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Future-proofing conveying processes

04 February 2019

As the food industry looks at ways to modernise its equipment to cut costs, increase operating efficiencies and reliability, Stefan Hamacher highlights the important role that the power system can play in food handling applications. 

The growth in materials handling equipment is driven directly by the increasing need for manufacturers to handle larger volumes and more diverse materials and goods. With this changing landscape – as well as the demand for faster and more precise workflows – there is a compelling argument to reassess existing conveyor systems to maintain competitive advantage and meet increasing efficiency requirements. 

The trend is particularly relevant in the food handling and food manufacturing industries where engineers are being tasked modernising processes to reduce costs, increase operating efficiencies and reliability, and to enable conveying processes to handle a wider variety of product variants, while at the same time ensuring that hygiene and food safety requirements are maintained. 

Although external gear motors are traditionally used to power belt-conveyors systems there is now increasing interest in the use of drum-motor drive technology. The drive mechanism of drum motors are fully enclosed in a crowned stainless steel or cylindrical steel shell with caps and seals at each end. This shields the drive components from contaminants, a useful design feature within food environments where hygiene and thorough, regular cleaning are critical. The sealed case also makes the motor easier and more cost-effective to fit, service, repair and clean. 

For the food industry drum motors can outperform traditional gear motors terms of hygiene, ease of installation and maintenance. They are also an energy efficient option, while additionally mitigating workplace noise and minimising space requirements.

Future-proofing food handling conveyor systems may also require engineers to make a choice between asynchronous and synchronous drum motors. Asynchronous motors are commonly used in industrial environments because they are robust, comparatively cheap to manufacture, and can operate at constant transport speeds without the need for additional electronic control systems. 

In comparison, synchronous motors are able to satisfy a considerably wider range of applications and offer advantages when installed in food manufacturing and processing conveyors. For example: 

Customisable velocity: With synchronous motors, the range of possible transport speeds is significantly larger compared to asynchronous motors. For this reason, synchronous motors suit more versatile flowing processes, where goods may need automated packaging – as required for dairy, poultry and other food items. 

It is possible for asynchronous motors to operate at variable speeds, but only by installing adjustable frequency drives that are within the design limitations. Unfortunately, these drives can be expensive. If an operation requires the installation of a variable frequency drive, consider opting for a synchronous motor which is designed to function with a variable frequency drive and not the older asynchronous technology.

Advanced automatic filling: In addition to offering a wider range of speeds, synchronous motors enable quick and frequent start-and-stop capabilities. This is an optimal control feature when handling intermittent flows of materials, such as the mechanical filling of food containers and jars, or with the processing and sealing of meat and more multifaceted goods. 

Synchronous motors can also include sensor technology, which boasts significantly more precise speed and positioning behaviours – a necessary requirement in automated food-cutting processes, for example. 

Added overload flexibility: Synchronous motors are more ‘overloadable’, meaning the conveyor belt can handle loads at maximum capacity multiple times in a shorter time period without experiencing electrical or mechanical problems. This is especially useful when the belt is required to speed up or slow down quickly and dynamically, down to the millisecond. 

Improved energy efficiency: Unlike in an asynchronous motor, the magnetic field in a synchronous motor’s rotor is generated by permanent magnets and does not require additional energy to create a magnetic field. This allows the motor to operate at higher efficiency levels over longer periods using less electricity to generate the same mechanical power, which helps reduce the overall cost of running the machine. 

Reduced contamination risks: Synchronous motors, as well as some of the newer generations of asynchronous systems that include a ‘platform motor’, are certified by The European Hygienic Engineering & Design Group (EHEDG). This makes drum motors increasingly more suitable for fish and meat processing and handling, where hygiene is critical to prevent foodborne illness, contamination and bacteria growth. 

Increased power: Compared with an asynchronous motor, synchronous motors can pack more power into a smaller dimensional space, due to the small frame of the permanent magnet rotors. Conveying systems equipped with smaller drum-shell diameter synchronous motors are significantly better equipped to transfer small goods to a downstream conveyor belt, which is a typical apparatus for bulk bag and bottle filling of grains, cereals, liquids and processed foods. 

Stefan Hamacher is technical sales drum motors and controls, Technology, Interroll Group.

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