Car Light Welding: The Laser Welding Process

When it comes to manufacturing car lights, precision, efficiency, and durability are paramount. Laser plastic welding is a favored method due to its ability to create strong, seamless joints. Here's an in-depth look at the essential considerations for laser welding car light assemblies, focusing specifically on the components and materials involved.

Key Components for Car Light Laser Welding

1. Mask (Lens or Cover)

• Material: The mask is typically made from PMMA (Polymethyl Methacrylate).
• Transparency Requirement: To ensure optimal laser penetration, the near-infrared laser transmittance must not be less than 85%. This ensures that the laser energy passes effectively through the mask to bond the underlying materials.
• Color Options: The mask can come in various colors, including transparent, red, and black.

Pro Tip: Ensuring that the mask meets the required transmittance level is crucial to avoid issues with energy absorption and to achieve a proper weld.

2. Housing

• Material: The housing is generally made from black PC+ABS (Polycarbonate and Acrylonitrile Butadiene Styrene blend). This blend provides the strength and heat resistance necessary for automotive applications.
• Color: Typically black to optimize the absorption of the laser and facilitate efficient bonding.

Recommendations for Optimal Welding

To achieve the best results, certain conditions and material properties should be carefully managed:

1. Vicat Softening Temperature: The difference in the Vicat softening temperature between the mask and the housing should ideally be controlled to around 10°C. This ensures that both components soften and bond efficiently without material deformation.
2. PC Content in Housing: If the housing does not require extreme heat resistance, it is advisable to keep the PC content between 30% to 40%. This range strikes a balance between strength, weldability, and cost-effectiveness.

Note: These suggestions are based on cumulative industry experience and should be tailored to the specific requirements of the car light assembly being produced.

Understanding Laser Compatibility

For plastic laser welding, the typical light source used is a 980 nm near-infrared laser. Here’s why maintaining an 85% transmittance in the mask is important:

• Below 85% Transmittance: When the transmittance falls below this threshold, about 15% of the laser energy can be absorbed by the housing. This absorption can cause unwanted burning or scorching of the material, compromising the integrity of the weld.

Final Thoughts

Laser welding in automotive lighting demands precision and attention to detail. From selecting the right materials to maintaining exacting standards in laser transmittance and temperature control, these factors all contribute to the efficiency and quality of the final product. Following these guidelines can help manufacturers create robust, high-quality welds that stand the test of time.