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Some of the products - particularly greenhouse vegetables and hard fruits - are packaged by the company before being delivered to retail. Packaging "traffic lights" - packets that each contain a red, yellow and green bell pepper - is a particularly labour-intensive task. With the help of a vision system and delta robots supplied by Omron, EasyPack Technologies has automated how the bell peppers are picked up and positioned. The result is a process that is more efficient and less prone to failures.
Combilo works with its suppliers and customers - including well-known European retailers and wholesalers - to provide consumers with fresh fruit and vegetables on a daily basis. Some products are delivered unpackaged; however, a significant number - particularly tomatoes, bell peppers, and cucumbers - are packaged first.
In his role as Production Manager at Combilo, Marcel Villerius is responsible for the packaging department, which consists of multiple packaging lines. In the last few years, a range of measures have been introduced to improve packaging efficiency. "For example, the layout of the department has been rearranged, which has optimised internal logistics. We are constantly looking for ways to improve our efficiency and are attempting to automate our operations as much as possible."
Packaging "traffic lights"
Since 2015, the hall has hosted a robot that is part of a packaging line for "traffic lights". The hall houses five lines that make millions of packages every year. "A conventional line is staffed by seven people," explains Villerius. "One person fills the trays with bell peppers of each colour. Three employees then correctly place the bell peppers on the belt in the correct colour order by hand. The bell peppers are sent through a flow packer in sets of three, where they are packaged in film. An operator stands by the packaging machine to check the supply to the machine and remove any failures. Once the bell peppers have been packaged, a check weigher checks the weight of the package. If a package is too light, it is removed from the line. Two employees stand at the end of the line to place the "traffic lights" in a crate and stack them on pallets."
Combilo decided to purchase a robot-assisted line to make packaging the triple-packs of bell peppers more efficient. "The automated line essentially does the same thing as a traditional line," says Jeroen Bugter, Director of EasyPack Technologies, the company that developed the robot-assisted line. "An employee fills the trays with bell peppers of each colour, before three robots assume the role of the employees who place the bell peppers on the belt. The robots pick up the bell peppers and correctly position them on the belt in the correct colour order, before they are sent through the flow packer. The process following the packaging machine stage remains the same."
Load cells and vision
Although the role of the robots may seem limited when viewed in isolation, the robots' control mechanism is underpinned by an intelligent concept. "Picking up items by hand results in packages that are too heavy and contain too much product or packages that are too light and have to be rejected," explains Villerius. "The starting point for the robots is a weight of 500 grams per package. The bell peppers are sorted and then delivered in weight classifications of 140–160, 160–180 and 180–220 grams. Load cells are integrated into the belts used to transport the bell peppers to the robots. The cells relay the weight of the individual bell peppers to the weight converter. When the first two robots pick up a bell pepper, they can choose between the two conveyor belts. When it comes to the last colour, there are four belts, so the robot has a greater choice to bring the total weight of the three bell peppers as close to 500 grams as possible."
But that is not all. After the bell peppers are weighed, the vision system - comprising three cameras - relays the position, the location of the bell peppers and the shape of the stem to the system. This then allows the system to calculate precisely how the bell pepper should be packaged and turned so that it can be placed in the correct position on the belt. According to Villerius, working with bell peppers is especially difficult because their shape varies so much and their stems are also rigid, so they have to face inwards to prevent the packaging from ripping.
Equipment from Omron
Two companies were involved in developing the automated packaging line. The contractor for the project was EasyPack Technologies; a young company that develops and builds packaging machines for the food industry. EasyPack worked closely with Rons Electronics Supplies; a regular partner that handled the electronics and controls. Virtually the entire control mechanism of the robot application - with the exception of the load cells and the weight converter - was supplied by Omron.
Jeroen Bugter from EasyPack Technologies explains which components were used for the installation: "We used three Omron R6Y Delta-3 robots. These are waterproof variants that can be cleaned thoroughly; this is important in the food industry, which sets high standards for hygiene. Each robot has four servo drives that control the three robotic arms and the rotation axis. Omron also supplied the FH-5010 vision system with three cameras and the controllers for the conveyor belts. Each robot has its own control box for the servo drives, and the central control box contains no fewer than 27 frequency controllers for the belts, as well as a NJ501 robotics controller. The latter processes the information about the weight, position and belt speed, thus steering the three delta robots. An encoder is installed on the flow packer to control the speed of the robots, ensuring that they run at exactly the same speed as the packaging machine. What is special about this is that all Omron components and controllers involved in the installation exchange data with each other via an EtherCAT network."
Rons Electronics Supplies used the Sysmac Platform supplied by Omron to configure the installation. According to Director Ron Schinkel, this is an efficient and flexible way of programming how the machine is monitored and controlled. The robots and the packaging line are operated using a touchscreen that allows the operator to configure and control parameters such as weight, position, and belt speed through simple pictograms. The display also shows error messages.
Product feed and rejections
"Rejected packages have to be unpacked manually and the bell peppers have to be returned to the start of the line. This is a time-consuming process, and the extra handling is detrimental to the quality of the bell peppers," explains Villerius. "The load cells and the weight converter control the robots so that the vast majority of packages now come out at the desired weight. The robots save us time, reduce the number of rejected packaged products, and use less packaging material."
Villerius is happy with the new robot-assisted line. After a year of test runs and a few adjustments, the performance of the line is outstanding. The robots save on manpower, and the robot-assisted line provides a productivity that is 30% higher per FTE than a traditional line - a comforting fact in a time where it is becoming increasingly difficult to find personnel that are adequately suited to the job.
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