SPC in Manufacturing: The Key to Quality

Clara Garviliuc
Contributing Writer

Statistical Process Control (SPC) is an industry-standard methodology that uses statistical techniques during the manufacturing process. Managers can get quality data in real-time during manufacturing and plot the data on a graph with predetermined control limits. The capability of the process determines control limits, while the client's needs determine specification limits. Food quality SPC is a means of measuring and controlling quality outcomes during food manufacturing or processing. According to the American Society for Quality (, Walter Shewhart developed the practice in the early 1920s to record data and help manufacturing companies observe unusual events versus typical process performance.

Here, we look at how these practices continue to deliver value for food and beverage companies today.

What Is the Role of SPC in Quality Improvement?

By implementing SPC, manufacturers use quality data to record and predict deviations in the production environment. The data is plotted on a graph, incorporating factors like control limits (natural process limits) and specification limits (the requirements set forth by the corporate). When data is recorded and falls within control limits, it indicates that everything is operating as it should.

However, a product can fall within industry specifications and still not meet corporate expectations. SPC can help manufacturers address deviations to reduce defects and waste from the production line, as well as satisfy customer expectations. The goal is to minimize the amount of rework or scrap as well as recall of a batch or several batches due to customer dissatisfaction. Many companies run processes and then utilize inspections after the fact to ascertain the final quality of a product before sending it out. Inspections are helpful as an additional screening tool, but they do not address process problems until the batch has already been run. The customer doesn't get the lower-quality product, but the manufacturer wasted the material, overhead, and operator hours. SPC is critical in proactively responding to issues while they are minor. Inspections function as a reactive tool.

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Using SPC in Real-Time to Improve Quality 

SPC charts have been around for decades, but then and even now, in many cases, managers must manually record the data in SPC charts and graphs. Not only is this method time- and labor-intensive, but it also introduces the opportunity for human error and takes time to complete. Now, however, food and beverage companies can employ food quality software to produce reports automatically and implement SPC

Utilizing an SPC software like SafetyChain helps to get everyone on board, from enterprise-level all the way to the operators on the production line. Managers can customize charts, and the software generates automated reports in real-time. Customers tolerate very little variation in food quality and taste. Real-time notifications allow operators to act quickly to make minor adjustments, correcting deviation before it affects the entire batch or multiple batches.

How Does SPC Software Help with Quality?

The margin of error for food manufacturers grows slimmer seemingly by the day. From the cost of raw materials to turnaround time, competition drives facilities to closely monitor production processes to allow for faster course corrections. Quality software will enable teams to identify and correct non-conformances promptly using real-time data capture and specification verification. It actively monitors operations to ensure outcomes are falling within your predetermined limits. 

When results do fall outside the control or specification limits, the software triggers alerts so the appropriate individuals can respond quickly. By applying this real-time SPC method, managers can ensure every shift achieves a consistent, efficient, and quality output. The analytics produced can also help managers monitor KPIs and drive continuous improvement over time by uncovering trends that can be addressed to promote maximum productivity and consistently on-spec customer shipments.

Manufacturers can customize the KPIs that matter to their facilities in SPC software. Here are a few of the most critical food manufacturing analytics:

  • Throughput—How well the process can produce units free of defects is an important indicator of the condition of the equipment.

  • Yield—Output divided by input and expressed as a percentage provides a simple number that everyone can understand.

  • The number of non-compliance events—A higher number of deviations can result in diminished quality and customer rejection, even if the product is within specs.

  • Downtime to operating time ratio—Often overlooked, the amount of time a piece of equipment or a line is down for repairs or other issues impacts the throughput and on-time delivery to the customer.

  • Reject ratio—Successful implementation of SPC results in an improved ratio of rejected material or scrap versus high-quality material the customer will accept. 

Benefits of SPC Software 

There are many SPC software platforms available today as more and more manufacturers adopt a prevention-based strategy. Response time to customers can make or break a manufacturer, and SPC software platforms instantly alert operators when an issue occurs. While the needs of manufacturers vary widely even in a single industry, SPC software can offer several critical benefits, including:

  • Customized X-bar S and X-bar R charts and control limits

  • Built-in run rules—Tests that ascertain whether the food manufacturing processes remain within statistical control

  • Automated report generation that instantly benefits everyone involved in the process and consolidates all of the data that everyone can universally understand

  • The ability to update specifications within the platform as industry standards adjust to customer demand

  • Managers can hone in on the requirements of individual facilities and also utilize the platform to make performance comparisons across multiple facilities.

You can learn more about how implementing SPC in your food manufacturing facility can vastly improve yield in this webinar Putting SPC to work in your facility, as well as how tools like SPC software can give you the edge to outcompete in an ever more crowded field.

Statistical Process Control Intro video