Laser-Based Additive Manufacturing of Hybrid Metal/Polymer Components

UoM administered thesis: Phd

  • Authors:
  • Yuan-Hui Chueh

Abstract

To produce complex functional devices while eliminating the need for assembly calls for a multi-material additive manufacturing technology (MMAM). While MMAM has progressed rapidly over the last few years, little progress has been made so far on the additive manufacturing of metal/polymer hybrid components due to significant property differences between materials. This PhD project aims to broaden the field of MMAM technology by developing laser-based MMAM systems to print discrete multiple-material components that consist of metal and polymer with either complex hybrid structures or reliable interface strength. The main objectives of this project are to: (i) develop an integrated fused filament fabrication (FFF) / laser-based powder bed fusion (LPBF) process MMAM technology and a multiple-material LPBF process to fabricate metal/polymer components; (ii) analyse the characteristics of the proposed MMAM system based on printed metal/polymer components; (iii) characterise the morphology of the metal/polymer joint interface and examine the joint strength; (iv) characterise the dispensing of polymer, polymer/ceramic, polymer/metal powder mixtures through the proposed ultrasonic vibration-assisted powder dispensing nozzle; (v) demonstrate the printing of multiple polymeric composites, 3D functionally graded composite components, and metal/polymer entangling structures through the LPBF process; (vi) investigate the material interaction between metal and polymer during laser melting. In this PhD project, metal/polymer components were printed through two MMAM processes: integrated FFF/LPBF and multiple-material LPBF. The integrated FFF/LPBF system comprised a multiple-material delivery unit and a pneumatic-based pressing unit that were specially designed to deposit metal and polymer. The joining of metal/polymer was created through the system and examined using tensile and shear tests. Laser-melting of metal on the top of a polymer substrate was also performed to fabricate metal-polymer-metal sandwich structures. Several 3D components composed of hybrid stainless steel 316L (SS316L), Cu10Sn, Polyamides-11 (PLA) and Polyethylene terephthalate (PET) were successfully printed to demonstrate the system’s feasibility. The multiple-material LPBF system used reengineered ultrasonic vibration-assisted nozzles to fabricate metal/polymer components. The dispensing of difficult-to-feed fine powder mixtures (such as PA11/Al2O3) with irregular powder geometries via the nozzles was investigated. Components composed of multiple polymer composites (PA11/Al2O3, PA11/glass, and PA11/Cu10Sn) with high volumetric ratios (up to 90%) of additives and 3D functionally graded structures were printed to demonstrate the feasibility of the nozzles. Metal/polymer (Cu10Sn, SS316L and PA11) components with complex geometries (such as entangling structures) was also printed through multiple-material LPBF. The interaction between metal and polymer within the powder bed during laser melting should be avoided. However, adding a moderate amount of polymer to metal led to improvements in the roughness of the printed metal surface and reductions in the hardness of the metal/polymer components.

Details

Original languageEnglish
Awarding Institution
Supervisors/Advisors
Award date1 Aug 2021