Process mapping is the graphic display of steps, events and operations that constitute a process• A pictorial illustration which identifies the steps, inputs and outputs, and other related details of a process by providing a step-by-step picture of the process “as-is” A graphics technique for dissecting a process by capturing and integrating the combined knowledge of all persons associated with the process. It is a team effort and is documented by everyone who contributes to the process and/or is a part of the process. Process maps help in characterizing the functional relationships between various inputs and outputs
Process Map – Flow charting Tools
Three commonly used process mapping tools to create detailed process maps are:
Alternate Path Flowchart
Flow charts, process maps, written procedures and work instructions are tools used for process analysis and documentation. Other Lean techniques such as value stream mapping and spaghetti diagrams are also often used.
Value Stream Mapping
A value stream map is created to identify all of the activities involved in product manufacturing from start to finish. This value stream may include suppliers, production operations and the end customer. VSMs typically focus on material and information flow. For product development, value stream mapping includes the design flow from product concept to launch. This is the large view, looking at the entire system for improvement opportunities.
Benefits of a value stream map include
Seeing the complete process flow
Identifying sources and locations of waste
Providing common terminology for process discussions
Helping to make decisions about the flow
Tying multiple Lean concepts and techniques together
Providing a blueprint for Lean ideas
Showing the linkage between the information and material flow
Describing how the process can change
Determining effects on various metrics (Rother, 1999)
The value stream mapping process includes:
Define the product family where we can use a product equipment matrix: A product family is defined as a group of products that pass through similar processing steps and over common equipment. Draw current state map which can be done personally: A current state map of the process is developed to facilitate a process analysis. Create future state map where we can use creative concepts: A future value stream map is an attempt to make the process lean. Plan for implementation which can take months or years. The final step in the value stream mapping process is to develop an implementation plan for establishing the future state.Define Product Family The recommended value stream approach is to map one product family.
A product family is defined as a group of products that pass through similar processing steps and over common equipment. A product and equipment matrix can be used to indicate common features. A work cell could be formed to handle a particular flow. Another method is to create a Pareto chart of the various products. The product with the highest volume should be used for the model line.
The value stream for a product family may cross department boundaries in the company. This creates the potential for difficulties in coordinating an effective value stream project. Such problems call for the creation of a new position for a value stream manager. This manager must have the authority to make things happen and should report to the plant manager.It is recommended that a production person handle the job of value stream manager. This manager would monitor all aspects of the project. Being a hands-on person, the manager should be on the floor on a regular basis.
Current State Map. A current state map of the process is developed to facilitate a process analysis.
Basic tips on drawing a current state map include:
Start with a quick orientation of process routes
Personally follow the material and information flows.
Map the process with a backward flow, from shipping dock to the beginning
Collect the data personally, do not trust the engineering standard times
Map the whole stream
Create a pencil drawing of the value stream
Some of the Typical process data included are:
Cycle time (CT)
Changeover time (COT),
Number of operators,
Working time (minus breaks, in seconds),
Analysis of the current status can provide the amount of lead and value-added time. In many situations teams take on the task of data collection. Both individuals and teams find it beneﬁcial to develop a VSM data box in advance.
Value stream mapping definitions worth noting include:
Valu e-added time (VAT) The amount of time spent transforming the product, which the customer is willing to pay for.
Lead time (L/T)
The time it takes one piece of product to move through all of the processes.
Cycle time (C/T)
The time it takes a piece to complete an individual process.
Future State Map
A future value stream map, is an attempt to make the process lean. This involves creativity and teamwork by the value stream manager and the lean team to identify creative solutions. Everything the team knows about lean manufacturing principles is used to create the process of the future.
Questions to ask when developing a future state map are:
What is the required takt time?
Do manufactured items move directly to shipping?
Are items sent to a finished goods supermarket for customer pull?
Is continuous flow processing applicable?
Where is the pacemaker process? (This process controls the tempo of the value stream.)
Can the process be levelled?
What is the increment of work to be released for kanban use?
What process improvements can be used: changeover, machine uptime, kaizenevents, SMED, etc.?
The final step in the value stream mapping process is to develop an implementation plan for establishing the future state. This includes
A step-by-step plan
Checkpoints to measure progress.
A Gantt chart may be used to illustrate the implementation plan.several Factors determine the speed of the plan.These include available resources and funding.
The plan could take months or years to complete and even then, there may be a need to improve upon it in the future.
Stream Mapping Icons
The following icons may be used with value stream mapping, kanban, and other lean manufacturing areas.