Fiber laser meets demands of Japanese automotive industry

Sumitomo Heavy Industries and JK Lasers show that a 1 kW fiber laser produces the necessary high-speed, high-quality welds demanded from Japanese automotive manufacturing companies for several applications.

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Tokyo, Japan -- Welding trials conducted by the Mechatronics Division of Japanese systems integrator Sumitomo Heavy Industries (SHI) show that a 1 kW fiber laser (JK1000FL) produces the necessary high-speed, high-quality welds for a range of demands from Japanese automotive manufacturing companies, for applications including the welding of diesel injectors and airbag initiators.

Compared to the 600μm spot size previously attainable using a CW Nd:YAG laser, a more focused 50-200μm spot size can be achieved with the fiber laser from JK Lasers, which allows for deeper penetration or faster processing speeds. When keyhole welding stainless steel, for example, this laser achieved nearly 2 mm penetration at 3.5 m/min and 3 mm penetration at 0.5 m/min (FIGURE 1).

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The exceptional beam quality of the 1 kW fiber laser also means it is tolerant to defocusing. As a result, processing parameters do not have to be altered to accommodate slight variations between the material and the nozzle tip or lens. SHI's trials demonstrate that the penetration depth of this laser is insensitive to defocus, in the range of ± 1 mm (FIGURE 2).

The ability to weld consistently while slightly defocused allows for manufacturing part variations and robotic welding arm path discrepancies, a major concern in on-line welding applications. Welding reflective materials such as copper and aluminum, commonly used in automotive battery applications, can cause damaging back-reflection. JK Lasers' patented delivery fibers protect the laser under these conditions.

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Fiber lasers' sealed optical design eliminates the need for routine maintenance. With a mean-time-to-failure (MTTF) of over 300,000 hours, the diode laser pump sources used in JK Fiber Lasers are extremely reliable and help deliver wall-plug efficiencies of over 25% as part of an optimized laser design.

Fiber lasers consume up to 10× less energy than Nd:YAG lasers of the same output power -- a feature of considerable interest in a country where electricity supplies are at an all-time low. Almost all of Japan's 54 nuclear reactors, responsible for a third of the nation's electricity, were shut down following last year's devastating earthquake and tsunami. A pair of plants has been approved to restart as soon as July 2012 (in Fukui Prefecture, about 500 km southwest of the ground-zero Fukushima Daiichi site), but Japan's long-term nuclear plans are still undecided.

The Mechatronics Division of SHI has worked closely with JK Lasers for over two decades, integrating the laser manufacturer's comprehensive range of Nd:YAG and fiber lasers into its production machines. JK Lasers, part of the GSI Group, manufactures fiber lasers, CW and pulsed Nd:YAG lasers as well as process tools and user-friendly software.

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