Fully automatic packaging line for steel fibres

'When a German manufacturer asked if we could build two identical packaging lines to pack steel fibres fully automatically into boxes and stack them on pallets, we enthusiastically embraced the challenge,' says Simon Rijke, CEO of The Hague-based Weighpack. But soon, their engineers realised that this required additional know-how, especially in the field of linear drive technology. Festo was brought into the project to collaborate on the final solution.

Celebrating its 50th anniversary this year, Weighpack develops, builds and maintains packaging machines. For example, for the sets of fasteners you get with an IKEA piece of furniture or for packs of screws, nuts and nails for sale in DIY stores. 'Everything we make is engineered to order (ETO),' says Rijke. 'And occasionally, we work with a configure to order process (CTO), which is easier and faster because you then start from pre-existing modules.'

Everything is engineered

Weighpack's customers are all over the world and specify their requirements to this specialist system builder. Often, we talk about the desire to package products fully automatically, put them in boxes, and stack them with palletisers. 'Nothing is standard, and everything is engineered here and then assembled, tested and installed at the customer's premises and sometimes maintained for many years afterwards,' says Rijke. 'This maintenance, based on our instructions, is often carried out by the customer's technical department or a specialised external service company. Virtually all the machines we build can be accessed via the internet, which means that when problems arise, we often know what is wrong before the customer does. If necessary, we go there immediately, but we can often instruct their technical service department 'remotely' on how to solve something and what part to replace, if any. Parts must be quickly available at that location, so we only work with reputable, globally available components for motors, cylinders, PLCs, etc.'

Boxes and big bags

What were the requirements for the new packaging machine for steel fibres? Rijke says: 'They were quite special because the machine had to be able to pack these fibres in boxes of different sizes as well as in big bags. So, that required flexibility. The fibres also clump together easily. That is an advantage when you apply them as reinforcement in shotcrete, but during the packaging process, it isn't easy. The solution uses magnetism and vibrating plates to correctly get the fibres into the boxes. Another important fact was that the factory where the lines will be located operates 24/7, and they wanted maximum output. That posed some challenges, so we brought in Festo, especially to solve specific drive issues.'

Linear actuators

All kinds of technology are used in Weighpack's machines. Powered roller conveyors, servo motors, pneumatics, box closing machines, weighing units, robots, palletisers, sensors, bus systems, PLCs, light curtains for security, etc. What was the challenge with the steel fibre packaging line, and why was a palletiser with Festo electric actuators chosen instead of a robot? After all, flexibility was important right? André Valstar, Sales Engineer at Festo responds: 'Palletisers are sometimes built based on a multi-axis industrial robot. These are, of course, quite flexible, but they have limitations in terms of accuracy and speed when stacking boxes and crates. In this case, we had to solve the stacking of the boxes differently, opting for large electric linear actuators. Combined with a rotating vacuum gripper, these allow boxes to be stacked 'in context' to create a compact and transport-resistant pallet.'

With the current palletiser solution, the speed but also the delay can be precisely controlled. This is important because different sizes of boxes are processed, which therefore also differ in weight.

Electric or pneumatic

In Festo's extensive motion-control range, we find both pneumatic and electromechanical linear solutions. 'Of course, the choice depends on the application,' stresses Valstar, 'but it is clear that electrical solutions are favoured, especially in applications like this integrated palletiser. Of course, we also considered a servo-pneumatic solution, but in this case, the required positioning accuracy meant this technology fell short.'

In terms of positioning accuracy, electric linear actuators perform much better. Moreover, with this new Weighpack machine, we are talking about an application operating for long periods of the day, with large movements and relatively heavy loads. If pneumatics were used in this application, it would use significantly more energy than an electromechanical solution. An additional advantage of electric linear actuators is that they have decreased in price in recent years. In addition, innovations in electric motors mean the total cost of ownership (TCO) has reduced in recent years. Apart from the technical and functional requirements, it is also very interesting to carefully compare the investment and energy costs of pneumatic and electric solutions.

Mechanical Engineering in Europe

Weighpack is currently putting the finishing touches to the two steel fibre packaging lines that will be installed in a factory in Germany in a few weeks' time. The question for Rijke is how a modest Dutch machine builder employing some 40 people manages to be successful globally. After all, you hear that Europe is losing out to Asian competitors in particular due to relatively high labour costs. 'For consumer products, that may be true,' Rijke responds. 'But special machine construction is quite different. Our country has a lot of know-how combined with the necessary experience. Technically, we are state-of-the-art and that is not always the case on the other side of the world. We are also very internationally oriented. The Dutch are active all over the world and have been for centuries.'

'By working efficiently and using high-quality products and techniques, we build machines that are top quality and combine high performance with the lowest possible TCO,' continued Rijke. 'That's something that's getting more and more attention worldwide and that buyers are also increasingly taking into account. As a buyer, you can squeeze a supplier and force them to use cheaper components, but if the result is inferior quality, lower performance, and characterised by high operational costs, you are simply selling yourself short as a user. We do not compromise on quality, use the best possible components and ensure that we deliver a solid machine that performs extremely cost-effectively. Only then do you stand up well in the international marketplace, and we have been proving that this is no myth for half a century.'