt Fuji in which robots were building other robots, around 50 a day, running totally unsupervised for up to a month at a time.