1. Material Science: Innovative Application of TPU Composite Film
The current mainstream air bag material uses 3D TPU mesh, and its three-layer composite structure (TPU film-mesh cloth-TPU film) takes into account both air permeability and structural strength. This material uses high-frequency medium heating technology to achieve melt bonding at the molecular level, avoiding the environmental risks caused by traditional glue bonding. The melting point of the TPU film is controlled in the range of 160-180℃, ensuring that a firm seal is formed during the heat sealing process and avoiding thermal degradation of the material.
In the industry benchmark case, the 3D Miller air bag system used by Audi Q5L improves ventilation efficiency by 25% and reduces fan noise by 3 decibels by optimizing the microporous structure of the TPU film. The material has passed SGS certification and its air permeability reaches 1200L/m²·s, far exceeding the industry standard.
2. Heat sealing process: precise control of high-frequency technology
As the core process of air bag manufacturing, high-frequency heat sealing technology generates heat energy by exciting molecular vibration through high-frequency current to achieve instant welding of plastic materials. Key technical parameters include:
Frequency control: 27.12MHz high-frequency current to ensure that the electromagnetic field penetration depth accurately matches the TPU film thickness
Pressure curve: Using a segmented pressurization strategy, the initial pressure is 0.3MPa for preheating, and the peak pressure is 0.8MPa to complete the welding
Temperature compensation: The built-in infrared temperature measurement system corrects the influence of ambient temperature in real time to ensure that the temperature difference in the welding area is controlled within ±2℃
The 15KW high-frequency heat sealing machine of the supplier in Shanghai Puxiong has a welding strength of 85% of the parent material. The residual amount of the weld edge can be controlled within 0.5mm, which reduces the waste of edge materials by 70% compared with traditional processes.
3. Equipment innovation: Efficiency breakthrough of automated production lines
The modern wind bag heat sealing production line has achieved full process automation:
Double-station alternating operation: The heat sealing cycle is compressed to 8 seconds/piece, which is 300% more efficient than a single machine
4. Industry trend: The integration of lightweight and intelligent
With the extreme pursuit of lightweight by new energy vehicles, wind bag materials are developing towards ultra-thin TPU (0.15mm) and honeycomb structures. Data from a certain laboratory showed that the weight of the air bag using the new honeycomb TPU film was reduced by 40% while maintaining the same ventilation efficiency.
In terms of intelligence, the heat-sealing equipment has been integrated with the MES system to achieve:
Cloud synchronization of process parameters
Real-time monitoring of equipment OEE (overall efficiency)
Dynamic optimization of energy consumption
Conclusion
The heat-sealing technology of automobile seat air bags has developed from a single process to a system engineering integrating material science, precision machinery, and intelligent control. With the breakthrough of TPU material modification technology and the intelligent upgrade of heat-sealing equipment, the future air bag system will continue to make breakthroughs in lightweight, quietness, energy efficiency, etc., setting a new technical benchmark for driving comfort. For OEMs, mastering the core heat-sealing process is not only the key to improving product competitiveness, but also an important means to build a supply chain moat.