Ultrasonic nodal point, a new configuration for ultrasonic moulding technology

Ultrasonic moulding is a new technology that uses high power ultrasound to melt and mould thermoplastic polymers to produce samples with mini and micro features. The main feature of this technology is the use of ultrasonic energy as the heating source instead of a conventional injection screw. Even if ultrasonic moulding overcomes some of the drawbacks of conventional mini and micro-injection moulding, it still presents two main limitations that are hindering its widespread applicability: the lack of stability of the process and the difficulty to obtain samples with good mechanical properties for some materials. This article presents a new configuration, called nodal point ultrasonic moulding (NPUSM), to surmount such limitations. This configuration improves the stability of ultrasonic moulding technology and it is capable of processing materials with good mechanical properties. To prove its efficacy, the nodal point ultrasonic moulding configuration is used to obtain the processing window of a polyoxymethylene material and these results are compared with standard ultrasonic injection and conventional injection moulding. The results obtained show that NPSUM configuration improves the capabilities of ultrasonic moulding technologies.