Sort, Set in Order, Shine

Sort

Remove everything not needed for the current work. The test is usage, not potential usefulness: if it has not been used in a defined period and there is no scheduled need, it goes. Use red tagging — label questionable items, move them to a holding area with a date, and dispose of whatever is unclaimed after the period.

Expect resistance. "We might need it" is the universal objection, and the honest answer is that the cost of searching around unnecessary items every day for a year exceeds the cost of replacing the rare item that turns out to be needed.

Set in order

Give everything that remains a defined place, determined by frequency and point of use — the most used items closest to hand, heavy items at waist height, items used together stored together. Then mark the place: shadow boards for tools, floor marking for equipment and material, labelled locations for consumables.

The test of this step is that a missing item is immediately obvious and anyone can find anything without asking. If you need to ask where something lives, the step is incomplete.

Shine

Clean, and understand that cleaning is inspection. Wiping a machine down is when you find the leak, the loose fitting, the cracked guard, the worn hose. The person who cleans the equipment should be the person who operates it, precisely so that they notice.

Cleaning also asks a question: where is the dirt coming from? Repeatedly cleaning up an oil leak treats a symptom. The purpose of the step is to reach a state where cleaning is quick because there is little to clean, which means the sources have been fixed.