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Flexible friends - robots can make the difference in end-of-line packaging operations


The BEUMER robotpac® palletizes and depalletizes the most different packaged goods using specifically developed gripper elements/tools. Image courtesy of Beumer Group.
Small, low cost robot arms are very easy to program and are aimed at SMEs like the UR5 pictured here. Image courtesy of Universal Robots.

Automation has been gaining ground rapidly in the food industry over the last two decades and fully automated production lines are becoming commonplace. End-of-line packaging is an operation ideally suited to automation, yet it is still done manually in many food factories, especially small and medium sized facilities. There are a number of reasons for this, but a growing need for flexibility at end-of-line and high capital costs are both major barriers to the uptake of automated systems. With rapid technological development, these obstacles are becoming less of an issue. Compact, robotized packing and palletizing systems bring more flexibility, while cost reduction initiatives are driving down the investment required to the point where even a small business can reap the benefits of automation.

 

There is a tendency within the food manufacturing sector to overlook the importance of end-of-line packaging. Once the product is processed and sealed safely within its primary packaging it is protected from the environment, from contamination and from damage. But the next steps on the production line are just as important in terms of presenting the product to the customer. Placing packed units into trays or cartons - now often required to be shelf-ready - labelling and palletizing must all be done accurately and precisely to ensure that the customer receives the correct order presented in the desired format.

Since the 1980s the trend, at least for larger manufacturers, has been to automate the processes involved. Centrally controlled machinery like tray and case erectors, packers and sealers, shrink- and stretch-wrappers and palletizers can be put together and integrated to add a dedicated end-of-line system to an individual production line. This type of ‘hard automation’ can be made to handle high line speeds very efficiently and is ideally suited to long production runs of high volume products. But the investment required to design and build a bespoke solution for a specific product can be considerable, and if the packaging changes, so the automated system must be modified to handle a new size, shape or format. Space too can be an issue. Conventional automated packaging systems are usually dedicated to a single production line and extend the area occupied by that line considerably.

Changing demands call for new solutions
The limitations of hard automation are a serious barrier for smaller manufacturers, or in situations where a variety of products are made on the same line. In these cases many manufacturers continue to rely on 100% manual packing and palletizing, or on semi-automated lines with some tasks still carried out by human operators. While human beings are much more adaptable than conventional automated systems, and are able to react to packaging changes immediately, there are big disadvantages inherent in manual handling. One of the most important relates to operator health and safety. Placing product in cartons or cases and making up pallets of packed product is hard, highly repetitive work and the incidence of repetitive strain injury (RSI) among staff carrying out these tasks is notably high. As a result, manpower shortages can be a problem, especially in regions where unemployment is low. Labour costs can also be high in many European countries. Furthermore, a manual end-of-line packaging operation can create a serious bottleneck if line speeds rise due to high demand or increased efficiencies, and additional packing staff are not available. Human error also comes into play when operators are under time pressures, resulting in wrongly packed cases, or incorrect pallet patterns.

Yet the flexibility of manual end-of-line packaging is becoming more and more important. Retailers’ specifications for palletized products are ever more demanding, while orders requiring mixed-load pallets are also increasingly common. Packaging changes and updates driven by marketing initiatives are more frequent, as are short production runs, multipacks of varying sizes and variations in pack presentation on pallets destined for different customers. All of these considerations demand above all that end-of-line packaging systems are flexible enough to handle constant change, without introducing errors that result in returned product, lost orders and additional costs. Hard automation is not designed to cope with such demands, so that even larger manufacturers are now finding that they sometimes need to revert to some degree of manual handling at end-of-line, or even bypass their automated systems completely on occasion simply to meet customer requirements. There is clearly a need for a more adaptable approach to take the pressure off human operators and exploit the efficiency gains that automation can provide.


Robot technology brings flexibility
Many automation specialists in the food industry see industrial robots as the long-term answer to the problem of greater flexibility. Robots have been used in manufacturing industry since the late 1970s and have developed rapidly as programming and sensor technology has improved. They became established in the automotive industry during the 1980s, but have since become increasingly common in other sectors, such as electronics and pharmaceuticals. More recently, food manufacturers have begun to see the value of robots, especially in Germany, Italy and other European countries with a large food industry, though less so in the UK where adoption of robot technology has lagged behind. End-of-line is still the most likely location to find robots in food factories, with case packing and palletization being among the commonest applications. However, as the technology advances, robots are increasingly finding their way into other aspects of food production, such as picking and placing delicate, awkwardly shaped food items like cooked meats, biscuits and even fresh produce.

The term robot covers a variety of automated devices, but four in particular have found applications in the food industry. Cartesian, or linear, robots can move only in straight lines along three control axes at right angles to one another. They are often used in palletizing or loading applications. The SCARA (Selective Compliant Assembly [or Articulated] Robot Arm) design mimics the human arm in that it has a jointed two-link layout, with a rotating ‘wrist’ enabling movement in four axes. It is highly versatile, can handle heavy objects and has a small footprint when retracted. A development of the SCARA concept adding additional rotation at the joints has produced an articulated arm with six axes of movement, which can tackle more demanding tasks. The first six-axis arm was launched in 1983 and this type is now employed in many automated operations across a range of industries.

US manufacturer Fanuc has developed a six-axis robot specifically for the food industry in the form of its M-430ia model. The third robot type used in food applications is the Delta, or parallel arm robot. Very different in appearance from the SCARA and six-axis types, it consists of three lightweight parallelogram arms linked to an overhead support housing the motors and actuators. The arms are connected via universal joints to a small triangular mobile platform. The platform has three axes of movement, but a fourth can be added using another arm to give rotational movement. Fitting the heavy components in the overhead unit means that the moving parts of the robot are very light, allowing the more rapid and delicate movements needed for picking and placing small items. Delta robot designs are being increasingly used, especially for pick and place operations. ABB is one of the leading manufacturers and its FlexPicker™ IRB360 Delta arms are designed for routine washing down and cleaning.

While basic robot design has improved in recent years, it is in the peripheral technology and operating software where the most significant developments have been made. For example, the range of grippers available to fit to robot arms has been greatly extended, allowing them to handle everything from a single biscuit to multiple cases for stacking. Gripper design has also improved in terms of minimizing product damage and ability to handle irregularly shaped items. A good example of this is the introduction of force/torque sensors, which can provide robot grippers with something approaching a sense of touch. Robots are now much easier to program using touch screens and drag-and-drop graphical interfaces instead of requiring knowledge of programming code. This means that they can be prepared for new operations very quickly by trained staff, without the need for expert automation engineers to make the changes.

The development of sophisticated 3D vision systems has also contributed enormously to the performance of robots. Examples include Fanuc Robotics Integrated Robot Vision system (iRVision®), Cognex Machine Vision systems and Italian-based Tattile Complete Vision Systems. These use high performance cameras to feed visual data directly into the robot’s control system, which allows it to adjust the position of the arm and gripper to correct for irregular items or positioning of packs on conveyors. Vision systems can also be used to read barcodes and labels on products - very useful for robots handling a mixed product feed - and carry out simple quality checks.
Coupled with easy-to-use software, 3D vision systems make it possible to program robots to replicate almost any task that a human operator can perform.

Finally, there have been considerable advances in the technology required to integrate robots and other automated equipment. While much of the machinery available is now modular, enabling packaging lines to be constructed and later modified easily, the various components still need to be integrated to work well together and maximize efficiency. This is a job for an automation specialist, but it has been made much easier by animated simulation software, operating rather like computer gaming technology, which enables designers to visualize exactly how their lines will operate, maximize efficiency and remove chokepoints and potential problem areas at the design stage. An example is the modelling tool Demo3D from UK-based Emulate 3D Ltd.

End-of-line applications
Robots are particularly suited to end-of-line roles where there is no direct product contact and the hygiene and cleaning requirements are less stringent than in food processing areas, such as pick-and-place into secondary packaging trays and cartons, case packing and palletization. SCARA and six-axis robot arms can accurately and consistently lift heavy loads and are ideal for these tasks. In many cases, off-the-shelf general purpose robots can be used without requiring special adaptations for food use. Robots can case pack a wide variety of products and can even handle delicate items like egg cartons, in some cases more precisely and with less damage than manual packing operations. Vision systems allow packing robots to reject items that are missing barcodes or labels, or are presented incorrectly for packing. Robots can also be used to load conventional packaging machinery with packaging materials or product, to increase the efficiency of existing systems. An example of a successful application of robot technology to an end-of-line problem is the system recently installed at Arla Foods dairy plant in Götene, Sweden. Automation specialists Graniten designed a new system to pack cheese into boxes, an operation responsible for an unacceptably high rate of RSI among workers.
The solution uses four packing cells fitted with ABB IRB 120 six-axis robots, which are able to pick up the cheese blocks from three different angles and pack them into cartons in varying patterns. The system saves about 16 man-hours each day, solves the RSI problem and is expected to pay for itself within two years.


The most common end-of-line application for robots is palletization, one of the most potentially labour intensive tasks carried out in many food factories. Robot palletizers, often based on large cartesian type robots, have been widely used for many years, but recent developments have helped them to keep pace with changing demands. The latest palletizing robots have much smaller footprints than earlier generations to fit into confined spaces and are much more versatile. They are able to handle a variety of pack shapes and sizes and adapt easily to new pallet patterns. They can handle shelf-ready packaging and operate at a range of speeds depending on the nature of the product. Examples include ABB Robotic’s IRB 760 robotic palletizer, fitted with its own RobotStudio Palletizing PowerPac software, and the BEUMER robotpac® system. Hybrid palletisers have also been developed to combine the speed and efficiency of conventional equipment with the flexibility of a robot arm. Integrated vision systems even allow a single robot palletizer to accept product from more than one line at the same time, differentiating product according to labelling or coding and loading it onto the correct pallet. This means that factories producing a variety of products at low line speeds only need one palletizer instead of a dedicated unit for each line. 3D vision control also allows robot palletizers to pack mixed load pallets specific to customer orders. The order can be programmed into the control system, which then picks the correct products and stacks the pallet according to the pattern requested by the customer. Previously this could only be done manually, with a high risk of errors. Specialized palletizing robots have also been developed for particularly harsh environments, such as freezers, where human operators cannot work comfortably. For example the Kuka Robot Group supply the KR 180-2 PA Arctic palletizing robot, which can work at temperatures down to -30°C, making it ideal for the frozen food industry.

Driving down the cost of robots
While capital costs associated with robot technology have come down as it becomes more widely used across the manufacturing sector, they remain relatively high compared with alternatives. In the food industry costs can still be a significant barrier even when ROI estimates are as low as two years. This is a particular problem for smaller businesses unwilling, or unable, to commit to high levels of investment. Fortunately, some new initiatives are helping to overcome the investment barrier and reduce costs.

The robots required for many end-of-line packaging applications are not specialized devices, but generic industrial robots. They do not need to be hygienically designed or cleanable if they are being used for palletizing.
This means that robots from other types of manufacturing can easily be adapted for such applications. Accordingly Pacepacker Services, A UK-based automated packaging specialist, has recently launched integrated packaging systems featuring reconditioned, second-hand pick-and-place robots, often taken from the automotive industry. The Blu-Robot range is serviced and reprogrammed for its new role before delivery and can be fitted with a range of different grippers and attachments. The robots used are typically a third of the way through their operational lifespan and the cost comes in at about half that of a new robot.

A very different approach is taken by Danish company Universal Robots, which has designed small, low cost robot arms that are very easy to program via a drag and drop touchscreen. The robots are aimed at SMEs and have built-in collision protection so that they do not need to be surrounded by guard rails. The smallest version (UR5), capable of handling a 5kg load and weighing just 18kg, reportedly costs approximately €22,000. Two of the UR5s have been installed at Iceland’s Mjólkursamsalan Akureyri dairy on a line producing cream cheese. The first picks 250g pots off the conveyor to pack into trays, while the second stacks the trays onto a pallet.


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