Fishbone Diagram (Ishikawa): 6M & Example
Definition
A fishbone diagram, also called an Ishikawa or cause-and-effect diagram, lays out all the possible causes of a problem in categories along the 'bones' of a fish whose head is the problem, so that a team can brainstorm and then test the likely ones.
| Term | Fishbone diagram (Ishikawa) |
|---|---|
| In Hindi | फिशबोन (इशिकावा) आरेख |
| Area | Production & quality |
| Search phrase | fishbone diagram |
| Try it | 5 Why analysis |
फिशबोन (इशिकावा) आरेख — हिंदी में अर्थ
फिशबोन आरेख, जिसे इशिकावा या कारण-प्रभाव आरेख भी कहते हैं, किसी समस्या के सभी संभावित कारणों को श्रेणियों में मछली की 'हड्डियों' पर दिखाता है, जिसका सिर समस्या है — ताकि टीम विचार कर सके और फिर संभावित कारणों की जाँच कर सके।
The 6M categories
Man (people — skill, training, fatigue), Machine (equipment, tools, settings), Method (procedure, sequence, parameters), Material (raw material, components, consumables), Measurement (gauges, calibration, inspection method) and Mother Nature or Environment (temperature, humidity, dust, lighting). Service businesses often use other headings, but 6M fits most shop-floor problems.
How to draw and use one
1. Write the problem as a specific effect at the head — 'Bore diameter oversize on part 4521, 3% of output in September'. 2. Draw the spine and the six category bones. 3. Brainstorm causes under each with the operators, setters, QC and maintenance people involved. 4. Add sub-causes by asking why. 5. Circle the most likely causes and verify each with data or a trial before acting.
The diagram lists possibilities; it does not prove anything. Pair it with data (Pareto) to pick where to look, and with 5 Whys to dig into a chosen branch.
Example
Effect: paint peeling on MS cabinets. Material — oily sheets from a new supplier. Method — pre-treatment dip time cut to 3 minutes. Machine — oven temperature drifting. Measurement — DFT gauge not calibrated. Man — new shift operator. Environment — high monsoon humidity. Checks proved two causes: oily sheet and short dip time.
Related tools and guides
Frequently asked questions
Why is it called a fishbone diagram?
Because the problem sits at the head and the cause categories branch off a spine like the bones of a fish.
Who developed the fishbone diagram?
Kaoru Ishikawa, a Japanese quality expert — hence 'Ishikawa diagram'.
What are the 6Ms in a fishbone diagram?
Man, Machine, Method, Material, Measurement and Mother Nature (environment).
What is the difference between fishbone and 5 Whys?
Fishbone spreads wide to list all possible causes; 5 Whys goes deep into one cause chain. They are often used together.
Related terms
- 5 Whys (root cause analysis)The 5 Whys is a root cause analysis technique in which a team asks 'why?' repeatedly — typically about five times — starting from a problem, until it reaches a cause that, if fixed, stops the problem coming back.
- 5S5S is a workplace organisation method with five steps: Sort (Seiri), Set in order (Seiton), Shine (Seiso), Standardise (Seiketsu) and Sustain (Shitsuke).
- CAPA (Corrective and Preventive Action)CAPA stands for Corrective and Preventive Action — a structured process to find the root cause of a quality problem, fix it so it does not recur (corrective), and stop similar problems before they occur (preventive).
- DMAIC (Six Sigma)DMAIC — Define, Measure, Analyse, Improve, Control — is the five-step, data-driven problem-solving method used in Six Sigma to improve an existing process by finding and removing the root causes of defects and variation.
- First pass yield (FPY)First pass yield (FPY) is the percentage of units that pass a process step correctly the first time, without rework, repair or scrap. FPY = units passed first time ÷ units entering the step × 100.
- Job workJob work means processing of goods belonging to another registered person (the principal) — such as machining, plating, painting or heat treatment. Under GST, the principal can send goods to a job worker on a challan without paying tax, if they come back in time.