By Emma Wood, Global Product Manager for Non-ultrasonic Technologies at Emerson
Laser plastic welding continues to grow in popularity worldwide because it provides a unique range of capabilities and benefits: gentle and vibration-free joining, particle-free cleanliness and precision fluid paths, strong bonds with hermetic seals, exceptional aesthetic appearance, and the versatility to bond an extremely wide range of polymers in assemblies large and small.
Typical laser welding transmits focused laser energy through a transparent/transmissive part to an absorptive part, heating the part interface, so that gentle compressive force can complete the weld. Photo courtesy of Emerson.
While laser plastic welding is a single technology, the key to its versatility is that it can be performed using two different methods: Simultaneous and Quasi-Simultaneous. Both of these laser plastic welding methods transmit laser light through a “transmissive” (transparent) part to the surface of an “absorptive” (dark) part. The laser energy generates heat at the interface between the two parts that melts the plastic. Then, with the help of controlled compressive force, the softened part surfaces are brought together and the weld is completed. Laser welds are clean and particle-free, with hermetic seals and an excellent aesthetic appearance.
Simultaneous laser plastic welding, (technically known as Simultaneous Through-Transmission Infrared or STTIr) delivers laser energy to the entire weld at the same time, using specially designed fiber-optic bundles. The Quasi-Simultaneous process relies on a single laser and a set of movable mirrors, positioned over the surface where welding takes place. In operation, the movable mirrors, steered by servo-driven galvanometers, trace a beam of laser energy along the contours of the weld joint in a continuous, closed loop. The heating effect on the plastic is very rapid, but not simultaneous, hence the name “quasi-simultaneous.”
Quasi-simultaneous laser welding uses movable mirrors, shown above to focus laser energy along the contours of the weld joint in a continuous, closed loop, such as in the sample pattern shown below. The ability to follow varied product contours when welding makes quasi-simultaneous laser welding a preferred option when welding involves a greater mix of lower-volume products. Photo courtesy of Emerson.
While simultaneous laser welding is well suited to high-volume, mass-production parts, the quasi-simultaneous process is often preferred by manufacturers that must weld a more varied, lower-volume mix of parts or those that often weld larger parts. Part for part, quasi-simultaneous weld cycle times are longer, though total cycle time can still be measured in seconds.
The quasi-simultaneous process offers manufacturers the flexibility of using a single, programmable laser welding platform to weld 2D parts, simpler 3D parts, and larger part assemblies. Welding different parts is done by way of programmable “recipes,” which can be developed and saved for future use in the welder control.
Quasi-simultaneous laser plastic welding platforms, like the new Branson GL-300 from Emerson, offer market-leading power (300 watts maximum) and advanced features to laser weld plastics used in everything from micro-sized medical or electronics products to larger automotive and industrial components. Photo courtesy of Emerson.
With the help of these recipes, quasi-simultaneous weld platforms offer the versatility to perform everything from micro-sized welds on electronic or medical devices to larger welds suited to industrial or automotive products. The sole limitation on this process is the maximum size of the part (not to exceed 300 millimeters in any dimension) and the ability of the laser-aiming mirrors to access all essential contours of the weld area.
Conclusion
Quasi-simultaneous laser plastic welding offers a versatile joining solution. Whether it is used to join large parts or micro-sized assemblies, this gentle, vibration-free process is friendly to embedded sensors and electronics. It produces particle-free and aesthetically pleasing products that complement product designs. The process also supports the cleanliness, precision, and transparency needed to meet demanding requirements for industrial, automotive, electronics, and medical applications.
Emerson
www.emerson.com/en-us
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