Root Cause Analysis (RCA) Method | Problem Solving

What is Root Cause Analysis (RCA)?

→ Root cause analysis is defined as a method, technique, or approach that is used to identifying the root cause.
→ The root cause is the core issue that is responsible for the problem generation. In other words, it is defined as a factor that is responsible for a non-conformance.

→ There are too many methods and tools are available for RCA.
→ Some tools are generally used for problem-solving such as (1) Six Sigma Methodology (2) 8D Methodology (3) A3 Methodology [very famous in Toyota motors], etc.
→ While other tools are dedicated to only RCA activities. such as (1) Why Why analysis or 5 Why analysis and (2) Cause_and_effect diagram (Fishbone diagram or Ishikawa diagram), etc.
→ Root cause analysis is the most important part of the TQM [Total Quality Management].
→ It is a heart of problem-solving process and in addition, sometimes it is used as a part of continuous improvement activity.
→ It is important to note that RCA is not able to generate a result but it is used as a part of a larger problem-solving project in the organization.

➨ Root cause:
     ⇢ A factor is considered the root cause of a failure or issue if after removing that factor, we will not find any repeated failure.
     ⇢ It is a proactive approach.
➨ Causal factor:
     ⇢ A factor is considered as a cause(s that is responsible for the failure but it is not a root cause(s) because by eliminating this casual factor we can improve the result of our process but the issue may repeat it will not prevent the recurrence of the problem with certainty.
     ⇢ Sometimes it is referred to as the probable or potential cause of failure but not the root cause.
➨ Counter-measure:
     ⇢ The action is taken against the root cause or casual factor so that the same problem for the same cause will not repeat again.
     ⇢ In other words, we can say that countermeasure is the opposite of root cause.

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How to write the problem?

→ Do not write problem by the assumption

→ People tend to include the cause in the same sentence which indicates the problem.

➨ Point 1: Write the facts clearly - This is ok

     ⇢ Example 1: FG marking was not available on the tire.
     ⇢ In the above example, no assumption found. The issue is clearly mentioned so that is the proper method for the writing.

➨ Point 2: Statement with Assuming - That is not ok

     ⇢ Example 2: The inspector forgets to mark on tire.
     ⇢ In the above example, there is the only assumption with the cause is mention so it may be right or wrong so that is not a proper method.

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Why problem analysis is required?

→ This analysis is required to prevent the recurrence of the failure.

→ To find out the root_cause and we can easily take preventive action against that.

→ It is also very helpful for developing our problem_solving skills and mitigate future challenges.

Basic approach points for doing an RCA

→ Be impartial

→ Do not proceed with any assumption and don't jump into a conclusion directly

→ All things process with logic not with assumption.

→ Do observation of the failure and understand the issue

→ Focus on the Gemba (the real place) and Genbutsu (the real thing)

→ Study RCA with 5W-1H method and study with data and statistics

→ Collect the information and data

→ Arrive at the Cause using a logical approach

Steps & Sequence of RCA

→ Form a team. Never do it alone, do it in a team.
→ The team should be cross-functional that means all necessary functions should be included in the team.

→ Observation should start immediately on receiving the issue. (on Genba – the real place, and on Genbutsu – the real thing)

→ Discuss with line members for better clarity on the actual issue.

→ Take photos of failed components/defects.

→ Write the issue statement in specific words, short sentence (do not use due/because/proper, etc)

→ Make a sketch of the item/process/mechanism

→ Link the observation points to link the why logic chain.

→ Verify the logic behind the failure.

→ The root_cause should touch one of the 5 basic causes

→ Countermeasure ideas to be evaluated for effectiveness

→ Implement the Countermeasure & check the effect

→ Standardize the countermeasure for sustenance - Read about the 5S methodology for better understanding

→ Look for horizontal deployment scope

→ Compile & file the RCA record

Five Reasons for Breakdowns

→ There are mainly five reasons that are responsible for the breakdowns as mentioned below.

1. Basic condition not maintained
2. Operating Condition not maintained
3. Deterioration unattended causes of the previous failure
4. Lack of Skill
5. Weak Design

Five Steps of RCA Process

→ In general, there are five steps that we are following during the root_cause analysis.

1. Define the problem
2. Data Collection
3. Identify Possible Causal Factors
4. Identify the Root Cause(s)
5. Recommend and Implement Solutions

Step 1:Define the Problem

→ In these steps, we have to define the issue what is the failure?
→ What are the symptoms?
→ We can use the 5W 1H Method.

Step 2: Data Collection

→ In this step, we have to collect data regarding the issue.
→ How long has the issue existed?
→ What are the consequences?
→ We need to analyze a situation fully independently.
→ We have to work in a cross-function team for the RCA.
→ Also, include the persons that are working on the line because they are the most familiar with the issue so they can help us to a better understanding of the issues.

Step 3: Identify Possible Causal Factors

→ Identify what sequence of events leads to failure.
→ Find out the conditions that allow the problems to occur.
→ What other problems surround the occurrence of the central problem?
→ During step 3, we have to identify as many causes as possible.
→ In most of the case, people identify one or two causes and then stop, but that is not sufficient.
→ In RCA, we don't want to simply treat the most obvious causes – we have to dig deeper.

Step 4: Identify the Root Cause(s)

→ Identify why does the causal factor exist?
→ Find out what is the real reason behind the failure?
→ You can use below tools for RCA
     ⇢ (1) Why-why analysis or 5 why analysis
     ⇢ (2) Cause and effect diagram

Step 5: Recommend and Implement Solutions

→ Identify what can you do to prevent the problem from happening again?
→ How will the solution be implemented?
→ Who will be responsible for it?
→ What are the risks of implementing the solution?
→ Analyze your process, and identify if any changes are required for our process or system or not?

👉 See Also:

➨ All Topics

➨ Lean Manufacturing

➨ ISO 9001:2015 & IATF 16949:2016

➨ 7 QC Tools

➨ MSA, FMEA, PPAP, APQP, SPC

➨ Six Sigma & Lean Six Sigma

➨ QA & QC Topics