{"id":"heijunka-box","model_id":"Heijunka Box","name":"Heijunka Box","summary":"A heijunka box, also called a leveling box, is a tool that holds kanban cards in rows for product types and columns for identical time intervals. At each interval, a material handler withdraws kanban from the box and distributes them to production processes. It levels production volume and mix by using short time increments instead of releasing a shift, day, or week of demand to the floor.","study_notes":["Each horizontal row is for one product type (one part number); each vertical column is an identical time interval for paced withdrawal of kanban.","In the illustrated example, the shift starts at 7:00 a.m. and kanban are withdrawn every 20 minutes.","Each kanban in a slot represents one pitch of production for one product type.","Pitch is takt time multiplied by pack-out quantity.","Product A has a 20-minute pitch with one kanban per interval; Product B has a 10-minute pitch with two kanban per slot; Product C has a 40-minute pitch with kanban in every other slot.","Products D and E share a production process with a 20-minute pitch and a demand ratio of 2:1 for D versus E; D has kanban in the first two intervals and E in the third, repeating in the same sequence.","The box levels demand by short time increments and by mix, for example producing Product D and Product E in a steady ratio with small batch sizes."],"safety_notes":[],"sources":[{"url":"https://www.lean.org/lexicon-terms/heijunka-box/","title":"Heijunka Box - Lean Enterprise Institute","accessed":"2026-10-25"}],"verification":{"status":"source_checked","checked_at":"2026-10-25","values":1,"method":"llm_source_check"},"updated_at":"2026-10-25","type":"operational","spec":{"kind":"tool","related":[]},"url":"https://machineschema.com/operational/heijunka-box","license":"https://creativecommons.org/licenses/by/4.0/"}