Pros and cons: balancing the robotic equation

24 July 2013



When it comes to end of line palletising operations, robots continue to become increasingly popular - but there is still plenty of demand for traditional systems, reports Nessan Cleary


Few packaging production lines are complete without some system for loading the final packed products to pallets ready for transport. These days, automatic palletising has become the norm thanks in part to safety regulations concerning manual handling and the growing necessity for businesses to reduce labour costs. But automated systems also have the advantage of working round the clock and adjusting easily to the loads going through the system.

The market has been dominated by traditional systems based around layer palletising machines, but Andrew Lawless, sales director at Phoenix Handling Solutions, says there has been a steady swing towards robots over the last 10-15 years. He notes: "They are more flexible. A robot can be stacking bottles today and cases tomorrow, because you can simply reprogram it and move it somewhere else."

However, using a robot does require some technical expertise as to how the robot itself works and the system within which it is
being used. But then, as Lawless says: "Robots are more reliable because they have very few moving parts."

Phoenix puts together systems using both layer palletisers and robots from different suppliers. It recently signed a deal to become the UK agency for the Italian palletising company Lorenz Pan. This includes the Europal49 low-level palletiser, a cost-effective option that can reach 30ppm.

PHS integrates robots from several suppliers, including ABB and Fanuc, depending on the customer's applications. Lawless says most robots offer a similar level of performance and reliability, adding: "The thing that will distinguish which type we use might be a technical reason such as the reach of the payload or the customer's preference."

Lawless also says that as a rough rule of thumb, it is the younger generation who prefer robots, whereas older people are used to the traditional palletisers.

But he adds that the determining factor for whether a robot or palletiser is more suitable is normally throughput: "If it's above 20 cycles per minute then a robot is going to be flat-out unless you have multiple picking." Lawless says it's a trade-off between the
speed of the product and the stacking pattern that you are building. He says: "The palletisers may be faster but the robots are
more flexible."

Indeed, quite a few manufacturers only supply robots. Bob Lloyd, former British Robot Association chairman and now part of the sales team at Kawasaki Robotics, argues that they are easier to configure than a traditional palletising system. He says that robots are more versatile because they can be programmed: "With a robot you can have multiple pallets and it can be palletising different patterns," he says, pointing out that it's often easier to fit a robot into a confined space, as there's a lot of reach in the arm.

Kawasaki Robotics has a selection of robot systems, but two in particular are designed for palletising. The Z series is a complete robot system capable of handling loads up to 500kg. By contrast, the R series is an arm that is more suitable for loads of up to 80kg.

Lloyd says that although any robot could be used for palletising, these systems have specific features such as the ability to keep the case parallel to the ground. He says: "They tend to be quite a long reach as you need to be able to reach over, and they need to be quite fast and to have good connectivity."

Robots generally offer several ways of picking up objects, such as mechanical or vacuum grippers.

Lloyd says: "The only time you might have an issue is if you have a mechanical gripper and you have to be able to get it in and out again when you put the case down, but there are ways around that, like putting the case down and nudging it over." He says that the robot has to be seen as part of the total system: "We have an example where we are gripping bottles and they can roll around because the shrink wrap is still hot at the point where we are palletising them. So we use a mechanical gripper to constrain them, which is more expensive than a vacuum gripper, but it suits that application."

One happy customer is contract bottler Edwin Holden's Bottling Company, based near Dudley, to the west of Birmingham, which recently marked 70 years of business, working mainly for small to medium-sized ale brewers. Holden's invested in a Kawasaki FD-50N palletising robot and a pallet positioning area. Pallets are manually positioned into the guarded area of the robot cell and the robot accurately positions cartons in a preprogrammed pattern. A cartonboard separator is positioned, by the robot, onto the top of each pallet layer when complete. Full pallets are removed manually and the cycle is repeated.

Production manager Mark Hammond explains: "We fill five bottle types and pack into eight different size cartons varying in weight from 6kg to 13kg. So the system design needed to allow for flexibility and fast program changeovers, to allow handling of over 30 tonnes per day."

Another well-known supplier is Webster Griffin, which sells the Okura range of robot palletising systems. These have been designed specifically for palletising and can be sold as standalone robots or as part of a conveyor system. There's a range of different gripper systems to suit most types of products, including boxes, bottles and bags.

The latest Okura series III boasts minimal maintenance and has a fully automatic OXPA programming system (Okura's specialised 'user-friendly' palletising software) to develop and select new pattern programs. There are four models, handling from 400 to 1,600 cycles per hour.

The top of the range Okura A1600-W can handle a 300kg payload to pick and place one layer at a time. One robot can load up to six pallets, with each robotic arm having 360 degree movement.

Okura also has a smaller robot, the Bilatron Jr, available in two versions for 40kg, running at 2,400 cycles/hour; and 60kg, running at 1,800 cycles/hour. These come with a standard control panel which includes a Soft-PLC, so that they can be supplied as a standalone unit.

Conventional options
Enterprise Tondelli
mainly supplies the food and beverage market and uses both traditional palletising and robotic systems. Managing director Craig Wilson says these can run up to 11 layers/min, "which is very, very fast". Features include 3D hand turners
that can grab a box and rotate it through 90 degrees and place on a layer. This avoids using an arm to knock a box, which is a common technique for turning boxes around, but which can risk damaging bottles, particularly given the current trend towards
lighter weight bottles.

Tondelli recently installed a palletiser line at a water bottling company that had two lines running at 20 packs/min, with one for
glass bottles and the other for PET bottles. Space was at a premium, which ruled out the obvious solution of an automated robot. Wilson explains that a robot would use fingers down the side of the bottle packs to pick them up, without any support underneath the packs, which would then leave a gap between the packs.

Instead, Tondelli used a single palletiser capable of processing both lines at the same time. The machine has two pre-formation areas, each dedicated to one product. The single palletising roller platform head selects from either of the two pre-formation areas
and then deposits onto either one of two pallets, which switch on a special pallet conveyor, thus using the space of a single palletiser but servicing two lines.

This solution was not only cheaper but also saved real estate and will be easier and therefore cheaper to maintain.

Supplier Penn Packaging sells the Meypack range, which includes end of line conventional palletising systems. Meypack supplies machines for shrink wrapping and for wrapping products in corrugated packaging so the palletising solutions are designed to handle these type of products. So, not surprisingly, Penn sales and marketing director Miles Goodwin estimates that about 75% of the installations are for food and beverage applications.

Goodwin says that such systems are better suited to medium and high volume applications than robots, noting: "They are able to handle a greater volume of products. Robots have a limited speed per cycle and during that time they can pick up multiple boxes,
whereas a high speed palletiser might be able to do five or six layers of a pallet, which is much faster."

Meypack's PK Series of layer palletisers are available with either low level or high level infeeds. They have a modular design so can be constructed in such a way as to fit the available space. They use servo technology with synchronised belt drives and process all standard pallet sizes. The low level system can handle up to four layers with one infeed, while the high level system can handle up to six layers/min.

In some respects reducing the choice of a palletising system simply down to the use of robots or layer palletisers misses the point, because there is a complex balance between the cost of installing and maintaining the system, and the level of productivity required. But also decisions such as whether or not the products are to be shrinkwrapped directly affect which kind of palletising system is
ultimately going to be more cost-effective.




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