A Yamazumi Chart is a stacked bar chart of work elements by operator or station, used to balance workload against takt time and expose waste.
Definition
A Yamazumi Chart is a Lean workload-balancing chart that stacks work elements for each operator, station, or role. It shows total cycle time, value-added work, necessary non-value-added work, waste, and relationship to takt time.
It makes workload imbalance visible so teams can redesign tasks, staffing, sequence, and standard work.
History
Yamazumi charts are used in Toyota Production System and Lean line-balancing practice. The word is often translated as stacking up, reflecting the stacked work elements on the chart.
When to Use
Use a Yamazumi Chart when balancing assembly cells, service teams, standard work, mixed-model flow, or any process where uneven work distribution creates waiting, overburden, or missed takt.
Step-by-Step
- Define takt time, scope, stations, and operators.
- Break work into observable elements.
- Time each element under normal conditions.
- Classify work as value-added, required, or waste where useful.
- Stack elements by station or operator against takt.
- Identify overload, idle time, sequence issues, and improvement opportunities.
- Rebalance by moving, splitting, combining, or eliminating work.
- Update standard work and verify performance at the gemba.
Examples
- Assembly cell: Station three exceeds takt while station one has idle time.
- Healthcare: Intake tasks are redistributed to reduce patient waiting.
- Office: Review tasks are balanced across roles by complexity and timing.
Common Pitfalls
- Using estimated times instead of observed work.
- Ignoring walking, searching, and setup elements.
- Balancing work without checking ergonomics.
- No standard work update after balancing.
- Assuming average time is enough for variable work.
- Not involving the people performing the work.