Value-Stream Mapping (VSM): How to Create and Get the Best of it for your Processes
Value-stream mapping is a visual process improvement tool for analyzing the current state and designing a future state for the series of steps required to take a product or service from the beginning of the specific process down to the customer by displaying all critical steps in a specific process and quantifying the time and volume taken for each step at each stage. Value stream maps show the flow of both materials and information as they progress through the process, hence can also be referred to as material- and information-flow mapping.
The goal of value-stream mapping is simply to identify and remove or reduce "waste" in value streams resulting into an increase in efficiency of a given value stream. VSM aids in waste removal with the intent of increasing productivity through creation of leaner operations, in turn, making waste and quality problems easily identified.
Application of VSM
Value-stream mapping aims to analyze and design flows across multiple processes, making use of various lean techniques. Value-stream mapping is associated with manufacturing, and can also be used in logistics, supply chain, service related industries, healthcare.
Creating a Value Stream Map
Before creating a value stream map, it is important you accurately understand the scope of the value stream under examination. The map is a single area in your organization which may be extended when multiple plants, customers, or suppliers are included. The following steps should be followed when creating a value stream map:
Team formation
This is a critical step of the process. This step involves creating a cross-functional team of high-level managers and supervisors across the various departments in the organization including sales, customer service, inventory, operations and some important suppliers to add outside perspective. These people will help ensure easy and adequate transmission of information without delay.
The team size should not be too small to avoid missing some important items; neither should they be too large so as to ensure that they can easily be managed. A team of about 10 members is recommended.
The Kaizen Kick-Off
Once the team is formed, the next step will be to hold a three-day kaizen event. Kaizen means "change for the better." The goal for the event should be for team members to develop current and future plans. The event should be facilitated by an individual with VSM experience in kaizen event.
At the kaizen event, the team should be able to complete following:
- Determining the process family.
- Drawing the current state map.
- Determining and drawing the future state map.
- Drafting a plan to arrive at the future state.
The Product Family
A product family is a group of products or services that goes through the same or similar processing steps. Determining the product family requires creating a matrix similar to the example shown below. This step should apply to all cross-functional teams and key areas within your organization to ensure all vital steps are included and no steps are overlooked.
Along the top row, draft all the process steps that the organization performs from a 30,000-foot point of view.
- In the first column, write down the parts such as components, stock keeping units, finished good items, or services that the organization makes or provides.
- Next, place an X in the corresponding box if the part goes through the processing step.
Identifying Similarities
This step involves examining the matrix and looking for sections with similar or identical processing steps. The next thing is to look for sections sharing about 80% of the steps. Next, consider items that sharing many of the same steps and procedures that can be grouped together by the same workers with similar or related steps in a cell.
Once the similarities have been identified, the team should next identify which product family it will concentrate on first. While picking certain areas the team should consider the following:
- Effect on the lead time or inventory
- Level of impact to the customer
- Probability level for success
- New product or service line
- Quantity
Create the Current State Map through Process Walk
Creating a current state map involves collecting data and information by "walking the flow" and interviewing the people who perform the task to ensure that the team have the opportunity to see the entire process, look for waste and, for the people who actually perform the work such as operators, technicians etc. can clarify any misconceptions or preconceived notions on how tasks are performed.
It is not necessary to ensure perfect or overly detailed information at this stage as long as the data provides a relatively clear picture of major issues.
High-value information that can be gotten from employees during the process walk includes the following:
- Cycle time or processing time
- Changeover time
- Reliability of equipment First pass yield and quantities
- Number of operators and shifts
- Hard copy and/or electronic information Inventory levels
- Queue or waiting times
Start by Creating the Basic VSM Template
Once your team has gathered and reviewed the information obtained during the process walk, start drafting map. Figure 2 below shows some common examples and strategies with VSM template development.
The VSM may look slightly different depending on the process and how it was drawn. The map should consist of the following areas:
- Customer information situated at the upper-right corner.
- Supplier information situated at the upper-left corner.
- Information flow situated at the top-half of the paper whiles the bottom half for material (or product) flow.
- The gutters on top and bottom to calculate value added and non-value added time.
- Calculated values for the cycle time vs. the inventory time (in days) for the material and information flow.
One good practice is to have the facilitator draw the map on a large dry-erase board and the team members draw each of their own maps on paper (ideally in pencil). The current state map is usually completed by the second day, but it may need refining.
Create the Future State Map
In order to create the future state map, the following should be considered:
The Takt time
Takt time refers to how frequently a part or component must be produced to meet your customers’ demand. The formula is the time available (per shift) divided by the demand (per shift). This needs to be determined before creating the future state.
Bottlenecks or constraints
Pay attention to the cycle times or processing times during the data collection phase of the kaizen event. If the cycle times are greater than your takt time, then you have a candidate for a bottleneck or constraint. This may result to overproduction in some areas, and/or or extra processing time, such as overtime, to meet demand.
Inventory or supermarkets reduction
A supermarket is simply a controlled inventory system in which the downstream process removes items from the shelf and the process owners (upstream) replenishing the amount removed to the supermarket. Determine whether the raw material, WIP, buffer stock, safety stock, and finished goods and associated paperwork inventories can be reduced or if it makes sense to put in a supermarket replenishment system. The goal is to look for ways to reduce inventory in a systematic way.
Process flow
Determine if you can put materials into a cell or eliminate materials from stopping or waiting, and if flow improvement isn’t possible, check if a "first in, first out" lane can be established between processes.
Opportunities for improvements
Areas for improvement may include:
- The reliability of equipment need to be improved.
- The first pass yield or quality levels acceptable.
- Training in 5S (workplace organization) etc.
Create the VSM Draft Plan
A good plan should include the description of the project, name of the project leader, possible team members, a schedule (or Gantt chart) of events and deliverables, an estimate of costs, and the impact, goals, or benefits. The plan isn’t a static document and may require further refinement, especially in determining resources required, such as time, people, and budgets.
About the Author
Adebayo is a thought leader in continuous process improvement and manufacturing excellence. He is a Certified Six Sigma Master Black Belt (CSSMBB), Digital Manufacturing Professional and ISO Management Systems Lead Auditor (ISO 9001, 45001 & ISO 22000) with strong experience leading various continuous improvement initiative in top manufacturing organizations.
You can reach him here.
