Laser welding ins and outs you don't know - By: Wilf Staton

Laser welding plastics is a fairly new process. It super heats the polymer without physical contact. Most applications processes are done by, directing the beam of infrared light. Directly at the weld joint. This is done by going through one of the parts. Commonly referred to as, through transmission.

By directing infrared beam of infrared light at the weld joint via( a laser)welding. This technique, the infrared beam, usually a laser, irradiates the joint through a part and the light is absorbed at the surface of the other. While broad band infrared beams can be used, the monochromatic lasers allow very fast heating of small areas of the part that allows the parts to be welded very rapidly, but with very small changes to the geometry part.

Laser welding is a example of electromagnetic plastic welding process. Once radiant energy it has been directed towards polymer surface, a series of three things will happen to it, most of the light transmits through, some is absorbed, and some is reflected away. The application the process involves directing the beam of infrared light towards the weld joint through one of the parts. The part (laser) that transmits most of the energy will not heat, but the absorbing part will super heat .Most virgin, organic polymers will not absorb energy. Certain dyes and fillers such as carbon black are used. To absorb the energy at the weld joint interface. This is commonly called to as through transmission infrared (or laser) welding. Welding results when materials are heated to a molten state and fused together.

One type of material must transmit the laser light while the other absorbs it, While converting it to heat. The great news is that the materials must be transmissive. This all depends on formulation of the pigment. Joints that require optical clarity can be done by the use of special coatings types. Thermoplastics, Laser welding, resin compatibility , resin chemistry or melt temperature differences than most all other plastic welding processes these days.

Nd:YAG laser welding is used commercially, a wide range of C-Mn steels, stainless steels, coated steels, molybdenum, titanium, and aluminum alloys. Low heat input welding. These lasers is utilized in the electronics, domestic items, automotive sectors, the most interest has been shown more recently, to particularly for the high power CW lasers in the shipping industry. Oil and gas, R&D issues involving development of highly powered lasers of better beam quality, the use of distributed energy in the beam focus, maintenance for both thick and thin sections and weld classification.

Light energy is generated by lasers. That can be absorbed into materials and converted to heat energy. Laser emits coherent radiation. Lasers do minimal divergence that can travel over significant distances without loss of beam quality or energy.

Relatively new techniques in Laser welding have been compared to other plastic welding processes. Dedicated laser labs at EWI’s are equipped with lasers creating and analyzing plastics welding. The laser beam used to melt the base material and filler rod, this process becomes line of sight ,as well as focal point limited process. If you cannot get a straight shot, or you can't re-line the position of the weld area, it will not work efficiently or correctly. Microscopic magnification is also is used in the laser welding process.

The system is capable of welding materials that are galvannealed, electroplated or hot-dipped galvanized, that the coating thickness be both consistent on top of surface of the material, as well as controlled to 14 microns or less. The 3-kW diffusion-cooled slab laser used in the Utica system can be used to weld materials, ie mild steel, high-strength steel, stainless steel, aluminum. The biggest driving factor behind the development of laser welding is the fact that it makes the cans more esthetically attractive.

Beam delivery used optics that are mounted directly on the laser housing and fixed in focal length and beam position relative to the housing. Moveable part concept ,diode lasers mounted on robotics. Multiple-beam processing is new , relatively new field that has the potential. Enhancing the capabilities of high intensity laser and electron beam process.

Post heating, multiple-beam laser preheating is shown, first presented and analyzed. Followed by multiple-beam flow. this application electron beam welding. Other applications using laser machining and cladding. Particles with high melting points were distributed on the plate material in order to see the motions of these particles. And the enclosed motions of the melt pool during welding with different type of process gases. Photos show a change in the melt flow direction ,with active gas components towards the center of the pool and downwards towards the root side.

About the Author

Roger Hathaway from Arcor laser is experienced in laser welding and knows the difficulties that arise from meeting the demands of the 21st century manufacturing by utilizing the many benefits realized by laser materials processing.

Article Directory: http://www.articlerich.com

Additional Articles From - Home | Reference & education | Science