Sustainability is about reducing the packaging material as much as possible. New and innovative solutions using Ultrasonic sealing technology reduce the amount of material being used for packaging. In addition Ultrasonic sealing improves the overall equipment efficiency (OEE) and reduces the energy consumption.
Ultrasonic sealing offers new solutions to reduce the amount of material used to seal plastic packages for the following markets: salad, beverage, coffee, dairy, retort, pasta, ready cook meals, and powder applications.
One of the primary benefits of ultrasonics sealing is its ability to seal through contamination in the sealing area, for example fluids, oils, powders or fibers. Ultrasonics will vibrate and cut the contamination out of the sealing area then create a strong hermetic seal. A typical Ultrasonic seal is 50-80% narrower than a heat seal, which results in significant material savings.
A new and smaller package design with less head space and a narrower seal requires significantly less packaging material. Due to potential smaller packaging sizes secondary packaging sizes can also be reduced.
There are new Ultrasonics technologies that allow sealing in intermittent or continuous modes while creating longitudinal and cross sealing lines. this new technology enables film suppliers to simplify structures by downgrading high priced coax layers, reducing the sealing layer gauge, and utilizing lower cost mono resin based structures.
Machine Performance Improvement
Ultrasonics sealing solutions have been successfully implemented in Form/Fill/Seal, carton and blister machines. Ultrasonic sealing stations can be implemented directly by the machine builders (OEM) for new machines or upgraded in the field for previously installed machines.
Ultrasonic sealing is a closed loop system. Measurable feedback can be obtained in the amount of energy consumed during each weld. Once a seal has been verified, process windows can be programmed to measure and validate each seal, which allows easy SPC monitoring.
Direct comparisons with installed heat seal stations have demonstrated that the leaker rates are significantly reduced. In addition, the simplicity of having a cool sealing system ready at any time increases the overall throughput of the machine.
The Ultrasonics station consists of an ultrasonics stack, a generator and an anvil. The stack includes a sonotrode, a booster and a converter which are driven by a generator. Due to the short cycle times and high sealing pressure required, specially designed converters and generators are required. Anvil design is a crucial component to consistently achieve the required sealing strength. The anvils are verified with FEA to ensure proper frequency behavior and durability.
The entire Ultrasonic sealing station has to be installed in an extremely rigid manner including rigid sonotrode mounting. In some cases the machine may need to be stiffened. Special attention is required when designing the force build-up assembly.
An Ultrasonics sealing station is a significant capital investment. Depending on integration levels and machine complexity, past experience has shown a ROI between 6 months - 3 years. See the chart for possible cost variables to be considered for Ultrasonic projects.
|Cost Variables||Heat Sealing||Ultrasonic Sealing|
|Material required for cross seal||5-20mm wide||2mm wide|
|Material required for fin seal||3-10mm wide||2mm wide|
|Reduced layer for film||-||Lower gauge
|Teflon Tape||Replace 2 x per shift||N/A|
|Parts cost to replace heating station or Ultrasonic generator||Lower||Higher, but less frequent replacement|
|Parts cost to replace cartridges or sonotrodes||Lower
|Time to change Teflon Tape||min./day||N/A|
|Time to clean the system||Hot station (burns)||Cool station|
|Time to replace heating station or Ultrasonic generator||Same||Same, but less often|
|Time to replace cartridges or sonotrodes||Faster||Slower, but less often|
|Energy cost for sealing station||100% hot||20-50% during sealing time|
|Energy cost for cooling station incl. cooling||100%||Not required|
|Set-up time||Frequently||Robust - one time|
|Start of system||Delay
|Machine speed||Fixed||Seal can be faster|
|Variable machine speeds||Wait for new Temperature set||Change on the fly (no change of seal settings)|
|Increase machine reliability
MTBF, MTBA, MTTR, MTTA
|-||Reliable robust sealing station|
|Internal product inspection
|Up to 100%
Less quarantine products
|Close loop sealing|
SPC controlled process
- Inspect only questionable products
|Leaker rates||Significant reduction in leaker rates|