Guide: Yamazumi Chart
The Yamazumi Chart is an effective tool that enables businesses to assess and balance workloads within their processes, increasing productivity and efficiency. The chart aids in locating bottlenecks, distributing resources unevenly, and pinpointing areas for improvement by graphically depicting the workload distribution across various steps or tasks.
This step-by-step manual will provide an in-depth walkthrough of how to use the Yamazumi Chart effectively, from comprehending its benefits and goals to putting workload balancing strategies into action and maintaining the improvements. You will have the information and resources necessary to optimize workloads, streamline procedures, and promote continuous improvement within your company if you follow this guide.
Table of Contents
What is a Yamazumi Chart?
In its simplest form, a Yamazumi chart is a process analysis tool. It is used to visually display and break down elements, cycle times, and the flow of a process into parts. Providing a detailed visualization will allow management and process improvement professionals to see the distribution of work and identify areas that may need improvement.
The Structure of a Yamazumi Chart
Each bar in a Yamazumi chart represents a single step in the process. These bars are then made up of value-added (VA), necessary non-value-added (NNVA), and non-value-added (NVA) activity; these two stacked on top of each other reflect the total cycle time. By stacking the categories, it is easy to identify which process steps take the longest time to complete and compare how much value-adding time each step has. This is an ideal analysis for reducing process bottlenecks.
To understand the concepts of VA, NNVA, and NVA in more detail, take a look at our Waste Analysis Guide.
These activities within a process step directly contribute to adding value to what the customer wants; they are done right the first time and transform material or information. For example, in manufacturing, this would include the actual shaping, assembling, or painting of a product.
Non-value-added activities are actions in the process step that create no value in the eyes of the customer. This could be travelling to the other side of the factory to collect tools, equipment, or material.
Necessary Non-Value-Add Steps:
These activities do not add value in the eyes of the customer but are required for legal or compliance reasons. For example, putting on PPE does not provide value to the customer but may be required to conduct an activity such as welding or using certain types of equipment.
Why use a Yamazumi Chart?
Using a Yamazumi chart to understand processes and breaking down there activities into VA, NNVA and NVA is useful for a range of reasons as detailed below:
Identification of Work Imbalances
Work imbalances can often lead to bottlenecks in a process and can cause delays or excessive inventory. The Yamazumi chart highlights these imbalances by showing the cycle times visually, making it easier to compare the workload across different steps or stations.
Highlighting of Waste
The principle of waste reduction is central to Lean Six Sigma. Waste can come in many forms, including defects, overproduction, waiting, non-utilized talent, transportation, inventory, motion, and extra processing. A Yamazumi chart can help identify these wastes, particularly in the categories of waiting, overproduction, and extra processing.
Support Workload Leveling (Heijunka)
Heijunka is a Lean technique to level the production schedule by volume and product mix. It does not necessarily mean producing at the same rate every day but rather smoothing out the peaks and valleys of production to meet customer demand with minimum waste. The Yamazumi chart can indicate where there are opportunities to redistribute work and create a more balanced process.
How to Create a Yamazumi Chart
Step 1: Collect Data
Before creating a Yamazumi chart, if you have not already, you will need to collect data. You must first understand the flow of the process from start to finish and list out each operation or task in the order it happens. This will form the basis of the sequence of tasks that will appear on the X-axis of the chart.
Next, for each operation listed, measure the cycle time (how long the process takes). This can be collected with direct observation using a stock watch or with digital tools that collect data from machines.
Step 2: Categorize Activities
Following the data collection, the next step is to break down the cycle time of the activities in each step into VA, NNVA, and NVA.
Value-added activities are those that directly contribute to meeting the customer’s requirements. The customer finds these steps valuable and is willing to pay for them because they directly transform the product or service.
- Machining a part to customer specifications
- Assembling components into the final product
- Painting a product in the customer’s chosen color
Necessary Non-Value-Added Activities (NNVA)
Necessary Non-Value-Added activities do not add direct value to the product or service but are currently required to support the value-added steps under the existing process configurations. These are often due to technical limitations, regulatory compliance, or current organizational structures and should be minimized whenever possible.
- Quality inspections to ensure the product meets quality standards
- Moving materials between workstations due to layout constraints
- Setup times for machinery
Non-Value-Added Activities (NVA)
Non-Value-Added activities are operations that take time, resources, or space but do not add any real value to the product or service from the customer’s perspective. These are considered waste and should be eliminated.
- Waiting for materials to arrive or machines to become available
- Excess inventory that ties up capital and space
- Rework due to defects in earlier stages of the process
By categorizing activities into these three groups, you can more accurately assess where your process can be streamlined. This categorization also informs where to focus your continuous improvement efforts: eliminating NVA activities where possible, reducing NNVA activities, and ensuring that VA activities are performed as efficiently as possible.
Step 3: Create the Yamazumi Chart
Most people use Microsoft Excel or a similar spreadsheet tool to create Yamazumi charts. These tools are flexible and allow you to input your data, create stacked bar charts, and adjust the visual presentation.
There are also specialized Lean Six Sigma software tools available that can help you create more sophisticated charts with additional features for analysis.
Creating a Yamazumi chart in Microsoft Excel involves several steps to properly visualize the process time for each step, along with the categorization into VA, NNVA, and NVA activities.
If you would like to follow the process but do not have data, feel free to download our demo data to practice the next steps: Demo data download.
Here’s a step-by-step guide on how to create one:
Step 3.1: Data
Before you open Excel, make sure you have your process data ready. You will need:
- A list of each step in the process sequence.
- The time taken for each step, broken down into VA, NNVA, and NVA.
Step 3.2: Table of data creation
Open a new Excel workbook and set up your data in columns:
- In Column A, list the process steps.
- In Column B, list the value-added time (VA) for each step.
- In Column C, list the necessary non-value-added time (NNVA).
- In Column D, list the non-value-added time (NVA).
Step 3.3: Insert Stacked Bar Chart
- Highlight the data you just entered.
- Go to the ‘Insert’ tab on the Excel ribbon.
- Click on ‘Bar Chart’ and choose ‘Stacked Bar.’
You should now have your Yamazumi Bar chart, and you can use the tools in Excel as needed to change the styling, etc.
Step 4: Analyze the Chart
Now that you have the chart, the next step is to analyze it and identify opportunities to improve the following:
Cycle Time Variations
Look for variations in cycle time across different steps. Steps that are significantly longer might indicate bottlenecks, while shorter steps might indicate areas where operations are highly efficient.
Examine the proportion of non-value-added time in each step. Large segments of NVA time are opportunities for waste reduction.
Assess the distribution of work. In a balanced process, steps should have relatively even cycle times. Discrepancies may suggest that some operations are overburdened while others are underutilized.
Step 5: Optimize the Process
Use the insights from the Yamazumi chart to make informed decisions about process changes. This might involve redistributing tasks, combining steps, or changing the sequence of operations.
The Yamazumi chart is not just a one-time analysis tool but part of an ongoing process of continuous improvement. After making changes, the process should be reevaluated and a new chart created to measure the impact of those changes.
By going through these detailed steps, you will not only create a Yamazumi chart but use it as a dynamic tool to drive process improvement in your organization.
A Yamazumi chart serves as a key visualization tool in Lean Six Sigma to delineate and analyze the flow of a process. By breaking down each process step into Value-Added (VA), Necessary Non-Value-Added (NNVA), and Non-Value-Added (NVA) activities, it allows for a clear identification of work imbalances and waste. It’s instrumental in implementing workload leveling and continuous improvement.
Creating a Yamazumi chart involves collecting data, categorizing activities, and constructing a visual representation, typically via spreadsheet software. This tool guides professionals in pinpointing inefficiencies and optimizing processes, thereby enhancing productivity and reducing bottlenecks.
- Kays, H.E., Prodhan, S., Karia, N., Karim, A.N.M. and Sharif, S.B., 2019. Improvement of operational performance through value stream mapping and Yamazumi chart: A case of Bangladeshi RMG industry. International Journal of Recent Technology and Engineering, 8(4), pp.977-986.
- Talapatra, S., Sharif-Al-Mahmud, Z.Z.Z. and Kabir, I., 2018, July. Overall efficiency improvement of a production line by using Yamazumi chart: A case study. In Proceedings of the International Conference on Industrial Engineering and Operations Management (Vol. 1, No. 1, p. 3166).
A: A Yamazumi Chart is a visual tool used to analyze and balance workloads within a process.
A: The benefits of using a Yamazumi Chart include improved productivity, reduced waste, enhanced process flow, and increased overall efficiency.
A: A Yamazumi Chart helps identify workload imbalances, bottlenecks, and areas for improvement within a process, allowing for optimized resource allocation.
A: To create a Yamazumi Chart, you need to identify the process steps, collect data on work content and cycle time, and plot the information on a graph or spreadsheet.
A: Analyzing the Yamazumi Chart involves identifying patterns, imbalances, and areas of overutilization or underutilization to make informed decisions for workload optimization.
A: Measures to balance workloads may include redistributing tasks, reallocating resources, streamlining processes, or improving training and skill levels.
A: Monitoring the impact involves collecting new data, creating an updated Yamazumi Chart, and comparing it with the initial chart to assess improvements in workload distribution and process efficiency.
A: Sustaining improvements involves communicating the findings and benefits, providing training on chart interpretation, integrating measures into standard operating procedures, and establishing monitoring systems for continuous improvement.
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