Sign-up to receive the latest articles related to the area of business excellence.

Spaghetti Diagram

View All Blogs

Author: Palak Kumar

Spaghetti Diagram

A Spaghetti diagram is a process analysis tool that visually represents a flow line tracing the path of an item or resource through the various processing steps required to transform a product or service. The flow line enables process teams to identify redundancies in the workflow and look for opportunities to expedite process flow. It documents the motion waste of the work and helps quantify the amount of walking the operators must do to get their job done. The motion waste not only adds to the waiting time of the products and thus increases the overall lead time but also increases the stress felt by the operators while completing the task and reduces their efficiency.

Spaghetti diagram is one of the widely used tools in the manufacturing, service, and logistic sectors. It helps eliminate or reduce motion and transportation wastes that exist in any process. In this article, we will go over a high-level overview of Spaghetti diagrams.

Why Use a Spaghetti Diagram?

The purpose of the Spaghetti diagram is to understand the current process, identify the obstructions in the process to optimal flow of work, and increase the efficiency by eliminating the wastes in the process. Spaghetti diagram maps the distance travelled by the product or people, the amount of waiting time in each stage of the process and the walking patterns of the operators for material movements or process operations. When documented it resembles a spaghetti dish and hence the name ‘Spaghetti diagram’.

Benefits of a Spaghetti Diagram

There are several benefits to using the Spaghetti diagram:
  • It helps visually identify inefficiencies in the process layout. Only when the “pain” is clear will the management team take action to eliminate the problem areas.
  • It helps reduce non-value-added time spent in moving from one location to another to get the work done.
  • It makes the product or service flow clear and reduces confusion in the order of processing items.
  • It allows us to analyse and optimize the distances for either faster delivery or achieve the same delivery with less effort.
  • It improves efficiency and reduces the stress and fatigue felt by employees due to unnecessary movements.
  • By reducing non-value-added activities and reducing the time to complete the work, it helps reduce the overall cost of the product/service.

When to use a Spaghetti Diagram?

Spaghetti diagrams are especially useful when the process involves multiple steps and equipment and the flow is rather complex. This can happen when you are setting up a new process where you can map the proposed layout for the process to determine if the layout is optimal. The tool can also be useful when a process was designed a long time ago and becomes sub-optimal due to changes that have occurred over the years. For example, areas where many walkways overlap are causes of congestion and delay. In general, the tool can be useful to assess the non-value-added activities when the team believes that the current process is not optimal and has non-value-added activities due to poor layout. Spaghetti diagram is useful when people perform repetitive tasks (for example on an assembly line) or similar types of tasks multiple times in a day.

Waiting is one of the eight wastes of Lean because it is an "unnecessary motion". A spaghetti diagram identifies the non-value-added activities and helps highlight major intersection points that may not be noticed otherwise.

How to draw a Spaghetti Diagram?

Use the following steps to create the Spaghetti diagram.
  • Identify the process that needs improvement. Clearly define the start and stop points for this process.
  • Plot the physical process flow by approximately scaling down the distance between each work point the equipment, machine, and desks, etc.
  • Draw the path that the product takes from start to end. You could also follow the movement of each employee continuously from beginning to end of the process. Mention the flow of materials and the walking pattern of people along with the waiting times and stoppages at different points.
  • You may want to draw motion lines in different colours to distinguish the motion of each operator.
  • The lines have to be drawn for every movement. More the number of lines, more complex the process. Take care not to miss minute tasks, small trips, and repeated motions.
  • Make sure to create both the current state process and the future state process. Document the travel distance, travel time, and travel costs for the before & after process.
You could use a video camera to capture the motion of the operators and then transcribe this motion onto a Spaghetti diagram.

Steps to Improve the Process

Here are the steps to improve the process layout.
  • Use the 5S process steps to improve the layout of each work area. This will reduce the motion and transportation within each work area.
  • Place the most connected tasks closest to each other as they are the most frequently used paths.
  • If there are multiple products that transverse the same area, make sure you consider all the motion paths to arrive at the optimal layout.
  • Improve documentation with clear routing so that there is no confusion for the operators on the motion path.
  • Determine if the task can be done electronically. For example, walking across the plant just to look something up is a waste of time, you can use a camera for the same purpose.
  • Critically look at common or pooled resources such as printers and scanners and their location with respect to the people working in that area.
  • Consider rearranging the tasks into a C or U shape to minimize the overall travel distance and improve interaction between team members.
Once the simplified workflow is created, simulated the new process, and determine the reduced walking distance, travel times and costs. It may be a good idea to perform a failure modes analysis to see if the new layout introduces any additional risk to the process and current ways of working. Make sure to get approval of the proposed changes from management before deploying the changes.

Example of a Spaghetti Diagram

Here is an example of a woodworking process in a workshop. The figure on the left shows the current process that is messy and time consuming. The workers have to travel long distances in order to get the job done leading to delays and confusion. Spaghetti Example
On the improved process, the layout was optimized as shown on the figure on the right and the overall travel distance and walking time was reduced by 30%.

Spaghetti Diagram Analysis in Sigma Magic Software

The Sigma Magic software can be used to create the Spaghetti diagram. The software can be used to calculate the total distance, time taken, and the cost for each scenario. Spaghetti charts can be used to compare different resources for an existing layout or to compare the before and after scenarios when you have made an improvement to the layout. Spaghetti Example

Things to Watch Out For

Here are a few things to look out for when creating and using a Spaghetti diagram.
  • Not engaging all the relevant operators for the exercise. Make sure that you include all the operators on all the shifts to create the Spaghetti diagram.
  • Not including all the product lines. When creating the Spaghetti diagram make sure that you consider all the variants of the product that are manufactured on that line.
  • Not creating the actual paths. Make sure that your Spaghetti diagram accurately depicts the actual motion of the product and/or operators. Capture all the steps within the process no matter how small.
  • Not performing a risk analysis with the proposed process layout changes which may cause more problems to the operations later on.

Follow us on LinkedIn to get the latest posts & updates.

sigma magic adv