Laser-enhanced bonding produces strong seams

A laser-enhanced-bonding (LEB) process developed by LightSeam Technologies (Golden, CO) may revolutionize the apparel industry by changing the way materials are joined. The process uses a laser to "drive" a polymer adhesive into the materials being joined, eliminating sewing, gluing, taping, and ultrasonic welding.

Laser-enhanced bonding produces strong seams

Rick DeMeis

A laser-enhanced-bonding (LEB) process developed by LightSeam Technologies (Golden, CO) may revolutionize the apparel industry by changing the way materials are joined. The process uses a laser to "drive" a polymer adhesive into the materials being joined, eliminating sewing, gluing, taping, and ultrasonic welding.

Upstream of a nozzle ti¥that discharges the polymer into the seam is a coaxial window where a laser beam is introduced into the bonding agent flow. The polymer acts like an optical fiber, conducting light energy to the nozzle area, where the slightly heated agent is driven into the adjacent materials forming the seam joint.

Key to the process is the improvement to the polymer cohesive strength by a factor of three, according to LEB inventor and LightSeam director of research and development Craig Neff. The resulting seam is impermeable, flexible, and neat. Environmental and occupational safety concerns also are addressed for joining materials such as neoprene, which currently requires use of hazardous toluene to produce a fluid-tight seam.

The LightSeam LEB machine uses a 200-W CW Nd:YAG laser from Colorado Laser, another company in the Light Technologies Grou¥founded by Neff and his wife Janie, the president and CEO. Additional markets are being explored for LEB in industries such as bookbinding, laminating, injection molding, and carpeting. For injection-molding applications the laser would be axially beamed though the nozzle that injects plastic into the mold, with strength improvement similar to that obtained with polymer adhesives, according to Neff.

Apparel companies have expressed interest in developing sportingwear using LEB, such as wetsuits, waders, and outdoor footwear, as well as protective garments for medical use and toxic- waste cleanup, and military equipment. The US Army Natick Laboratory (Natick, MA) has also shown interest in the technique for making tents, parachutes, and ballistic vests. Neff notes that in fabricating a wetsuit, not only are toxic chemicals eliminated but the time to make a suit would be "a hundred times quicker than the 16 hours now needed" because a seam can be completed on one pass rather than multiple passes for stitching, sealing, and so forth.

The LEB process is nondestructive to the materials being joined--sewing makes holes that can stretch, and ultrasonic joining melts the material. And dissimilar materials can be joined to each other; the only compatibility necessary is with the adhesive. Materials including cotton blends, leather, and wools can be bonded.

Light Technologies and industrial sewing-machine maker Union Special (Charlotte, NC) will have machines available for the apparel industry by the end of the year. Don Ford, Union Special vice president of automated systems, says, "We are taking their prototype and making it manufacturable, and we`ll produce them. [Light Technologies] has the basic unit to apply the adhesive, and we supply the material-handling technology. It`s done a good job in developing an effective laser."

Meanwhile, Timberland (Hampton, NH), a shoe and outdoor-footwear manufacturer, will rent an LEB machine for a year to investigate the process. Acceptance in either of these areas would open a wide market and mark a major change in the way materials have been joined in the more than 150 years since introduction of the first sewing machines.

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