What is 5 Why
5 Why is a root cause analysis technique where you ask the question Why five times (or as many times as needed) to drill down from a symptom to the true root cause. It was developed by Sakichi Toyoda and is widely used in Lean, Six Sigma, and TQM. It is one of the simplest tools in Industrial Engineering but also one of the most powerful.
How 5 Why Works
You start with a problem statement. Then you ask Why did this happen. The answer becomes the new problem, and you ask Why again. You repeat until you reach a cause that, if fixed, prevents the problem from recurring. Usually five iterations are enough, but sometimes fewer or more are needed.
Practical Example 1 — Machine Breakdown
Problem: Sewing machine stopped. Why? The needle broke. Why? The needle hit a thick seam. Why? The operator used the wrong needle size. Why? The needle tray was not labeled. Why? 5S was not implemented in the tool room. Root cause: missing 5S in tool room. Fix: label trays and train operators.
Practical Example 2 — Late Shipment
Problem: Shipment was late by 5 days. Why? Finishing was delayed. Why? Trims did not arrive on time. Why? The supplier was not confirmed early. Why? Purchase order approval was delayed. Why? No standard lead time for approval. Root cause: missing approval standard. Fix: create a purchase approval SLA.
Practical Example 3 — High Defect Rate
Problem: 8 percent rejection in sewing line. Why? Fabric puckering. Why? Tension was wrong. Why? Operator was new. Why? No skill matrix used for line allocation. Why? Skill matrix was not maintained. Root cause: no skill matrix system. Fix: introduce and maintain skill matrix.
Practical Example 4 — Low Line Efficiency
Problem: Line efficiency dropped to 55 percent. Why? Frequent waiting time. Why? Material shortage at workstation. Why? No hourly material feeding. Why? No feeder assigned. Why? Line layout had no feeder role. Root cause: missing feeder role. Fix: assign dedicated feeders per 2 lines.
Why 5 Why Matters in Garments
In garments, most problems are stopped at the symptom level. Fires are fought daily. 5 Why forces the team to find the real cause and fix it permanently. This reduces repeat problems and improves overall efficiency and quality.
Common Mistakes
The biggest mistake is stopping at the first answer that comes up. Another mistake is blaming a person instead of a system. Good 5 Why digs into the process. Another mistake is not verifying the root cause with data. Each answer should be verified on the floor.
How to Run a 5 Why Session
Start with a clear problem statement and evidence. Gather a small team including operators and supervisors. Ask why and record each answer on a whiteboard. Use data to verify each step. Stop when you reach a systemic cause. Assign a countermeasure with an owner and due date. Recheck after one week.
When to Use It
5 Why is used for machine breakdowns, quality defects, delivery delays, safety incidents, efficiency drops, and any recurring problem. It is fast, needs no cost, and works for every level of staff.