An update on world-class additive manufacturing research

In the op-ed article covering the demand for additive manufacturing (AM) skills (also in this issue), there was a distinct differentiation made between the skills required for research environments and those for shop-floor manufacturing environments. In terms of progressing the industry, both are vitally important, and this article highlights some of the essential AM research currently underway.

The purpose here is to provide an update on some of the new and ongoing research projects coming out of the UK’s Engineering and Physical Sciences Research Council (EPSRC) Centre for Doctoral Training (CDT) in Additive Manufacturing and 3D Printing. The CDT projects cover a wide range of disciplines from chemistry and physics, to computer science, engineering and biomaterials.

Led by The University of Nottingham, in partnership with Loughborough University, Newcastle University and The University of Liverpool, the CDT provides a world-class collaborative training environment in the multi-disciplinary field of additive manufacturing (AM). It aims to deliver 66 researchers, over the course of the grant , that will have the necessary technical understanding and transferable industry-facing skills to become future leaders in this field of research. The CDT receives funding from the EPSRC, with contributions from each of the four partner universities. Every research project is also sponsored by an industrial partner, ensuring the research conducted within this CDT is highly relevant to industry. These, combined with financial support, will allow the CDT to provide specialist AM training to PhD students until 2022.

Two directors lead the program, Professors Chris Tuck and Ian Ashcroft from the University of Nottingham, with three co-investigators from the associated universities, Professor Chris Sucliffe (University of Liverpool), Professor Kenny Dalgarno (University of Newcastle) and Doctor Daniel Engstrom (University of Loughborough). The CDT is managed by Romina Davoudi at the University of Nottingham campus.

Research project highlights

Project title: Development of Methods for Measuring the Surface Topography of Additive Manufactured Parts; conducted by Lewis Newton at the University of Nottingham

Overview: Methods will be developed to measure the surface topography of additively manufactured parts. Commercial measurement techniques will be used, such as stylus profilometry, focus variation, confocal microscopy, interferometry and electron microscopy. This is to assess the appropriate measurement spatial bandwidths to be used and appropriate parameters to control manufacturing or correlate to function. A number of industrial case studies will be investigated to formulate ways to control the surfaces during manufacture and finishing.

Project title: Directed Neural Cell Growth in Additive Manufacturing Systems for Applications in Next Generation Prosthetics; conducted by Nathalie Sallstrom at Loughborough University.

Overview: This project will conduct research in the field of next generation prosthetics and the additive manufacturability of these devices. One of the objectives of this work is to establish an interface between the human body and the prosthetic device. This essentially aims to connect the prosthetic device to the wearer’s nervous system, which will provide both signals from and to the wearer. This will improve the wearer’s control of the prostheses since the device would be thought controlled, like a natural limb. Furthermore, this project will be focusing on the bridging from a residual nerve to the electrode/prosthetic interface. To do this, the neurons need to be guided and directed effectively towards a surface. This project will first focus on conditions required to direct neuronal growth and subsequently to adapt current AM systems to successfully manufacture the neural guide.

Project title: Additive Manufacturing of Advanced Ceramic Materials; conducted by Yazid Lakhdar at the University of Nottingham.

Overview: This project aims to use colloidal processing and AM technologies, such as inkjet printing and binder jetting, to develop the routes to controlled-density and fully dense advanced ceramic parts. The project will also evaluate the use of laser sintering to further the understanding of its use on advanced ceramic materials. By firstly developing the processing routes and then exploiting the materials they yield so as to better understand the potential engineering application, the project aims to make advanced ceramic materials much more accessible in the AM world. Using alumina as the starting point, the project will develop the techniques and explore the equipment and characterization required to deliver material for testing. AM of non-oxide ceramics will also be investigated, as the project develops a broader understanding of the processing techniques most applicable to each type of ceramic material.

Project title: Selective Laser Melting of Lattice Structures for Heat Transfer Applications in Gas Turbine Engines; conducted by Sam Catchpole-Smith at the University of Nottingham.

Overview: Working in partnership with Siemens Industrial Turbomachinery, this research is based on the development of nickel alloys for use in high-temperature and high-performance environments, specifically for industrial gas turbines. Nickel alloys with a high percentage of aluminum and titanium are susceptible to cracking if the thermal profile during manufacture is not carefully controlled.

This is a particular problem for the selective laser melting (SLM) process due to the very high cooling rates involved during material deposition. Hence, careful consideration of the process steps and how the thermal profile will affect the material in question is required. Commercially available machines have little room for flexibility in this regard and so alternative techniques, such as altering the laser scan strategy, are necessary to enable manufacture in these high-performance alloys. Once the processing steps have been optimized and verified, more complex geometrical parts can be designed and tested. Lattice structures, particularly for thermal transfer, have been discussed for further work.

Project title: Bioprinting Osteoarthritic Joint Co-Cultures; conducted by Joseph Dudman at Newcastle University.

Overview: This project focuses on the development of reliable procedures to print precise numbers of cells resident within the articular joint in order to manufacture co-culture models of osteoarthritis. Following characterization and optimization, these models can then be used to replicate the pathophysiology of osteoarthritis to further understand disease progression and screen potential drug candidates in vitro.

The optimized printing technology and co-culture conditions may also be used to generate living tissue from patient cells that can be transplanted into the body within next generation surgical procedures, such as autologous chondrocyte implantation.

Project title: Synthesis of Natural/Synthetic Hybrid Polymers, conducted by Kegan McColgan-Bannon at Newcastle University.

Overview: This research explores using synthetic techniques to modify the structure of currently available biocompatible polymers to enhance the surface characteristics for cellular adhesion. The current focus of the project is the synthesis of PCl-collagen hybridized material, performing analytical groundwork (physicochemical, mechanical and cell work) and developing a methodology to take the materials from ground state to a lament that can be extruded into a scaffold for bone tissue regrowth.

Other targets of interest are PHBV-Collagen hybrids that have shown promise as replacements for tendon tissue. Similar to the PCl-Collagen work, a synthetic route will be established and a considerable amount of analytical work will be performed to establish the viability of the material in animal/medical trials.

Project title: Quantum DotSilicone Nanocomposites via Reactive Inkjet; conducted by Liesbeth Birchall at the University of Nottingham.

Overview: All current AM used for silicones produce elastomers from viscous precursors, which react in situ. However, the strength of elastomers that can be produced via standard inkjet is severely limited by two main factors. First, long polymer chains are required for good elastomers, which means viscous reagents beyond the operating range of inkjet printing. And second, silicone elastomers are intrinsically weak compared to organic rubbers, and reinforcing fillers are employed in industry; a strategy towards good particle loading in inkjet
is therefore of interest. Silicone resins are strong without the need for high-viscosity reagents and are relatively unexplored within inkjet. Fluorescent nanoparticles require low loading for functionality and complement the optical clarity of silicones. This project aims to print quantum dots in silicone matrices via reactive inkjet, exploring MDTQ composition for polymer properties and suitable solvent systems to aid dispersion. These nanocomposites would be developed for application in sensors or electronic displays.

Project title: Additive Manufacturing of Bioactive Composite Scaffolds for Osteochondral Implants; conducted by Niloufar Hojatoleslami at Newcastle University.

Overview: The general aim of this PhD project is to make bioactive composites for osteochondral implants. This is quite a broad aim and requires some particular subjects to be addressed, developed and optimized. A number of AM techniques will be exploited throughout the project to determine the best method of acquiring the required scaffolds and to incorporate biomaterials and cells together to develop the osteochondral implant. The scaffold material will be developed significantly throughout the project to ensure optimum conditions for cell growth and development. Mechanical testing and in vivo testing of materials and printed scaffold will be performed throughout the project. Many new skills will be acquired and developed which will aid successfully fulfilling the overall aim.

Project title: Additive Manufacturing for Quantum Systems; conducted by Iliya Dimitrov at Loughborough University.

Overview: The goal of this project is to create a 3D printer that will serve as laboratory equipment for exploring micron and sub-micron systems. Such a machine can benefit researchers by offering an accurate and affordable way to reproduce theoretical models. Electronics has brought a revolution to human technology and its limits continue to be explored. While trying to exploit the already observed quantum phenomena, such as particle-wave duality, entanglement, etc., reproducing complicated three-dimensional features is crucial. The obvious advantage that 3D printers can provide is further underlined by the relatively low cost for manufacturing individual items. Research-tailored 3D printers can serve teaching purposes, as students usually need to break their equipment to understand how it works. Another desired output of the project is the ability to restore damaged RLC-circuits in teaching laboratories. The question therefore is how to utilize AM in research facilities without shifting their focus to manufacturing.

The breadth and depth of research underway at the CDT is both impressive and inspiring and points to real and positive future developments of this technology sector—developments that will impact industry and society.

CDT student recruitment for October 2017 is now closed. To apply for the October 2018 start, please visit findaphd.com.

About Rachel Park

Rachel is a passionate advocate of additive manufacturing/3D printing technologies and the industry that has sprung up around it. However, as the hype and hyperbole has gathered momentum, her aim is always to offer a reasoned voice in the midst of inflated expectations and to cut through the noise in order to provide a realistic outlook of how things are.