What is Laser Welding of Plastics?

Dukane Corporation's Intelligent Assembly Solutions division is one of the world's leading suppliers of plastic welding and assembly solutions. We have always incorporated new technologies into our offerings. With so many diverse applications, we found it necessary to address our customers' needs with many different bonding processes. Using new laser welding 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 Process

Laser welding of plastic parts has established itself as a robust, flexible and precise joining process. Laser welding enables highly efficient and flexible assembly from a small-scale production of parts with complex geometries to a high volume industrial manufacturing, where it can be easily integrated into automation lines.

This highly repeatable and clean process with no relative parts movement during the welding cycle offers numerous advantages. Thanks to its localized heat input and low mechanical stresses, this process enables welding of sensitive assemblies in medical device manufacturing, industrial and consumer electronics and automotive components without damaging delicate inner components by heat or vibrations.

Welding Process Fundamentals

Laser welding uses a laser beam to melt the plastic in the joint area by delivering a controlled amount of energy to a precise location. This level of precision in controlling the heat input is based on the ease of adjusting the beam size and the range of methods available for precise positioning and moving the beam.

The process is based on the same basic requirements of material compatibility as other plastic welding techniques, but is often found to be more forgiving of resin chemistry and melt temperature differences than most other plastic welding processes. Nearly all thermoplastics can be welded using a proper laser source and appropriate joint design.

In Through Transmission Laser Welding (TTLW) the parts are pre-assembled and clamped together to provide intimate contact between their joining surfaces. The laser beam is delivered to the parts interface through the upper "transparent" part and is absorbed by the lower absorbing part, which converts IR energy into heat. The heat is conducted from the lower absorbing part to the upper part allowing the melt to propagate through the interface and form a bond. Precise positioning and clamping of the assembly is essential, as intimate contact is required for heat transfer between the parts. Carbon black and specially designed absorbers are blended into resin or applied to the surface to enable IR radiation absorption in the lower part of assembly.

The TTLW welding technique is dependent on the presence of an absorbing agent in the lower component, and this limits the process applicability for manufacturing of medical devices, electronics and some consumer goods when a "clear-to-clear" or a "clear-to-colored" assembly is required.

Dukane engineers have successfully overcome this obstacle by integrating in its new welding systems a recently developed 2 micron lasers. This laser is characterized by a greatly increased absorption by clear polymers and enables a highly controlled melting through the thickness of optically clear parts. This has resulted in a greatly improved and simplified technique for laser welding of clear polymers for the medical device industry, which now can fully capitalize on benefits of this advanced assembly process.

Laser Welding video

Advantages of Laser Welding

Joint Characteristics

  • Minimal or no flash. Clean and aesthetically pleasing appearance
  • No particulate matter, residue, or other debris generation
  • Localized heat input
  • Non-contact process with minimal mechanical stress level on inner components during the weld
  • Excellent Bond Strength and Long-Term Stability
  • Hermetic seals are achievable
  • Reduced residual stress
  • Welding of complex shapes is possible

Assembly Process

  • Non-contact, minimized tool wear and retooling cost
  • Process Adjustability and Precision
  • Process Repeatability - highly controlled and consistent heat input, precision clamping with no relative motion of parts during the welding cycle assures a highly repeatable welding process and consistent joint quality. This results in Reduced scrap and QC cost
  • No consumables
  • Minimum maintenance requirements and long life expectancy of lasers
  • Lower Cost per Unit. Initial investments for laser systems are typically higher, however when the whole production chain and cost of ownership is taken in consideration, this assembly process results in significant savings, as operations and maintenance costs are significantly lower than of other assembly techniques.

Competitive Advantages of Dukane's Laser Welding Technology

  • Highly sophisticated Custom Tooling for precise parts positioning and clamping is critical for laser welding process. All tooling for laser welding applications is designed and manufactured in the same U.S. facility where the laser work stations are built. This allows Dukane engineers to have better control over the manufacturing process and delivery times. Our tooling engineers and CNC machine operators can readily discuss and decide if modifications need to be made during the fabrication/assembly process.
  • Beam Delivery: Fiber-optic cable, scan head with mirrors coated for appropriate wave length, focusing optics, programmable multi-axis servo stages.
  • Robotic and Servo Technology. Dukane systems utilize servo motors to move and precisely position the laser when larger parts are welded. Servo Technology can also be used to move the part instead of the laser beam to simplify beam delivery options and reduce system cost while preserving the ability to weld large parts.
  • Work cell designs or automation line integration are available. Dukane's design platforms support any degree of automation, from stand-alone work stations to fully integrated systems. Dukane maintains strong relationship with automation equipment builders, which benefits its customers by meeting their specific needs.
  • Parts handling, loading/unloading. Part loading options include manual and automated slide fixtures, quick-change tooling and part identification techniques. Robot loading is an option for automated assembly lines. Mechanical, pressure and vacuum technologies aided by various types of sensors are used for parts precise positioning and clamping.
  • Laser Safety Enclosures. All laser enclosures are Class I laser tight and utilize laser-safe glass viewing windows where appropriate. Light-curtain-protected doors are sometimes utilized for access to the fixture/weld area for operation, setup, or automated parts handling. All access doors are safety-interlocked.

For more information contact
Mike Luehr at 630-797-4913 or