6M Root Cause Analysis in Lean Six Sigma. Everything to Know

Over 20 years of experience applying Six Sigma principles across industries, I have conducted countless root cause analysis utilizing various methodologies. 

One such approach that I have leveraged is the 6M Root Cause Analysis technique. 

Machines, Materials, Methods, Manpower, Measurement, and Mother Nature provide an intuitive framework for categorizing inputs based on potential factors contributing to process variation.

Key Highlights

  • The 6Ms refer to six key inputs that contribute to process variation: Machinery, Manpower, Materials, Methods, Measurement, and Mother Nature
  • Categorizing causal factors into the 6Ms provides an intuitive framework for structured brainstorming and analysis
  • The approach helps identify root causes by mapping relationships in an Ishikawa/fishbone diagram
  • Drilling down under each Ms category uncovers hidden sources of problems
  • While utilized in manufacturing, 6Ms adapts well to service, transactional, and administrative processes
  • An impact-difficulty matrix can help focus on remediation efforts for most ROI
  • For optimal outcomes, verify root causes with data before implementing corrective actions
  • Practitioners should refine the 6Ms method based on learnings from completed analyses

This article will explore an overview of the 6M Root Cause Analysis, including its origin and evolution from the foundational principles established by pioneers like Kaoru Ishikawa. 

We will explore the mechanics of constructing a 6Ms fishbone diagram to map different causes and drill down to the root sources of quality excursions. 

Whether the challenge resides within manufacturing plant floors or informational business processes, the adaptable 6Ms approach facilitates a comprehensive interrogation of inputs to diagnose and remedy issues. 

Equipped with this understanding, continuous improvement practitioners can further enrich their causal analysis toolkits to drive transformations.

Introduction to Root Cause Analysis

As an industrial engineer and statistician by training who has led optimization efforts across global corporations, I recognize the major impact that a root cause analysis can have. 

Before exploring the versatile 6Ms approach, review foundational concepts and alternative causal analysis techniques.

Types of Causal Analysis

5 Whys Methodology

This iterative interrogation method identifies root causes by repeatedly asking “Why?” 5 times.

Each answer forms the basis of the next why question until the source is revealed. While simple in premise, it tests assumptions and deepens understanding.

Pareto Analysis

This statistical approach leverages the Pareto principle that 80% of problems stem from 20% of causes. By quantifying and ranking issues, efforts can concentrate on high-impact vital sources. 

Graphical Pareto charts visually depict the disproportionate influence of certain factors.

Benefits of Root Cause Analysis

Whether through 5 Whys, Pareto analysis, or the 6Ms, causal analysis generates breakthrough improvements by fundamentally addressing problems versus merely treating surface symptoms. 

This analytical approach directly enhances quality, reliability, and profitability metrics that underpin competitive advantage.

Additionally, the collaborative process of mapping relationships through tools like cause-and-effect diagrams builds shared understanding between functions. This lays the cultural foundation for preventing future issues.

Fishbone Diagram

We will delve deeper into the prevalent Ishikawa or fishbone diagram which offers a structured graphical approach for categorizing the many potential and hidden causes affecting processes. The versatile 6Ms method leverages this visual format to relate causes to the core problem.

Overview of the 6M Root Cause Analysis

While many causal analysis tools exist, the 6Ms approach holds a special place in every Master Black Belt’s toolkit. Its simplicity, adaptability, and completeness uniquely equip the methodology to diagnose the drivers of process variation. Let us explore the anatomy of the 6Ms.

Defining the 6M of Root Cause Analysis

The 6Ms encompass six fundamental inputs that impact manufacturing and service delivery processes. Kaoru Ishikawa standardized these categories while pioneering quality management principles that remain foundational today.

Machinery: Any equipment, production tools, or facility systems involved in operations
Manpower: The human resources conducting and managing process execution
Materials: Components, consumables, and raw input materials flowing through the process
Methods: Specific procedures followed to transform inputs into outputs
Measurements: Metrics, inspection readings, instrumentation, and data generated to assess quality
Mother Nature: External environmental conditions that can influence process stability

While terminology permutations exist across industries, these six elements comprehensively map the key variables affecting processes.

5 Ms + 1P Variation

A popular variation replaces Mother Nature with “Process” itself as the sixth factor. This firmly widens the scope to include aspects like process flow, plant layout, production sequencing, etc. 

The approach also frequently substitutes “People” for “Manpower” and “Equipment” for “Machinery” to reflect modern sensibilities.

Origins and History of the 6M of Root Cause Analysis

The pioneering quality guru Kaoru Ishikawa first outlined the 6Ms in the 1960s while developing cause-and-effect and fishbone diagrams. 

As companies adopted these analytical tools, the versatile 6Ms cemented as standard inputs when troubleshooting issues to pinpoint root causes. 

Iterations like the 5Ms and 1P demonstrate the flexibility of the approach to adapt to specific needs. Nonetheless, the methodical ethos of interrogating key process contributors persists as the framework’s core.

Using the 6M for Root Cause Analysis

While understanding the backbone of the 6Ms is crucial, its true value manifests while actively diagnosing problems. Let us walk through utilizing the approach for root cause analysis.

Building a Fishbone Diagram

The intuitive visual construct of a fishbone diagram lends itself perfectly to categorizing causes within our 6Ms framework. The problem statement acts as the “head” while each Ms branch composes a “bone” seeking respective sources.

Brainstorming Causes

With the diagram in place, cross-functional teams can brainstorm factors that may contribute to process instability across all Ms branches. The structured format with pre-defined categories stimulates ideas that may otherwise remain hidden without this prompting.

Categorizing Issues

As numerous hypotheses emerge, the team catalogs each cause under the appropriate 6Ms branch. If ambiguity exists, quick voting can determine placement before resuming brainstorming. This organization reveals trends within certain domains.

Drilling Down into Causes

The most fertile territory lies in the deeper roots where few have dug before. Leveraging the 5 Whys approach, the team drills down repeatedly to unravel root causes. When similar suspects arise across multiple branches, pay extra attention to potential smoking guns.

Determining Root Causes  

Vet and prioritize all hypothesized causes until primary root cause candidates rise to the forefront for each 6Ms branch. Gather validation data before pursuing any one root issue to prevent resource squandering.  

Verifying with Data  

While speculative causes should undergo initial vetting earlier, extensive analysis should follow to definitively pinpoint a significant few vital root issues. 

Funnel efforts into what the data substantiates rather than assumptions alone. This prevents wasting resources on superficial factors versus high-impact causes requiring remedy.

Applying 6M Root Cause Analysis to Manufacturing

While originally developed for manufacturing environments, the ubiquity and flexibility of the 6Ms framework enable adaptation across functions. Nonetheless, its ability to handle complexity at scale remains a cornerstone application for process improvement practitioners.

Production Line Methods

The structured workflow mandated by production lines introduces risks of variability being introduced and propagated. 

The 6Ms analysis can assess if procedures are overly complex, machines are adequately capable of meeting takt time, inspection systems provide actionable data, and environmental conditions meet operating parameters.

Machine Maintenance

As the backbones of manufacturing ops, machines both influence and are influenced by upstream and downstream processes. The 6Ms lens evaluates age, condition, calibration standards, PM rigor, utilization levels, and capability gaps that may manifest as a quality variation.

Raw Material Quality

Input material integrity affects process stability and output quality. The 6Ms will trace inconsistencies back to supplier QA programs, handling, inspection methods, storage conditions, and formulation changes that bleed impacts.

Operator Skills

Frontline personnel directly or indirectly influence production, whether through operation, maintenance, or quality assurance. The 6Ms weigh their proficiencies, knowledge, and experience levels that could contribute to deviations.

Measurement Procedures

Sensors and analytics serve as the eyes and ears providing actionable visibility. The 6Ms evaluate risks of bias, imprecision, uncertainty, latency, and veracity of data streams fueling decision loops.

Environmental Conditions

Cleanrooms to chemical plants mandate stringent ambient parameter compliance. Temperature, humidity, atmosphere, vibration, etc. represent considerations within the 6Ms arena both for facilities and utility systems.

While exhaustive analysis requires blurring the borders between branches, the 6Ms structure accelerates framing the problem space. This omnibus approach prevents overlooking blindspots plaguing narrowly targeted efforts. 

Manufacturing staples like TPM and Kaizen enrich remediation insights during and post-6Ms activities.

Applying 6M Root Cause Analysis to Other Domains

While the 6Ms originated from manufacturing environments, its flexibility enables adaptation across other functions lacking direct types of machinery and materials. The technique can diagnose process variability within service operations, administrative workflows, and creative endeavors.

Adapting Methodology

Thoughtful tuning of terminology and perspective broadens the 6Ms beyond production lines. “Equipment” and “People” can substitute “Machinery” and “Manpower” while “Processes” captures workflows. Categorizing contributor types remains central to the refined framework.

Service Delivery Processes

The 6Ms lens can scrutinize variability within service interactions, whether in healthcare, hospitality, or professional services. It weighs procedure consistency, staff skills, data transparency, customer acuity variances, and environmental factors driving execution excellence.

Information Systems

Even virtualized environments interacting with informational systems have relevant analogues for each Ms branch. The methodology evaluates computational capacities, system resources, data integrity, codebases, infrastructure robustness, and external dependencies that could undermine stability.

Marketing Mix

While lackadaisical marketing may not cause catastrophic failures, the 6Ms approach can optimize campaign effectiveness and ROI. 

It examines channel selection, offers structuring, metrics visibility, budget allocation, partner coordination, and contextual influences that could enable or hinder resonating with audiences.

The versatility of the 6Ms to not only understand but also actively improve processes indeed spans far beyond the factory floor. 

While traditional terminology assumes a manufacturing backdrop, adaptation to match specific environments puts the tool’s utility within reach for knowledge workers.

Keys to Success with 6M Root Cause Analysis

While the 6Ms provide an intuitive checklist for structuring root cause analysis, proper application and mindset tuning unlock its full potential. 

Based on extensive practitioner experience, the following keys set the table for 6Ms excellence.

Asking Why Repeatedly

The “5 Whys” philosophy suggesting iterating to root levels applies perfectly to drilling down within the 6Ms branches. Assess each cause through recursive questioning to unravel the deepest underlying contributors.

Updating with New Learnings

Just as processes evolve, so too should refresh the 6Ms framework with additional categories as new process knowledge comes to light through completed analyses.

Ensuring Proper Categorization

As the 6Ms structure seeds the diagram’s construct, judiciously map causes to appropriate branches. If ambiguity exists, democratically vote to maintain momentum.

Considering All Inputs

A common pitfall lies in overlooking certain inputs during the brainstorming. 

However, actively hypothesizing potential factors across the wide 6Ms landscape guards against confirmation bias and premature assumptions around root issues.

While formal procedures govern the application, injecting these foundational principles into the 6Ms drives optimal analytical outcomes. Adopting this comprehensive mindset and regularly revisiting assumptions ushers full benefits.

Conclusion & Next Steps

As we bring this exploration of the versatile 6Ms methodology to a close, let us recap key insights and opportunities to enrich future causal analysis efforts.

Summary of the 6M Root Cause Analysis

The elegance of the 6Ms lies in its simplicity and comprehensiveness for categorizing the broad range of process variables that contribute to outcomes. 

Whether applied in manufacturing or technical and creative domains, the structured decomposition empowers deeply focused diagnosis.

Importance of Quality Improvement

By methodically considering equipment, talent, materials, procedures, data, and environmental factors influencing processes, the 6Ms approach structures discoveries of significant root causes underlying quality issues. 

Targeted remediation of vital inputs then uplifts stability.

Areas for Further Analysis

While powerfully employing the 6Ms as part of a broader analytical toolkit along with data-driven hypothesis validation unlocks maximal benefits. Furthermore, adapting the framing for specific process types can improve relevance. 

Continued evolution of the approach will drive ever more incisive insights.

I hope this guide has enriched your understanding of the 6Ms framework thus empowering your continuous improvement initiatives with a sharpened causal analysis toolkit. Please reach out with any other questions as we collectively elevate our practice.

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