Fishbone Diagram
A fishbone diagram is a cause-and-effect analysis tool used to organize possible causes of a problem into logical categories before evidence is used to confirm the real causes.
What this term means in maintenance
A fishbone diagram is a cause-and-effect analysis tool used to organize possible causes of a problem into logical categories before evidence is used to confirm the real causes.
How a fishbone diagram works
The problem or effect is written at the head of the diagram. Major cause categories form the main branches, and possible contributing causes are added beneath them.
Common categories include:
- Machine
- Method
- Material
- Manpower or people
- Measurement
- Environment
The categories may be changed to suit the equipment or process.
Practical example
For repeated pump seal failures, the team may explore:
- Machine: shaft runout, misalignment, vibration
- Method: incorrect installation, unsuitable cleaning
- Material: wrong seal material, contaminated lubricant
- People: insufficient training
- Measurement: no runout or alignment verification
- Environment: temperature, dust, washdown exposure
Purpose of brainstorming
The diagram helps the team avoid focusing immediately on one preferred explanation. It creates a broader list of possible causes that can then be tested using evidence.
Relationship to root cause analysis
A fishbone diagram generates and organizes hypotheses. It does not prove a cause by itself. Measurements, inspection, history, and physical evidence are still required.
Common mistake
Treating every brainstormed item as a confirmed cause leads to weak corrective actions. The team should clearly separate possible causes from verified causes.
Related concepts
Related maintenance terms
Keep exploring connected CMMS, reliability, and maintenance planning terms.
Root Cause Analysis
Root cause analysis is a structured investigation used to identify the underlying conditions that allowed a failure or problem to occur and determine actions that reduce recurrence.
5 Whys Analysis
The 5 Whys is a simple root cause analysis technique that repeatedly asks why a problem occurred until the team reaches an evidence-supported and actionable underlying cause.
Failure Mode and Effects Analysis
Failure Mode and Effects Analysis, or FMEA, is a structured method for identifying how an asset or process may fail, the effects of each failure, existing controls, and actions needed to reduce risk.
Glossary FAQs
- What are the common fishbone categories?
Common categories are machine, method, material, people, measurement, and environment, but they can be adapted to the problem.
- Does a fishbone diagram identify the root cause?
Not by itself. It organizes possible causes that must then be tested using evidence.
- When is a fishbone diagram useful?
It is useful when a team needs to explore several possible cause categories and avoid focusing too early on one explanation.