The Basics of Ultrasonic Lamination
Ultrasonic lamination uses the conversion of acoustic energy to heat to form spot welds of specific size in exact locations. This
technique is an ideal method to join layers of different or similar
materials (nonwovens, films, composites, or fabrics) into a single
composite or laminate.The
layers of raw material are arranged and brought together as in any
traditional lamination process to pass over a central rotating roll or
“anvil”.
Instead
of the uniform smooth surface roll used for pressure bonding,
Ultrasonic Laminating uses an embossed pattern on the anvil or “pattern”
roll. Each peak is the site of an individual weld across all layers of the lamination. The peaks are exactly shaped and located to yield the desired size and location of the weld.
NP
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Open Diamond
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Diamond
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BC
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F
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TX
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Accoustic energy is generated from a “horn”. Each horn is individually powered so that its output can be exactly tuned to a series of pulses. Each
pulse is a pressure wave that acts as a tiny hammer. The frequency of
the pulses impacts the material tens of thousands of times per second
over each peak location on the anvil. While all of the material passes
under the horns, welding only occurs over the peaks of the anvil.
The
degree of welding at each peak is determined by the nature of the
material in the layers, the amount of energy applied from the horn, the
size and shape of the peak, and the “dwell” time of the material in
relation to the peak. The
discrete bonding at specific points is an important feature of
Ultrasonic Lamination, as it allows the unbonded materials to function
as they were designed.
Ultrasonic Lamination is a non-contact and therefore non-wearing process. As the layers to be laminated move across the dwell area, the layers are not stretched or pressured onto the anvil. For
effective bonding, the layers need to be flat and almost lie in a
relaxed state as they dwell over the peak, so the conversion of acoustic
energy to heat for bonding is not dissipated or wasted.
