5 Why analysis starts from the visible symptom of a problem and asks “Why did this happen?” It is a method of reaching the controllable root cause by asking the question sequentially. The goal is not to find guilt or fill out a five-answer form, but to identify process changes that will prevent the same mistake from happening again.
Don't Mistake the Symptom as the Root Cause
Measurement out of tolerance
The visible result of the problem; It is not the sole cause.
Tool offset is incorrect
Explains the error; but it does not explain why the incorrect setting was not caught.
Control standard missing
After the tool change, the first part approval and the responsible person are not defined.
Change standard
Require initial part measurement, offset approval and activity control.
How to Perform 5 Why Analysis?
Define the problem measurably
Instead of “Parts are defective”, write the product, operation, measurement, tolerance, time, machine and the quantity affected.
Collect evidence from the field
Combine real data such as measurement records, production orders, tool changes, downtimes, operators, shifts and material lots.
For each answer, ask again "why?" problem
Make the previous answer the beginning of the next question. Do not accept the assumption as fact; Every link in the chain must be verifiable.
Verify the root cause in the field
Test with experiment, observation or past records whether the problem recurs when the identified cause is eliminated.
Close the activity with the result
Identify the person responsible, completion date, and success criteria. Do not accept the problem as solved just because the work order is closed.
How was the root cause of the recurring measurement error found?
Target diameter on the turning line 20.00 ±0.05mm In the first production after the tool tip change, in parts with 20.12mm was measured. The same deviation has been seen in three of the last five tool changes.
This definition; Includes product, operation, target, realized value, and repeat condition. So the team asked “who did it?” instead of “Which condition produces the same result?” can focus on the question.
Example 5 Reason Chain
Why was the part diameter over tolerance?
The tool offset in the finishing operation was not updated to the new size after the insert change.
Evidence to check: First part measurement and machine offset recording
Why wasn't the offset updated?
After the tool change, new measurement and offset approval was not mandatory before starting mass production.
Evidence to check: Tool change form and operator application
Why wasn't the new measurement and approval mandatory?
The work instruction describes how the team will change, but it did not define the first‑piece inspection and the approval responsible.
Evidence to check: Current work instruction and control plan
Why was the work instruction missing?
There was no rule that initiated document revision for tooling changes and recurring nonconformities.
Evidence to check: Revision history and nonconformance records
Why wasn't there a rule that started the revision?
Previous events were closed by extraction and reprocessing; process owner, permanent activity and activity control were not assigned.
Evidence to check: Historical operating records and closing metrics
The Root Cause Is Not “Operator Forgot Offset”
Confirmed root cause; The lack of a controlled standard that links tool change to initial part measurement, offset approval, document revision and activity effectiveness control. If the same deficiency is seen in different shifts, the problem is not caused by the person but by the process design.
Separate Correction from Corrective Action
Stop questionable production
Separate parts after the last conforming check and prevent new non-conformities from reaching the customer.
Check available parts
Manage existing non-conformity by deciding to sort, reprocess or scrap.
Change the process
Revise the instruction; Add measurement, offset registration and first part confirmation after tool change.
Watch the replay
Compare subsequent tool changes and size deviations during the specified follow-up period.
To find which production order and material lot an unsuitable part is related to party and lot tracking guide; to see how quality records are linked to the production process Quality control letter with ERP and examine it.
Common Mistakes in 5 Whys Analysis
Declaring humans as the root cause
The explanation “the operator was careless” leaves invisible the missing standard in the system, the need for training, or incorrect job design.
Guessing at the table
When the causes are not confirmed by measurement, recording and observation in the field, the analysis becomes only team opinion.
Stopping at the first reasonable answer
Worn tooling or incorrect adjustment can cause a significant break; It should also be investigated why these were not noticed in time.
Ask exactly five questions in every situation
In some issues three questions may be enough, while others require multiple cause chains. Reaching a verified cause, not a number, is essential.
Closing the activity with training
Training may be required; However, if the standard, control point and process design do not change, the same error may repeat.
When is the 5 Why Method Not Enough?
If the problem is affected by more than one machine, material, method, and environmental condition, a single linear cause chain can simplify the reality. Fishbone to group possible causes, Pareto to see the order of importance, 8D for events with high customer or security impact; If the measurement system is in doubt, measurement system analysis and technical testing may be required.
How to Keep a Root Cause Record in ERP?
Event link
Product, lot, production order, operation, machine, shift and measurement record.
Reason and evidence
Each reason answer, verification method, and the record on which it is based.
Operations management
Responsible, target date, changes to be made and revised document.
Result validation
Follow-up time, success criterion, previous and next error result.
To see the recording and cause relationship of machine downtimes machine efficiency guide; to review the management of production orders and operations data production management page use it.
Frequently Asked Questions
Are there always five questions asked in a 5 Why analysis?
No. The number five directs the method; The root cause may be reached in three questions, or more questions may be required for multiple cause chains.
What is the difference between root cause and intermediate cause?
The intermediate why explains how the problem occurred. The root cause is a proven and controllable system cause that, when eliminated, reduces the possibility of reoccurrence with the same mechanism.
Who should do the analysis?
The operator experiencing the problem, the process owner, quality and, when necessary, maintenance or engineering should work together. Performing the analysis in only one department may result in loss of field information.
How do you know if the corrective action was successful?
The effectiveness can be verified if the same error does not repeat and no new risk occurs during the measurement and follow-up period determined before the activity.
To identify production records that will be the source of root cause analysis Scope of production tracking module you can review. Software registration is not a substitute for verification of cause in the field.
Track recurring error with event, cause and activity log
Production orders, operation results, quality controls and activity tracking KG Palaimon see how you can manage it in the same process with