What is the 8D method?

Problem solving

written by Fulvio Boselli

31 January 2022

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 to get to the root of a problem, determine the corrective action and ways to verify that the identified solution really works. The 8D method does not settle for the 'healing symptoms' of the 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 production is suffering, so that the same problem is unlikely to recur in the future.

The method of problem solving 8D is only appropriate in the case of problems with 'unknown causes', it is not the right tool if we are 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) consists of 8 stepdocumented by means of special records, normally referred to as 'Form 8D'; this is why many small and medium-sized companies wonder what Form 8D is and look for some practical examples of it to fill out and send to the customer who requested it, probably for yesterday.

In fact, if you look closely at the 8 D forms, you will quickly realise that it is not just a quality form to be filled in, but a process of analysis of the problem encountered that must lead to its radical solution.

Problem solving

Le steps of the 8D method are as follows:

0. Planning

1. Identification of the group of analysis

2. Definition and problem description

3. Implementation of the containment actions

4. Identification and verification of root causes

5. Implementation and effectiveness verification of thePermanent Corrective Action

6. Implementation and effectiveness verification of the Corrective Action

7.    Prevention of the recurrence of the problem

8.    Acknowledgement of the analysis group's effort

In reality, there are 9 steps because the initial activity of planning the entire process is included.

These steps should be documented in an 8D form, e.g. more correctly called "Problem solving sheet according to the 8D method".

Solving technical problems

Let us now analyse the individual steps.

 0 - Planning

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

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

1 - Identifying the analysis group: forming the team

Arguably, care and emphasis in the composition of the operational team is the key to the 8D system; it is the prerequisite for major success. First, therefore, form a team (4 to 10 members), choose a leader, a facilitator and a secretary. Although a great difference in cultural backgrounds between people offers more chances of finding a solution, the participants should all have in-depth product and process knowledge, time availability 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. A very thorough analysis must first be conducted so as to be very sure that we have not confused the symptoms with the actual problem. It is best to define and circumscribe the problem in quantitative terms (who, what, when, where, why, how, how many) and use standard terminology that is shared by all team members.

The product code, possible serial number, customer, production order, 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 a 'is/isn't' table in the columns and - per line - the classic 'who, what, why, where, when, how much/how often' questions 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 factory. At the same time, interim measures or buffer actions must be taken to prevent the problem from getting worse and spreading to other products or batches. Despite the fact that certain preventive measures cost money (e.g. acceptance inspection at 100% before shipment), 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 cause is crucial in order to then plan effective and lasting corrective action. In this phase, an attempt is made to identify the 'why', the reason why the problem occurred. Team members investigate all potential causes using flow charts, stratification diagrams and cause-effect diagrams (fishbone or '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 should 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 that emerged 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. Various approaches are available for testing, both in the short and long term. From an engineering point of view, design checks and production approval tests provide much useful data. Additional laboratory tests and process control charts can verify other parameters of the problem one is trying to solve. Any method chosen for solving the problem should be emphasised in 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 the CA

The team now moves on to the implementation part of the action plan: its implementation, in terms of who, what and when. All elements must be recorded in order to verify that the actions decided upon are undertaken using the forms provided for corrective actions, including time schedules, responsibilities, methods and timing for verifying effectiveness. Changes in the situation as corrective actions come into operation should also be recorded. Sometimes training sessions, partial re-planning or re-engineeringor the selection of new suppliers. If additional measures are required, they must also be developed and documented.

Upon completion, the customer must be notified of the outcome of the corrective action and the closure of the NC must be formalised.

7 - Prevention of recurrence

Where necessary, a cause/effect diagram should be developed to analyse and discover which process segments could cause the problem to recur, perhaps in a different guise. There is sometimes a need for a change in the style of managementor the implementation of a different procedure to avoid the conditions that generated the problem. It should not be ruled out a priori that training sessions should also be held for those responsible at higher levels. The suggestion could also be to set up another, more specific and competent team to locally improve the system and the motivation of the leaders.

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

8 - Acknowledgement of the analysis group's effort

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

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