Tips for an effective 8D
- 24 April 2019
- Posted by: Stagiaire Communication
- Category: Actuality
The 8D problem solving method, short for 8 disciplines, was introduced by FORD in 1987. It aims to systematize the use of a structured, participative and traversable method to effectively solve a quality problem.
First of all, let’s remember that the objectives of an 8D are to protect the customer and avoid recurrence.
An effective 8D necessarily involves:
- The constitution of a multidisciplinary team that will deal with the problem.
- The description of the problem through the use of the QQOQCCP and the Is/Not in order to limit the scope of the investigations and quickly identify plausible leads to explore.
- A daily follow-up of the defects by date of manufacture and by place of detection with the objective to be reached to check graphically the effectiveness of the protection measures and the corrective actions.
- Immediate customer protection measures for all products at risk, regardless of their stage in the manufacturing process, covering all storage and delivery points.
- An analysis of the causes with the 5 Whys (5Ws) which allows to identify the technical root causes and to go back to the organizational and managerial causes.
- Corrective actions that address all identified causes.
- Removal of customer protection measures after demonstrating the effectiveness of corrective actions.
- Recognition of work done and sharing of knowledge throughout the organization.
- Capitalization and transversalization of corrective actions on similar products and processes: updating of FMEAs and monitoring plans, creation or updating of design and manufacturing standards.
“If I had one hour to solve a problem, I would spend fifty-five minutes defining the problem and only five minutes finding the solution. “Einstein
In this spirit, we will develop the first steps of an 8D that are the most crucial for a robust problem resolution.
The first step is to designate the working group. The size of this group will depend on the nature and complexity of the problem to be addressed. A problem has cross-cutting origins and consequences, and is rarely confined to a single process or department: you must therefore involve all the functions concerned.
The working group will be led by a leader who will be a facilitator and a moderator. This leader must be trained and experienced in the use of the 8D method and in group facilitation techniques.
Description of the problem
In addition to the classic characterization of a problem using the QQOQCCP, the essence of the Is/Not tool is to ask not only why, in certain circumstances, the defect appears, but also why, in other circumstances, the same defect does not appear. And from there, identify the differences that constitute influential factors to investigate (potential causes).
You must then trace the defective parts as precisely as traceability allows: by date of manufacture, by production team, by place of manufacture. This is an opportunity to justify the requirements for product traceability in clause 22.214.171.124 of the IATF 16949 standard. It is also a question of being able to reduce as much as possible the production window of the products at risk in order to limit the costs of security.
The objective of this step? To identify all the parts at risk and define immediate protection measures.
For the security actions to be effective, it is necessary that :
- The inventory of suspect lots is carried out for each storage location: in-house, at the customer’s premises, not forgetting parts in transit.
- Rework and/or sorting instructions are defined and validated by Quality.
- The results of the security actions feed the description of the problem (QQOQCCP, Is/Not).
- A specific marking is present on the controlled / reworked parts.
- A special label is present on the packaging units.
- The security actions and the traceability of the first guaranteed batches are communicated to the customer.
- The analysis of the defect has started with the involvement of the production operators.
From potential to proven causes
This step is the most complex of all. Let’s start by defining what a problem is: a problem is a gap between an actual unsatisfactory situation and a desired situation. Problems often originate from a failure to comply with standards, an absence of standards or inadequate standards.
The team must therefore analyze the gaps between the current situation (good and bad parts) and the target situation (the standard) to then confirm or deny the influence of the factors identified during the problem description stage.
How do we do this? By comparison using a factor tree (FTA) that helps understand the conditions that made the parts different. This is a key step in the analysis. We can’t stress enough that the best way to validate a cause is to reproduce the defect.
For each validated factor, a 5-Why analysis (5P) must be launched. Indeed, it leads to several root causes that allow you to identify the reasons why a defect appeared and escaped you. With the first 2 Whys, you deal with the causes related to the process, this is the “technical” explanation. The 3rd Why is essential for a successful transition from the obvious to the less obvious. You don’t need to answer all 5Ps at once, this is an investigative activity and each Why must be validated with evidence. When you finally get to the 5th Why, it is likely that you have found a systemic cause.
“Why do we have this defect now? ” If you can’t answer this question clearly, you may have moved too fast or your 8D is geared to fit preconceived conclusions. Take time to define the problem before looking for the solution and justify your conclusions with data.
For more information :
- Quick Response Quality Control (QRQC): react quickly to eradicate problems