Definition
Number of defects per million; Ext PPM refers to external quality measures after delivery to clients.
In detail
Parts Per Million (PPM) is a metric for measuring quality levels, indicating the number of defects per million products. External PPM specifically refers to defects occurring after delivery to the customer, reflecting product reliability in real-world use. It addresses the need for standardized quality measurement, facilitating cross-industry comparison. Compared to defect rate percentages, PPM can more precisely reflect low defect levels. Its output is quality data used for monitoring and improvement, often associated with Six Sigma and reliability systems.
Example in practice
When an electronics manufacturer sees customer complaints rising, it uses external PPM to quantify the problem. Counted by the CVD definition: defect count includes customer complaints, installation and warranty-period repairs; take the defect count over the past 3 months, ×4, then divide by shipments over the past 12 months (or use a 12-month rolling value), and multiply by one million to get external PPM. If PPM exceeds target, launch Root Cause analysis and improve using FMEA and Six Sigma tools. Through continuous PPM monitoring, the company can detect problems in time, reduce warranty costs, and improve customer satisfaction.