Table of contents
- What is a value stream map?
- Definition of Value Stream Mapping, (VSM).
- Characteristics of a Value Stream with Leanness
- Guidelines #1: Create to your takt times
- Guidelines #2: Create continuous flow where possible
- Guidelines #3: Use supermarkets for production control where continuous flow is not extended upstream
- Guidelines #4: Send the customer schedule to only one production process
- Guidelines #5: Spread the production of different products equally over time using the pacemaker process (level production mix).
- Guidelines #6: Create an “initial draw” by releasing small, consistent amounts of work at pacemaker (level the production volume).
- Profitable applications of lean Value Stream Mapping
- Your Value Stream Map:
- History of value stream mapping
- Benefits and purpose of VSM
- Value Stream Map symbols and meaning
- Related articles
What is a Value Stream Map?
A Value Stream Map in Six Sigma is a lean tool that employs a flowchart documenting each step of the process. Value Stream Map symbols and their meaning are a key tool for lean practitioners to identify waste and reduce cycle times.
VSM is a workplace efficiency tool that combines material processing steps with information flow. VSM is a vital tool in the lean process for any organization that wants to plan, implement and improve its lean journey. VSM allows users to create an implementation plan that maximizes their resources and ensures that time and materials are efficiently used.
Definition of Value Stream Mapping, (VSM).
You can create detailed visualizations of every step in your work process using the Value stream mapping process. It represents the flow of goods between the supplier and the customer in your organization.
Software solutions, including all features, are an example of the value that a software company can deliver to its customers.
The value stream map shows all the steps in your work process that are essential to deliver value. It allows you to visualize each task in your team’s work and gives a single glance status of each assignment’s progress.
It is important to understand that Lean value is all that the customer would pay. While some steps might not be directly beneficial to the customer when mapping a value stream for Lean, they can help you ensure that the end product or service is delivered.
One example of such steps are the quality inspections, which are essential in every production step. Although your customer may not pay you for these inspections, if the final product doesn’t meet their expectations or quality standards, they won’t be able to purchase from you again.
Characteristics of a Value Stream with Leanness
Guidelines #1: Create to your takt times
Takt Time is the time it takes to produce a product or part based on sales. It is therefore a proxy for customer demands.
Guidelines #2: Create continuous flow where possible
Continuous flow is the ability to produce one piece at a given time. Operators move each piece from one step to the next without pause.
Guidelines #3: Use supermarkets for production control where continuous flow is not extended upstream
Sometimes, continuous flow is not possible in certain areas of the value stream. This is where batching is required. Refrain from scheduling these processes via an independent scheduling function. Instead, manage their production by connecting them to downstream customers via a supermarket-based pull system.
Guidelines #4: Send the customer schedule to only one production process
You will usually only need to schedule one point when using supermarket pull systems. This point is known as the pacemaker. This is because the pace of production in all downstream processes can be controlled at this point.
Guidelines #5: Spread the production of different products equally over time using the pacemaker process (level production mix).
It is easier for most assembly departments to schedule large runs of one product type and avoid changingovers. This creates problems for the rest and customers.
- This increases the time it takes to deliver an order
- Stockpiles increase in the process
You will respond faster to customer requests if you adjust the product mix (aka “heijunka”) during the pacemaker process and have less inventory.
Guidelines #6: Create an “initial draw” by releasing small, consistent amounts of work at pacemaker (level the production volume).
Many companies allow large quantities of work to be released to shop floor processes. This causes many problems such as:
- There is no pull or “takt” from the customer, to which the value stream could respond.
- It’s very difficult to respond to customers who demand changes.
- It becomes hard to monitor the state of production.
Establishing a consistent, level production pace creates a predictable production flow. This allows managers to spot problems faster and take corrective actions quicker.
It is a good idea to release a very small amount of production instructions (usually between 5-60 mins worth) to the pacemaker and then take away equal amounts of finished goods. This practice is called a paced withdrawal. The pitch refers to the constant increment of work.
The pack out quantity, or the number of finished goods containers that contain each part), is used to calculate the pitch. If your takt-time takes 30 seconds and you have 20 pieces in your package, your pitch will take ten minutes (30 second x 20 pieces = 600 seconds, or 10 minutes). Also, the pacemaker will give instructions to make one pack and then take away one pitch quantity every ten minutes.
Profitable applications of lean Value Stream Mapping
Toyota Motor Company created the original VSM template and used it via process flowcharts and material. The VSM showed the steps required from order entry through final product delivery. It was helpful in gaining a broad view of the company’s activities. Toyota was able to eliminate unnecessary activities that create waste, while still maintaining its manufacturing process.
The VSM system’s “value stream” section focuses on adding value to products or services by changing their market form or function to suit the customer’s needs. This is the addition of functionality and features to a product/service that benefits the customer, without increasing wasteful time or materials (also known as muda the Japanese term meaning waste).
Your Value Stream Map:
Planning your lean process is easier if you know the scope of the value stream being examined. This map represents a single area within your company. An extended-level map can be created if multiple suppliers, customers, and plants are included.
An extended level map is the view of the value stream at 60,000 feet, the facility-level map at 30,000 feet, and the process-level map at 10,000 feet. To avoid optimizing one area while sub-optimizing another, it is best to begin by drawing a facility-level map.
History of value stream mapping
This type of mapping is more common than most people realize. Charles E. Knoeppel, 1918 book Installing efficiency Methods contains examples of diagrams that show the flow of information and materials. This type of diagramming was later associated with the lauded Toyota Production System and the entire lean manufacturing movement. However, examples of flow diagrams are found in a 1918 book called em>Installing Efficiency Methods/em>, by Charles E. Knoeppel. People most commonly credited with the creation of the Toyota Production System, which began in earnest in 1950s are: Shigeo Shingo (1909-1990), an industrial engineer from Japan, a Toyota consultant, and the namesake for the Shingo Prize in lean excellence; and Toyota executives Taiichi Ohno (from 1992 to 1990); KiichiroToyoda (1894-1952); and Eiji Toyoda (from 2013 to 2014).
As lean production methods were being spread to other industries and the United States in the 1990s, the term “value stream map” was becoming more common. VSM was central to many lean methodologies. Six Sigma also uses value stream mapping. Both Six Sigma and Lean have the same goal, which is to eliminate waste and create an efficient system. They identify waste in a different way. Six Sigma practitioners are more focused on the non-valued-added activities of lean, while Six Sigma followers pay more attention to process variations that lead to waste. Both have been successful in different situations which led to Lean Six Sigma being a combination of both.
James P. Womack is the founder of Lean Enterprise Institute. Daniel T. Jones founded the Lean Enterprise Academy in U.K. John Y. Shook, Chairman of the Lean Enterprise Institute; Karen Martin founder of the Karen Martin Group, lean consulting; and Mike Osterling founder of Osterling Consulting.
Benefits and purpose of VSM
Six Sigma Value Stream Mapping can be used to identify waste in any process. This is its core purpose. Each step of a significant process is described and evaluated from the perspective of the customer to determine if it adds or subtracts value. This focuses on value, which allows the company to be competitive in the market. VSM can be used by lean practitioners to anticipate or face any competitive threat and produce the highest value for customers in the most efficient manner possible. It should be used continuously for continuous improvement and to bring better and more efficient process steps online. VSM allows you not only to see the waste but also the source and cause.
As with all good visualizations, value stream mapping is a powerful tool for communication, collaboration, and even culture shift. Decision makers can see the current process state and identify areas where waste is occurring. They can spot problems such as process delays, excessive downtime and inventory issues. They can also see how to improve with the Future State or Ideal State VSM.
VSM is not only used to eliminate waste but can also be used to add value. This is what the customer really cares about. The goal of creating value is to eliminate waste. Value is what a customer will pay for. A popular VSM book’s title is Learning To See: Value Stream Mapping in order to Add Value and Eliminate Muda by Mike Rother, John Shook. Muda refers to lean terminology for reducing waste.
Value Stream Map symbols and meaning
Value Stream Map symbols and their meaning can be found in many places. However, they all fall under the following four categories: material, process, information, and general. Although the symbols may be complex, some simply suggest their meanings in a layman’s sense. For example, a truck icon to indicate external shipments or eyeglasses to indicate something to see. These are some of the most commonly used symbols.
