Pulse Welding of TPU Film: Process Principle and Application Analysis

I. Process Principle: Pulsed Thermal Energy Control & Material Fusion

Pulsed welding utilizes cyclic electrical or laser energy to generate intermittent heat input at TPU film interfaces. Key principles:

1. Energy Pulsation

• Current Pulse Welding:
  Alternates between peak current (rapidly melts TPU surfaces) and base current (partial cooling), minimizing heat accumulation.
• Laser Pulse Welding:
  Delivers intermittent high-energy laser beams. Each pulse forms an independent weld point, with heat input controlled by adjusting pulse energy, width, and frequency.

2. Heat Transfer & Fusion

• Pulsed energy melts TPU interfaces, creating a molten pool. Under pressure, melted molecules interdiffuse to form weld seams upon cooling.
• Post-pulse rapid solidification (e.g., millisecond-level in laser welding) minimizes heat-affected zones (HAZ), preventing deformation or degradation.

3. Critical Parameters

• Pulse Energy: Matches TPU film thickness for optimal melting.
• Pulse Width: Adjusts penetration depth (excessive width causes burn-through).
• Frequency:
  • High frequency (10–500 Hz): Dense, smooth seams for automated systems.
  • Low frequency: Manual control of molten pools.
• Duty Cycle: Balances peak/base current durations to prevent overheating.

II. Technical Advantages: Precision, Efficiency, Low Damage

1. Minimal HAZ: Fast heating-cooling cycles reduce bulk heating, preserving TPU elasticity.
2. High-Quality Welds: Seam strength approaches parent material (98–100%), with smooth, defect-free surfaces for medical/electronic sealing.
3. Material Versatility: Welds TPU films of varying hardness/thickness; compatible with composites (e.g., TPU-PC, TPU-PMMA).
4. Automation Readiness: Programmable parameters enable robot/vision system integration for high-speed production.

III. Core Applications

1. Medical

• Implantable Devices: Smooth seams on TPU catheters reduce tissue irritation.
• Surgical Gowns/Protective Gear: Seamless sealing via pulsed welding for waterproof, antibacterial performance.
• Blood/Drug Bags: High-strength laser welds withstand ethylene oxide/gamma sterilization.

2. Industrial

• Waterproof Membranes: TPU-coated tents, inflatable boats with weather-resistant seams.
• Automotive Interiors: TPU airbag covers and seals pass rigorous burst-pressure tests.
• Electronics: IP68-rated TPU casings for dust/waterproof protection.

3. Advanced Manufacturing

• 3C Product Housings: Laser-pulsed welding for smartphone/tablet enclosures.
• MEMS Packaging: Masked welding for micron-scale accuracy in microelectronics.

IV. Process Types & Selection Criteria

1. Current Pulse Welding

• Applications: Low-speed automation (e.g., medical micro-assembly).
• Pros: Low-cost equipment, flexibility for small batches.

2. Laser Pulse Welding

• Applications: High-speed, precision welding (e.g., 3C components).
• Pros: Ultra-narrow HAZ, ideal for thin films (<0.5 mm).

3. Masked Pulse Welding

• Applications: Localized heating in microelectronics/medical devices.
• Pros: Micron-level precision via shielding templates.