What is heijunka?

Some articles on heijunka:

Heijunka Box
... A heijunka box is a visual scheduling tool used in heijunka, a concept originally created by Toyota for achieving a smoother production flow ... Whilst heijunka refers to the concept of achieving production smoothing, the heijunka box is the name of a specific tool used in achieving the aims of heijunka ... The heijunka box is generally a wall schedule which is divided into a grid of boxes or a set of 'pigeon-holes'/rectangular receptacles ...
Lean Construction FAQs
... Can the concept of Heijunka be used in construction? Why? Heijunka = production leveling ... Crew balancing is not an example of heijunka ...