This project involves the development of processes specifically for the 3D printing of solid dosage forms. The key focus will be on the optimisation of 3D printing based processes to scope out the range of qualities achievable (e.g., in appearance, repeatability and speed), identify the relationships and trade-offs inherent in the process and achieve optimal process conditions. The form and distribution of the Active Pharmaceutical Ingredient (API) will be assessed in situ within the formulation. Mechanisms of drug release will be established for the different printed dosage forms. A focus will be to characterise and understand the possibility of crystal form control in the printed dosage forms and to evaluate potential in-line tools that could be used to monitor key parameters during manufacture by 3D printing

Polymers are used in different additive manufacturing (AM) techniques such as material jetting, material extrusion, binder jetting, vat photopolymerisation, sheet lamination, and powder bed fusion. In general, they are all suited for low-volume production/prototyping, complex geometry, bespoken parts, avoiding the losses of expensive materials (usually involved in traditional fabrication), rapid tooling/mould manufacture, and reverse engineering.

Only a small percentage of the available polymers on the market are suitable to be processed with an AM technique as particular material properties are required for each method. The lack of a diversified portfolio of materials is one of the main limitations of AM, thus research in this field is essential for the advancement of the technique and to reduce the gap between AM and the traditional manufacturing industry.

This project will focus on fluoropolymers, a particular family of polymers with outstanding properties such as high thermal stability (service temperature up to 300°C and down to -250°C), high chemical resistance, high purity, flame resistance, low permeability, low surface energy (non-stick), low dielectric constant (insulating), low refractive index, and good transparency to UV, Visible, and IR light. Any one of these properties can be found in other materials, but fluoropolymers are unique when two or more of these properties are required in the same application. Still, all these qualities come with a price, they require particular manufacturing processes, where some of these processes are highly wasteful and do not allow complex geometries. Special recycling systems are also required to reuse fluoropolymers. Therefore, as aforementioned, AM could decrease the amount of wasted material and simplify the manufacturing process. 

Titanium Aluminides offer great potential as a lightweight alternative to the Nickel-based superalloys currently used in many aerospace applications. This research will look into processing Titanium Aluminides through the Direct Metal Deposition process to produce near-net shape aerospace parts. The research will also investigate the capabilities of functional grading, Oxide Dispersion Strengthening, and the ability to embed sensors within components during processing.

This research will develop new methods to produce novel, functionally graded lattice structures. The use of Additive Manufacture (AM) enables the creation of novel lattice structures that are difficult and expensive, or not currently possible, using conventional manufacturing methods. By varying the density of a lattice its mechanical properties can be varied across the structure to provide a more optimal design solution. This has applications in many research areas, notably in biomedical implant design, where it has been identified as a key means to reduce an issue known as stress shielding in orthopaedic implants. Stress shielding is a primary cause of implant failure, due to its detrimental effect on the remodelling of the surrounding bone. Therefore the research aims to improve the design of implants through developing new methods to produce functionally graded lattice structures in order to overcome these effects.

Orthopaedic implants are primarily made of metallic materials; therefore the research will focus upon design for manufacture using Selective Laser Melting (SLM). SLM is an AM process specifically designed for the processing of metals and has advantages over other metallic AM processes, e.g. Electron Beam Melting (EBM) and Direct Energy Deposition (DED), such as superior mechanical and surface properties. For biomedical applications SLM currently provides better component characteristics compared to both EBM and DED, and is already being used in implants. However, SLM can limit design freedom due to certain aspects of how the process operates, most noticeably the need for support material. The limitations in design freedoms will be incorporated into the design methodology to ensure the structures can be manufactured using SLM.

The aim of this research is to develop robust design rules relative to the structural integrity of Additive Manufactured (AM) wrist splints, in order to bring the digitised splinting process closer to realisation. This research is to follow on from previous research carried out at Loughborough University by Paterson (2013).

The main objectives of this research are to perform mechanical testing on samples made using low cost 3D printing (PLA, ABS) and high-cost Material Jetting (acrylic-based photopolymer Digital Materials) to gather local base data, analyse how build orientation affects the mechanical properties of an artefact (specifically splint designs), identify optimum geometric properties of pattern cut outs and wall thickness to mechanical strength ratio using FEA, validate findings and establish conclusions.

This additive manufacturing project will investigate various Borgwarner products to potentially replace one or more component manufacturing methods with AM techniques. The primary goals of the project are to reduce the weight of a number of current automotive products whilst improving product functionality.

Polymer Laser Sintering is the most widely used Additive Manufacturing process in industry, but almost all use is with either nylon 11 or 12. It is also recognised that the lack of materials, measured both in quantity of options and their quality, is one of the main barriers to the more widespread adoption of the process in industry. Improved materials for Laser Sintering could make Laser Sintered parts a possibility in a wider range of more demanding applications.

The literature shows that there is no single analytical technique which definitively shows how a polymer will perform in the Laser Sintering process. However, models based on computational fluid dynamics (CFD) for the related processes of Laser Melting and Electron Beam Melting have been developed and demonstrate the potential for extension to modelling polymer laser sintering.

This project aims to develop a predictive tool for Laser Sintering using CFD simulations. This requires two strands, one practical and one computational. The latter requires the development of software since no commercial or free software with the required capabilities exists. The former requires the development of a measurement setup that can measure the fluid properties of the polymer melt. These properties are required for input into the simulations, and it is rare for them to be well characterised for a large range of polymers. The desired goal is to predict the suitability of arbitrary polymers for Laser Sintering, and therefore potentially find a novel polymer to improve the material selection available for Laser Sintering.

This PhD project will entail a number of research topics, focussed around the validation of x-ray computed tomography (XCT) for the purposes of metrology for additively manufactured components. XCT is widely used in medical applications for volumetric scanning, but recent work is beginning to integrate the technology into the industrial setting as a precision measurement tool.

Additive manufacture is capable of producing complex internal geometries that are not measurable using traditional metrological techniques, and the volumetric scanning offered by XCT proposes a potential method of successful measurement of these geometries. This PhD is planned to contain the design of an XCT validation artefact for comparison between XCT and traditional measurement data, as well as similar comparisons of industrial case studies. The research will then likely address imaging and measurement of porosities and unsintered powders in additively manufactured parts, to verify the use of XCT for the measurement of production defects.

The project further aims to form part of an industrial XCT “Good Practice Guide” and the applications of this project are heavily focussed towards industry. The work produced during the PhD intends to forward the usage of XCT as an industrial metrological technique, which should lead to the production of more accurate parts and benefit many areas of manufacture.