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The fishbone diagram is one of many tools used in root cause analysis (RCA). A fishbone diagram is a visual way to look at cause and effect.

The value to organizations of using a fishbone diagram is in identifying possible causes for a problem that might not otherwise be considered by directing the team to look at the categories and think of alternative causes.

Common uses of the fishbone diagram are product design and quality defect prevention to identify potential factors causing an overall effect. Each cause or reason for imperfection is a source of variation. Causes are usually grouped into major categories to identify and classify these sources of variation.

The fishbone diagram has become a popular RCA approach because:

  • It allows organizations to see all causes of a problem simultaneously
  • It presents clear visualization for presenting issues to stakeholders
  • Because it’s a highly visual brainstorming tool, it can initiate further examples of root causes
  • The fishbone diagram can quickly identify if the root cause is found multiple times in the same or different causal tree

Using this fishbone tool, several categories are explored in order to hone in on root causes. For example, under the category people, the RCA team digs deeper into the possible human cause of a problem, such as an operator didn’t complete training, or an employee couldn’t physically see defect or an incorrect tool was used in maintenance.

Another popular category is machines. This category is for all elements related to the machines used in a process.

Depending on the process, this category could capture anything from robots employees in a foundry to printers in a book shop.

Machine causes might be issues such as a preventative maintenance schedule wasn’t followed, or there are broken or missing parts on a machine that caused the problem.

Or maybe a machine didn’t have the correct tool head.

Want to learn more? Tonex offers Fishbone Diagram Training, a 2-day course that explains the concept and definition of the method and then trains students on how to develop a fishbone diagram to analyze and discover the cause(s) of a problem.

For more information, questions, comments, contact us.

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