Additive Manufacturing Education in the UK

There has been and continues to be a considerable effort regarding education for Additive Manufacturing (AM) in the UK. This generally started in 1992 with a seminar organised by the Institution of Mechanical Engineers and an industrial exhibition stand at Mach 92. However, before the education activities are discussed it is useful to show the AM research landscape in the UK as this will give an indication of the level of activity It should be noted that there will also be a considerable number of organisations involved in using AM but not involved in research.Mechanical Engineerin

Rapid Manufacturing Research Group

Rapid Product Development and manufacture is a major focus for companies wanting to compete in the more open Global Marketplace. This has created considerable interest in techniques and technologies that help companies introduce new products more quickly, at lower cost and with greater flexibility. Computer Aided Design (CAD) and the introduction, in the late 1980s, of a group of technologies known as 'Rapid Prototyping' have greatly helped this. It is now possible to design and manufacture objects within a few hours. The next stage is to use these layermanufacturing technologies to manufacture saleable end-use items. However, few companies have invested in the technology, but many are very interested in investigating their use. The research portfolio of the RMRG is directed at providing the future technologies industry will require, and, through the Consortium, is providing a route that allows partners, and others, to gain the required knowledge and expertise concerning the technologies and their use.Mechanical Engineerin

Conformal Cooling and Heating Channels using Laser Sintered Tools 490

The EOS Direct Metal Laser Sintering (DMLS) and DTM Rapid Steel 2 processes may be used to create tools incorporating conformal channels behind the tool surface through which fluids may be passed. To date, a significant amount of work has been carried out to investigate the efficiency of using conformal channels to cool tools. This work suggests the use of conformal channels to both cool and heat a single tool. This may appear self-defeating at first but the selective nature by which conformal channels may make this a worthwhile means of generating hitherto unavailable thermal conditions within a tool. Such conditions may then allow the successful production of geometries which had previously been impossible to mould.Mechanical Engineerin

Thermal Effects on Accuracy in the 3DKeltool™ Process

The 3DKeltool™ process has been used to produce injection moulding inserts capable ofproducing millions ofparts with quick cycle times (1). Short lead times are possible however accuracy is reduced for dimensions over 150mm. The use ofroom temperature vulcanising (RTV) silicone rubber in the 3DKeltool™ process is a possible reason for the loss of accuracy in larger parts. Effects of temperature changes during the process are assessed both theoretically and experimentally. The results show close agreement between theoretical predictions and experimental results for dimensional changes. Suggestions which could allow accurate manufacture oflarger 3DKletool™ parts are presented.Mechanical Engineerin

Rapid prototyping for direct manufacture

Advances in rapid prototyping and machining have resulted in reduced lead times for injection moulding tooling. Comparisons between aluminium and stereolithography (SL) tools are made with regard to the ejection forces required to push mouldings from the tools, heat transfer through the tools and the surface roughness of the tools. The results show that ejection forces for both types of tools are increased when a longer cooling time prior to ejection is used. The ejection forces required from a rough aluminium tool are considerably higher than those from a smooth aluminium tool. SL tools do not appear to be subjected to any smoothing as a result of moulding polypropylene parts, this is explained by the fact that the tool’s surface acts in a rubber like manner during part ejection. The rubber like nature of the tool’s surface is as a direct consequence of the low glass transition temperature and low thermal conductivity of the tool material. Further potential benefits of the low thermal properties of the tool are discussed

Selective Laser Melting (SLM) of pure gold

This work presents an investigation into the Selective Laser Melting (SLM) of 24 carat gold (Au) powder with a mean particle size of 24μm. An SLM 100 system was used which is intended for production of highly detailed and intricate parts. Gold powder was tested for its properties such as tap density, Particle Size distribution (PSD) and reflectance etc. A suitable processing window was identified and gold cubes were produced using these parameters. Gold cubes were also checked for their internal porosity and mechanical properties

Predicting stereolithography injection mould tool behaviour using models to predict ejection force and tool strength.

The work reported involved Finite Element Analysis (FEA) modelling of heat transfer in a stereolithography (SL) tool and then performing a series of experiments to measure true heat transfer in the tool. The results from the practical measurement of heat transfer were used to validate and modify the FEA model. The results from the modified FEA model were then used to predict the tensile strength of the tool at various stages after injection of the thermoplastic melt. Previously developed equations to predict ejection forces were used to estimate the ejection forces required to push the moulding from the SL core. During the practical experiments the true ejection forces were measured. The combination of predicted tool strength and ejection forces were intended to be used a basis for to determine whether certain SL tool designs will fail under tension during part ejection. This would help designers and manufacturers to decide whether SL tooling is suitable for a specific application. The initial FEA heat transfer model required some modifications and the measured ejection forces were higher than the predicted values, possible reasons for these discrepancies are given. For any given processing conditions there was an inherent variance in the ejection forces required however longer cooling periods prior to ejection resulted in higher ejection forces. The paper concludes that, due to the variations in required ejection forces, a reliable tool to predict tensile failure will be difficult to produce however improved performance may be gained by adopting processing conditions contrary to those recommended in the current process guidelines

A comparison between stereolithography and aluminium injection moulding tooling

Advances in rapid prototyping and machining have resulted in reduced lead times for injection moulding tooling. Comparisons between aluminium and stereolithography (SL) tools are made with regard to the ejection forces required to push mouldings from the tools, heat transfer through the tools and the surface roughness of the tools. The results show that ejection forces for both types of tools are increased when a longer cooling time prior to ejection is used. The ejection forces required from a rough aluminium tool are considerably higher than those from a smooth aluminium tool. SL tools do not appear to be subjected to any smoothing as a result of moulding polypropylene parts, this is explained by the fact that the tool’s surface acts in a rubber like manner during part ejection. The rubber like nature of the tool’s surface is as a direct consequence of the low glass transition temperature and low thermal conductivity of the tool material. Further potential benefits of the low thermal properties of the tool are discussed

Analysis of rapid manufacturing—using layer manufacturing processes for production

Rapid prototyping (RP) technologies that have emerged over the last 15 years are all based on the principle of creating three-dimensional geometries directly from computer aided design (CAD) by stacking two-dimensional pro les on top of each other. To date most RP parts are used for prototyping or tooling purposes; however, in future the majority may be produced as end-use products. The term ‘rapid manufacturing’ in this context uses RP technologies as processes for the production of end-use products. This paper reports ndings from a cost analysis that was performed to compare a traditional manufacturing route (injection moulding) with layer manufacturing processes (stereolithography, fused deposition modelling and laser sintering) in terms of the unit cost for parts made in various quantities. The results show that, for some geometries, it is more economical to use layer manufacturing methods than it is to use traditional approaches for production in the thousands

A comparison between stereolithography and aluminium injection moulding tooling

This is a journal article. It was published in the journal, Rapid prototyping journal [© Emerald Group Publishing Limited (MCB University Press)]and the definitive version is available at: http://www.emeraldinsight.com/1355-2546.htmAdvances in rapid prototyping and machining have resulted in reduced lead times for injection moulding tooling. Comparisons between aluminium and stereolithography (SL) tools are made with regard to the ejection forces required to push mouldings from the tools, heat transfer through the tools and the surface roughness of the tools. The results show that ejection forces for both types of tools are increased when a longer cooling time prior to ejection is used. The ejection forces required from a rough aluminium tool are considerably higher than those from a smooth aluminium tool. SL tools do not appear to be subjected to any smoothing as a result of moulding polypropylene parts, this is explained by the fact that the tool’s surface acts in a rubber like manner during part ejection. The rubber like nature of the tool’s surface is as a direct consequence of the low glass transition temperature and low thermal conductivity of the tool material. Further potential benefits of the low thermal properties of the tool are discussed