A closer look at the carbon footprint of an adhesive application system with a melt rate of up to 8 kg/h reveals that the operational phase accounts for the largest share of the environmental impact. Over a ten-year life cycle, the hot melt adhesive throughput accounts for 429 metric tons of CO₂-eq., followed by electricity consumption at 13.7 t CO2eq. Excluding the operational phase, the environmental impact of an adhesive application system amounts to only 1.55 t CO2eq.
Consequently, approximately 99% of CO₂ emissions from industrial adhesive application occur during adhesive production and the melting of the adhesive. The greatest and most direct way to reduce CO₂ is therefore through economical adhesive application. Particularly in the packaging industry, which primarily uses bead application, Scope 3 emissions can be significantly reduced by optimizing adhesive application quantities.
For secure bonding, a sufficient amount of adhesive must be applied to the correct location. But what does “sufficient” mean? More adhesive does not automatically mean stronger adhesion. To verify adhesion, the transverse tear strength can be used as a performance indicator. It describes the force required to tear or separate a bonding or a material across the intended direction of force. This provides a reliable answer to:
whether the seam strength is sufficient for transport and handling stresses.
Tests show that shorter beads or dot applications require a greater tear-off force than longer beads. This is exactly where hot melt stitching comes into play: Instead of applying the adhesive as a long bead, the application is divided into short beads or dots. This allows the amount of adhesive to be reduced while maintaining a secure bonding.
The following real-world example demonstrates how optimizing adhesive application can positively impact glue consumption.
On a carton sealer with a throughput of 40 cartons per minute, the two pneumatic jetting heads used for gluing the lid flaps were replaced with electric jetting heads. This step was necessary because the application of many small beads or dots requires a high switching frequency and a large number of operating cycles.
Cardboard flap gluing: Reduction in adhesive consumption through hot melt stitching and subsequent process optimization
Originally, 18 g of adhesive was applied per carton. The introduction of hot melt stitching resulted in glue savings of 8.2 g. The subsequent optimization of the application process led to a further savings of 2.6 g per carton. This results in a total adhesive savings of 60%.
Projected over a full year of operation, optimizing adhesive application yields benefits on multiple levels. The example of the carton sealer mentioned above demonstrates that using a smaller amount of adhesive significantly reduces CO₂ emissions and adhesive costs. Additional savings on maintenance and replacement parts result from the use of electric application heads. These operate without compressed air and therefore do not require a dynamic seal or solenoid valve. Furthermore, the service life of Volta, the hot melt stitching head from our example, is up to two billion operating cycles. Although stitching results in a switching frequency up to four times higher than that of bead application with a pneumatic jetting head, the lifetime is ten to forty times longer, depending on the comparable pneumatic model. In summary, the following savings result:
The use of an electric application head with a hot melt stitching function, as well as the targeted optimization of the application process, directly reduces CO₂ emissions. By reducing the amount of hot melt adhesive applied, production costs are lowered and the reliability of the bonding actually increases. In industrial adhesive application, sustainability is therefore not a cost factor—but rather a driver of efficiency with measurable economic benefits.
Are you curious about how you can specifically improve your metrics for CO₂ emissions and adhesive consumption? We’d be happy to analyze your gluing process and, if desired, calculate your ROI.