Process control: integration, safety and traceability

In the past and, indeed, at present, a typical food manufacturing plant would be controlled by five or six separate systems, including one for batching, motion, safety and processing.

While this may get the job done, it is not often the most cost and time efficient way for a plant to run.

For instance, integrating the production process so that all machines communicate with each other becomes difficult, particularly since machines supplied by various original equipment manufacturers (OEMs) in the one plant will be programmed differently.

It becomes time consuming and expensive for these multi-vendor systems to communicate with each other to ensure a smooth production run.

The integration of different control systems is possible, but a lot of engineering is often required for information to be exchanged between machines, representing an additional expense.

Streamlining production

Integrated control refers to a single platform that facilitates communication between machinery, supervisory systems, manufacturing execution systems, and a company’s enterprise resource planning (ERP) system, using industry standard communication networks such as an industrial Ethernet.

Automation companies Siemens and Rockwell Automation supply control systems that not only streamline processing equipment but offer single, multidisciplinary control systems that can be integrated into a company’s ERP.

Integration capabilities such as those offered by Siemens and Rockwell Automation, which include increasing machine and product safety, traceability, production efficiency, flexibility, product changeover times, and reducing machine downtime, meet the demands of food manufacturers.

Siemens’ Component-Based Automation System, for example, counters the difficulties associated with machine-to-machine communication.

“Put simply, our system looks at a machine’s electrical and mechanical parts as a component and creates a shell, or a predefined format, for communication between one machine and another,” Siemens business development manager Daraius Battiwalla explained.

“Once the OEMs provide those components, the system integrator only has to worry about one thing – connecting the appropriate inputs and outputs of the components so the data can be exchanged seamlessly.”

This replaces the complicated task faced by engineers connecting conflicting control systems and software platforms.

Return on investment

Integrated control offers manufacturers a good return on investment.

Having one system results in a low cost of ownership as a result of reducing integration costs due to simplified engineering, being able to carry fewer spare parts in inventory, having one software environment to buy, maintain and upgrade, and having fewer training costs for maintenance personnel.

Integration can also decrease product changeover times and the time taken to get a product to market.

It can also assist with scheduling and order execution, making production more efficient and profitable.

Rockwell Automation identifies flexibility in manufacturing as a major demand and challenge for food companies that rely on quick product changeovers to introduce new products to market.

“In the past if a beverage manufacturer, for instance, wanted to roll out a new soft drink line using the same machinery, but was just changing the product’s label and ingredients formulation, the changeover could take months,” Rockwell Automation field business leader for Integrated Architecture, Geoff Irvine said.

“However some of the companies we have been working with can now do this in a matter of minutes.”

“With integrated control systems, it’s a simple case of reprogramming the central control unit to produce X instead of Y, and the machines will take it from there.”

Multidisciplinary control

Rockwell Automation supplies a plant automation solution, known as the Integrated Architecture, which is founded on the Logix multidisciplinary control platform and FactoryTalk plant information system.

This enables one controller to look after different aspects of production including processing, motion and safety, reducing the cost of introducing numerous systems and training staff, while promoting seamless, simplified, and efficient production.

Unlike conventional programmable logic controllers (PLCs) that are typically designed for sequential control, the Logix platform is fit for sequential, process, motion, drive and safety control.

The system can also control the motion of robots that, for instance, gather the finished product at the end of the line and place it onto pallets.

It can perform safety functions on the same platform, preventing working injuries.

Siemens’ agrees that multidisciplinary control systems simplify production and offer manufacturers cost savings.

“We offer an integrated system for doing normal control as well as safety control from the one PLC,” Battiwalla said.

Track and trace

Both Siemens and Rockwell Automation recognise food safety and security as major priorities for food manufacturers.

Having the means to track a product throughout the supply chain, or trace a finished product back to its raw materials suppliers is vital, particularly for food companies exporting to the US, Europe, Japan and New Zealand.

An integrated system that links the data collected by the real-time process control system to a company’s ERP system to produce a concise, consolidated report that displays a product’s genealogy is essential for brand protection.

Siemens supplies a manufacturing execution system (MES) that sits on top of the control system and facilitates data exchange between the control system (real time) and ERP system (transactional).

The MES layer also tracks and traces through the supply chain.

“Once the batch process is completed, all the product information, including its raw materials, ingredients, and the process parameters and alarms, is recorded against the batch ID and is stored in the MES and then transferred into the ERP,” Battiwalla explained.

“In the incidence of milk contamination, the MES allows the manufacturer to identify the batch that has been contaminated, into which cartons the milk has gone and where it is sitting on the shelf, and they can do silent recalls.”

Rockwell Automation’s FactoryTalk system incorporates various software applications that provide different plant information and MES needs.

One of these is FactoryTalk Historian, a plug-in module that performs a tracking and tracing function at the machine level.

FactoryTalk captures data at a faster speed than a computer and feeds the information into the company’s ERP to produce an electronic report showing details of what is being made, and how.

In the event of a product recall this reporting mechanism performs a vital role and it can also assist in ensuring product consistency during the processing stage.

Rockwell Automation’s Irvine said that in biscuit manufacturing, for instance, the flavour of the biscuits can be altered by outside conditions such as temperature, resulting in the product having to be reformulated.

As FactoryTalk keeps a record of all processing data, the manufacturer can use it as a point of reference if, and when, a similar problem occurs.

Process control systems that not only integrate different functionalities into the one control platform and enable one machine to communicate with another, but which feed information into an ERP for reporting, are becoming increasingly sophisticated and in demand by manufacturers wanting increased product safety, flexibility and production efficiency.

When asked whether a company should invest in a good control system or good machinery Irvine said while it is important to have both, a good control system that is fully integrated will enable manufactures to get the most out of their existing machinery and process in general.

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