Problem-Solving Technique: Step 3- Root Cause Analysis: Ishikawa Diagram (Fish-Bone Diagram)

“When solving problems, dig at the roots instead of just hacking at the leaves." – Anthony J. D’Angelo

Introduction

Companies that are committed to quality are always looking for ways to improve. When a process is running smoothly, they explore new ways of enhancing workflow. When something breaks down, they take extra steps to ensure a clear?understanding of the problem’s root cause. Instead of simply fixing the surface issue.

Objective

In the problem-solving technique (like the 8D Model), one of the most pertinent steps is to find a real reason why that failure/problem/defect has occurred. Once it is adequately identified, the organization can take appropriate corrective action. There a different types of root cause analysis techniques which include 3Leg/5Why Analysis, Ishikawa Diagram, PDCA and many more.?

As part of a sustainable quality program, you need to identify the issues related to the quality issues, otherwise, you will keep spinning your wheels and using your resources to constantly correct the issue, but never addressing the cause(s). There are many root cause analysis techniques you can use. Here we will focus on the fishbone diagram, in the context of quality.

Synonym(s):?

?Ishikawa diagram, herringbone diagram, cause-and-effect diagram, or Fishikawa

Definitions (ISO 9000: 2015):

Complaint (clause 3.9.3): Expression of dissatisfaction made to an organization related to its product or service or the complaints handling process itself where a response or resolution is explicitly or implicitly expected.

Complainant (clause 3.1; ISO 10001: 2018): Person, organization or their representative making a complaint.

Corrective Action (Cl 3.12.2): Action to eliminate the cause of nonconformity and to prevent reoccurrence.

Correction (Cl 3.12.3): Action to eliminate a detected nonconformity

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Detailed Information:

The following are the 7 key steps for problem-solving.

1.?????? Define the Problem

2.????? Correction, Containment, Interim Action

3.????? Root Cause Analysis: 3 Layered 5 Why Analysis (3L5Y), Ishikawa Diagram, PDCA

4.????? Implementation of Corrective Action

5.????? Effectiveness Evaluation

6.????? Horizontal Deployment

7.????? Documentation, Lesson Learned and Promotion of Awareness

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The Ishikawa diagram focuses on the multiple root causes for one quality issue.?Each root cause or reason for bad quality is added to the diagram and grouped into categories to identify and classify these causes. The result looks like a fishbone, hence its name. The contour of the fish is optional.

Brief History:

The Ishikawa diagram was developed by Kaoru Ishikawa during the 1960s as a way of measuring quality control processes in the shipbuilding industry. The main issue is recorded on the right side of the page because the traditional Japanese script reads down a vertical column from right to left across the page.

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More about Fishbone:

• Problem-Solving Tool
• A systematic way to identify the causal factors
• Big / High-Level Problems
• Behavioural as well as Technical
• Also used for smaller problems.

When to use the fishbone diagram:

• While conducting a workshop to identify the possible causes of the issue
• If the team’s thinking is not going towards a root cause

?Step for using Fish Bone Diagram:

• Define the effect. Be specific about the problem
• Choose the categories: Most common set à Man (People); Machine (Equipment); Process (Method); Material; Environment (Mother Nature); Management, Measurement, Money
• Brainstorming possible causes

§? Ask Why?

§? And Why Else?...

§? Using diagrams helps broaden and focus thinking

• Don’t forget that there are multiple causes.

§? Primary Cause à leads directly to the effect

§? Secondary Cause à leads to primary but does not directly cause and effect

Tip: It is not always mandatory to use 4, 5 or 8 factors for the fishbone diagram. Instead, all relevant factors for the problem should be addressed. And you can of course use other terms that do not begin with M.

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Industry Challenges:

• How often are organisations aware of the root cause even before conducting the Fish-Bone diagram analysis?
• How many organizations believe in the Ishikawa diagram and utilize a cross-functional team for the analysis?
• How often the corrective action is based on the root cause and not on the symptoms?

References:

IATF 16949: 2016

ISO 9001: 2015

ISO 9000: 2015

OEM Supplier Manual

CQI 20: Aug 2018, 2nd Edition (Effective Problem-Solving Guide)

Industry Experts