A dry powder micro delivery device for multiple material additive manufacturing

Abstract

This thesis focuses on developing a novel material delivery device for a Multiple Material Additive Manufacturing (MMAM) system using a Dry Powder Printing (DPP) technique developed recently. The goal of the thesis was to study in detail the characteristic of a micro dispensing device utilizing ultrasonic vibration via a piezoelectric transducer, which was designed and constructed to handle a wide range of fine powder materials. The research systematically investigated the nature of the interaction between the device and the materials, which allowed the design and processing parameters to be understood. Experiments were conducted to explain the effects of the printing parameters on printing results so as to discover the basic characteristics of the new dry powder printing device. Moreover, weight measurements of the deposited powder, microscopy and image visualization was used to assess the behavior of the device. The device developed can successfully provide continuity, consistency and reliability of layer printing of multiple material powders. The results demonstrated that the device is capable of dispensing various types of fine powders, such as metals, polymers and ceramics, with particle sizes of between 14-72?m. The relative standard deviation of the device is less than 7%. The minimum mass flow rate can be reached at 0.14 mg/s for a cohesive powder such as a copper powder. The maximum moving speed is up to 50 mm/s for a free flowing powder such as a solder powder. Currently, the precise printing of micro geometries can be achieved up to a diameter as small as 85?m. Moreover, the study also reveals that the performance of the device mainly depends on the dispensing parameters (e.g. nozzle diameter, nozzle angle, and piezo electric position), material parameters (e.g. type, particle size, flowability) and process parameters (e.g. moving speed, signal voltage and standoff distance). High resolution printing by the device can be achieved by controlling these parameters. This work has shown that the dispenser can deliver different powders in very precise and small quantities at almost any designated position. This demonstrates the potential of this method for a multiple material delivery system for MMAM in the near future.

More information

Identifiers

ORCID for Shoufeng Yang: orcid.org/0000-0002-3888-3211

Catalogue record

Export record