SPC: the Strangest Acronym in MES

What is SPC? Simply, SPC stands for Statistical Process Control. Statistical Process Control is used when testing product quality within production runs.

Let’s say you make 50,000 pounds of sausage everyday. In a perfect world, each sausage link would be exactly the same. But since we don’t live in a perfect world, some of the sausage links will have a little extra, and some are going to be a bit lean. The overfilled sausages will usually be tracked as “giveaway” (and increase overall costs) while the under-filled ones would likely get marked as scrap since they can’t be sold as a mislabeled product.

How do you figure out if the product is over or under filled? Take measurements along the way! Usually this means taking some spot checks throughout the production run, or check every product. To improve your process, your LIMS system will store the data and allow you to track the measurements against process values.

Once the measurements are complete, we can use statistical modeling, regression analysis, and graphical representation to see how the process is doing. Beyond simply tracking the measurements themselves, SPC will correlate them with real-time and historical process data so you can see how adjusting setpoints will impact quality.

Why is SPC Important?

Screenshot of an SPC analysis system — *An SPC Analysis System*

Simply because if we’re over or under filling the sausages, we need to know ASAP. If all 50,000 pounds of sausage are under filled and we cannot use them, then we’ve wasted all that production time. At Corso Systems, we like to use dynamic screens to depict what is occurring on a production run. This way, you can quickly gain the most information with the least number of screens.

The main goal of statistical process control is to catch an issue before it occurs. If the sausages are trending closer and closer to the limits, then there’s a problem. This could mean that there is a machine issue that requires preventative maintenance before it malfunctions. Or, it could mean that the incorrect setpoints are being used, or operator errors. Take SPC to the next level, compare daily, weekly, monthly (and longer) results against preventative maintenance and process data to better understand your process.

Don’t make sausage?

Not a problem. SPC works for any facility making production runs. All food and beverage facilities, manufacturing, automotive, consumer electronics, and most things you purchase in a store hopefully have SPC as part of their process. Learn more about Manufacturing Execution Systems.

Updated 2/15/2022