The conventional vibration welding process of polyamide 66 only has a continuous and steady melt flow during the quasi‐steady phase. The process and resulting welds have been thoroughly investigated. Radiation cross‐linking of polyamide 66 with electron beams alters the material's characteristics. Consequently, the resulting energy balance during vibration welding changes and the squeeze flow is impeded. Additionally, this causes the cross‐linking to attain a residual stiffness above the crystallite melting temperature, thereby influencing the characteristics of the vibration welding process. Further, higher weld temperatures and a change in meltdown behavior can be observed. This leads to a varied relationship amongst the process, structure, and properties for vibration welding cross‐linked polyamide. Hence, weld strengths up to the value of the base material strength are possible. The scope of this article is to investigate the influence of radiation cross‐linking on the material characteristics and, by extension, the resulting processing and welding characteristics. Calorimetric, chemical, rheological, mechanical, and optical investigations serve to highlight the influence of radiation cross‐linking on the vibration welding process of polyamide 66. POLYM. ENG. SCI., 55:2493–2499, 2015. © 2015 Society of Plastics Engineers

An energy harvesting system is presented that converts energy out of flowing media, like water or wind. Without the need for any rotating part the harvester converts the energy out of the bending of a piezoelectric cantilever. A bluff body, which the cantilever is attached to, causes vortices and therefore pressure differences above and beneath the cantilever. Thus the cantilever oscillates and generates an alternating voltage. A first macroscopic model proofed this working concept for air and water. Measurements showed good coupling between flow velocity and power generation. Furthermore a self synchronization of different cantilevers could be observed in water. A second model of the harvester was build with improved distribution of piezoelectric layers. To store and distribute the generated energy of the harvester, it was combined with a low power circuit that was developed, too. Therefore, a complete autonomous system that is able to supply a load and the necessary electric circuit with power is presented.

The weldability of polylactic acid (PLA) is examined in this article. Biaxially oriented PLA films of various thicknesses were joined with impulse and ultrasonic welding techniques. Relatively high weld strengths were achieved with impulse welding over a wide range of welding parameters. Ultrasonic welding produced high weld strengths with relatively short cycle times. In detail, ultrasonic welded samples had a weld factor (weld strength/base material strength) of 1 at cycle times of 0.25 sec. The weld factor was significantly lower at shorter weld times and weld times above 0.35 sec. In contrast, 100‐μm thick samples joined by impulse welding for 2–3 sec had a weld factor of 1 and a standard deviation of only ±5%. The peak temperature during the impulse welding was measured to determine the fusion temperatures of the films. Mechanical, thermal, and optical analysis was used to examine the properties of the PLA at various welding and annealing conditions. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

Adhesive bonding is known to be particularly suitable for thermoset composites with continuous fiber reinforcement as it does not interrupt the fibers because of drilled holes. The frequently used two-part adhesives often require long curing times for the chemical reaction. At the Institute of Polymer Technology (LKT), a vibration-assisted hot melt bonding technique (vibration joining) was developed, which offers short cycle times and represents a modification of hot melt bonding, using the machine technology from vibration welding. It is suitable to join thermoplastics with thermoset materials or thermosets using a thermoplastic interlayer, by taking advantage of short cycle time and good lap shear strength, compared to bonding with reactive adhesives.

A conventional vibration welding process of fiber‐reinforced Polyamide 66 is characterized by a continuous melt flow in the quasi‐steady phase. This squeeze flow leads to a disadvantageous fiber reorientation in the weld zone. The fibers are oriented parallel to the melt flow and thus perpendicular to the common stress direction. This causes relatively low weld strength compared to the strength of the base material. Radiation crosslinking fiber‐reinforced Polyamide 66 with electron beams influences the material characteristics. As a consequence, the resulting energy balance during vibration welding is changed and the squeeze flow is impeded, thus averting the fiber reorientation in the weld seam. The scope of this article is to demonstrate the influence of radiation crosslinking on fiber orientation in vibration welds. Mechanical, calorimetric, rheological, scanning electron microscope, and light microscope investigations serve to highlight the influence of radiation crosslinking on the vibration welds of fiber‐reinforced Polyamide 66. POLYM. COMPOS., 38:489–495, 2017. © 2015 Society of Plastics Engineers

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To provide high quality in production and assembly processes need to be controlled. This paper analyzes the effect and necessity of online monitoring and closed-loop control of pin insertion. In this investigation pin insertion is an assembly process wherein metallic pins are pressed into polymer structures. The investigations described in this paper are made at the Robert Bosch GmbH and according to their requirements towards production standards, quality and traceability.

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