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June 21, 2024

7 Common Mistakes in Manufacturing Root Cause Analysis (RCA) & How to Avoid Them

Root cause analysis (RCA) in manufacturing is a systematic process used to identify the fundamental reasons behind failures or problems. This investigative method is essential in pinpointing not just what and how an issue occurred, but why. By understanding these underlying causes, manufacturers can implement more effective solutions that prevent recurrence, leading to safer, more efficient, and cost-effective operations. It also ensures that resources are not wasted and are being used for the correct fix.

Key Benefits of Root Cause Analysis

Firstly, root cause analysis ensures the stability and reliability of production lines and processes. By identifying the root causes of faults, companies can avoid implementing fixes and avoid repeated downtime, which in turn minimises waste and increases productivity. Implementing RCA also provides a deeper understanding of process dynamics and the interdependencies among different process elements.

This understanding allows manufacturers to preempt potential problems before they manifest into actual faults. Additionally, RCA fosters a proactive approach to problem-solving, rather than reactive, which significantly improves operational efficiencies and reduces costs associated with fixes and rectifications. Lastly, through systematic RCA, businesses can maintain and even enhance their competitive edge by ensuring consistent product quality and reliability.

Common Mistakes in Root Cause Analysis

Although RCA is an amazing habit for manufacturers to get into, many organisations make the same mistakes. These mistakes can lead to identifying the wrong causes of certain issues, and wasting time and money trying to fix the wrong thing. To make sure this doesn't happen to you, we will now go through these common mistakes and how you can avoid them.

Inadequate Problem Definition

One of the first steps in RCA, defining the problem, is often rushed. This leads to a flawed or incomplete understanding of the issue at hand. A vague or incorrect problem statement can misdirect the entire analysis, resulting in ineffective solutions that fail to address the core issue. It's crucial to involve relevant stakeholders in this phase, including those on the production floor and in quality control, to gather comprehensive insights about the problem.

Here's an example...

Situation: A manufacturing plant experiences repeated, unexpected downtime on one of its packaging lines, specifically with a sealing machine that seems to stop functioning at random intervals. This downtime is causing significant delays in production schedules and increasing operational costs.

Initial Problem Definition: The initial problem statement defined by the maintenance team is: "The sealing machine stops working intermittently." This was too vague and did not provide information on the conditions under which the machine stops (time of day, production loads etc), the symptoms observed (error messages, unusual noises etc) and the frequency and duration of the downtime.

As a result, the maintenance team might focus solely on the mechanical or electrical aspects of the sealing machine, assuming that the issue is due to hardware failure. They might replace various components or adjust settings without truly understanding why the machine stops intermittently.

Corrective Action with Adequate Problem Definition: After further consultation with operators, quality control staff, and reviewing production data, the problem statement is revised to: "The sealing machine stops working intermittently during high-speed operations, typically after running for more than 5 hours continuously, accompanied by overheating warnings and a specific error code XYZ on the control panel."

With this detailed problem definition:

  • The RCA team conducts a targeted investigation, focusing on the thermal management of the machine, software issues related to the error code, and potential operational overload. They find that the overheating is caused by inadequate cooling due to a clogged air filter
  • They discover that the overheating is caused by inadequate cooling due to a clogged air filter and old thermal paste on the heat sinks, exacerbated by the continuous long runs at high speeds.
  • Further analysis shows that the error code XYZ is related to a software glitch that misinterprets sensor readings when the machine overheats.

Outcome: The team replaces the air filters, applies new thermal paste, and updates the machine's firmware. These actions resolve the intermittent stops, reduce downtime, and enhance the machine's reliability and efficiency.

As such, when defining the problem you need to document all symptoms and relevant operational data at the time the issue occurred. Engage with personnel who witnessed the issue first-hand and use visual aids such as diagrams and flowcharts to map out the problem area. This approach helps in creating a precise problem statement that guides the subsequent analysis effectively.

Focusing Only on Symptoms

Many RCA efforts falter by concentrating solely on the symptoms of a problem rather than its actual causes. This symptomatic approach can lead to temporary fixes that do not prevent recurrence of the issue.

For example: The conveyor belt keeps slipping and you find it's as a result of the load being too heavy due to increased orders. Your fix is reducing the amount of load on the belt, but this reduces your productivity and efficiency. By looking into the actual cause, you find that the root cause is the motor for the conveyor belt was not strong enough to power the high loads. Replacing the motor for a more powerful one stops the breakdowns occuring and keeps productivity at the same level.

Using the "5 Whys" method

The "5 Whys" technique is a powerful tool in RCA that involves asking "Why?" repeatedly until the root cause is uncovered. Each answer leads to another "Why?", drilling down into more detail. This method encourages thorough investigation and helps avoid the trap of accepting superficial explanations as true root causes. Check out our previous blog post which explains the 5 Whys method in a bit more detail.

Ignoring Human Factors

Human factors such as operator error, insufficient training, or poor maintenance practices can significantly influence manufacturing outcomes. However, these factors are often overlooked or underexplored during RCA, possibly due to their complex and sensitive nature. Understanding and addressing these human elements is crucial for developing more effective and holistic solutions.

To effectively consider human factors, manufacturers must look at ergonomic, administrative, and workflow aspects that could contribute to errors or inefficiencies. Implementing training programs that focus on these areas, alongside regular assessments of employee performance and process design, can help reduce the incidence of human error and enhance overall operational efficiency.

Overlooking External Factors

External factors like supply chain variability, vendor issues, or environmental conditions often exert significant impacts on manufacturing processes but are sometimes neglected in RCA. These factors can introduce unexpected variability and complications that need to be accounted for in the analysis. For example, you may be having consistent issues with your product quality. This may be due a change in materials from the vendor, so it's important to consider this.

In order to avoid overlooking these factors, you need to review all external elements regularly, and consider their potential impacts during the RCA. For example, regular audits of supply chain processes and vendor quality can highlight external influences that may not be immediately apparent but are critical to addressing the root cause of issues.

Stopping at One Cause

It is rarely the case that a significant problem has a single cause. Most issues are the result of complex interactions between multiple factors, but a lot of manufacturers tend to focus too narrowly. A comprehensive RCA should consider all potential causes and their interrelations, rather than prematurely focusing on one presumed cause. For example: a packaging machine frequently breakdowns. Initial action was to change the conveyor belt, but later investigation found that it was also incorrect calibration and increased humidity that were impacting the process.

Using cause-and-effect diagrams that map out all possible causes and how they might interlink is an effective way to ensure you are considering all causes. A fishbone diagram or fault tree analysis are great tools to aid in this.

Failing to Implement or Monitor Solutions

After identifying root causes, the next critical steps are implementing solutions and monitoring their effectiveness. Failure to execute this phase properly can result in the recurrence of the problem and may even cause new issues if solutions are not appropriately tailored or integrated. There's not much point in carrying out a root cause analysis if the identified problems aren't fixed, so it's important to develop a detailed implementation plan. This needs to include specific actions, responsible persons, timelines, and resources needed. Regular follow-ups and adjustments based on the results seen from implemented solutions are vital for ensuring the long-term success of RCA efforts.

Jumping to Conclusions

A common pitfall in RCA is rushing to conclusions without sufficient evidence. This can lead to incorrect assumptions and ineffective solutions, wasting resources and potentially exacerbating the problem.

For example:

  • An electrical components manufacturer discovers a particular machine responsible for soldering components onto circuit boards begins to fail sporadically, leading to significant production delays and increased scrap rates.
  • They assume this is due to the machine being very old, so they replace the machine, yet the problem still persists.
  • With a more detailed analysis, the team discovers that the failures correlate strongly with periods of high humidity. Further investigation reveals that the humidity affects the properties of the solder paste used in the machines, not the machine components themselves.
  • Instead of further unnecessary replacements of machine parts, the factory improves the environmental controls in the soldering area, installing dehumidifiers and updating the HVAC system to maintain a consistent humidity level optimal for the soldering process.

To avoid this happening, make sure you consider multiple data sources and analytical methods. This approach not only solves the problem but also saves resources and prevents similar issues in the future by setting a standard for comprehensive problem analysis.

By understanding and avoiding these common mistakes and by adhering to best practices, manufacturers can significantly enhance the effectiveness of their root cause analysis processes. This leads to more reliable, efficient, and cost-effective manufacturing operations, ultimately improving overall business performance.