Laser Welding
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Contained weld joints have no flash or particulate outside the joint to cause problems. The assembly sees no heat or vibration, and the parts do not move relative to one another in the laser welding process. The process can produce visually pleasing joints on parts with complex geometries, both very large and very small. The laser welding process is extremely precise and controllable. Full-wall collapse welding in quasi-simultaneous mode even has some gap-filling capability. Laser welding is versatile and capable, and it probably costs less than you think.

It's all about color, specifically what color the laser thinks your part is. More scientifically, one material must transmit the laser light while the other absorbs it, and converts it to heat. The good news is that the materials must be transmissive or absorbtive only at the specific wavelength of the laser source used. Parts that appear to be black to the human eye can be either transmissive or absorbtive, depending on the formulation of the pigment. Even joints that require optical clarity (clear-to-clear) can be achieved by the use of special coatings. Laser welding of thermoplastics depends on 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.

Diode Lasers are essentially high-powered LEDs that 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.

Robotic or Servo Technology uses servo motors to precisely position a direct or fiber-delivered laser beam in contour welding mode. The use of modern path-following robots allows for considerable freedom of part design geometry. 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 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. Also called fixed-beam systems, this technique works best with moderate sized parts. Selection of moving stage concepts or robotic fixture manipulation depends on the complexity of the joint geometry.

Combining Various Technologies combines the best of both worlds. If both part and laser beam are moved in coordinated fashion, large and complex parts can be welded using simple part moves and complex beam moves, or vice versa. This allows for the best of all possible worlds and a complete arsenal of approaches to both large parts and parts with complex joint geometries. The possibilities for combining motion control technologies and beam delivery methods are nearly endless.

Direct beam delivery used 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 Nd:YAG or CO₂ beam to a robot end effector or for fixed mounting in a small space within an automated machine.

Beam Splitting is useful for welding larger parts. A single higher-power laser beam can be split into two beams each at half the power of the original beam, and may be divided again if needs be. This allows for multiple-part production from a single motion source, or attachment of multiple galvo heads to a single laser so quasi-simultaneous welding can occur on a part larger than the working field of a single galvo head. Cost-per-unit-power drops as laser size increases, so beam-splitting is a good option for welding large parts quickly.

Complete Systems Capability

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 guillotine 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 or galvo heads 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.

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