FINAL PROJECT REPORT FORM

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1 FINAL PROJECT REPORT FORM IMCRC Project number 251 Budget code J11774 INVESTIGATOR DETAILS Principal Investigator Co-investigator 1 Co-investigator 2 Title Dr Mr Forename(s) Neil Barry Surname Hopkinson Haworth Organisation Loughborough University Loughborough University Division or Department Wolfson School Department of materials PROJECT DETAILS Title of Research Project Advanced Understanding and Control of Polymer Sintering Funds Awarded ( ) 250K - 1M (Large) Start Date: 1/7/09 End Date: 30/9/11 OBJECTIVES AND RESEARCH SUMMARY Original objectives as presented in the grant proposal 1. Establish if sintering by hot stage microscopy along with cast and layer manufactured polymers adheres to fundamental sintering progression models. 2. Investigate practical implications of sintering progression in layer based sintering processes 3. Determine whether established PM equations to predict sintered part properties in metals and ceramics apply to polymers and generate new, polymer-specific, equations if appropriate. 4. Investigate the potential to increase homogeneity and repeatability of layer sintered polymer parts through novel in-process methods. 5. Investigate the potential to increase properties homogeneity and repeatability of layer sintered polymer parts through novel post-processing methods These objectives remained valid throughout the research (tick box), or These objectives were changed (tick box). (If so, please explain how/why in your report) New objectives 1. Establish if sintering by hot stage microscopy adheres to fundamental sintering progression models. 2. Investigate practical implications of sintering progression in layer based sintering processes 3. Investigate the potential to increase homogeneity and repeatability of layer sintered polymer parts through novel in-process methods. 4. Investigate the potential to increase properties homogeneity and repeatability of layer sintered polymer parts through novel post-processing methods 5. Identify new material(s) to be used in laser sintering (as requested by project partners after project start)

2 Project abstract at time of proposal Rapid Manufacturing (RM) technologies are growing in importance in terms of manufacturing and offer unique opportunities to encourage retention/growth of manufacturing in western economies such as the UK. Selective Laser Sintering (SLS) currently dominates today s RM applications especially in the manufacture of polymer components. Various researchers have studied methods to improve SLS polymer part properties including an abundance of research into the processing and properties of nano-composites i,ii,iii. Evans et al iv have proposed a generic methodology for the development of powders of all material types including practical issues such as flowability of powders. Despite the recent, and predicted future, growth of RM there has been little systematic research work focussed on understanding the fundamental sintering process and its impact upon part properties. Instead the RM field has gradually accrued a range of often anecdotal evidence regarding the effects of processing on the properties of sintered parts. Conversely the mature fields of Powder Metallurgy (PM) and injection moulding have seen a large body of in-depth research that has improved understanding of the processes. Polymer sintering has also been addressed in research relating to processes such as rotational moulding and powder coating although the extent of work in this area is much less than that for PM and injection moulding. This proposed research seeks to bring together research expertise in RM (Neil Hopkinson) and polymer science / process technology (Barry Haworth) to establish a deeper understanding of polymer sintering as a science, especially in terms of its application to layer based sintering processes. Building on this deeper understanding, the research will progress to develop novel in-process and post-processing methods to improve properties, homogeneity and repeatability of layer manufactured polymer parts. Many of the concepts proposed here are influenced by previous research into PM, injection moulding and other polymer sintering technologies. Principles and concepts from other processes such as rotational moulding and fusion/gelation during polymer powder processing (in which IPTME has an international reputation) may carry some relevance towards process enhancement in sintering. Careful thought, based on research to date in the field of SLS, has been applied to ensure that the concepts proposed are relevant to the unique characteristics and capabilities of layer based polymer sintering technologies. The research can broadly be split into two main phases, namely: 1. Advancing the scientific understanding of polymer sintering in layer based processes 2. Applying the new understanding to novel methods to improve part properties Within the context of the IMCRC, this research will tackle the research issues of Rapid Manufacturing Processes along with heterogeneous and graded materials. Summary of Outcomes: In simple terms describe your work in such a way that it could be publicised to a general audience. Progress to date has exceeded that originally scheduled for the research programme. Benchmarking of laser sintering repeatability against injection moulding repeatability has been evaluated. Knowledge and understanding of chemical changes in un-sintered nylon has been increased significantly, helping to explain many aspects associate with recycling of powder. A greater understanding of the analysis methods such as DSC (effect of heating rate) and MFI (effect of moisture) has been generated with potential impact in standards that are being developed. Advanced testing methods not yet used in the AM industry has shown interesting and beneficial aspects of fracture toughness of laser sintered parts that are dependent on specimen geometry. Further work has shown that specimen geometry does not influence tensile properties in the same way this work was selected from the SFF Symposium for journal publication and is expected to contribute to the developments of standards in AM. Various methods of post-processing have been investigated including some requested by the project partners. The results have not identified obvious benefits. The study of new elastomeric material has identified new opportunities for research with three journal publications intended and high levels of interest from industry partners and other companies who are not current project partners. Two student placements have been conducted, with clear benefits to the industry partners in terms of understanding of the laser sintering process. Web address with further details if you wish:

3 BENEFICIARIES Beneficiaries of the research Project partner Burton Snowboards has a new material available that precisely matches their needs Project partner EOS has the opportunity to develop and commercialise the new material identified in the research Project partner EOS has gained further levels of information and understanding on issues such as increase in molecular weight of nonsintered powder in a powder bed. Project partner the University of Louisville has benefitted from further knowledge and understanding of the laser sintering process and has benefitted from joint publications note that Loughborough University has benefitted equally. The Additive Manufacturing industry has new levels of information regarding the capabilities of laser sintering through published and presented work by the researchers

4 Publications (1) Please state how many research results arose principally as a result of the research funded through this grant and indicate the type (journal, conference, book, patent, software, other) JOURNAL CONFERENCE PAPERS Total Number of Publications 12 (anticipated) 6 BOOK PATENT SOFTWARE OTHER Number of Refereed Publications (if different from above) Number of Publications That Contain An Industrial Co-Author Number of Publications That Contain An International Co-Author n/a (anticipated) 0 (2) Please list up to five significant publications that arose principally as a result of the research funded through this grant and indicate the type (journal, conference, book, patent, software, other); whether there was an international or industrial co-author and whether the publication was refereed. AUTHOR(S) TITLE REFERENCE Journal/Conf. year vol. page TYPE Refereed? Industrial co-author? International co-author? DJ Hitt, B Haworth and N Hopkinson Fracture mechanics approach to compare laser sintered parts and injection mouldings of nylon-12 Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture. Mike Vasquez, Neil Hopkinson, Barry Haworth Optimum Sintering Region for Laser Sintered Nylon-12 IMechE Part B: Journal of Manufacturing Engineering Mike Vasquez, Neil Hopkinson, Barry Haworth Laser Sintering Processes: Practical Verification of Particle Coalescence for Polyamides and Thermoplastic Elastomers Society of Plastics Engineers - ANTEC

5 PROJECT PARTNERS Administrative Area/County Project Partner 1 : Actual Burton Snowboards Product Development Burlington VT Postal Code Country USA Address Line 1 Postal Code Project Partner 2 : Actual EOS Ltd Sales 70 Warwick Street Birmingham B12 0NL Address Line 1 Address Line 2 Administrative Area/County Project Partner 1 : Actual University of Louisville Speed School Vogt Building University of Louisville Louisville KT Postal Code Country USA i Cao, S. and Ren, N, Research progress of the coated metallic nano-composite powder materials fabricated by selective laser sintering, Heat Treatment of Metals, v 30, n 2, 2005, p ii Kim, J. and Creasy, T.S., Selective laser sintering characteristics of nylon 6/clay-reinforced nanocomposite, Polymer Testing, v 23, n 6, September, 2004, p iii Xu, Z.; Zhang, J., Zheng, H.; Zheng, Y. and Huang, Y., Study on the behavioral characteristics of inorganic nano-particles in PS/Al2O3-reinforced nano-composite fabricated by SLS, Polymeric Materials Science and Engineering, v 23, n 4, July, 2007, p iv Evans, R.S., et al, 2005, SLS materials development method for Rapid Manufacturing, SFF symposium, Austin, Texas, 2005, pp