9 min read · TaktClock Learning Center · Interactive
A Yamazumi chart is a stacked bar chart that shows operator cycle times relative to the takt time line. It makes line imbalance immediately visible — which operators are above takt (overloaded), which are below (underloaded), and by exactly how much.
The problem it solves: Line imbalance is invisible without data. The Yamazumi makes it a picture — a bar above the takt line means overloaded; a bar below means unused capacity. The fix becomes obvious.
Reading a Yamazumi Chart — Live Example
📊 Live Yamazumi — Assembly Line 1 · Click any bar to inspect
5h4h3h2h1h0
TAKT 2.22h
Torres
1.87h
Kowalski
1.46h
Hawkins ▲
2.44h
Okonkwo ▲
2.28h
Patel
1.33h
Nguyen
1.22h
↑ Click any bar above to inspect that operator's detail
Why Time Studies Become Outdated
Traditional Yamazumi charts are built from time studies — an engineer observing cycle times for a sample of cycles. This snapshot reflects the product mix, operators, and process conditions at that moment. Three months later, most of those conditions have changed.
Approach
Data Source
Frequency
Accuracy
Time Study
Observer with stopwatch
Quarterly or less
Reflects past conditions
TaktClock Live
Actual session elapsed times
Every shift, automatic
Reflects today's floor
❓ Knowledge Check
On a Yamazumi chart, what does it mean when an operator's bar is significantly below the takt line?
✓ Correct! A bar below the takt line represents an operator with capacity to spare. In line balancing, work content can be moved from an over-takt operator (bar above the line) to this under-takt operator, reducing the bottleneck without adding headcount.
See It Live
These Concepts, Running on Your Floor
30 minutes. Real product. We'll show TaktClock implementing these principles live against your production configuration.