The drive to integrate - controlling the complex conveying system at a snack food plant

The choice between fully integrated systems or a mix-and-match approach can be a difficult one for engineers seeking to optimise drives and control systems. By selecting from different suppliers, they can match each component in the system to their overall design. Alternatively, integration offers simplicity, guaranteed compatibility and the advantages of dealing with a single supplier. In a recently installed snack food conveyor system, an integrated system of MOVIFIT drives was implemented without compromising the design objectives.

A quick check of the local supermarket shelves gives a clue as to the complexity of the snack food manufacturing process. The variety on display is enormous. Everything from high-energy breakfast alternatives and morning pick-me-ups to chips and party foods is readily available.

Imagine, then, the logistical exercise of continuously moving all these different snack foods through a clean manufacturing plant, where hygiene, energy efficiency and reliability are the priorities. To achieve the tight production schedules, all these items must be boxed in their various manufacturing zones and moved along sophisticated conveyor lines to the appropriate packing and despatch areas. Design of the conveyor systems and the motors and drives that power them is of critical importance in this environment.

According to Jason Thompson, director of Contech Engineering, there was no need for compromise when designing the drive system for a recently installed snack food conveyor system in Sydney. By choosing integrated and flexible motors and drives from a single supplier that was able to meet the technical requirements for the entire system, his design team had the best of both worlds. While the mix-and-match approach had worked well in the past, the opportunity to source suitable drives and electronics from a single supplier, SEW-Eurodrive, produced the optimal result at the snack food manufacturing plant.

The layout of the snack food plant called for a complex set of conveyor lines, feeding into the despatch area like a multitude of tributaries flowing into a major river. From the manufacturing line, each snack food carton is placed on a conveyor that joins other lines before moving at a steady rate to an upper level in the manufacturing plant. To achieve this, and to keep the snack food production targets on track, the design incorporated a number of high grip and inclining conveyors. At the upper level, these lines feed into a single conveyor that carries the cartons to the distribution area.

Investment and planning

Thompson had a clear goal in mind when planning the project. “We were looking for a reliable and integrated system of drives to keep the conveyor belts moving,” says Thompson. “We wanted simple drive operation and decentralised installation, to save on space and cabling costs.”

To accomplish this goal, Thompson deployed 34 MOVIFIT FC, 0.75 kW variable speed drives. “The decentralised control units of the drive systems required less cable and fewer cabinets in the field, and that was where we made most of the space savings,” he says. This reduced the design complexity and overall costs, while allowing for easy diagnostics and maintenance. The simplified design also reduced possible sources of errors in the wiring-up stage.

The layout of the snack food plant called for a complex system of conveyor lines.

The use of these standardised, industry-specific components for the conveyor system allowed Thompson and his team to minimise the amount of time spent on planning and reduce costs accordingly.

The decision to close couple the gear motors to SEW-Eurodrive decentralised motor controllers was a significant step says John Gattellari, national industry specialist food and beverage, with SEW-Eurodrive. “The inclusion of our MOVIFIT system, particularly suited for food-grade environments, provided a perfect match in terms of compatibility and reduced the time required for installation and set-up. We provided some initial training and they did the rest. The system has run like clockwork ever since,” he says.

Gattellari says that the MOVIFIT solution allows for flexible topology, which simplified the design process for the snack food conveyor system. This was aided by built-in local intelligence and local control functions.

Isolators are also local, providing an important safety feature. Additional protection devices were not required for the snack food application. This is typical of such projects and applies to wet areas as well.

Energy efficiency was another important consideration in the design of the snack food conveyor system. “The energy efficiency of the drives reduces costs, while also complying with new energy-efficiency laws,” says Thompson.

Decentralised

Being modular and flexible, the MOVIFIT drive control fulfilled Thompson’s important criteria for decentralised drive systems, with fewer components required in the system design. A decentralised electronics unit enables control of several drives, which reduces the number of units required in the system.

The three versions of the unit available afforded his team the options they sought for the snack food project. A flexible communication system was a major requirement. The designers selected DeviceNet for this project, and also had the choice of other commercially available fieldbuses such as Ethernet, PROFINET, PROFIsafe and PROFIBUS.

Looking to the future, the system offers easy diagnostics and maintenance; for example, when the electronics are replaced. Expansion of the system can be carried out with minimal disruption due to the modular, decentralised design concept. Furthermore, the modules can be re-used, reducing project planning time and costs. Gattellari says that the units have been designed with installation in mind. The inside of the robust housing is large enough for electricians to comfortably work in, so that any wiring that may be required can be completed quickly and efficiently.

Minimal training

The connection technology enabled quick installation and commissioning. With SEW-Eurodrive providing training from its Drive Academy, Contech Engineering only required two half-day sessions for one of their engineers in order to complete the project. Following this training, the installation and commissioning of the drives was carried out by their own staff.

“All we required was updates on the new technology to assist with the design,” says Thompson. “The process was straightforward and we are familiar with SEW-Eurodrive equipment as we have used it since our inception 17 years ago. The robust housings of the MOVIFIT drives add to the reliability of the conveyor system. The drives are excellent - second to none.”

After the conveyors were built and tested, they were disassembled in preparation for shipping to site. The entire project took eight weeks to complete, with the locally assembled drive units delivered within three weeks of the order being placed.

Despite the complexity of the conveyor system, Thompson says that because of the system design and the equipment chosen, disassembly and reassembly on site were easily implemented.

The integrated design approach, with all drives sourced from a single supplier, allowed Thompson’s team to reduce the complexity of the conveyor system by minimising the number of different components. At all phases of the project - planning, design and implementation - this approach proved to be cost effective and fulfilled all technical requirements. For the snack food conveyor system, integration of the drives was achieved without compromising the design objectives