Problem Solving with the 8D Method

by | Oct 6, 2020 | Quality

It is likely that some small mechanical engineering firm in the automotive industry has received a request from its customer to prepare an 8D form in response to a non-performance identified by the customer.

The requirement is made necessary by the IATF 16949quality management system for the automotive automotiveindustry.

Unfortunately, these companies that have been asked for the '8D form' are not able to develop this problem solving methodology adequately, even though they have probably declared to their client that they apply a whole series of methods and procedures in accordance with IATF 16949.

When asking the customer for clarification, the same company will probably receive a form applied by the customer for its 8D.

The analysis of the root causes of the non-conformity detected by the customer and the implementation of the relevant corrective action with verification of its effectiveness according to the 8D method, however, requires a certain amount of expertise, which is not normally possessed by the quality service of a small mechanical engineering company supplying a customer in the automotive sector.

The 8D method is a quality management tool that allows an inter-functional team to convey ideas to scientifically determine the causes of particular problems and provide effective solutions.

Many organisations can benefit from the 8D approach applied to all business sectors. 8D provides excellent guidelines for getting to the root of a problem, determining corrective action and ways to verify that the identified solution really works. The 8D method does not settle for the 'healing symptoms' of traditional corrective actions implemented in ISO 9001 quality systems (although this was not the philosophy of the standard), but aims at a complete cure of the disease from which the production is suffering, so the same problem is unlikely to recur in the future.

The 8D problem solvingmethod is only appropriate in the case of problems with "unknown causes", it is not the right tool when dealing with potential problems (to be dealt with by preventive actions) or with decisions to be made about already well defined problems.

The 8D method (8-Disciplines ) is divided into 8 steps, in fact, documented through special records, normally called 'form 8D'; that's why many small and medium-sized companies wonder what form 8D is and look for some practical examples to fill it out and send it to the client who requested it, probably for yesterday.

In reality, if you look closely at the 8D forms, you can immediately see that it is not just a simple quality form to fill out, but a process of analysis of the problem encountered that must lead to the radical solution of the same.

The steps of the 8D method

  1. Planning
  2. Identification of the analysis group
  3. Problem definition and description
  4. Implementation of containment actions
  5. Identification and verification of root causes
  6. Implementation and verification of effectiveness of CA
  7. Implementation and verification of effectiveness of CA
  8. Prevention of recurrence
  9. Recognition of the effort of the analysis team

In reality, there are 9 steps as the initial activity of planning the whole process has been included.

These steps should be documented in an 8D form, e.g. more correctly called '8D problem solving form'.

Let's look at the individual steps.

0 - Planning

It must first be established whether the reported problem requires or deserves an 8D method, i.e. if the cause is unknown and it is not a standard problem that can be solved with standard corrections/treatments and/or corrective actions.

If you decide to proceed with the 8D method, you should describe your reasons for doing so (e.g. explicit customer request) and prepare the registration forms.

1 - Identifying the analysis group: establishing the team

Probably the care and emphasis in the composition of the operational team is the key to the 8D system, it is the prerequisite for important successes. First, therefore, form a team (4 to 10 members), choose a leader, a solicitor and a secretary. Even if a great difference in cultural background between people offers more chances to find a solution, participants should all have in-depth knowledge of the product and processes, availability of time and, in addition, sufficient authority in relations with other people and skills in the technical disciplines involved in solving the problem.

2 - Definition and description of the problem

Describing the problem is the next step: identifying the roots of the problem and understanding why it arose. First of all, a very thorough analysis should be carried out in order to be very sure that you have not confused the symptoms with the real problem. It is better to define and circumscribe the problem in its quantitative terms (who, what, when, where, why, how, how many) and to use a standard terminology that is shared by all team members.

The product code, serial number (if any), the customer, the production order, the processing steps in the cycle, etc. should be recorded on the appropriate forms. A flow chart of the problem and an examination by means of an "is / is not" table in the columns and - per line - the classic questions "who, what, why, where, when, how much / how often" can be helpful,

3 - Implementation of containment actions

The priority now is to isolate the customer from the negative effects of the problem, the failure must remain within the plant. At the same time, interim measures or buffer actions must be taken to prevent the problem from worsening and spreading to other products or batches. Despite the fact that certain preventive measures cost a lot of money (e.g. 100% acceptance control before dispatch), the customer must be protected by all means until permanent corrective actions can be implemented and verified. The effectiveness of containment actions must be verified and documented.

4 - Identification and verification of root causes

Identifying the root causes is crucial for planning effective and lasting corrective action. In this phase one tries to identify the 'why', the reason why the problem has arisen. Team members investigate all potential causes using flow charts, stratification diagrams and cause-effect diagrams (fishbone). If the problem is new, it may be useful to examine all the events that have affected the product under investigation in chronological order; this analysis sometimes provides very useful clues. Participants have to determine which potential causes are the most significant.

Once the possible root cause has been identified, it must be verified and validated.

5 - Identification of permanent corrective action (CA)

It goes without saying that this is the most critical phase. All the proposals made in the previous point must be evaluated; in any case, shortcuts and provisional solutions must be avoided. Team members must be aware that the chosen solution will be permanently incorporated into the product (or process) in the future. Several approaches are available for verification, both in the short and in the long term. From an engineering point of view, design checks and production approval tests provide a lot of useful data. Additional lab tests and process control charts can verify other parameters of the problem you are trying to solve. Any method chosen to solve the problem should be emphasised in the terms of "who" (the person responsible), "what" (the action to be taken, basically the solution), and "when" (the time set to complete the action).

6 - Implementation and verification of effectiveness of CA

The team at this point moves on to the implementation part of the action plan: its implementation, in terms of who, what, and when. All elements should be recorded in order to verify that the actions decided upon are undertaken using the forms provided for corrective actions, including time schedules, responsibilities, and how and when to verify effectiveness. Changes in the situation as corrective actions become operational should also be recorded. Sometimes training sessions, partial re-designs or re-engineeringor choosing new vendors may be necessary. If additional interventions are needed they must also be developed and documented.

At the end it is necessary to communicate the outcome of the corrective action to the customer and formalise the closure of the NC.

7 - Prevention of recurrence

Where necessary, a cause/effect diagram should be developed to analyse and discover which process segments might cause the problem to recur, perhaps in a different guise. Sometimes there is a need for a change in managementstyle, or the implementation of a different procedure to avoid the conditions that created the problem. It is important to consider the need for training sessions for senior managers as well. The suggestion, could also be to install another team, more specific and competent, to improve locally the system and the motivations of the leaders.

Standardisation of the action includes review of all documentation involved: quality management system procedures, work instructions, work cycles, control plans, FMEA, PPAP, etc.

8 - Acknowledgement of analysis group effort

It is important to congratulate the team at the end of the process. First, publicly acknowledging success will gratify those involved. A few ideas: prepare a case studypublish an informative memoir, or produce a video detailing the problem and its solution, an official dinner, commendation or award.


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