From time to time we want to see whether a working station is set up right and effectively. To help us do so we will use a powerful visual tool called spaghetti diagram.
On this diagram we follow a person/forklift/robot in a specific environment and document its movement.
Examples of workstations with which we can use the spaghetti diagram:
Labs – this is a classic case. We follow one lab technician and record the exact places he goes to (see the diagram below).
Operational area – we will follow a forklift where it goes and record the exact location.
Warehouse – we will follow a specific person who prepares an order.
The output will be as seen in the following diagram:
This diagram shows very vividly from where the lab technician went where. We can easily see where most of the movement is. In this case we see that the lab technician went from the center (labeled computer) to the lower left corner. There is one exception – the “FTIR” which is located on the other side. If we replace the location of the “FTIR” tool with the “fridge”, we will improve the effectiveness of the lab technician.
How to create a spaghetti diagram
- We need to create the following in advance:
- A clean sketch of the area we are observing. We need to add important points on the sketch in advance and can add more later. Every important point gets a number so that we can easily write down the location. Try to add the numbers in a specific pattern to the chart, so that you can easily find any number.
- Create a table such as the one in the following picture. You can optionally add cumulative time (which is the time passed since we started observing), and later calculate how much time every action took. Make a lot of copies of this table so that you do not have to stop the observation in its middle.
- Actual observation – the observer follows the target (human/forklift etc.) wherever he/it goes. If he can, he picks a place where he can observe from a distance. Every destination that the target reaches is recorded (if we use cumulative time, then we record it as well). Please record only the destination that the target reaches. We don’t need the target’s origin, since we wrote it in the line above the current line.
- Creating the spaghetti diagram: if we have a CAD program, we can use it (it can also calculate the distance that the target passes). If not, we can use any program that can draw lines such as PowerPoint or MS Word. By the way, this diagram also works with a pencil and paper 🙂 Steps:
- Draw each line from a point in the previous line (in the table) to the current point. If you pass between the same 2 points more than once, try to move the line a little so that it be next to the line already drawn, but not on top of it.
- If the movement of the target is not in a straight line, use several straight lines to describe the movement.
- If you have a CAD program, you can ask it to calculate the distance of all the straight lines. If you use a pencil, you can add a ruler, and by using the scaling factor calculate the distance along which the target moved.
- The time for each action is the difference between the current cumulative time and the previous one.
Important tip:
Do not record the time and location of the person when he goes for coffee or to the toilet. It would make the diagram more complex and result in privacy issues.
Summary:
The spaghetti diagram is a very visual tool that helps us understand where the different tools/points of interest should be at a glance.