Ultrasonic Extruded Weld-Riveting
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Ultrasonic Extruded Weld-Riveting
Traditionally, either fasteners or adhesives have been used to join metal parts to carbon fiber-reinforced thermoplastic (CFRTP). Alternatively, welding is being used to join metal and CFRTP. The mainstream method of welding metal and CFRTP is first to modify the metal part by creating macro- or microstructures on its surface. These structures help to increase the effective connection area and improve the mechanical interlocking between the two parts. Next, a thermal technique, such as laser welding, friction stir welding or hot-press welding, is used to heat the metal part above the melting point of the CFRTP. Heat from the metal then melts the CFRTP, and the molten resin flows into the surface structures of the metal part to form a joint.
The problem with this method is that the heat can adversely affect the metal part, especially for metals with poor high-temperature resistance, such as magnesium alloys. We have developed a new technique, ultrasonic extruded weld-riveting, that shows promise for joining metal to CFRTP without a third component and without damaging either part. In our method, prefabricated through-holes are machined on the metal part. The CFRTP part is placed on top of the metal one. Ultrasonic welding is used to melt the CFRTP, and the molten plastic is squeezed into the holes in the metal. A riveted joint will then form after the plastic cools and solidifies.