Raamsdonksveer, May 2003

Press release

A robot is not a palletiser

A robot on its own is not a palletiser but when equipped with a gripper tool and a complete periphery of conveyors and controls then yes it is a very flexible palletiser. However, there are advantages and disadvantages. The question is when to consider using a robot to palletise or when to use a conventional palletiser. Furthermore it is also a search for the most suitable system solution for “end-of-line” or “multi-line”?

Besides the robot itself, a palletising robot needs more, like a pickpoint, a gripper, a safety fence and a pallet in and outfeed. A simple calculation rule proves that a palletising robot in the end will cost about three times as much as the robot itself. But today a robot is thought by many to be much more attractive than a conventional palletiser.
The robot is extremely flexible in picking up individual or groups of cases. Robots are fast, but will however never reach the speed of traditional palletisers that can normally deal with much higher capacities. Robots approach the products from above or from the side. Palletisers carry their products from below (support their products). Robots are built up of separate modules while palletisers are more integrated. That’s why robotic solutions often ask for a more thorough study and are therefore more expensive than the more standardised, traditional palletisers. However, the latter can more easily deal with a more extensive range of products. A robot would need a different gripper tool for this.
How can one see the wood for the trees? CSi developed a CD Rom on how to select a system including an evaluation table that hopefully makes the choices clearer and easier to make.
At the same time one can appreciate that more often than not there is not one but many solutions to a problem and that a lot depends on the specific circumstances in a company. In addition there can also be a combination of both types of palletiser which can provide a solution for the more complex system.

Questions, questions and more questions
Certain criteria that should be taken into account with every solution are the products to be handled, the cost price, the required capacity, the layout, the reliability of the solution, the technical experience available (with regard to training, maintenance etc) and the standardisation.  A great deal of questions will have to be answered. What are the features of the product? Can the product be palletised by a robot? What does the product range consist of? Which volumes have to be dealt with within which time frame? At all times one will have to take into consideration the investment costs as well as the operational costs. Is there enough space available and how easy is the daily operation of one or the other options? How does the solution fit within the existing equipment? Is there any flexibility on top of that? What if the machinery breaks down? Is there a back-up facility?

CSi produced a list of different palletising options. Automatic palletising can take place at the end of just one line or at the end of several lines simultaneously. In both cases one can immediately link the palletising to the packaging line or transport the separate products in order to palletise them elsewhere in the factory. If more lines are involved variation can be made between multi layer and multi load.

Before a palletising project starts it will depend on many factors, for example the available space, the direction of the packaging lines, the product flow, the capacity of the packaging lines, hygiene regulations and the general philosophy of the company.

One product
If one starts palletising immediately after the packaging line it might be possible to completely control this part from the packaging area. Another advantage of this is that less product is being accumulated between packaging and palletising so that less conveyors will be needed to bridge distances.
On the other hand the palletising element will occupy space that could have been used for production and each line has to be equipped with a palletiser or robot.
If one wants to keep pallets away from the production area then the palletising will have to take place elsewhere. This will require the use of extra conveyors which can also be used as accumulation. If enough space is available one can choose an installation with more palletising places. In this case one will also end up with one palletiser per line. If necessary an additional machine can be put in as a back-up.

Different products
If limited space is only available one can arrange a minimum number of conveyors to its packaging lines only a robot can offer the solution. In this case the pallet will serve as a carton buffer. This requires a central in- and out-feed of pallets and it should also be taken into account that it will become very difficult to build in any margin or redundancy in the process. Furthermore robots have a limited capacity. In short: although a robot is a cost efficient investment it will occupy production space and is a vulnerable solution because only very limited product accumulation is possible. In case something goes wrong downstream (with the palletising or transport of products) soon the packaging or even the production will have to stop.
A robot is the single solution if one wants to palletise more lines further away. Cartons can be transported via conveyors, so that some accumulation is possible. Pallets can be supplied and removed centrally without having to be transported through the production area (think of the hygienic advantages, no dirty pallets in the production area.). Because of the length one can also take care of some of the redundancy. However, such a solution will always be more expensive than a robot immediately linked to the production line.
The choice for a robot or a palletiser is less clear if one starts palletising outside the production area and is able to work on different levels, which means carton accumulation conveyors connected to the ceiling or a platform. Then the choice depends on actual possibilities. Can more lines be brought together on one machine? There are a lot of examples of one palletising machine serving more lines. Often a sorting system is needed to read bar codes and divert products into individual lanes. Again you have the advantage of redundancy and central in- and out-feed of pallets. The same goes for multi load palletising.

Palletiser
A difference is made between palletisers that transport the pallet to the layer or the ones that transport the layer to the pallet. In line palletisers a pallet elevator can deal with high capacities, with up to more than 120 cartons per minute, but are less flexible in handling complex stacking patterns. Palletisers with a right-angled row infeed are not as fast but are extremely flexible in stacking patterns and capable of capacities of 20 to 100 cartons per minute, depending on product dimensions.

There are also two types of layer lift palletisers: the first handles one pallet, the other one handles more pallets at the same time, but layer-by-layer. This is called a shuttle palletiser. Both have a small to medium size capacity and are equipped with a right-angled row in-feed. The first can handle both small and middle size cases. The shuttle palletiser requires short pack accumulation lines for each layer.

Robot palletisers
When choosing robots there are different options.  Difference is made between spherical or Scara robots and gantry or portal robots. Spherical robots have a donut form working envelope and move fast between 1 to 4 palletising stations but they can only deal with a limited load. Regarding the layout one is limited because of the working range.
Gantry or portal robots can handle more palletising stations (between 1 and 8) as well as heavier loads. They also move rather fast but only within the rectangular reach of their frame. They require more height but are more efficient in their use of floor space. A portal can be equipped with different gripper heads.
The product will determine the capacity of a robot palletiser. Depending on the product the gripper is chosen. One can, however, choose a gripper that palletises more cartons at the same time. A robot with 6 to 12 cycles per minute can then palletise 6 to 96 cartons per minute. The stacking quality of a palletiser is typically better because the layer is centered on four sides before going to the pallet. On the contrary, robots work with one or more cartons per movement whereby the carton tolerances negatively influences the stacking quality. This can also be the case with the clamping device of the gripper. On the other hand, such a machine can also, besides the palletising of cartons, take care of the transport of pallets and intermediate sheets.

But a robot on its own is still not a palletiser! As we have already commented: a palletising robot will cost about three times as much as the bare robot itself.