Concentration Diagram

Introduction: Concentration Diagram

A Concentration Diagram, also known as a Defect Concentration Diagram, is a visual quality management tool used to locate and analyse defects, errors, or failures on a product, component, or process. It is one of the Seven Basic Quality Tools within Lean and Six Sigma and provides valuable insights into recurring problem areas.

Background

The Concentration Diagram was developed as a practical method to make defects visible. Instead of only counting the number of defects, this tool highlights where they occur. By mapping their location, patterns become easier to recognise, which supports targeted root cause analysis. This visual method is widely used in manufacturing and service industries to improve quality and safety.

Key Elements / Features

• Defect Mapping: A diagram of the product, part, or process is created and defects are marked on it.
• Pattern Recognition: Repeated marks in the same area reveal clusters or concentrations.
• Root Cause Link: By identifying locations, teams can connect defects to likely causes such as handling, design flaws, or machine errors.
• Flexibility: Can be applied to physical products, service forms, digital systems, or workplace layouts.

Applications / Examples

• Manufacturing: Locating scratches or dents on automotive parts or electronics.
• Service Processes: Marking errors on application forms or screen interfaces.
• Maintenance: Identifying frequent breakdown points on a machine.
• Safety: Mapping workplace incidents to high-risk areas.

Relevance / Impact

The Concentration Diagram provides a simple yet powerful way to visualise defects. By focusing on where problems occur, organisations can prioritise improvements in the most critical areas. This encourages fact-based discussions during problem-solving workshops, strengthens root cause analysis, and improves both quality and customer satisfaction.

See also

• Seven Basic Quality Tools
• Cause & Effect Diagram
• Pareto Chart
• Scatter Diagram