Understanding Non-Conformity
Before we talk about root cause analysis, it’s important to understand what a non-conformity is. It refers to a divergence from established standards or procedures. Identifying a non-conformity is the first step, followed by immediate actions to contain the problem, preventing it from negatively impacting the customer or the company’s internal processes.
Root Cause Analysis
After implementing immediate actions, the focus shifts to root cause analysis. At this stage, it’s necessary to understand why a problem occurred, going beyond the initial symptoms to identify the problem’s origin. To facilitate this analysis, there are a series of tools and techniques, such as the five whys, the Ishikawa diagram (or fishbone diagram), Pareto analyses, histograms, and fault trees, among others. Below we provide an example to demonstrate the difference between an initial cause and a root cause analysis.
Problem: Delay in product delivery.
- Why was there a delay in product delivery?
Answer: Because the production of the batch was completed later than planned.
- Why was the production of the batch completed later than planned?
Answer: Because there was a failure in the production machine that caused an unexpected stoppage.
- Why was there a failure in the production machine that caused an unexpected stoppage?
Answer: Because the machine did not undergo preventative maintenance in the recommended period.
- Why did the machine not undergo preventative maintenance in the recommended period?
Answer: Because the maintenance management system did not alert the maintenance team about the schedule due to a software error.
- Why did the maintenance management system not alert the maintenance team about the schedule?
Answer: Because it was not updated with the updated maintenance calendar after the last review of maintenance procedures.
Root Cause: The root cause of the product delivery delay was the failure to update the maintenance management system with the updated maintenance calendar, resulting in the preventative maintenance failure of the machine.
Suggested Corrective Action: Update the maintenance management system with the most recent maintenance calendar and implement a regular verification procedure to ensure the maintenance calendar is always up to date. Additionally, the maintenance team can be trained to perform manual checks of the calendar as a contingency measure.
Tools and Techniques for Root Cause Analysis
- Five Whys: This technique, due to its simplicity, encourages continued questioning until the root of the problem is reached.
- Ishikawa Diagram: Helps in identifying possible causes of non-conformity, categorizing them into aspects such as method, labor, materials, environment, measurement, and machinery.
- Pareto Analysis and Histograms: Assist in prioritizing causes, identifying the most significant ones.
- Fault Tree Analysis: Particularly used in technical areas, such as software, to visualize cause-and-effect relationships.
The Importance of Collaboration
Root cause analysis should not be conducted by a single individual. It is essential to assemble a multidisciplinary team to view the problem from various perspectives, making the discussion much more enriching. Brainstorming sessions, analysis meetings, and the use of whiteboards or flipcharts are recommended practices to foster collaboration and debate.
Conclusion
Root cause analysis is a powerful tool for managing non-conformities, not only effectively resolving problems but also preventing their recurrence. The involvement of a multidisciplinary team and the appropriate selection of analysis tools are crucial to the success of this process.
