—Meeting Modern Process Challenges with Short Run, CUSUM, and EWMA

Driven by global competition and demand for personalization, manufacturing is undergoing a profound transformation—shifting from the old paradigm of “high-volume standardization” toward a new normal of “high-mix, low-volume” production.
According to our own surveys of customers, as well as statistics from publicly available data, more than 78% of discrete manufacturers worldwide now list “small-batch, customized production” as their primary production mode.
This trend is also expected to be incorporated into the new 2026 SPC standard, formally becoming a core topic in quality management.

Traditional SPC Hits a Wall in High-Mix, Low-Volume Production

In the past, mass production was the mainstream, with standardized processes, stable specifications, and roughly 25 to 30 accumulated sample groups.
Using X-Bar R charts and normal-distribution analysis, you could establish stable control limits and carry out long-term monitoring.
Adopting an SPC system effectively reduced inspection costs and improved process stability.

Today, however, these conditions may be difficult to reproduce.

To keep pace with rapid market changes, the production scenarios in modern factories have long since shifted: intermittent production, frequent specification changes, only 5 to 10 pieces per batch, and even a single line handling multiple part numbers at once. These “high-mix, low-volume” situations are gradually becoming the everyday norm,
which also poses a major challenge for applying SPC system charts.

“High-mix, low-volume” scenarios make traditional SPC charts difficult to apply, and they have led many people to start raising questions.
Can SPC still be used? Can you still plot charts when there are too few samples? Can it still give early warnings?
The answer is: Of course it can! The SPC system is still very much a necessity.

The MiDFUN SPC System Has Long Been Ready for the New Normal

Years ago, we already foresaw this shift in the manufacturing environment, and we had integrated into our SPC system the specialized statistical chart functions needed to support “high-mix, low-volume processes.” At the time, they were simply not yet widely used.
But today is precisely the moment when they can meet the changing demands of the market.

Control Chart Analysis Tools for High-Mix, Low-Volume Production-Short Run, CUSUM, EWMA

The following three tools are exactly the new quality-control solutions that today’s manufacturing shop floor cannot do without:

1. Short Run SPC-Using Z-Value Conversion to Break Through Sample Limitations
   When each batch is small in quantity and specifications vary widely, Short Run SPC can use Z-value conversion or centering methods to bring different products back onto a unified, comparable standard.
   Even with only 5 to 20 pieces per batch, it can monitor variation trends across products, free from the influence of means or tolerances, truly achieving quality control even for small batches.
2. EWMA Exponentially Weighted Moving Average Control Chart
   By blending past trends with current data, it is especially sensitive to “small shifts” and can detect process anomalies early, making it particularly well suited to short processes and high-precision requirements.
3. CUSUM Cumulative Sum Control Chart
   It tracks the accumulated amount of variation in real time, making it well suited to quality-assurance scenarios that require rapid response. It smooths out fluctuations and reinforces trend recognition, and is especially effective for gradually drifting process changes.

All of the tools above have already been incorporated into the current MiDFUN SPC system, allowing it to respond flexibly to the diverse production-line needs of today,
so that companies can maintain sharp quality monitoring and early-warning capabilities even in high-mix, low-volume production environments.

We have always believed that the core value of SPC has never changed; what has changed are the ways and the tools we use to apply it.

How should these charting tools be put into practice on the shop floor? To learn more in depth and to hear real case examples, please contact us right away.