Yamazumi Chart = 山積み (yah-mah-ZOO-mee)
A Yamazumi Chart is a stacked bar chart showing the cycle time of each operator or station, broken down into elements, value-adding work, non-value-adding work, and waiting time, with a horizontal line marking takt time. It is one of the most useful visual tools for line balancing and work-content analysis.
Each vertical bar represents one operator or station. Its total height is that station's cycle time. Segments within the bar show the different elements of work. The horizontal takt line shows the pace required by demand. Stations above the line cannot keep up; stations below the line have spare capacity that will produce overproduction if unregulated.
A balanced line has all stations at similar cycle times, close to but below takt. An unbalanced line shows one station towering above the rest, the bottleneck, and others with large gaps below takt. The rebalancing exercise is to move small elements of work from the tall station to the short ones, ideally eliminating waste along the way.
The color coding of segments makes waste visible. If value-adding work is one color and non-value-adding another, the eye immediately sees stations dominated by waste. Those become the priority for elimination, reducing motion, waiting, and extra processing, before rebalancing.
The Yamazumi Chart takes an abstract concept, balanced flow, and makes it visual and specific. Combined with standard work analysis and takt time, it turns line balancing from an opinion into a data-driven redesign that shortens cycle time, reduces manpower and matches pace to demand.
