Yamazumi Chart (Definition, Example, and Uses)

What is Yamazumi Chart? What are the benefits of using Yamazumi charts for process improvement? Are you in search of answers to these questions? Then, you have come to the exact place.

This article will furnish you with all the details you need about Yamazumi charts and how to use them for process improvement. We will also provide some examples of how Yamazumi charts can improve productivity and efficiency in your workplace.

What is Yamazumi Chart?

Yamazumi is a Japanese word for a heap or pile, and that is exactly what the chart looks like. It is a stacked bar chart in which each bar is one operator or one workstation, and the blocks stacked inside that bar are the individual work elements that person performs, drawn to scale by cycle time. You will also see it called an operator balance chart.

Two things make it a lean tool rather than just a bar chart. The first is a horizontal line drawn across the whole chart at takt time. Any bar poking above that line is an overloaded operator, and any bar falling well short of it is idle time. The second is that the blocks are colour coded by the kind of work they represent, not merely to look tidy:

• Value added, work the customer would actually pay for, such as fitting the part.
• Incidental, or necessary non value added, work you cannot currently avoid, such as picking up a tool or a required inspection.
• Waste, pure muda such as walking, waiting, searching or rework.

That split is the whole point. A plain bar chart tells you which station is slowest. A Yamazumi tells you what that station’s time is made of, which is what decides whether the fix is to move an element to a neighbour, change the layout, or delete the activity outright. It is also how the chart exposes the three classic problems together: muda (waste), mura (unevenness between operators) and muri (overburden above takt).

Organizing data in the form of a Yamazumi chart allows managers to quickly identify which tasks are taking up too much time, resources, or money and which are efficient.

Takt time: the line everything is measured against

The Lean Enterprise Institute defines takt time as available production time divided by customer demand. It is the rate at which you must finish one unit to keep pace with the customer, and LEI calls it the heartbeat of a lean production system.

If a line runs a 480 minute shift and the customer needs 240 units that day, takt time is 480 / 240 = 2 minutes per unit. That 2 minutes becomes the horizontal line on the chart. Note that takt is set by demand, not by how fast the line happens to run: if demand falls, takt gets longer and the balance has to be redrawn.

Uses

Manufacturing process optimization

The chart can identify which steps within a manufacturing process are taking up too much time or resources, allowing managers to make changes that will reduce costs and increase efficiency.

Workflow improvement

It can also improve the flow of information within an organization, allowing team members to easily see which tasks are taking up too much time or energy.

Project planning

This chart can be used in project management, allowing managers to plan each process step and anticipate potential problems. For example, suppose a company is introducing a new product launch.

In that case, a Yamazumi chart can identify potential bottlenecks in the launch process, allowing managers to devise solutions.

Performance tracking

It can track the performance of different processes or tasks over time, allowing managers to identify areas for improvement easily.

Improve productivity

Yamazumi can improve productivity and efficiency within an organization by identifying areas for improvement or monitoring progress over time. For example, suppose a manufacturing process takes more time due to inefficient processes. In that case, a Yamazumi chart can be used to identify which methods are taking more time and how they can be improved.

Control over time and save cost

This chart allows users to pinpoint time-consuming activities and take action for efficient use of resources. No more wasting precious hours or money on tasks that don’t add value – instead, you can focus your investments on areas with potential payoffs.

Helps in line balancing

This chart is a powerful tool for optimizing the performance of your production line. It can help you identify overburdened or underutilized processes, compare cycle times between workstations and machines, and rebalance the process if the time changes.

This will lead to greater predictability in meeting customer demand consistently on schedule – ensuring increased efficiency throughout!

Helps in setting up continuous improvement (Kaizen mindset)

Businesses can visually display their process tasks to empower employees to strive for continuous improvement. This chart effectively motivates workers and keeps them focused on the end goal – ensuring that all stages add value.

Yamazumi Chart Creation Steps

1. Break the job into work elements. Not “assembly”, but the smallest chunks you could physically hand to another operator: fetch bracket, align bracket, drive four bolts, scan barcode.
2. Time each element on the floor, repeatedly. Use observed times, not routing standards. Take several cycles and use a repeatable time rather than the best one you saw.
3. Classify every element as value added, incidental or waste. Do this before you start moving work, or you will simply move waste from one operator to another.
4. Calculate takt time as available production time divided by customer demand, and draw it as a horizontal line.
5. Stack the elements per operator and colour them by classification, so each bar shows both the total and its composition.
6. Rebalance. Remove waste first, then move elements between operators so that no bar exceeds takt. Consolidating the leftover time into one operator is deliberate, and it is covered below.

Yamazumi Chart Example

A worked example makes this concrete. Take a five station assembly line running a 480 minute shift against demand of 240 units, so takt time is 2 minutes, or 120 seconds.

Operator	Value added (s)	Incidental (s)	Waste (s)	Total (s)	vs takt 120s
1	72	18	22	112	8s spare
2	95	25	18	138	18s over
3	60	12	9	81	39s spare
4	88	20	10	118	2s spare
5	44	10	6	60	60s spare

Read the chart, not just the totals. Operator 2 is the constraint at 138 seconds, so the line cannot beat 138 seconds per unit no matter what the other four do. Everything downstream of station 2 waits, and inventory piles up in front of it.

The instinct is to shift 18 seconds of work from operator 2 to operator 3. Look at the composition first. Operator 2 carries 18 seconds of waste, and if that is walking to a shared rack or hunting for a tool, moving the rack removes the overload without touching anyone’s job content. Balancing should always spend the waste column before it spends a neighbour’s spare time.

Now look at the total: 509 seconds of work across five operators. At a 120 second takt that is 509 / 120 = 4.24 operators. The line is running five. A balanced chart would load four operators close to takt and free the fifth, which is why a good Yamazumi often ends with one deliberately short bar rather than five even ones. Spreading the work evenly so that every operator is 15 percent idle hides the opportunity instead of showing it.

That is the difference between a balanced line and an evenly loaded one, and it is the judgement the chart exists to support.

How to Make a Yamazumi Chart Template in Excel?

This chart can be easily created using Microsoft Excel, making it an ideal tool for quickly creating visual representations of data. 

1. Lay the data out with one column per operator and one row per work element, so the sheet mirrors the chart. Put the seconds for each element in the cell, and the element’s labor classification alongside.
2. Select the range, then Insert, Charts, Column, and choose Stacked Column. This is the step most guides get wrong: a plain clustered Column chart puts the elements side by side and is not a Yamazumi. The bars must stack so each operator’s total height is their cycle time.
3. Colour the segments by classification rather than by element, so value added, incidental and waste each read as one colour across the whole chart.
4. Add the takt time line. Add a second series holding the takt value repeated once per operator, then right click that series, choose Change Series Chart Type, and set it to Line. Without this line the chart cannot tell you who is overloaded.
5. Set the vertical axis to seconds and label it, then save the workbook as your template. Re-timing the elements and refreshing is far quicker than rebuilding it each time.

Disadvantages

Although Yamazumi charts have many advantages, there are also some potential drawbacks. 

• It is only as good as the timings behind it. Times taken from routings rather than the floor, or a single lucky cycle, produce a chart that balances a line which does not exist.
• It becomes unreadable if you stack too many work elements into one bar. Group them once a bar turns into a barcode.
• It is a snapshot. Product mix, demand and therefore takt all move, and a chart that is not re-timed quietly goes stale.
• It shows manual work time and says nothing about machine cycle time, changeovers or downtime, so a machine-paced constraint will not appear on it at all.
• It assumes elements can actually be moved between operators. Precedence, tooling, reach and certification often stop the rebalance the chart appears to recommend.

Conclusion

In conclusion, Yamazumi charts are a simple and effective tool for improving productivity and efficiency within any organization or project.

By using this, managers can quickly identify areas for improvement and plan for potential problems. Whether looking to improve processes or save time, resources, and money, Yamazumi charts offer an easy way.