Packaging plays an important role in food and beverage manufacturing. It protects, extends shelf life and informs consumers about the contents. Brand owners rely on hot melt packaging adhesives to assure a strong seal in their customer products. To meet the demands of producers, it is critical to keep packaging lines running and minimize downtime while avoiding common issues with the hot melt adhesive application.
One of the most common issues with hot melt adhesive on packaging lines is stringing. When adhesive is applied to the case or carton, it may not cleanly or completely separate from the extrusion nozzle. The adhesive remaining on the applicator nozzle is pulled into a string away from the applied surface. The adhesive string is sometimes called “angel hair.” These thin strands float through the air and can cause many issues on the production line. Some common variables leading to stringing include:
- Distance between the nozzle and package – closer is better
- Configuration and nozzle type – single-bead nozzles firing straight down are optimal
- Size of a nozzle – nozzle size should be considered along with other application specific elements
- Condition of a nozzle tip – damage or char prevents the valve from operating properly leading to poor cut-off
- Low solenoid pressure – higher pressure results in better cut-off
In many cases, the adhesive buildup caused by stringing can be fixed by changing operating parameters or the equipment setup. Stringing on a hot melt packaging line can impact operation efficiency by blocking packaging sensors or impacting printing of barcodes and labels. If the photo eye sensors are blocked, additional cleanup and downtime can result.