The American Society of Quality (ASQ) defines a spaghetti diagram as a “visual representation using a continuous flow line tracing the path of an item or activity through a process.” If people or things are walking or moving around, it is unlikely any value added work is being done. Let’s learn some more about a spaghetti diagram.
Overview: What is a spaghetti diagram?
It might not be the best idea to have people walk back and forth at work to get the job done. If the product has to traverse back and forth in the plant, maybe that isn’t good either. Using a spaghetti diagram to visually show this movement will allow you to analyze and reduce the number of steps or distances something or someone has to travel. This transportation is one of the 8 wastes of lean.
The first step in making a spaghetti diagram is to make or obtain a floor plan of the work area you are interested in analyzing. If you are analyzing the movement of a person, meet with him or her and follow them around on their normal work tasks. Note the start time on the diagram. Once the person starts moving, mark the route with a pen on a layout of the workplace. Record times and distances during the complete work cycle. You can use the same process if you are analyzing the movement of a part, materials, or paper documents.
When done, look for ways to reduce the time, steps, and distances of the person or item. This can be done by rearranging the location of work stations, using decentralized activities rather than centralized, and consolidating work activities into work cells.
Keep in mind the actual distance traveled is not the sole criterion, but it must be evaluated along with the time it takes and the number of times the path must be traveled.
Below is an example of a spaghetti diagram.
An industry example of a spaghetti diagram
The shipping department was having problems getting trucks loaded and on the road in a timely manner. The drivers were always complaining they had to walk all over the warehouse to get product and supplies before loading and leaving the site.
Since one of the shipping supervisors had been certified as a Lean Six Sigma Green Belt, he offered to do a spaghetti diagram to see what changes could be made to reduce the walking around and wasted time.
Below, see the results of the Green Belt’s efforts.
Frequently Asked Questions (FAQ) about a spaghetti diagram
1. What is a spaghetti diagram used for?
It is used to observe and record the movement of people and objects in the workplace as they complete their work activities.
2. Can’t I just do a spaghetti diagram from my desk?
Yes, physically you can complete a spaghetti diagram from your desk. But it is not recommended. Observing the actual physical flow rather than relying on what is supposed to be happening will give you more insight into the realities of the movement.
3. What are some things I can do to improve the flow once I complete my spaghetti diagram?
Here are a few changes you can make to improve the flow:
- Move parts closer to where they are needed.
- Rearrange equipment and processes to be closer and determine whether changing the sequence of steps will help.
- Use 5S to clean up the workplace.
- Determine if the work can be done automatically or electronically so there is no need to go out to the workplace for the work to be completed.