Adhesive Dispensing Systems

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A Noteworthy Complete Conversion with Tankless Adhesive Dispensing Systems

27 Apr 2017

Heilbronn, Germany

*Note: This article originally appeared in the special Interpack 2017 issue of "Verpackungs-Rundschau." To read the original, click here.

As part of a major project, Unilever has invested in modern end-of-line gluing technology from Nordson

Sustainability and work safety play an important role at all locations of the British-Dutch Unilever Group, and the plant in Heilbronn is no exception. One of the most recent steps for optimising processes in this regard is the extensive modernisation of end-of-line gluing in one of the two production areas. Numerous Freedom and ProBlue Liberty tankless hotmelt application systems from Nordson are now in use. These systems are especially efficient in terms of energy and material and are also very user-friendly.

The production site in Heilbronn is not only the largest of its kind Unilever has in Europe, it is also inseparably connected with "Knorr", the name of the corporate group's best selling brand. It is sold in more than 100 countries, and given the fact that according to Unilever over 80% of all Germans buy at least one of the over one billion packages sold domestically every year, there is no need here for a detailed description of the exceptionally diversified assortment of the brand.

Production can be broken down essentially into two main areas. Dehydrated products for mixing with water to make soups, sauces and dressings are produced in the first area, "Produktion Eins". The second area, referred to as “Produktion Zwei”, concentrates mainly on paste-like foods and dry premixes. The company counts about 800 employees including management. The amount of product delivered annually comes to about 90,000 tonnes.

17 processing lines run in “Produktion Eins” alone. Starting in the middle of last year, they were successively fitted with the new hotmelt adhesive application devices. As part of the major project, a total of 20 innovative Nordson systems have now been installed, six Freedom and 14 ProBlue Liberty melters. They are used mainly as case packers for forming slip-lid cartons, but they also perform other tasks as well, for example to glue folding boxes.

Tankless demand-driven melting

The two holtmelt application systems have some significant technical features in common, for example the absence of a conventional tank. The central unit consists of the melt section, which functions essentially like an instantaneous water heater, keeping only the amount of adhesive actually required at the processing temperature in a reservoir with reduced volume. Preparing only what is needed cuts heating up and flow-through times by as much as two thirds, to 15 - 30 minutes. This significantly reduces energy consumption for the melters.

The enclosed nature of the system also brings many other advantages. Gluing quality is improved because the hotmelt is not exposed to any environmental effects such as dust, dirt and other accumulations. In addition, a lower temperature load for the adhesive prevents cracking, so that clogging in the filters, hoses and dispensing gun nozzles is largely eliminated, which in turn lowers maintenance and repair costs. The lower heat requirement also makes it possible to use specially optimised types of hotmelt, which results in minimised consumption. Essentially all standard commercial hotmelt adhesives can be used.

Another important aspect is increased work safety. Because the granulate is now supplied automatically from a storage tank equipped with a pump that works based on the Venturi principle instead of manually, the risk of burn injuries – unavoidable with conventional tank devices – is completely eliminated.

Numerous optimisations

They agreed that the melters are also similar in terms of their performance capability and their greatly reduced dimensions, which allows for flexible installation. Further advantages are clear from this specific case. At a plant tour in March of this year, Thomas Bittner, the responsible WCM (World Class Standard in Manufacturing) project manager of the Unilever plant in Heilbronn, Thomas Fritsch, department manager of Produktion Eins and Martin Schweiger from the repairs department explained some technical details involved in the practical implementation of this major project. The question concerning the criteria for choosing the one system or the other was also answered.

The numerous improvements brought by modernisation are evident everywhere. This has to do in part with technical aspects of the installation. For example, by arranging the Freedom systems in the area of the Hesser machines mentioned above, the number of gluing devices required was deftly reduced from eight to four. Due to the compactness and relatively low unladen weight of the melters, it was possible to install them at head height. This not only saves space, but also makes the solution more user-friendly.

The connections between the melters and the dispensing guns were also optimised. The Freedom melter can be used to supply up to four applicators with hotmelt simultaneously, while the ProBlue Liberty 14, the version used most commonly, can supply as many as six applicators. This option, which allows for more sophisticated gluing configurations, is the main reason why the Liberty variant was chosen instead of a Freedom system for some case packers in the conversion.

The Freedom variant also features the impressive integrated EcoBead function. This is an application control system that saves material by replacing long continuous beads of adhesive with multiple short ones. It is also available as an accessory for the ProBlue Liberty series. The highly compact unit is plug and play and can easily be inserted between machine control and the dispensing gun. An EcoBead is currently being tested in Heilbronn with extremely positive results so far.

Dispensing guns to suit the application

Two models from the MiniBlue II series that work with a minimum switching time of 2 ms and achieve a service life of more than 100 million cycles were selected as applicators. The patented SureBead type is used to glue folding boxes. Since small nozzles are used for this application, it is a great advantage that the pneumatic dispensing gun is equipped with a self-cleaning needle and seat module so that nozzle clogging can be optimally prevented. Fully insulated MiniBlue II standard heads, pneumatically opening and closing with ball-and-seat module, are also used.

Another important factor contributing to the improved overall configuration is the 240-litre adhesive storage container, which offers the option to connect as many as four filling hoses. That means that only seven of the large-volume reservoirs are now needed for all 20 melters. The Multi-Feed function is controlled by a sequencer which determines the order required for pumping hotmelt adhesive based on melter level signals.

Major savings of energy and material

The savings in electrical power and glue consumption achieved so far are especially worth noting. After more than six months of experience with the new application systems, Thomas Bittner can now give some specific figures: "Because of the way the systems work, the selective use of the right modules and nozzles for our specific requirements, and by changing to an optimised type of adhesive, we have achieved savings on adhesive in the range of about 20 to as much as 35 percent, depending on the system. The energy requirement has also fallen significantly. This is partly because the total number of devices has been reduced, but especially due to the general efficiency of the modern melters with their reduced heat-up times."

He emphasises that all important aspects were implemented very satisfactorily in this major project. "The competent support by Nordson and the problem-free way in which the conversion proceeded will form the basis for the upcoming modernisation of “Produktion Zwei”, which will be similar in scope. According to plans this will take place before the end of the year". The Adhesive Tracking System (ATS), which is new to the market, will also be tested at that time.

Precise adhesive tracking

ATS, which will also be available as an upgrade kit in spring 2017, is integrated into the ProBlue and ProBlue Liberty systems. To boost process reliability, it directly and precisely measures the add-on weight per product. Tolerance limits can be defined so that warning signal is triggered if the quantity is too low or too high and the line can be stopped if necessary.

In this manner the tracking system optimises consumption of adhesive and reduces product waste. It also makes it possible to detect batch and age-related changes to the adhesive viscosity and faults in individual application units. ATS also allows for extensive data analysis and documentation using various interfaces.

Text: Bernd Neumann
Photos: Kimberly Wittlieb