Visit PPM (Parts Per Million, or Parts Per Million) is a quality indicator (KPI) which measures the number of defective (non-conforming) units produced in relation to one million units manufactured. It is the standard for measuring the performance of processes aimed at near-perfection, particularly in the following areas Six Sigma.
In-depth definition : In the context of the Series Production and Industrial Engineering, PPM enables defects to be quantified with very high resolution, where simple percentage rates are insufficient. For example, a defect rate of 1% may seem low, but it's equivalent to 10,000 PPM - a catastrophe in volume terms. The PPM is the universal indicator for assessing a process's ability to guarantee quality. Quality required by the Technical specifications (CCT).
The objective of a company aiming for’Operational Excellence (including the Six Sigma) is to aim for a rate of 3.4 PPM, i.e. 3.4 defects per million units produced.
PPM calculation and interpretation
PPM is calculated by dividing the number of defective parts (rejects) by the total number of parts produced, then multiplying by one million.
Calculation example : A production line makes 250,000 units in a month and identifies 500 non-conforming parts:
Interpretation : The process produces 2,000 defective parts for every million units. That's a rate of 0.2%.
PPM and Continuous Improvement (Six Sigma)
PPM bridges the gap between simple defect detection and strategic root cause analysis (Root Cause Analysis).
- Measurement Standard : PPM forces teams to see quality not in terms of success (parts that conform), but in terms of failure (parts that don't), which stimulates a culture of innovation.’Continuous Improvement (KAIZEN).
- Prioritization : Using the Pareto method on the PPM, the team can identify the types of defects that contribute most to non-quality, thus targeting problem-solving efforts (such as the’8D analysis or the 5 Why) where the impact on TRS and the Cost of Goods Sold is the heaviest.
- Anti-error systems : A high PPM indicates an urgent need to set up or reinforce systems. Poka-Yoke to eliminate human or technical error.
PPM and ROI (Return on Investment)
Reducing PPM is one of the most powerful levers for improving Return on Investment (ROI) of a company. Every point of PPM gained translates into a reduction in Muda related to waste, over-processing and loss of material (such as Refractory Materials wasted on redesign). Visit Quality rate from TRS increases mechanically with decreasing MPP.
In conclusion, the PPM is the essential indicator for companies aiming for perfection. It enables them to quantify the gap between their current performance and the ideal of the Six Sigma, The company's strategy is to focus all optimization efforts (from the Manufacturing methods Standardization) towards zero defects.