Anchorless Selective Laser Melting (ASLM) of high temperature metals

Additive Manufacturing is a family of technologies that are used to build up 3D objects, layer by layer, from 3D Computer Aided Design (CAD) files. In many respects Additive Manufacturing can be thought of as a 3D version of 2D printing where 3D objects are created. Additive Manufacturing processes create high added value products across many sectors, the industry was born in the late 1980's and has seen average annual growth of over 10%. The high added value nature of Additive Manufacturing means that it is predominantly used in developed economies and represents an area of potential strategic growth for the UK manufacturing industry. Additive Manufacturing processes have the unique selling point of being automated manufacturing processes that require no tooling. Elimination of tooling provides many advantages including the possibility of creating hitherto impossible geometries. However, most Additive Manufacturing processes require supports or anchors that are added to parts as they are built which restricts geometric freedom. Selective Laser Melting (SLM) is an Additive Manufacturing process that creates parts from various metal alloys. The process works by depositing a thin layer of metal powder, typically ~ 0.1mm, onto a metal platform. A laser then scans across selected areas of the powder surface melting powder particles together where it scans. The particles also weld to the platform keeping them fixed in place. The 2D shape scanned by the laser corresponds to the bottom slice of the part being made. The platform drops by the distance of one layer and a fresh layer of powder is deposited on top. The laser then scans the shape of the next slice of the part being made. A 3D object is beginning to grow.If the part being made by SLM includes any overhanging features then the material will quickly cool, solidify and warp upwards. Warping during manufacture causes catastrophic process failure so the part cannot be made. In order to prevent warping, anchors are routinely added to the CAD files of parts and are melted in place. These anchors are made of the same material as the part and they need to be removed when the part has been built. This adds significant labour cost for many geometries, while other geometries simply cannot be made using SLM or indeed any automated metal manufacturing process. We have patented a process that allows SLM parts to be built without anchors including geometries that, without our method, would require anchors - we call our process Anchorless Selective Laser Melting (ASLM). ASLM works by employing a method that is currently under patent application and out of the public domain. We have already succeeded in making hitherto impossible geometries with ASLM using low melt temperature metals. However low melt temperature metals have limited uses and value. In this project we intend to make ASLM parts using metals with higher melt temperatures - in particular we want to make parts based on aluminium. Aluminium alloys can be used in many applications, especially in transport.

Our most tangible impacts will be achieved in four areas: Economic impact: The economic impact of ASLM will be most obvious in high value manufacturing, where Additive Manufacturing is seeing it greatest rate of growth. ASLM will be able to replace machining and casting in many applications. As Additive Manufacturing is predominantly used in developed economies it is in these countries where ASLM will most frequently replace traditional casting and machining. Manufacturers will use ASLM to manufacture parts for an enormous range of sectors including medical devices, electronic equipment, household goods, industrial equipment etc. Current users of SLM equipment will be best placed to benefit from ASLM. One of the world's leading industry experts on SLM technology believes that ASLM will allow the SLM industry to build 60-70% more parts than today's SLM allows. Suppliers of SLM equipment and materials, including those in the UK, will benefit from the increased market size for SLM that ASLM enables. Societal impact: By making hitherto impossible geometries in aluminium based alloys we should be able to make parts that are cheaper, lighter and whose design is better optimised for purpose than is currently possible. This will provide significant opportunities across the transport sector, reducing the weight of vehicles and thus the carbon footprint of transport in the future. Optimised geometries will allow better design of products so they are designed more for function and restricted less by manufacturing process, leading to lighter better performing products across all manner of sectors such as medical devices, electronic equipment etc. Another environmental impact of our work will be that many metal products will no longer be made by machining. Machining involves high waste and so the high environmental (and economic) costs of extracting metal ores (e.g. bauxite to create aluminium) is largely wasted. Using ASLM in place of machining will incur considerably less material waste. Academic impact (leading to further societal and manufacturing industry impact): If we can get ASLM to work with aluminium alloys then we should be able to progress to metals with even higher melt temperatures (e.g. Titanium and Nickel alloys). There will be considerable technical challenges with these materials but also considerable benefits to be achieved. The novel process that allows ASLM to work is under patent application and is currently confidential but we anticipate that it will allow control of microstructure to manufacture products that are capable of working in the harshest of environments such as in a jet engine. Controlling microstructure will be a significant technical challenge and will likely require input from academic experts in a variety of fields. Personal/institutional impact: Loughborough University, the Additive Manufacturing Research Group and the staff involved in the project will see a major impact from this project. The University has a strong reputation for working with industry and this project will involve a high degree of industry interaction and is intended to result in commercial outcomes of benefit to the university and to industry partners. A successful project will help to enhance the university's reputation for successful work with industry. Similarly, the Additive Manufacturing Research Group at Loughborough, which is widely recognised as the world's leading group in the Additive Manufacturing field, will help to maintain and enhance its position as the global leader in this fast growing sector. Last, but by no means least, the individuals working on the project will see tremendous impacts. Research staff will be able to develop their commercial knowledge and understanding and the individuals who are named inventors on the ASLM patent will benefit directly from any commercial income generated by the technology.