NEW LASER-WELDABLE AKULON® PA6 FROM DSM OPENS BROAD 3D PRODUCTION OPTIONS FOR ASSEMBLED PRODUCTS THAT REQUIRE STRONG, SMOOTH BONDING

DSM Engineering Plastics, a business group within the DSM N.V. (Euronext Amsterdam:DSM) Performance Materials cluster, today introduced a new, laser-weldable Akulon® black polyamide 6 (PA6) 30% glassfibre reinforced grade, UltraLas™ K224-HWXG6, that offers strong, smooth assembly and sealing along complex geometries.

In addition to enhancing design freedom, K224-HWXG6 broadens the scope of welded product design, from ultraminiature to extremely large. In addition, the new material permits new types of hard/soft combinations such as those for cushions, armrests, and vibration or noise-control components. The announcement was made here at K 2004, International Trade Fair for Plastics + Rubber, where DSM is exhibiting at Stand B11 in Hall 06.

The heat stability of UltraLas™ K224-HWXG6 is that of general Akulon grades, which can sustain service temperatures of 170 °C and short-term exposure up to 190 °C. The black colour of the new material matches that of other black DSM compounds, allowing the welding of parts onto black substrates without visible seams. In contrast to solvent welding, laser welding is environmentally friendly.

“Laser welding has especially caught the attention of design engineers in the automotive industry,” said Bert Havenith, general product manager Akulon Injection Moulding for DSM. “Many conventional welding techniques require straight-line designs along the weld, but automotive components increasingly require sculpted or complex shapes. Unlike vibration welding’s limitation to 2D flat surfaces, lasers permit full 3D design freedom. We expect to see a rapid adoption of laser-welded parts as soon as model year 2006.”

In contrast to vibration or conventional heat welding which leaves a more or less prominent ridge on welded surfaces, parts designed in laser-weldable Akulon K224-HWXG6 can be welded smoothly anywhere a laser energy beam will penetrate. The weld’s smooth surface is ideal both for aesthetic and fluid or gas flow requirements.

The PA6 base polymer of Akulon K224-HWXG6 offers high transmissivity of laser energy. As a result, just a 2 mm layer of the new grade transmits fully 70 percent of the energy from a 1064-nm Nd-YAG laser, enabling short production cycles, more complex geometries, and/or thicker walls.

Laser welding is indicated in a range of designs, from miniature components to encapsulation of functional elements, to assembly of large structures. The heat energy applied to the welded surfaces is small and of short duration, helping to maintain the mechanical and chemical properties inherent to Akulon. In addition, it is a contact-free process, avoiding distortion from weld tooling and greatly simplifying welding setup. Finally, it offers large quality-inspection savings, as welds can be scanned using infrared (IR) energy rather than mechanical or burst testing that ironically can stress the part and may result in early field failure.

In automotive, laser welding is well-suited for assembly of sensors, where transducer elements are sealed against fluids and dust in housings that are often geometrically complex. Other applications already in use or in development include sealed number-pad entry modules and air ducting.

Welding is useful when enclosures hold functional components (often electromechanical or mechanical in nature) that are inserted in one or more sections of the enclosure prior to final assembly. Laser welding also handles extremely intricate geometry, enabling production of components where net-shape mould tooling would be prohibitively expensive and complex.

Akulon UltraLas™

In addition to laser-weldable grades, the UltraLas™ family of compounds from DSM includes laser-marking grades. These can provide dark markings on a light background or vice-versa. Colour ranges are possible, developed on a custom basis. Laser marking provides a ready means of decorating, serial numbering, dating, and or otherwise individually labelling customised products. Because the process uses no inks it is, like laser welding, environment

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