Definition
Six categories of elements to be considered in resolving the problem: person, machine, material, method, environment (natural), measurement.
In detail
The 6M elements are six categories of potential causes systematically considered during problem solving: Man, Machine, Material, Method, Mother Nature, and Measurement. They provide a comprehensive checklist to avoid missing possible causes. In fishbone diagrams or CEDAC, 6M often serves as major bone categories, guiding teams to analyze from multiple dimensions. Unlike 5W1H, 6M focuses more on sources of variation in manufacturing or processes. Outputs typically include categorized cause lists as a basis for further analysis.
Example in practice
An electronics factory saw an increase in welding defect rates. The QC team used a fishbone diagram with 6M classification for brainstorming: unskilled operators, equipment parameter drift, solder batch differences, unclear process standards, workshop humidity changes, and uncalibrated measuring instruments. Through step-by-step investigation, they finally identified humidity as the key factor; after installing a dehumidifier, the defect rate decreased.