Laser welding of plastics was demonstrated in the early 1970s. However, the process has recently gained popularity as a propitious joining technology due to high weld quality, high precision, high performance, high speed, good flexibility, low deformation, free of residues, and is environment friendly. To achieve good welding results certain additives need to be added in the plastics for controlling the absorption and transmission of light such that heat could be generated at the joining part of the pre-assembled entity without melting the outer surface. The additives alter the properties of the plastics in such a way that can be reshaped or welded above a certain temperature. Hence, these plastics are called thermoplastics. <\/p>\n\n\n\n
The laser welding technology of the thermoplastics is called \u201cThrough Transmission Laser Welding (TTLW)\u201d or \u201cLaser Transmission Welding\u201d. This technology involves joining two plastic components, one that is transparent to the laser wavelength and the other that is absorbent to that laser wavelength. During the welding process the laser beam first passes through the transparent part causing no significant heating in the part, and then reaches the absorptive part that soaks up the laser, resulting in heating of its surface. This energy from the absorptive part reaches the transparent part through conduction due to both components being pressed together through clamping. Hence, another factor that is crucial to obtain good welding strength is proper clamping of both the parts.<\/p>\n\n\n\n
Welding of Canister Purge Valve<\/h2>\n\n\n\n
The canister purge valve is an important part of the EVAP (Evaporative Emission Control System). The canister purge valve, which is operated using solenoid, confines the harmful fuel vapour from the fuel tank to prevent them from escaping into the environment. It is widely applicable in automobiles, gasoline, and hybrid vehicles. <\/p>\n\n\n\n
It is extremely crucial for the valve to function properly as it\u2019s malfunction will lead to more fuel usage for producing same level of power. Hence, causing reduction in fuel economy. The canister purge valve is made if PA66 material has two components-one is the lid (30 % glass filled) which is transparent to the laser and the other is the can (13 % glass filled) that is absorptive part as shown in Figure 1.<\/p>\n\n\n\n<\/figure>\n\n\n\n
In order to achieve proper welding results, a proper fixture has been designed to clamp both the parts together as shown in Figure 2.<\/p>\n\n\n\n
\n
\n<\/figure>\n\n\n\n
Figure 2 (a): Fixture for clamping<\/h3>\n<\/div>\n\n\n\n
\n<\/figure>\n\n\n\n
Figure 2 (b): Fixture for clamping<\/h3>\n<\/div>\n<\/div>\n\n\n\n
A lap joint configuration was used to weld both the components of the valve. The dimension of the valve is 32.82 x 51.5 mm. A fibre laser of 70 W is used to weld the valve. The laser beam fired at the valve is wobbled to achieve higher welding integrity.<\/p>\n\n\n\n
Results:<\/strong><\/h2>\n\n\n\n
The welding results obtained is very impressive as shown in Figure 3. There is no material damage observed after the welding process. The welding strength is great as there is no air leakage observed when air at high pressure is passed through the fuel filter.<\/p>\n\n\n\n<\/figure>\n\n\n\n
![\"\"](\"https:\/\/www.markolaser.com\/blog\/wp-content\/uploads\/2026\/07\/Fuel-Tank.webp\")
<\/figure>\n\n\n\n![\"\"](\"https:\/\/www.markolaser.com\/blog\/wp-content\/uploads\/2026\/07\/Fixture-for-clamping.webp\")
<\/figure>\n\n\n\n![\"\"](\"https:\/\/www.markolaser.com\/blog\/wp-content\/uploads\/2026\/07\/Fixture-for-clamping-1.webp\")
<\/figure>\n\n\n\n![\"\"](\"https:\/\/www.markolaser.com\/blog\/wp-content\/uploads\/2026\/07\/Figure-2-b-Fixture-for-clamping.jpeg\")
<\/figure>\n\n\n\n