8D stands for 8 disciplines or 8 critical steps for solving problems.
The Eight Disciplines of Problem Solving (8D) is highly disciplined and effective scientific approach of problem solving typically used by manufacturing industries to find the root cause of a problem that is for resolving chronic and recurring problems.
Ford Motor Company developed this problem solving methodology, then known as Team Oriented Problem Solving (TOPS), in the 1980s. The early usage of 8D proved so effective that it was adopted by Ford as the primary method of documenting problem solving efforts, and the company continues to use 8D today.
The 8D problem solving model establishes a permanent corrective action based on statistical analysis of the problem and focuses on the origin of the problem by determining its root causes. Although it originally comprised eight stages, or disciplines, the eight disciplines system was later augmented by an initial planning stage.
8D is a systematic & scientific approach and it takes several weeks to several months in order to solve a problem and should not be used for following.
Non-recurring problems or problems which can be solved quickly by individual effort.
Problems with known root causes.
Making a decision between different alternatives.
Problems where the simplest and most obvious solution is likely to be the best or adequate solution
D0: Plan
Plan phase is a preparation step before starting the 8D process. Plan for solving problem and determine the prerequisites.
Simply it is an information collection step on symptoms of the problem
A deeper understanding of the problem and its history are necessary to determine if the 8D is the right method to be used for solving the identified problem.
D1: Define Team
Team formation is the first discipline of 8D approach.
Establish a small group of people from cross-functional disciplines with the process and product knowledge and have time to solve problem and implement corrective actions.
There should be at least one member knowing the 8D approach as subject matter expert and to keep a track of the investigation and document the minutes of meeting.
Generally 8D team consists of 4 to 8 people who are closely related to the problem. It usually involves people from different functions/departments in the organization coming together to solve a common problem.
D2: Describe the problem
The success of the root cause analysis depends on the problem description.
A correctly defined problem is 50% solved.
Define and describe the problem in measurable terms, asking questions similar to following will help you to address actual problem and not just symptom.
Key questions:
What is wrong with what?
What is happening?
What are symptoms?
Tools like ‘is’ and ‘is not’ could be used to ask questions and describe the problem
The problem statement will
§ Communicate the scope of the problem that the team is working on and get the team focused.
§ Provide information relevant to the problem: data and information on what the problem is and what the problem isn’t.
§ Clarify the role the team should play (determine root causes and implement or recommend a solution), specify the deadline and include monetary limits for the team.
§ Lays down expectations from the team and deliverables that will be measured.
§ Be the output of a process used to amplify the problem statement in terms of Who, What, Why, Where, When, and How Big (how much, how many, how often - level of pain) as stated above.
Gather and Verify Data
When the problem is identified, it is time to begin data collection.
The factual information and data necessary to assure a thorough cause analysis needs to be collected.
Data may have to be collected several times during this process, but the preliminary collection phase occurs now and will guide the analysis process.
Initial data gathering starts at the scene. Data has a shelf life, the longer you wait the more difficult it becomes to obtain good information.
When possible, go to the scene and take note of who was present, what is in place, when the event occurred and where the event happened. If the event is in the form of an audit finding, try to recover as much of the scene as possible.
Types of data to collect:
Location -the site, building, department, or field location where the event took place
Names of Personnel -operations personnel, visitors, contractors
Date and Time
Specifications -what are the requirements?
Operational Conditions -start up, shutdown, normal operations
Environmental Conditions -noise levels, visual distractions, lighting, temperature, etc.
Communications -verbal or written, what orders were being followed?
Sequence of Events -in what order did things take place?
Equipment -what was being operated?
Physical Evidence -damaged equipment or parts, medical reports
Recent Changes -in personnel, equipment or procedures
Training -classroom, on-the-job, none
Other Events -have there been similar occurrences?
Once gathered, verify the accuracy of the data. Because analysis is performed based on fact. Remember, if you don’t look, you will not find the problem.
Make sure that gathered data is correct and complete. Then go where the data takes you. Do not take the data where you want it to go.
D3: Develop Interim containment action
These are the actions taken immediately after you become aware of the event to stop the event from occurring and preventing or minimizing any impact from the event. Please note that there are no actions here to correct the problem, they are just damage control
Not a problem solving but a means to control the bleeding also referred as corrections.
Define and implement those intermediate actions that will protect from problem until permanent corrective actions are implemented.
Each of these steps should be described in detail. Advise exactly what steps you took to stop the event from occurring, what was the impact and how you determined this.
Describe in detail the steps you took to contain any effects (while we are critically concerned with hardware, effects may go beyond product). If product has, or may have, been shipped to a customer, advise who and how you notified customers.
D4: Determine the Root causes & Corrective actions
Root cause analysis is about finding the true cause(s) of event.
Identify all the potential causes which could explain why the problem occurred.
Investigation process should be structured, but done in so simple manner. It should consists of following steps
· Evaluate all currently available relevant information
· Evaluate any additional information available from horizontal analysis.
· Inspect facilities or environment of the event
· Interview appropriate people
· Communicate with appropriate stake holders
· Clearly define next steps
· Decide a team if needed, Determine team makeup & Leadership
· Do not discount any data or information
During investigation organisation must make all decisions by using a risk based approach. It must determine probability of negative event and its consequences.
There are number investigation tools available but most commonly used are as follows.
1. Genchi & Genbutsu
2. Brain storming
3. WHY-WHY Analysis
4. Fish bone / Ishikawa cause & effect diagram
5. Kepner Tregoe decision making analysis
After identifying the root causes, plan for corrective actions. Corrective action is an action to eliminate the cause of detected non-conformity to eliminate the re-occurrence.
During the implementation of CAPA following shall be ensured.
· The identified CAPA addresses the root cause
· The solution can be implemented
· There is a clear understanding of overall impact of CAPA
D5: Develop the permanent Corrective actions
Plan and implement the corrective actions addressing the root causes.
The permanent corrective action is addresses identified root cause and removes / changes the conditions of the product or process that was responsible for the problem
Often the solution or solutions become obvious once the root causes are known. However, sometimes, a systematic approach is needed to use the root cause analysis to develop a solution. If the solution is obvious, select the best solution or mix of solutions that will lead to a robust, yet cost-effective, resolution. If solutions are not yet evident, follow the data trail. When solutions are not obvious, often the root cause has not been found.
Criteria for choosing the best solution (Corrective Action):
· Practical & Feasible
· Cost effective
· Robust & Error proofing
Validation of solution / Effectiveness of corrective action:
It is necessary to establish that the solution will make the problem go away without leading into other unwanted issues. That is why the 8D team should try out the solution with small quantities first to verify its effectiveness.
A design verification test (DVT) and/or a reliability demonstration test (RDT) may be required depending on the solution.
The solution is first to be tried on small lots to validate that it has indeed solved the problem prior to full implementation.
D6: Implement & validate permanent Corrective actions
Once the solution and its implementation are approved, the next step is to create an Action Plan.
The Action Plan outlines what steps are needed to implement the solution, who will do them, and when they will be completed.
A Simple Action Plan merely documents what needs to be done, who will do it, and when will it be done by.
A complex solution needs more thorough planning and documentation.
D7: Take preventive measures
The job of a problem-solving team is not complete once the solution is implemented. Preventing recurrence is an important part of a problem’s solution.
To prevent recurrence of the problem, the team must verify that the outcome of their Action Plan works and they must validate that the outcome is on-target.
Verification is testing that the solution produces the desired outcome; validation is ensuring that the outcome really solves the problem.
D8: Closure and team celebration
Once a team has completed implementing the solution and ensured that the solution works, all team members deserve to be congratulated. Team members need to know that their efforts are appreciated and that the organization knows about their accomplishments.
The organization (leadership group) shall recognize the team for their efforts in a timely manner.
