Outdated control systems cause product quality issues

Chris Jones, group sales manager, controls, tna,​told FoodProductionDaily, product quality issues are often caused by badly specified, outdated or poorly configured control systems.

“Improving traceability throughout the entire production chain can help operators regain control over product quality and food safety​,” he said.

Food safety regulations​

“To achieve this, it is important detailed and reliable data from as many parts of the production process as possible is collected and evaluated​.

“For example, barcode scanning and in-line monitoring systems can ensure products are within specification and adhere to food safety regulations. ​

"Using a tracking system to monitor any goods that arrive, control existing stock and keep up-to-date on products’ shelf life, will reduce raw material wastage, make inventories more accurate and maintain product quality​.”

He added control systems, such as programmable logic controllers (PLC) and supervisory control and data acquisition (SCADA) can be integrated into existing production lines to expose inefficiencies.

They can also identify where technology could improve workflow.

“As production lines become more automated, products are now processed at unprecedented speeds, increasing the chances of damage or breakage​,” said Jones.

“Often caused by inaccurate control equipment or badly tuned processes, material waste is a real problem for any plant manager and can affect the entire production cycle. If unnoticed, just one fault could cause damage to a large number of goods, resulting in unnecessary downtime and excessive wastage​.”

Reliable product flow​

According to Jones, a user requirement specification (URS), control system can identify key performance indicators (KPIs) that a particular manufacturing process requires.

Once analysed, the URS is translated into a functional design specification (FDS) that can be used to tighten up the process leading to a smoother and reliable product flow.

“Control systems typically require a precise set-up and careful tuning to ensure efficient processing​,” he added.

“Due to practical reasons, however, control systems are rarely commissioned with a full set of finely tuned control loops. As a result, many variables are simply left to chance, causing frequent stoppages, affecting product quality and diminishing production line efficiency​.”

Jones said it is essential for operators to revisit the original PLC control code and fine-tune the proportional integral derivative (PID) loops.

Some plants may require more complex loop tuning, in which case operators should consider a model-based controller. This system sits above the PLC control loop on its own PC-based platform and predicts the direction the process is taking, initiating corrective actions before it can deviate from its set points.

Soaring energy prices​

“With energy prices soaring, keeping a close eye on consumption levels is essential for all operators to maintain profitability​,” said Jones.

“According to the Carbon Trust​, a 20% cut in energy costs can represent the same bottom line benefit as a 5% increase in sales. By deploying sensing equipment, such as flow meters, motion sensors and kWh meters, energy consumption can be monitored across the whole plant​.

“Once a control system has been installed, it can provide operators with detailed energy reports, giving them the viability they need to ensure energy is only used when and where it is needed​.

“Keeping energy costs low is a good way of achieving a more efficient and sustainable production process. However, as production output levels increase, so does the amount of discharges and emissions into the environment​.

“Industrial pollution remains a major problem within the industry and poses a real environmental threat. With governments across the globe closing in on polluters, the lack of an effective environmental control system can not only incur huge financial losses, but in some cases even result in plant closures. Detecting violations and leakages quickly is therefore vital to maintain sustainable production.”

tna is exhibiting at Snaxpo, Dallas, US, from March 1-4, 2014.​

Click here to read tna’s White Paper​ on automation.