Q: Some of our assembly processes are 100% labor intensive, and in some areas it is difficult to implement mistake proofing. Occasionally, one piece gets rejected at the customer’s end out of, say, 10,000 pieces.
The error is purely nontechnical, such as a missing label or paint mark, visual defect or wrong orientation. We know it is a human error and not a sporadic issue, but some customers insist on exact root cause identification. Is there any specific method to identify root cause in such cases?
P. R. Ramesh
Head of lean and business excellence
A: There are many people who can honestly say they feel your pain; they’ve been there, done that and got the T-shirt. Those people have had similar problems with the production of defects reported directly from the production floor or from the customer via complaints, in which case identifying the root cause may be somewhat difficult.
Do these scenarios sound familiar? There is an important order for a major client. The goods are at the distribution center ready for shipment, when suddenly the production supervisor says, "Hold the boat—we’ve got a problem!" The call is made to put the goods on hold, and the order is missed. Or maybe a customer received 600,000 parts, and fewer than 10 had broken latches. "How dare they complain! We got 599,990 parts correct!"
In both scenarios, regardless of any indignation the manufacturer may feel, the problem must be addressed. One way to identify root cause is the Team Oriented Problem Solving (TOPS) technique from Ford Motor Co. Back in the 1980s, when its motto was "Quality Is Job One," Ford developed its TOPS methodology.1 Referred to as the TOPS 8 Discipline (8D), it is a systematic means of arriving at the true root cause.
The question you posed is a perfect opportunity to use the TOPS 8D technique. It is an excellent tool to document problem-solving activities in a manner the customer should accept. The technique has been used to document root-cause and corrective-action activities to the satisfaction of many customers, including General Electric and Intel.
TOPS 8D is structured in such a way as to lead a group through a problem-solving activity. The structure is depicted as follows:
- D-1: Define concern, organize and plan.
- D-2: Describe problem in detail.
- D-3: Contain problem.
- D-4: Identify and verify root cause.
- D-5: Develop corrective action plan.
- D-6: Implement and verify corrective action.
- D-7: Prevent recurrence.
- D-8: Celebrate and communicate success.
When the customer brings an unacceptable part to your attention, the first thing to do if you are using the TOPS 8D is to define the concern or problem in succinct, clear verbiage (D-1). A project plan should be created for the purpose of eliminating the problem and improving the process.
This plan should include scope, key activities, boundaries, responsibilities, timelines and resources. The resources required for problem solving are best supported by a cross-functional team that best represents the manufacturing process.
Next, the team should describe the problem or opportunity for improvement and write a problem statement (D-2) describing the gap that exists between the as-is and desired states. The problem statement must be clear and focused on the specific nonconformance. It should clearly state what is wrong and effectively capture the degree, magnitude and scope of the nonconformance.
With the problem noted, attention must be shifted to containing the problem (D-3). Typically, these are the interim actions taken to ensure the customer receives no additional defective parts. Many organizations make the huge mistake of stopping here, often confusing containment with corrective action. In fact, it is impossible to move from containment to corrective action. Using this process will prevent that monstrous mistake.
At this point, the team is ready to start determining the root cause (D-4). This often starts by brainstorming potential causes, and then selecting which ones to address. Depending on the initial results, it might be necessary to revise the problem statement. Often overlooked here is the verification of the root cause, which means the problem can be turned on and off by manipulating the root cause.
With the root cause identified, the team is now ready to develop a corrective action plan (D-5). The team must decide on the optimum corrective action and plan its implementation. Once the corrective action is ready for implementation, a pilot test should be performed to make sure the action prevents the problem from occurring. During this pilot, the corrective action’s effectiveness can be evaluated. Potential improvements can be documented, and open issues can be addressed.
For corrective action verification (D-6), remove the interim stopgaps. If these can be removed and the root cause does not manifest itself, the corrective action is successful and has been verified.
Another often-overlooked process step is the identification of practices that can prevent the recurrence (D-7) of the defect. Thoroughly evaluate the process, practice or system that allowed the root cause to occur. Regularly monitor and modify it to prevent the problem’s recurrence.
Finally, the effort’s success should be communicated (D-8). Everyone involved should be recognized, and the effort’s completion should be celebrated. This simple practice helps ensure the continued use of the process. Even in difficult situations, it can pull people and teams closer together as collaboration is sought and built.
If you, as a practitioner of the TOPS 8D, document what you have done (your findings) and share them with your customers, you may find they will accept this means of documentation for the root-cause work you have done. The key is the documentation of the work. Creating an 8D template to capture the work done by the team is the perfect way to convey the answers your customer desperately wants. In fact, using this template can become somewhat of a project plan when initiated back in D1.
This process might strike some as cumbersome at first glance. Once a group gives it a try, however, its problem-solving benefits are immediately recognizable.
Director, Continuous Improvement
Lincoln Financial Group
- David Bruce Doane, "8D Problem Solving," www.12manage.com/methods_ford_eight_disciplines_8D.html.
For more information
Ronald D., "Use DMAIC to Make
Improvement Part of ‘The Way We Work’,"Quality Progress, September 2007,
Q: There is ongoing discussion at my company regarding nonconforming material. At what point in the process should material be identified as nonconforming and moved to the quarantine area?
Our process allows for product adjustments during manufacturing, and we have customers that require notification when a product is repaired, but some members of the staff do not consider those adjustments to be repairs. Can you provide a definition of repair as opposed to rework?
Business quality manager
Quantum Silicones LLC
A: Material should be identified as nonconforming as early in a process as possible, removed from the process and relegated to the quarantine area. The later in a process that material is found to be nonconforming, the more expensive it is to take actions to meet requirements or specifications.
The difference between repair and rework is debatable. Repair is defined as: "Action taken on a nonconforming item so it will fulfill the intended usage requirements, although it may not conform to the originally specified requirements." Rework is defined as: "Actions taken on a nonconforming item so it will fulfill the originally specified requirements."1
Therefore, from a common-sense point of view, repair means redoing a step in a process or on a material so requirements are met, and rework means completely redoing a process or reworking a material so requirements are met.
You mentioned a problem at your organization in which some staff members do not consider product adjustments to be repairs. Most likely, the real issue is that the company has not established its own definition of repair. By clearly defining the term, your organization will eliminate any need for staff members to interpret things on their own.
Principal, Mehta Consulting, LLC
- Donald L. Siebels, The Quality Improvement Glossary, ASQ Quality Press, 2004.
For more information
Robert, "Improving a System," Quality Progress, January 2009, p. 72.