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FOOD & BEVERAGE


GO ERROR-FREE WITH DIGITAL WEIGHING


By implementing smart and adaptable weighing technology in plant machines and equipment, Stephen Hayes, managing director of Beckhoff UK, explains why food manufacturers require control automation to increase efficiency, and prevent avoidable costs due to


mechanical quality control checks which risk being inaccurate


T


he old saying ‘time is money’ reaps true across many industries. However, in the world of food processing, good quality control is money, with errors the costly enemy. From logistics and transportation to food manufacturing and agriculture, weighing technology plays a crucial role. Yet, in the past, these industries relied on manual methodologies and traditional measurement techniques.


Weighing scales, predominantly mechanical in nature, operated through spring or lever mechanisms that required manual adjustments and calibration. Such systems were susceptible to inaccuracies, stemming from factors like friction and wear, with operators carrying out labour intensive practices that made them manually position objects on scales before visually interpreting measurements.


The resulting documentation and record keeping involved paper-based methods, which are not only prone to errors but time consuming too. All of these factors made quality control very challenging, often resulting in discrepancies, delays and increased risk of regulatory non-compliance. These challenges have influenced the advancement of digital weighing technology. In fact, the global industrial weighing equipment market is predicted to expand over 1.7X between now and 2033, due to the increasing demand for automated


weighing solutions.


As an advanced technology, these replace the traditional analogue weighing systems, offering accuracy and ease of integration for the food processing industry. In blending operations, for instance, digital weighing systems use digital signals for measurement, allowing for more precise weight readings and optimal mixing performance, even with challenging formulations.


Just look at how system integrator, Taylor Controls, helped a grain blending company to upgrade its existing semi-automated process to increase throughput and support more rapid changeovers between recipes. They relied on auger feeders, start-stop motor controls and weigh cells for production, which lacked flexibility for recipe changes, meaning that the existing system was pushed to the brink and exhibited unexpected errors. Without self-learning capabilities too, the


fluctuating material behaviour in the feeder, which is influenced by type, quality and moisture content, ultimately led to deviations in weighments.


Through control technology, the process required each recipe ingredient to be dispensed into a weight scaled vessel individually. The feeder operated at high bulk speed initially before transitioning to low dribble speed near the setpoint for precise weight attainment. In addition, the system also autonomously learns the free fall


34 JULY/AUGUST 2024 | PROCESS & CONTROL


amount post-dispensing to accommodate fluctuating conditions, ensuring accurate and consistent ingredient measurements. To achieve this, motor controls were upgraded from simple starters to a variable frequency drive (VFD), which networked with the host programmable logic controller (PLC) via Ethernet, enabling precise speed control. In cooperation with the PLC, a human- machine interface (HMI) platform was also integrated. Its user friendliness and large graphical space allowed for visuals on batching and mixing status, dry ingredient auger free fall calculations, formula selection and dry ingredient recipe configuration. Accurate weighing is a crucial part of the process within food manufacturing applications. From the initial raw material inspection to the final product shipment, sometimes they span the full process. Interestingly, they influence how every batch looks and tastes too, with inaccurate weighing of raw ingredients causing food products to be out of specification. And that’s before factoring other potential slip ups, like issuing raw materials into a batch that has not passed its quality control checks or incorrectly adding raw materials to a production batch.


All of these mistakes cost money and come at an unwanted price. Unfortunately, there have been several food product recalls because of these types of errors, where a lack


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