Trisa AG, with headquarters in Triengen in the Swiss canton of Lucerne and just under 800 employees, is a leading provider of products for oral and dental hygiene and cosmetics, not only nationally but worldwide as well. Great emphasis is placed on continuous modernisation of the extensive machine park. So it is that in October of last year one of the cartoning machines, which is used for secondary packaging of toothbrushes, was equipped with a closed, automatically filled ProBlue Liberty hotmelt application system from Nordson. This configuration offers significant advantages compared to conventional devices, especially in terms of energy efficiency, savings in adhesive and increasing work safety.
Manufacturing of manual and electrical toothbrushes as well as interdental care products plays a dominant role in the extensive product range of the company, founded in 1887 and now in its fourth generation as a family-owned enterprise. The oral hygiene business segment accounts for about 70 percent of sales. The remainder comes from products such as hair brushes and brooms for room cleaning, etc.
Sales volumes corroborate the status of Trisa as one of the most important European manufacturers of toothbrushes. More than a million units are produced according to strict quality criteria every day. The Group also includes Ebnat AG with headquarters in Ebnat-Kappel in the canton of St. Gallen. Together with this subsidiary based in Toggenburg and three additional companies – Trisa-Electronics AG, Trisa-Accessoires AG and a Bulgarian branch office – the Group employs about 1100 with 2017 sales of about CHF 223 million.
The export rate in the core business of toothbrushes has risen sharply over the last ten years to the current level of 95 percent. The traditional Swiss brand is now sold in over 60 countries on all continents through the company’s own sales organisations or independent distributors.
The recently upgraded cartoning machine opens folded blanks and places six toothbrushes in blister packs in each one. After hotmelt adhesive has been applied to the flaps on both sides, the secondary packages measuring 232 x 132 x 42 mm (L x W x H) are stacked in shipping cartons by hand.
The ProBlue Liberty melter was installed inside the cartoning machine housing on movable rails to save space and can be pulled out for service purposes.
Demand-driven hotmelt preparation
The innovative hotmelt application system of Nordson Corporation, the US adhesive technology specialists with European headquarters in Erkrath and Swiss branch office in Vilters, is the first fully automatic configuration Trisa AG has used. The enclosed system with advanced hotmelt preparation features major differences compared to the conventional units of another manufacturer still in use for the other systems, which have tank devices filled manually in the standard manner.
The centrepiece of the Nordson system is a ProBlue Liberty melter size 7. As the type designation suggests, the melter provides a melting capacity of seven kilogrammes per hour. Its most significant feature is that it does away with the conventional tank. Equipped with a reduced-volume reservoir, it functions essentially like an instantaneous water heater, preparing only the amount of adhesive actually required. Heating only what is actually required results in significantly shorter heating up and flow-through times. Depending on the utilisation level of the system, the intervals can be minimised from 90 minutes to about 30, which is equivalent to a reduction of energy consumption in the range of five to eight percent.
With dimensions of approximately 539 x 490 x 372 mm (W x H x D), the ProBlue Liberty 7 melter is also compact enough to be placed inside the machine enclosure – as it actually was in this specific case. To make maintenance easier, the engineers of Trisa AG also mounted the melter on movable rails so it can be pulled out easily.
Controlled adhesive application pattern
The hotmelt is applied by two pneumatic applicators type MiniBlue II with ball-and-seat module and Saturn precision nozzles. Because they feature a minimum switching time of two milliseconds and a long service life of more than 100 million cycles, they are often referred to as “non-stop sprinters”.
Two pneumatic applicators type MiniBlue II are responsible for application of hotmelt Consumption is significantly reduced by the two EcoBead controllers which can be seen in the lower right area of the picture.
Each of the two MiniBlue II units at Trisa works in combination with an EcoBead application controller. Measuring only 127 mm in length, the somewhat inconspicuous device without a dedicated power supply can easily be integrated between the machine control unit and dispensing gun. It ensures enormous reduction in adhesive consumption by applying multiple short beads instead of single continuous beads.
The space between the beads can be defined individually as a percentage of the original application. This ensures that the final bead is always located at the end of the original length and the pattern always ends with an application of adhesive. With the toothbrush secondary packaging, for example, four 20-mm beads are applied on each end at the upper edge of one of the side flaps along the overall length of 126 mm.
The granulate is supplied automatically from a 120-litre storage tank by means of a pump that works based on the Venturi principle. This makes it possible for the hotmelt application system to be completely enclosed. An integrated sensor monitors the fill level in the melter and reports when adhesive is required. This configuration not only prevents contamination in the hotmelt and impurities in system components such as clogged nozzles, but also significantly increases work safety. The risk of burn injuries, unavoidable with manual refilling of hotmelt adhesive, is eliminated.
Practical experience confirms advantages
Thomas Röthlisberger, Manager of Packaging Process Technology at Trisa AG, fully confirms the numerous advantages of the modern end-of-line packaging technology after a half a year of practical experience: “We are very satisfied with the Nordson system. It works extremely reliably. In addition to its energy efficiency, the savings in adhesive are surely worth mentioning, due especially to the use of the EcoBead controllers. Based on initial measurements, we estimate a reduction of about 30 percent. I have also received especially positive response from our employees, who appreciate in particular the simplified adhesive handling and how user-friendly the components are. Of course the enhanced work safety should also be explicitly mentioned in this connection. And not least I would like to emphasise the excellent collaboration with the Nordson sales representatives and technical support. Service including the availability of spare parts is absolutely exemplary.”