Modern seamless activewear and technical ski jackets avoid needle stitching in favor of laminated assembly. Installing magtech® TPU encapsulated magnetic snaps via ultrasonic or high-frequency (HF) dielectric welding creates hermetic, waterproof closures without seam tape.
1. Ultrasonic Sonotrode Geometry and Clearance
The ultrasonic welding horn must never contact the rigid magnetic core directly. magtech® snaps feature a dedicated perimeter welding flange (5 mm margin). Standard sonotrodes should feature a recessed cavity matching the central disc diameter ($D + 1.0\text{ mm}$) with an anvil relief depth of at least 2.0 mm.
2. High-Frequency (HF) Dielectric Welding Parameters
- Frequency: 27.12 MHz standard industrial band.
- Pneumatic Clamping Pressure: 4.0 to 5.5 bar uniform bed pressure.
- RF Generator Output: 1.5 to 2.2 kW depending on base fabric polyurethane thickness.
- Dwell / Cooling Cycle: 2.5 seconds weld cycle followed by 3.0 seconds under pressure to recrystallize TPU molecules.
3. Peel Strength Testing and Delamination Benchmarks
Correctly bonded magtech® TPU snaps yield cohesive textile failure (substrate tear) rather than boundary delamination when tested under ASTM D903 peel standards at 300 mm/min.
Download CNC sonotrode CAD tool files and machine setup protocols at magtech.global.