Visual controls are a key lean manufacturing principle. The intent of a visual factory is that the whole workplace is set-up with signs, labels, and colour-coded markings, so that anyone unfamiliar with the process can, know what is going on, understand the process, know what is being done correctly, and what is out of place.

A visual factory is made up of visual displays and visual controls. Visual displays and controls help keep things running as efficiently as they were designed to run. Sharing information through visual tools helps keep production running smoothly and safely. Shop floor teams are often involved in devising and implementing these tools through 5S and other improvement activities.

Visual controls describe workplace safety, production throughput, material flow, quality metrics, or other information. Visual controls supply the feedback to an area, much the same way that SPC can give process feedback to the operator running a particular operation.

A visual display relates information and data to employees in the area. For example, charts showing the monthly revenues of the company or a graphic depicting a certain type of quality issue that group members should be aware of.

The efficient design of the production process that results from lean manufacturing application carries with it a set of assumptions. The process will operate as it was designed as long as the assumptions hold true. A factory with expansive visual controls and displays will allow employees to immediately know when one of the assumptions has not held true.

Audio signals in the factory are also very important because they signal malfunctioning equipment, sound warnings before the start of machine operation, or other useful information.

A visual factory allows the people operating the process to stay on target.