The origin of the spaghetti diagram – when and where it was first used or who first recognized its resemblance to a plate of pasta – is not well known. What is clear is that this simple tool can be a very powerful representation of waste in various processes. An easily-understood visual presentation often provides the impetus needed for an organization to advance its improvement efforts.
While flow charts (see Vol. II) depict logical progressions through a process, spaghetti diagrams illustrate physical progressions. The movements tracked may be made by people, materials, paperwork, or other entities. As is the case with other maps, spaghetti diagrams can be created in very simple form, with information added as improvement efforts advance.
To create a spaghetti diagram, begin with a black and white layout of the area, be it a single work cell, a department, or an entire facility. For best results, the layout should be drawn to scale; if it is not, the diagram loses value as a visual tool, providing an inaccurate, possibly misleading, representation of the work flow. A current facility layout (see Vol. III) drawing is an excellent starting point.
Trace each movement of a single subject – person, product, document, etc. – on the layout with a colored line. These lines should be drawn freehand, reflecting the imperfect, imprecise motions that they represent, as shown in Exhibit 1. Doing so, also allows greater focus on observing the process than on creating the diagram. While the movements of people and material can be assumed from information contained in a process flow chart, it is best to observe the physical movements directly. Direct observation provides the opportunity to collect additional information that may be useful in process improvement efforts – wait times, overlapping or interfering processes, intersecting paths, shared resources, and so on.
Estimate or measure the distance of travel represented by each line drawn on the diagram. Measurement of travel distances is best (most accurate), but estimates may suffice if conditions inhibit direct measurement.
Record the time required to traverse each path drawn on the diagram and each point at which there is a significant delay. The additional information referenced above should be correlated with the travel times effected to aid in identifying improvement opportunities.
Multiple cycles and operators (“instances” and “subjects”) should be observed to determine the variation that exists in travel times and distances and any deviations in process performance that occur. Multiple observations can be recorded on a single diagram by using a different color for each, as shown in Exhibit 2. A legend should be included to identify the subject represented by each color.
Improving the Pasta
A completed spaghetti diagram represents the motion waste (unnecessary movement of people) and/or transportation waste (unnecessary movement of materials) that exists in the process studied. The two main methods of reducing these wastes are (1) modifying the process, as shown in Exhibit 3, and (2) redesigning the layout, as shown in Exhibit 4. Maximum benefit will be gained by considering both methods.
To modify the process, use accurate flow charts for reference. First, a value-added flow chart (see Vol. II) can be used to identify process steps to target for elimination. Next, a swim lane diagram (see Vol. II) can aid in identifying process steps that can be combined. A flow chart can also be used to analyze the efficiency of the process sequence (i.e. Is the current process sequence the best option?) in terms other than transportation and motion wastes.
The layout can be redesigned for the existing process sequence or to optimize it for a modified process. In either scenario, the objective is to relocate processes to minimize transportation and motion wastes. This usually means that successive processes are located in close proximity. There are two key caveats, however:
Prior to making changes to the process or layout, “pro forma” documents should be created. Process flow diagrams, layouts, and spaghetti diagrams that illustrate the proposed changes facilitates communication to the team of the changes to be made and estimation of the benefits to be gained. Example diagrams are shown in Exhibit 4.
Once the changes have been implemented, final documents should be created. Repeat the spaghetti diagramming process to verify the improvement achieved and identify any unforeseen consequences of the changes.
A Special Case
Service providers that utilize “front-office” and “back-office” operations in a single facility present a special case for process improvement via spaghetti diagramming. The previous discussion recommends noting intersecting paths and overlapping processes, the presumption being that these are detrimental and should be targeted for elimination. In the situation now considered, however, intersecting paths and overlapping processes are necessary and must be strategically planned for optimum performance and efficiency. Customer and servicer activities will be independent at times and coincident at others. A spaghetti diagram can aid the analysis of both front- and back-office operations and the optimization of their interactions.
The simplicity of the spaghetti diagram creates opportunities to embellish it with additional information, some of which has been discussed here. However, the cartographer must be judicious in the selection of information to include on any single map. Becoming overzealous in the attempt to convey the maximum amount of information may preclude the diagram from conveying any coherent message. The optimum number of cycles or subjects to be tracked on a single map will vary with each application, as will the amount of detail in the additional notes. It is up to the cartographer’s discretion, based on the intended audience and the project’s objectives.
For additional guidance, or to share other food-related improvement tools, feel free to leave a comment, use our Contact page, or message me directly.
For a directory of “Commercial Cartography” volumes on “The Third Degree,” see “Vol. I: An Introduction to Business Mapping.”
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[Link] “The LEAN paper airplane.” CadetHeat.com, June 27, 2016.
[Link] “The Spaghetti Diagram.” Eponine-Pauchard.com, September 2010.
[Link] “How & When To Use The Spaghetti Diagram Technique.” BusinessAnalystLearnings.com, May 23, 2016.
[Link] “Spaghetti Diagram.” 4improvement.one.
Jody W. Phelps, MSc, PMP®, MBA
JayWink Solutions, LLC
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