Manufacturers who have production capacity constraints, or struggle to understand where they lose capacity, can use Root Cause Analysis (RCA) to thoroughly investigate downtime incidents, and implement targeted corrective actions that lead to long-term improvements in productivity, cost savings, and equipment reliability.
This article looks at Root Cause Analysis, with a focus on how it can be used to identify the symptoms and remove altogether the causes of machine downtime.
What is Root Cause Analysis (RCA)?
Root Cause Analysis (RCA) is a systematic approach used to identify the underlying cause of a problem rather than just addressing its symptoms. In manufacturing, RCA is a critical tool to support a Lean manufacturing production method, as it is used for diagnosing and eliminating the causes of an issue, for example, machine downtime, thus improving efficiency, and preventing recurring issues.
Benefits of Root Cause Analysis in Manufacturing
Uncovers hidden inefficiencies
RCA isn’t about searching for problems—it’s about understanding them. The process often highlights underlying inefficiencies or risks that might have otherwise gone unnoticed, enabling teams to address multiple issues at once and drive broader improvements.
Creates structured, effective problem-solving processes
By embedding Root Cause Analysis (RCA) into daily operations, teams develop a consistent, structured approach to tackling issues. While every problem has its nuances, RCA ensures a systematic and repeatable method for identifying and resolving challenges across departments.
Drives a proactive mindset
Teams that regularly use RCA develop a habit of questioning why issues occur and how they can be prevented. This mindset fosters a culture of continuous improvement, enhancing operations, safety, maintenance, and quality across the organisation.
Accelerates improvement across teams
When one department successfully applies RCA, its insights and best practices can be shared across the business. By leveraging data and learnings from each analysis, teams can collaborate more effectively to solve problems and drive company-wide improvements, this is especially effective in organisations that have a culture of continuous improvement.
Reduces costs and operational waste
By tackling the root cause rather than just the symptoms, RCA helps prevent recurring issues that drain time and resources. This approach minimises unplanned downtime, reduces defects, and streamlines processes—ultimately improving efficiency and profitability.
Benefits of using Root Cause Analysis to reduce Machine Downtime
Manufacturers that use RCA to reduce machine downtime can experience significant operational benefits, including:
- Reduced Unplanned Downtime: Identifying and fixing underlying issues prevents repeated breakdowns.
- Improved Machine Reliability: Addressing root causes enhances equipment longevity and performance.
- Increased Productivity: Minimising downtime leads to higher production output, supporting better capacity management.
- Lower Maintenance Costs: Preventive measures reduce emergency repairs and part replacements.
- Enhanced Safety and Compliance: Eliminating root causes of failures can improve workplace safety and regulatory adherence.
The Root Cause Analysis Process
Conducting an effective RCA involves a structured, step-by-step approach. Below is a framework for using RCA to diagnose and resolve machine downtime issues in manufacturing.
Step 1: Define the Problem
Clearly outline the issue by gathering key details such as:
- When did the downtime occur?
- What equipment was affected?
- What were the observed symptoms?
- How long did the downtime last?
- How often does the downtime occur?
- Were there any contributing factors, such as operator involvement or environmental conditions?
Step 2: Collect Data and Evidence
Gathering accurate data is essential for diagnosing the root cause. This includes:
- Machine downtime Logs
- Historical Machine utilisation data
- Maintenance records
- Operator and maintenance team feedback
- Production records
Step 3: Identify Possible Causes
Use analytical tools to explore potential causes. Three effective methods are: A downtime Pareto analysis, The 5 Whys and a Fishbone diagram. We explore each of these in more detail below.
Downtime Pareto Chart
A Pareto Chart is a valuable tool for performing Root Cause Analysis (RCA) on downtime, as it helps prioritise the most significant factors contributing to the issue. Based on the 80/20 rule, it visually highlights the few key causes that account for the majority of downtime, allowing teams to focus on solving the most impactful problems first.
FourJaw's machine monitoring system allows users to see the top downtime causes using its Downtime Pareto chart.
How to Use a Pareto Chart for Downtime RCA
Collect Downtime Data
- Gather data on downtime events over time (e.g., a week, month, or quarter).
- Categorise downtime causes (e.g., machine failure, operator error, material shortages, maintenance delays).
- Record the frequency and duration for each cause.
Sort Causes by Impact
- Rank downtime causes from highest to lowest based on their total impact (e.g., total minutes lost).
Create the Pareto Chart
- The X-axis represents downtime causes (arranged from most to least impactful).
- The left Y-axis shows the total downtime (e.g., minutes or occurrences).
- The right Y-axis displays the cumulative percentage of downtime.
- Use bars for downtime values and a line graph for cumulative percentage.
Identify the Key Contributors
- Look for where the cumulative percentage reaches ~80%—this helps pinpoint the small number of causes responsible for most downtime.
Prioritise RCA Efforts
- Focus RCA on the top downtime causes, as eliminating these will yield the biggest improvements.
- Investigate why these issues occur and implement corrective actions.
The '5 Whys' Method
The '5 Whys' is a simple but effective questioning technique that helps drill down to the fundamental cause of a problem.
Example:
- Why did the machine stop? → A motor failed.
- Why did the motor fail? → It overheated.
- Why did it overheat? → The cooling fan was not working.
- Why was the cooling fan not working? → A build-up of debris blocked airflow.
- Why was debris accumulating? → Routine maintenance was missed.
Root Cause: Lack of scheduled maintenance leading to overheating issues.
Fishbone Diagram (Ishikawa Diagram)
A visual tool that categorises potential causes into different groups such as:
- Equipment: Faulty components, ageing machines
- Processes: Inefficient maintenance schedules, poor standardization
- People: Lack of training, human errors
- Materials: Poor-quality spare parts, supply chain delays
- Environment: Temperature fluctuations, dust contamination
This method helps teams systematically identify and categorise all possible contributing factors.
Step 4: Verify the Root Cause
Before implementing solutions, validate the root cause by:
- Running tests or simulations
- Comparing similar past incidents
- Checking whether eliminating the suspected cause prevents further downtime
- Consulting experts or experienced operators
Step 5: Implement Corrective Actions
Once the root cause is confirmed, apply appropriate solutions such as:
- Adjusting preventive maintenance schedules
- Training operators to follow best practices
- Upgrading or replacing outdated equipment
- Enhancing environmental controls (e.g., dust extraction, temperature regulation)
- Refining the layout of the cell/production line
Step 6: Monitor and Continuously Improve
RCA should not be a one-time activity. To ensure long-term improvements:
- Track the effectiveness of implemented solutions
- Use machine monitoring software to analyse downtime trends
- Conduct periodic RCA reviews for recurring downtime events
- Standardise best practices and integrate them into training programs
Case Study: Using RCA to Reduce Machine Downtime
Challenge: A manufacturer experienced frequent unplanned downtime on its CNC machines, leading to production delays and high maintenance costs.
RCA Process:
Problem Defined: Machines frequently stopped due to spindle motor failures.
Data Collected: Maintenance logs showed repeated overheating incidents. Machine downtime logs showed how many hours of downtime had been lost because of breakdowns.
Analysis: 5 Whys: Overheating was traced to clogged air filters, which were not being cleaned regularly.
Root Cause Identified: Lack of scheduled filter cleaning caused airflow blockages, leading to overheating and eventual motor failure.
Solution Implemented:
- Introduced automated alerts for filter cleaning.
- Trained operators to inspect filters daily.
- Implemented real-time monitoring to track temperature fluctuations.
Results:
- Unplanned downtime was reduced by 40%.
- Maintenance costs were lowered by 25%
- Improved overall equipment effectiveness (OEE) by 10%.
Conclusion
Root Cause Analysis is an essential tool for manufacturers looking to reduce downtime and improve operational efficiency. By systematically identifying and eliminating root causes, manufacturers can enhance productivity, reduce costs, and create a more reliable production environment.
For companies seeking a proactive approach to downtime reduction, machine monitoring systems like FourJaw provide real-time visibility and actionable insights, making RCA more efficient and data-driven.
