Ultrasonic Velcro Welding
Ultrasonic Velcro welding quickly bonds hook-and-loop material to compatible plastic or synthetic substrates without stitching or liquid adhesives.
How It Works
The system converts electrical energy into high-frequency mechanical vibrations, typically at 20, 30, 35, or 40 kHz. A horn presses the Velcro against the substrate, generating localized heat at the interface. The thermoplastic surfaces soften, fuse, and solidify under pressure.
Typical arrangement:
Horn → Velcro → Plastic or fabric → Fixture or anvil
Materials
Best results are achieved when both the Velcro backing and the mating material are chemically compatible thermoplastics.
Material Ultrasonic weldability
Nylon Velcro Good in suitable combinations
Polyester Velcro Very good
PP hook & loop Excellent with PP substrate
Polyester fabric Good
PP nonwoven Excellent
ABS plastic Possible, depending on Velcro backing
PE More difficult
Cotton fabric Generally poor without a thermoplastic layer
Velcro construction varies by product. Differences in hook-and-loop material, backing, coating, and adhesive layers can significantly affect weldability.
Machine Configuration
For production applications, consider the following:
• 20 kHz — suitable for larger or thicker Velcro pieces that require more weld energy.
• 30 or 35 kHz — a practical balance for smaller textile and plastic assemblies.
• 40 kHz — ideal for small, delicate parts where surface marking must be minimized.
• Pneumatic or servo actuation for precise pressure control.
• A custom horn face designed for the required weld pattern.
• A hardened fixture or anvil to support the component.
Rather than welding the entire surface, use parallel lines, dots, rectangles, cross-hatching, or perimeter welds. These patterns reduce energy demand and help prevent damage to the hook-and-loop structure.
Important Design Consideration
When welding Velcro directly to a rigid injection-moulded plastic part, horn and fixture design are critical. The ultrasonic energy should be concentrated at the interface between the Velcro backing and the plastic, not within the hook-and-loop structure.
Provide the Velcro material, plastic type (such as ABS, PP, or PC), and Velcro dimensions Dsonik can provide recommendations for a 20 kHz horn, weld pattern, pressure, amplitude, and initial process settings.
Dsonik has vide range of ultrasonic plastic welding machine:
DX-Eco series - low price standard analog welding system
DX-1 series – Standard analog/digital ultrasonic welder in square column
DX – 2 Series – High end Digital ultrasonic welder in square column
DX – Servo Easy – Entry level Servo control ultrasonic welder in square column
DX – Servo High End – Advance level Servo control ultrasonic plastic welding machine
DX – Euro – European standard Digital and Servo control high end ultrasonic plastic welding machine
