Currently the dominant approach for cooling and lubricating machining processes, such as drilling, milling and turning, is to use emulsion-based coolants (otherwise known as metalworking fluids) at high flow rates. There are many serious environmental, financial and health and safety reasons for reducing industry's reliance on emulsion coolants - an estimated 320,000 tonnes/year in the EU alone, up to 17% of total production costs, and over 1 million people are exposed regularly to the injurious effects of its additives which can cause skin irritation and even cancers. Serious environmental problems are also caused by the up to 30% of coolant that is lost in leaks and cleaning processes and which eventually ends up polluting rivers. These issues have motivated extensive research efforts to identify more sustainable machining processes. There is growing and compelling evidence from preliminary studies that cryogenic machining with supercritical CO2 (scCO2) with small amounts of lubricant (Minimum Quantity Lubrication, MQL, referred to as scCO2+MQL machining) can provide a high-performing and more sustainable alternative. Current knowledge gaps in the relationships between key input and output variables, the reasons for variations in performance and concerns over the release of CO2, are preventing a major uptake of this technology by UK manufacturers. This project aims to test the hypothesis that optimising combinations of CO2 with small amounts of the appropriate lubricant can provide reliable, step-change improvements in the performance and sustainability of machining operations. It will carry out a systematic investigation into the effect of scCO2+MQL on cutting forces, heat and tool wear mechanisms during machining of titanium, steels and composite stacks. It will develop: (a) advanced experimental methods in combination with full-scale machining trials to explore how lubrication and heat transfer affect machining performance; (b) lifecycle assessment and scavenging methods for sustainable re-use of CO2; (c) machine learning methods to predict the relationships between process inputs and outputs and (d) develop an effective and efficient optimisation methodology for balancing competing financial, performance and sustainability objectives in scCO2+MQL machining. These will deliver the knowledge, experimental and modelling methods and software tools that UK industry needs to exploit this enormous as-yet untapped potential. The project will involves staff and postdoctoral research assistants from the Universities of Leeds and Sheffield and the Advanced Manufacturing Research Centres in Sheffield, with advice and guidance from a Project Steering Group comprised of leading international academic and industrial experts. Collectively, the team has the expertise in (a) manufacturing systems and tribology; (b) energy systems and lifecycle assessment; (c) fluid mechanics and heat transfer, and (d) machine learning and optimisation, needed to provide the 'how' and 'why' UK industry needs to reliably achieve or exceed the performance improvements seen in preliminary studies, namely doubling of tool life. We will work with our industrial and business sector collaborators to drive transformations in machining rate, process cost and accompanying safety, environmental and quality metrics for the benefit of the UK's defence, civil nuclear and medical manufacturing industries through the 2020s and beyond.

This work will change the way we think about machining high value titanium components - for example, turning an aeroengine shaft on a lathe. Rather than apply global rules about how much metal we can remove and how fast we can rotate the part, we will develop a technique that can monitor - in real time - the "microstructure" of the part, in order to determine how much pressure we apply with the cutting tool. Microstructure in metals is analogous to the different parts of timber - heartwood, sapwood, knots, how the grain runs - but on a much smaller scale (usually fractions of a millimetre). A master carpenter will see and feel these features of the timber by sight and touch, and instinctively work the wood with their tools in such a way as to maximise strength and/or visual appeal whilst using the least amount of effort. Such finesse has not been possible in metal working as - until now - there has not been a technique available that can "see" the microstructure. A technique called spatially resolved acoustic spectroscopy (SRAS for short) uses lasers to generate and detect very high frequency ultrasonic waves that travel on the surface of the metal component. These waves interact with the microstructure, and this allows us to "see" it. By relating this information to knowledge of how machining the metal affects its performance - which is another part of the work - opens up the possibility of intelligently crafting the cutting process. Not only will this lead to faster machining processes and less damage, it will also mean that a map of the microstructure of the final part is available - this will be invaluable for confirming quality.

The Materials Made Smarter Centre has been co-created by Academia and Industry as a response to the pressing need to revolutionise the way we manufacture and value materials in our economy. The UK's ability to manufacture advanced materials underpins our ambitions to move towards cleaner growth and a more resource efficient economy. Innovation towards a net zero-carbon economy needs new materials with enhanced properties, performance and functionality and new processing technologies, with enhanced manufacturing capability, to make and deliver economic and societal benefit to the UK. However, significant technological challenges must still be overcome before we can benefit fully from the transformative technical and environmental benefits that new materials and manufacturing processes may bring. Our capacity to monitor and control material properties both during manufacture and through into service affect our ability to deliver a tailored and guaranteed performance that is 'right-first-time' and limit capacity to manage materials as assets through their lifetime. This reduces materials to the status of a commodity - a status which is both undeserved and unsustainable. Future materials intensive manufacturing needs to add greater value to the materials we use, be that through reduction of environmental impact, extension of product life or via enhanced functionality. Digitalisation of the materials thread will help to enhance their value by developing the tools and means to certify, monitor and control materials in-process and in-service improving productivity and stimulating new business models. Our vision is to put the UK's materials intensive manufacturing industries at the forefront of the UK's technological advancement and green recovery from the dual impacts of COVID and rapid environmental change. We will develop the advanced digital technologies and tools to enable the verification, validation, certification and traceability of materials manufacturing and work with partners to address the challenges of digital adoption. Digitisation of the materials thread will drive productivity improvements in materials intensive industries, realise new business models and change the way we value and use materials.

Manufacture Using Advanced Powder Processes - MAPP Conventional materials shaping and processing are hugely wasteful and energy intensive. Even with well-structured materials circulation strategies in place to recondition and recycle process scrap, the energy use, CO2 emitted and financial costs associated are ever more prohibitive and unacceptable. We can no longer accept the traditional paradigm of manufacturing where excess energy use and high levels of recycling / down cycling of expensive and resource intensive materials are viewed as inevitable and the norm and must move to a situation where 100% of the starting material is incorporated into engineering products with high confidence in the final critical properties. MAPP's vision is to deliver on the promise of powder-based manufacturing processes to provide low energy, low cost, and low waste high value manufacturing route and products to secure UK manufacturing productivity and growth. MAPP will deliver on the promise of advanced powder processing technologies through creation of new, connected, intelligent, cyber-physical manufacturing environments to achieve 'right first time' product manufacture. Achieving our vision and realising the potential of these technologies will enable us to meet our societal goals of reducing energy consumption, materials use, and CO2 emissions, and our economic goals of increasing productivity, rebalancing the UK's economy, and driving economic growth and wealth creation. We have developed a clear strategy with a collaborative and interdisciplinary research and innovation programme that focuses our collective efforts to deliver new understanding, actions and outcomes across the following themes: 1) Particulate science and innovation. Powders will become active and designed rather than passive elements in their processing. Control of surface state, surface chemistry, structure, bulk chemistry, morphologies and size will result in particles designed for process efficiency / reliability and product performance. Surface control will enable us to protect particles out of process and activate them within. Understanding the influence between particle attributes and processing will widen the limited palette of materials for both current and future manufacturing platforms. 2) Integrated process monitoring, modelling and control technologies. New approaches to powder processing will allow us to handle the inherent variability of particulates and their stochastic behaviours. Insights from advanced in-situ characterisation will enable the development of new monitoring technologies that assure quality, and coupled to modelling approaches allow optimisation and control. Data streaming and processing for adaptive and predictive real-time control will be integral in future manufacturing platforms increasing productivity and confidence. 3) Sustainable and future manufacturing technologies. Our approach will deliver certainty and integrity with final products at net or near net shape with reduced scrap, lower energy use, and lower CO2 emissions. Recoupling the materials science with the manufacturing science will allow us to realise the potential of current technologies and develop new home-grown manufacturing processes, to secure the prosperity of UK industry. MAPP's focused and collaborative research agenda covers emerging powder based manufacturing technologies: spark plasma sintering (SPS), freeze casting, inkjet printing, layer-by-layer manufacture, hot isostatic pressing (HIP), and laser, electron beam, and indirect additive manufacturing (AM). MAPP covers a wide range of engineering materials where powder processing has the clear potential to drive disruptive growth - including advanced ceramics, polymers, metals, with our initial applications in aerospace and energy sectors - but where common problems must be addressed.