Lights out or lights-out manufacturing is a manufacturing methodology (or philosophy), rather than a specific process.
Factories that run lights out are fully automated and require no human presence on-site. Thus, these factories can be run with the lights off. Many factories are capable of lights-out production, but very few run exclusively lights-out. Typically, workers are necessary to set up tombstones holding parts to be manufactured, and to remove the completed parts. As the technology necessary for lights-out production becomes increasingly available, many factories are beginning to utilize lights-out production between shifts (or as a separate shift) to meet increasing demand or to save money. An automatic factory is a place where raw materials enter and finished products leave with little or no human intervention.
One of the earliest descriptions of the automatic factory in fiction was the 1955 short story "Autofac".
CNC machine tools do not require continuous operator attention, and some models can run unattended. A few machine shops run unattended on nights and weekends.
FANUC, the Japanese robotics company, has been operating a "lights out" factory for robots since 2001. Robots are building other robots at a rate of about 50 per 24-hour shift and can run unsupervised for as long as 30 days at a time. "Not only is it lights-out," says Fanuc vice president Gary Zywiol, "we turn off the air conditioning and heat too."
In the Netherlands, Philips uses lights-out manufacturing to produce electric razors, with 128 robots from Adept Technology. The only humans are nine quality assurance workers at the end of the manufacturing process.