News | September 27, 2018

Preserve The Aroma With Ultrasonic Sealing Technology

When it comes to encasing coffee in different kinds of packages (capsules or bags), ultrasonic sealing technology performs a number of production steps. The tools do not heat up, making this technology gentle on packaging material and easy on the valuable filling goods – whole coffee beans or ground coffee

Filter liners for a better crema
One of the main indicators of a quality coffee is the crema. When using a coffee capsule, filter material ultrasonically welded onto the bottom of the capsule produces the crema; this process is called embedding.

The PET filter liner has a higher melting point (up to 250 degrees) than the PP material of the capsules, which reacts more quickly to the ultrasonic vibrations; as a result, it becomes viscous and flows into the PET. The result is a strong connection, which keeps the filter in position and ensures a high quality crema even at very high brewing pressure.

In a recent project by a major packaging machine manufacturer, ultrasonic technology was used to embed filter liners into coffee capsule bottoms. The machine concept consists of 48 stations where filter liners are welded into the capsule bottoms – or more precisely, they are embedded using ultrasonics. 24 generators supply the ultrasonics, each producing power for 2 stacks. The ultrasonic generator monitors and independently regulates the welding parameters. Integration into the machine controller via fieldbus interfaces makes it possible to exchange and evaluate process data in real time.

Combined cutting and sealing capsule lids
The covering foil is cut out and ultrasonically sealed onto coffee capsules in a single step, at one workstation with the combined ultrasonic sealing and cutting unit for capsule lids. Herrmann Ultrasonics will be demonstrating the combined method at Pack Expo (booth #S-2769). The single step process reduces the overall footprint. A vacuum function for the lid transfer guarantees precise positioning of the covering lid within the process. Ultrasonic sealing is capable of sealing through product residue like coffee powder in the seal area, producing tight seals. This ensures that the barrier function of the complete capsule is on a maximum level and the aroma stays inside.

Degassing Valves
Aroma valves allow a controlled degassing of the package, safeguarding the aroma of the coffee. This requires a reliable and stable sealing process when applying the valves. At up to 120 valves per minute ultrasonic technology delivers fast and secure sealing of aroma valves. The materials are melted and bonded in a controlled way by ultrasonic vibrations. Because tools do not heat up the optical appearance is good and machine downtimes (for cleaning) are reduced. As the cutting of the film is integrated, there is no separate process step required.

Increased output and improved quality control
Even if there is residual coffee in the sealing area, the ultrasonic technology still produces a tight and firm seal. The coffee is driven out of the sealing area before actual sealing occurs by mechanical ultrasonic vibrations. The whole process is accomplished in an average of 200 milliseconds, enabling an output of up to 1500 capsules per minute.

The digital generator from Herrmann Ultrasonics, specifically developed for fast packaging processes, is immediately ready for operation once the system powers on. No need for heat-sealing units with a lengthy warm-up process. Errors in the weld process are transferred directly to the packaging machine control and the affected part can be discharged, allowing for 100% reliable quality assurance and boosting the overall equipment effectiveness.

Visit Herrmann Ultrasonics at Pack Expo, booth #S-2769 – for a live demonstration of ultrasonic sealing and cutting for capsule lids along with demonstrations of other ultrasonic sealing methods. For more information, visit

Ultrasonic sealing for your coffee application?
Ultrasonic sealing is a fast and repeatable method for joining rigid and flexible packaging materials. It generates a true molecular bond with high strength by converting electric voltage into mechanical vibrations and inducing them into the film by a welding tool, called sonotrode. The applications for ultrasonic sealing are as varied as the packaging industry itself: stand-up pouches, flat pouches, blister, pods and coated cardboard.

Source: Herrmann Ultrasonics