Diode lasers can be employed to weld thermoplastic materials such as polypropylene to itself and other materials.

New welding technology allows the joining of polypropylene to itself, which was previously a problem due to the material's chemically inert nature.
Developed by Coherent Inc., Semiconductor Group, Santa Clara, CA, and Gluco Ltd., Leeds, United Kingdom, plastics-to-metal joining technology centers on a type of interlayer material that enables the joining of low surface energy and dissimilar substrates.

Using LaserBond adhesive interlayers, it has been shown that diode lasers can be employed to weld thermoplastic materials such as poly-propylene to itself and to metals, including mild steel, auto body zinc-coated steel, stainless steel and aluminum. Polypropylene commonly is used in applications in the automotive, packaging, food and pharmaceutical industries.

According to Tony Hoult, applications manager for Coherent Semiconductor Group, "The LaserBond film interlayer materials are tailored in such a way that they allow the joining of poly-propylene to itself, which has always been a problem be-cause of the chemically inert nature of the material." The film also allows poly-propylene to join to other substrates and produce high-strength joints when used in conjunction with high-power diode lasers.

Historically, plastics laser welding has depended upon conventional lasers, but widespread industrial use was considered unrealistic due to their relative high cost and complexity when compared to heat sources such as flame and infrared lamps. While diode lasers have been available for some time, developments in ease-of-use, reliability, power and brightness have only recently accelerated their acceptance within industry as materials processing tools.