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Why Use 8D
Companies apply 8D to solve problems. The 8D root cause analysis identifies the underlying cause of the problem rather than treat symptoms. To analogize, it attempts to seek out and eliminate the fuel of the fire rather than try to douse the flames. Instead of trying to repair a product broken in the assembly line, it strives to identify the reasons why the product broke and keeps breaking, and effects measures to remove the reason of the breakage. Such an approach brings about permanent resolution, preventing recurrence of errors, defects, and mistakes.
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8D is an eight step structured approach to define the problem, identify the root cause of the problem, and effect resolution. The eight disciplines are:
- Team: Select people with knowledge, time, authority, and skill to solve the problem and implement corrective actions as team members. The underlying premise is that the team as a whole is smarter and better than the sum of individuals within the team.
- Definition: Define the problem in measurable terms and based on the internal or external customer’s perspective. For instance, a statement “The machine breaks down on overheating" remains vague. The statement “Malfunctioning of the electrical breaker leads to periodic short, causing the machine to churn up incomplete products at periodic intervals, causing a scrap rate of 15 percent. Quality control fails to identify ten percent of all faulty products leading to supply of defective products to customers and thereby higher engagement of customer support helpdesk and product returns" provides a good description of the problem.
- Temporary Fix: Implement and verify short-term corrective actions or adjustments to serve as a temporary fix or to prevent the problem from escalating until the team identifies a permanent resolution to the problem. In the example above, the temporary fix might be to shut down the machinery for 15 minutes after every hour, to allow cooling down and prevent overheating.
- Root Cause: Define and verify the root cause of the problem. This requires understanding why the problem occurred, listing out all potential causes for the occurrence, and testing each potential cause against the problem description and available data to determine whether such specific cause is the root cause. In the example above, the various causes for defective products are the machine shorting, and poor quality control. The root cause however is what causes malfunctioning of the electrical breaker. Repairing the machine or improving quality control will only solve the problem temporarily.
- Corrective Action: Identify corrective actions to address the root cause of the problem, and verify whether such actions serve as permanent fix and not cause side adverse effects. Possible solutions, depending on what is the root cause in the example above are replacing the electrical breaker, changing the electrical wires, or installing a cooling fan.
- Implementation: Implement the corrective actions on a permanent basis after verifying its effectiveness. Monitor the process or product in follow-up to ensure no adverse side effects.
- Prevent Recurrence: Apply initiatives such as modifying specifications, redesigning workflow, offering training to the workforce to improve practices and other interventions to prevent recurrence of the problem
- Conclude: Finally, recognize and reward the team effort, and share the knowledge and experience with others.
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8D root cause analysis constitutes the core of the problem identification and solving process. Brainstorm for possible causes, and analyze each cause as a possible root cause. This requires asking questions such as who, what, when, where, why, and how, ensuring that the discussions stay structured and focused on the situation or issue. Success depends on discussing with an open mind rather than going into the exercise with a possible solution already in mind.
Apply tools and techniques such as problem statements, “Is and Is Not" statements, 5 Why technique, or asking questions to identify cause-effect relationships, Failure Mode and Effects analysis using Cause and Effects or fishbone diagrams, Difference and Change Analysis and checklists or assessment questionnaires on each possible cause to determine whether such cause is the root cause of the issue. If so, apply the same techniques to identify possible solutions, and if not repeat the process with another possible cause.
The 8D approach serves the same purpose of Six Sigma and other problem solving disciplines, but has the advantage of not requiring extensive statistical application. Application of 8D helps the organization identify the root cause with consideration of cost, timing, effect on customers, and the impact on the organization.