Home > News > Industry news

A New Process for Plastic Welding

  • Time:2021-07-01

  • Read volume:449

  • Share:

Laser welding has been well known to most people as a welding process for metal materials. However, as a process of plastic welding, it is still relatively advanced, and most people may not know much. Laser welding, ultrasonic welding, vibration welding, hot plate welding, etc. are welding technologies widely used in the field of resin plastics.

In recent years, with the continuous development of domestic laser application technology and the continuous development of laser welding equipment, more and more manufacturers have begun to introduce plastic laser welding technology, and the technology that was originally considered "high-end" has gradually been recognized by the public. Because laser welding technology has the advantages of good welding appearance, fast welding speed and high welding strength, it is gradually adopted in the automotive field.



Classification of laser equipment

Depending on the structure of the laser emitting device, laser irradiation methods can be divided into sequential, reflective, and full-circumferential irradiation types.





Principle of laser welding

Part 1 is a transparent material and part 2 is an opaque plastic. The laser beam passes through part 1 to part 2, and the interface between part 2 and part 1 absorbs the laser energy. When the energy is concentrated to a certain extent, the plastic at the interface will be melted. When a certain pressure is applied to the upper and lower parts, the two parts are fused together, and the two parts are fused together after cooling.



Features of Laser Welding



①Short welding time, generally only takes a few seconds ②High degree of freedom of shape, controllable laser path ③Applicable to precision welding ④Good appearance, less burrs, suitable for parts with high appearance requirements ⑤High degree of automation ⑥The heat-affected area is small, and local heating can be achieved.




①The upper parts are required to be able to pass through the laser, and opaque plastics cannot be welded by laser. ②The equipment investment cost is high. ③The professional and technical requirements are relatively high, and it is necessary to have a certain understanding of the laser routing route, speed and irradiation time.


Laser welding process

1Four steps of laser welding:


First, the two parts are mounted on the fixture and tightened; second, by controlling the device to emit a laser, it is ensured that enough heat is generated at the interface of the parts to melt the plastic; third, by applying a certain pressure to the parts, the two parts are melted The parts are integrated under the action of extrusion; finally, by turning off the laser irradiation and maintaining a certain pressure for a period of time, the two parts are cooled, and finally the


                                                                                                                 Laser welding process


Process parameter management

1Laser power:


Laser power is an important factor affecting the quality of laser welding, and insufficient laser power is an important factor causing insufficient welding strength and even interface peeling. Laser power is a top priority for day-to-day management. The attenuation law of laser power is an important task that must be clarified in daily management.


2Laser Speed (Welding Time):


It is an important parameter to ensure the welding strength. If the laser speed is too fast, it may lead to insufficient fusion depth. If the laser speed is too slow, it may cause excessive burrs and reduce the welding strength.


3Pressure (stroke):


For different production lines, the management parameters are different. If the welding strength is guaranteed by the pressure, it is necessary to ensure the accuracy of the pressure and the pressing angle of the pressure. If the welding strength is ensured by the stroke amount, it is necessary to conduct regular inspections to confirm the wear of the positioning pins and the adhesion of foreign matter.




Cooling time is an important parameter to ensure that the two parts can be effectively joined together in the end. Sufficient cooling time can effectively ensure that the melted parts of the two parts can be integrated.


In the daily management work, in addition to the management of process parameters, it is also necessary to conduct regular spot checks on the jig. If the jig is displaced or has foreign matter attached, it may cause that the welded parts of the two parts are not on the same level after installation, so , In the welding process, there may be insufficient welding strength or no effective welding in some parts. Of course, ensuring that the parts are not deformed or shrinked is also an important part of ensuring the quality of welding.


Quality Control Project Management


1Weld strength:


Testing whether the welding strength meets the specification requirements by the tensile testing machine is an important characterization to confirm whether the welding quality is qualified. If it does not meet the requirements, it is necessary to adjust the process parameters to ensure that the specifications are met.


2Welding depth:


It is also called sinking amount or dissolving generation. It is mainly to confirm how much plastic is effectively combined after the two parts are melted, which is an important parameter to ensure the welding strength.


3Destruction method:


Periodically check whether there is interfacial peeling at the welded part by means of a component failure test. Only when the base metal is damaged can the best welding strength be guaranteed.




Whether the centerline of the two parts is offset. If the relative offset of the two parts is relatively large, it may lead to insufficient welding strength.