The Real Problem with Non-Conformities

Most companies know how to detect non-conformities. The real challenge is handling them effectively so they do not recur. All too often, organizations settle for correcting the visible symptom without addressing the underlying root cause. The result: the same NC keeps coming back, again and again.

This is where structured root cause analysis methods come in: 8D and Ishikawa.

The 8D Method: Structured Problem-Solving in 8 Disciplines

The 8D (8 Disciplines) method is a problem-solving approach developed by Ford in the 1980s. It is particularly well-suited for complex or recurring non-conformities.

D1: Form the Team

Objective: Bring together the right skills to solve the problem.

Appoint a team leader (responsible for the 8D process)
Identify the required experts (production, quality, maintenance, engineering, etc.)
Include someone with first-hand field knowledge (operator, technician)
Limit the team to 4-7 people

Pitfall to avoid: Forming a team of managers who have never seen the problem on the shop floor.

D2: Describe the Problem

Objective: Understand precisely what happened.

Use the 5W2H method:

What? What is the defect / deviation observed?
Who? Who detected the problem? Who is affected?
Where? Where was the problem observed? On which site, which line, which workstation?
When? When did it happen? How long has it been occurring? How frequently?
How? How does the problem manifest itself?
How much? What is the scale? How many parts / batches / customers are affected?
Why? Why is this a problem? What is the impact?

Golden rule: Describe facts, not interpretations. “The part has a dimension of 10.5 mm instead of 10.0 +/- 0.2 mm” is better than “the part is bad.”

D3: Implement Containment Actions

Objective: Protect the customer immediately, before the root cause has been found.

Typical actions:

Isolate suspect batches
Sort current inventory and work-in-progress
Implement temporary enhanced inspection
Notify affected customers
Recall products if necessary

Important: Containment is not the final solution. It is a temporary measure.

D4: Identify the Root Cause

Objective: Understand why the problem occurred.

This is the most critical step. Two tools are particularly effective:

The 5 Whys: Ask “Why?” successively until you reach the deep-rooted cause:

Why is the part out of tolerance? –> The machine drifted
Why did the machine drift? –> The cutting tool is worn
Why is the tool worn? –> It was not replaced at the right time
Why was it not replaced? –> There is no replacement schedule
Why is there no schedule? –> Preventive maintenance is not in place for this tool

The Ishikawa diagram (see detailed section below)

Pitfall to avoid: Stopping too early. “The operator made a mistake” is not a root cause. Why did they make a mistake? Lack of training? Ambiguous procedure? Fatigue? Inadequate working environment?

D5: Define Permanent Corrective Actions

Objective: Eliminate the root cause in a lasting manner.

For each identified root cause:

Define one or more corrective actions
Assign a responsible person
Set a realistic deadline
Define the criterion for verifying effectiveness

Best practices:

Favor technical solutions (poka-yoke, automation) over organizational solutions (procedures, training)
Verify that the solution does not create new problems
Estimate the cost of the solution vs. the cost of non-quality

D6: Implement and Validate

Objective: Deploy the actions and verify that they work.

Implement the corrective actions according to the plan
Measure results (has the problem disappeared?)
Wait long enough to confirm (at least 1-3 months)
Remove containment actions (D3) once permanent actions are validated

D7: Prevent Recurrence

Objective: Ensure that the same type of problem cannot occur elsewhere.

Apply lessons learned to other similar products / processes / sites
Update standards, procedures, and training materials
Modify control plans if necessary
Share feedback with teams

D8: Congratulate the Team

Objective: Recognize the work accomplished and reinforce a culture of continuous improvement.

Communicate the results to the organization
Thank the contributors
Archive the 8D report (it will serve as a reference for similar problems)

The Ishikawa Diagram in Detail

Principle

The Ishikawa diagram (also known as the cause-and-effect diagram, or fishbone diagram) structures root cause analysis around predefined categories.

The 5Ms (or 6Ms)

The classic categories are:

Material: Raw materials, components, consumables

Non-conforming material?
Defective batch from the supplier?
Inadequate storage conditions?

Machine: Equipment, tooling, software

Machine improperly adjusted?
Worn tool?
Insufficient maintenance?
Software malfunction?

Manpower: Skills, behavior, organization

Trained operator?
Instructions known?
Fatigue, workload issues?
Temporary worker not qualified?

Method: Procedures, standard operating procedures, work instructions

Does the procedure exist?
Is the procedure up to date?
Is the procedure being followed?
Is the procedure ambiguous?

Milieu (Environment): Working environment

Temperature, humidity?
Adequate lighting?
Noise, vibrations?
Cleanliness, organization?

(Measurement): Inspection and measurement means

Calibrated instrument?
Appropriate measurement method?
Sufficient inspection frequency?
Clear acceptance criteria?

How to Facilitate an Ishikawa Session

Display the blank diagram on a wall or screen
Restate the problem (D2 description) to the entire team
Brainstorm by category: for each M, list all possible causes
Prioritize: Identify the most likely causes (voting, data)
Verify: Go to the shop floor to confirm or rule out each hypothesis
Circle the confirmed root causes

Typical duration: 1 to 2 hours with a group of 4-6 people.

When to Use Which Method?

Situation	Recommended Method
Simple NC, obvious cause	5 Whys alone
Complex NC, multiple causes	Ishikawa + 5 Whys
Major customer NC, complaint	Full 8D
Recurring NC despite previous actions	Full 8D with reinforced D7
Minor, one-off NC	Correction + simple corrective action
Multi-factor, cross-department problem	8D with Ishikawa in D4

Common Mistakes in NC Management

Confusing correction with corrective action: Replacing the defective part is a correction. Ensuring the machine no longer produces defective parts is a corrective action.
“Train the operator” as the universal corrective action: If training is always your answer, you are not digging deep enough. The real cause is often in the process, not in the person.
Not verifying effectiveness: A corrective action without effectiveness verification is an act of faith. Always define a measurable criterion and a verification date.
Accumulating open NCs: If you have 200 open NCs, you are not effectively addressing any of them. Prioritize and handle them within deadlines.
Blaming individuals: Root cause analysis is not a courtroom. If people fear being penalized, they will hide problems.

Conclusion

Non-conformity management is the engine of continuous improvement. The 8D and Ishikawa methods are not reserved for large companies or complex problems. They structure thinking, prevent hasty conclusions, and guarantee lasting solutions.

The key: go beyond the symptom to address the root cause. It takes longer, but it is the only way to truly improve.

Betterfly includes a non-conformity management module with built-in 8D and Ishikawa tools, automated corrective action tracking, and performance dashboards. Request a demo to structure your NC management process.