Laser Welding of Plastics

Dukane Corporation’s Intelligent Assembly Solutions division is one of the world’s leading suppliers of plastic assembly solutions for over 35 years. As new technologies emerge, Dukane has incorporated these new technologies into their line-up. With so many diverse applications, we found it necessary to address our customers' needs with many different bonding processes. Using new laser technologies allows us to provide a welding solution to customers that require a method that has benefits that one would not get from other bonding methods.

Laser Welding Concept

The laser beam penetrates the upper "transparent" component and is converted into heat by the absorbing lower component. Since both components need to be pressed together (as in other methods), heat is conducted from the absorbing lower component allowing both parts to melt and create a bond only where the laser beam is directed. Clamping of the plastic components that are to be assembled is still essential so that intimate contact is made to allow the laser beam to melt exactly where the parts need to be bonded together.

Nearly all thermoplastics can be welded using the proper laser components. Special additives/pigments also allow welding of dark to dark materials as well as transparent to transparent combinations. It's all about color, specifically what color the laser thinks your part is. Parts that appear very dark to the human eye can be either transmissive or absorptive, depending on the formulation of the pigment. Even joints that require optical clarity (clear-to-clear) can be achieved. Laser welding of thermoplastics depends on many of the same rules of resin compatibility that the other processes do, but is more forgiving of resin chemistry or melt temperature differences than most other plastic welding processes.

Advantages of laser welding

No particulate is generated

Vibration-free process

Hermetic seals are achievable

No wear on the tooling

Optically perfect weld joint area

High-precision

Simple joint geometry

Beam Delivery

Diode Lasers operate at a specific wavelength. They are relatively compact, light, and cost-effective. Our diode lasers are available in a wide range of power levels at both 808 and 940 nanometer wavelengths.

Direct Beam delivery use optics that are mounted directly on the laser housing and fixed in focal length and beam position relative to the housing. They are used primarily in systems using the moveable part concept or with diode lasers mounted on robot arms.

Fiber Delivery is used to get the beam into a tight spot where the laser housing may not be able to go. It is useful for delivering a beam to a robot or for fixed mounting in a small space within an automated machine.

Laser Welding Solutions

Contour Welding
In contour welding, a laser is guided along a predetermined welding pattern. The material only melts on the path that the laser is directed. Relative motion is achieved by moving the laser source, the part or a combination of both

Simultaneous Welding
In this technique, a laser will heat the entire weld area simultaneously. Almost any beam geometry can be generated by means of a special, state-of-the-art beam shaping elements. Parts, up to an area that equals 2.000" diameter, can be welded using this method.

View animation of Simultaneous Welding

Mask Welding
With this patented technique, a mask is inserted between the laser source and parts to be welded. A curtain laser beam is moved across the entire joining area of the parts. The laser beam welds only where the components are not covered by the mask. The mask welding method makes it possible to weld extremely delicate weld areas.

Typical Applications: medical micro-fluidic devices and electronic components

View animation of Mask Welding

Radial Welding
A unique welding method for bonding cylindrical components whereby a mirror deflects the laser beam such that it impinges radially on the outside symmetrical surface of the component. The designed tight fit between the parts that are to be joined ensures the clamping pressure required for laser welding to be successful is incorporated.

Globo Welding
Globo welding works along the lines of Contour welding. A laser beam is focused at a point on the joining plane via an air bearing, frictionless, free rotating glass sphere. The glass sphere not only focuses the laser beam; it also serves as the mechanical clamping tool. While the sphere rolls on the components, it applies continuous pressure at a point on the joining plane. The glass sphere replaces the mechanical clamping device and expands the scope of laser welding for both continuous and three-dimensional applications.

Typical Applications: automotive taillights, apparel

View movie of Globo Welding of automotive tail light

Complete Systems Capability

Robotic or Servo Technology uses servo motors to precisely position a direct or fiber-delivered laser beam in contour welding mode. This method allows for parts with complex joint contours, as beam delivery is dependent only on the capability of the robot to follow the welding path. Large parts are easily accommodated using this method. Robotic or Servo Technology can also be used to move the part instead of the laser beam to simplify beam delivery optics and reduce system cost while preserving the ability to weld large parts.

Enclosures are required for laser systems in a factory work environment. All Dukane enclosures are Class I laser tight and utilize laser-safe glass viewing windows where appropriate. Light-curtain-protected doors are utilized for access to the fixturing area for operation, setup, or automated parts handling. A common concept involves a two-position turntable with an integrated door.

Positioning systems run the full spectrum from simple servo stages to complex robotic installations. If you have a need, we will find a way to accommodate it.

Integration of the beam controls with the beam or part positioning system is simple with Dukane's software tools. Using sophisticated computer controls, we work with you to ensure that each weld program results in a robust process and maximized part quality.

For more information contact
Mike Luehr at 630-797-4913
Or e-mail us at:
Ussales@dukcorp.com