What is a Spaghetti Diagram
Spaghetti diagram is also called as spaghetti chart, spaghetti model is a visual flow or activity of a process to identify areas for improvements. In other words it is a visual representation that captures the basic flow of people, products and process documents or papers.
Usually if the roles are not well defined in an organization or standard work is not in place people move around in the shop floor. Moreover, sometimes operators don’t even know how much distance they walk each day in the shop floor which leads to low productivity. Spaghetti diagram helps to redesign the layout to reduce the unnecessary moment of people, products and information.
When Would You Use a Spaghetti Diagram?
Spaghetti diagram is one of the widely used lean tool in manufacturing, service and logistic sector which will helps to eliminate or reduce the some of the 7 deadly wastes in the process like transportation and motion.
Spaghetti diagram is useful to assess the wasteful moment in a fixed environment and an environment where people will do repetitive task or similar type of tasks multiple times in a day (Example: Assembly line in shop floor, product moment from one building to other building, people moment in office space etc.,)
Why would You Use a Spaghetti Diagram?
The basic purpose of Spaghetti diagram is to understand the current process, identify the bottlenecks in the process and increase the efficiency by eliminating the wastes in the process.
Spaghetti diagram refers to a mapping tool to identify the distance traveled by the product or people, waiting time in each stage of the process and also captures the walking patterns of the operators especially back and forth moment for material or process operation. It resembles like a spaghetti dish (hence spaghetti diagram name). This tool helps to optimize the distance and restrict the moment (obviously moment is a waste in the process).
Top management agreement or support required to implement the Spaghetti model as sometimes it requires budget for layout changes or for resources. Map total path of the process, identify the opportunity for improvements and list the items that requires top management approval.
Document the actions and display the status of improvements (open and closed actions) in shop floor or work area to monitor the progress. This is a long term action plan and requires multiple iterations before finalize the ideal process flow. It is recommended to conduct one more spaghetti diagram after implementation of process improvements or redesigning the layout, machines etc.,
How to Make a Spaghetti Diagram
- Identify the process that needs to be improved
- Collect required resources (like floor plan, color pencils or markers, stopwatch, team, operators, flip charts, measuring tape etc.,)
- Draw the layout of the process on a paper scaling down to match the distance between each work point include all the equipment, walls, machinery, bins etc.,
- Draw path of the process from starting to ending, follow the moment of each employee continuously from beginning to end of the process
- Each moment between two locations draw with a continuous line and also use different line for each moment
- Use different color pencil or markers to capture different employees moment or material moment
- Measure the time or distance of the each path, number of hand-offs, shifts, operator and other related information.
- Create a new diagram showing the ideal state of the process that reduce the walking time or eliminate the non value added activities.
How to use Spaghetti Diagram to improve the process or layout
- Spaghetti diagram only provides the outlook of current state process, team has to review and optimize the total distance and time for the process
- Collect the ideas from the team especially those who regularly work on the shop floor and rearrange the layout as “U” shape (aka circular shape) or “C’ shape which specifically eliminates the waste
- Keep continuous flow concept and move the parts to closer where they needed
- Identify the longest path or longest wait time in the process and then try to reduce the distance
- While mapping the process, identify the bottlenecks, use mistake proof solutions and try to automate the process wherever it possible
- Lean six sigma experts to help team members to achieve the robust layout, and also team has to simulate the new process to see the new path, waiting in the process and make the appropriate adjustments.
- Explore the option to use the visual management to create fast and reliable process
- Once the new process is in-place, compute the dollars saved with the new process and communicate with the top management.
Do’s and Don’ts of Spaghetti Diagram
- Follow the moment of each individual and keep the line flowing in a singular path
- Engage all the relevant operators for the spaghetti diagram exercise
- Provide basic training to the operators on spaghetti diagram
- Use different color for each operator and material
- While mapping the process identify the intersections, waiting points, bottlenecks etc.,
- Make sure to measure the time and also the distance of each path
- Take consent from top management before performing the spaghetti diagram exercise
- Don’t draw through walls, equipment and also cupboards, draw only actual paths
- You should not ignore any steps in the process
- Don’t consider restrooms and personal activities in the exercise
Practical Example of Using a Spaghetti Diagram in DMAIC
Example: A car battery manufacturer unable to deliver the batteries on-time to the dealer. A Lean six sigma team initiated the DMAIC approach, during Measure phase of DMAIC, team reviewing the product layout using the spaghetti chart, mapped the following steps and indicated each operation with different colors.
- Order received from the dealer via email
- Production team collects the material from store
- Produce Lead strips from the lead ingots
- Apply Lead paste on the lead strips
- Place the pasted lead strips in the curing chamber and perform curing
- Collect battery containers
- Place the cured plates in the battery containers in the assembly unit
- Perform charge and discharge cycles at battery charging unit
- Finally, deliver the fully charged, fault free batteries from the delivery point to dealer
Team measured the total distance and also the time required for the total operation. While mapping the process team identified bottlenecks, waiting and storage locations. Process improvement team discussed with operators and analyzed various options and finally come up with U shaped layout
Now the above diagram is not looking like a spaghetti, and also the total distance and time reduced drastically.