Automotive engine coolant reservoir caps maintain system pressure, preventing coolant boiling and leakage, requiring good sealing, high temperature resistance, and pressure resistance (up to 1.2 bar). Traditional rubber caps have short service life, easy to age and leak, while mechanical caps have poor sealing. DaokeDao laser welding provides a reliable sealing solution for PP and rubber cap materials, forming a dense, pressure-resistant weld, with leakage rate ≤0.01ml/min, ensuring system pressure stability. The weld has high temperature resistance (up to 120°C), adapting to engine compartment high temperature, and good flexibility, ensuring proper cap opening and closing. The equipment supports high-volume production, cycle time 5-8 seconds per unit, suitable for mass production of engine component suppliers, improving coolant system reliability and reducing engine overheating risks.