Ultrasonic welding systems have been successfully implemented to seal bags, blisters, pods, and cartons. Hermetically tight seams reduce the leaker rate while the ultrasonic cold tools are gentle on sensitive foods. Take a closer look at this alternative to heat sealing.
During the ultrasonic process, mechanical vibrations in an ultrasonic frequency are applied to a packaging foil or film at a specific amplitude, force, and duration. The process parameters depend on film structure, thickness and joint geometry. The resulting friction heat causes a substance-bonded connection at the molecular level, meaning the packaging materials are firmly connected with each other. Ultrasonic seals are slimmer than heat contact seals, but equally tight and strong and in addition, they save packaging material. Precise focusing of energy to melt the material is ensured by the small contact surface between the weld tool, called sonotrode, and the anvil.
Tight sealing through product-contaminated surfaces
Strong seams are also achieved for product-wetted sealing layers, since the mechanical ultrasonic vibrations literally "knock off" any feed material residues. This significantly reduces the number of leaking packages. The sealing parameters can be adjusted to layer thickness, humidity content, and temperature differences. The ultrasonic generator detects creases and saves all data allowing for a superb quality assessment – unlike any other sealing method. Since ultrasonic tools hardly warm up at all, packaging and feed material are protected from thermal overloads. Cleaning is reduced and sealing tools are not soiled even in case of malfunctions in the filling process. The use of nonstick coating, such as Teflon strips, is not required.
At one glace – the benefits of ultrasonic sealing:
- Short cycle times between 80 and 200 ms
- No thermal influences on feed material and packaging material, great for salad and chocolate
- Quality assurance by means of detailed parameterization
- Sealing of product-contaminated surfaces (liquid, powder, paste)
- Saving of packaging material due to narrow seams
- Reduced effort for cleaning of sealing tools
- Good hot tack
- Good overall equipment effectiveness (OEE)