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This paper describes tests to determine if the Bauschinger effect can act as an additional source of formability, this may possibly explain the enhanced formability observed in incremental sheet forming Small cylindrical products have been made by deep drawing and wall ironing. The upper edges have been necked to various levels of reduction. Tensile test specimens have been cut from the necked upper edges and tested, causing an almost perfect stress/strain reversal. An increase of strain could be observed indeed. The results are discussed using the Considère condition as a guideline.

In this paper an overview is given about laser surface modification processes, which are developed especially with the aim of hardness improvement for an enhanced fatigue and wear behaviour. The processes can be divided into such with and without filler material and in solid-state and melting processes. Actual work on shock hardening, transformation hardening, remelting, alloying and cladding is reviewed, where the main focus was on scientific work from the 21st century.

This work investigates the feasibility of a novel method to simultaneously alloy and reinforce a low alloyed Al alloy (i.e., Al6061) during selective laser melting (SLM) via in situ decomposition of zinc oxide (ZnO). Based on Gibbs free energy calculations, an Al6061+6wt%ZnO powder mixture is designed and prepared. The thermal decomposition of ZnO, resulting in the formation of Al oxide and free Zn, necessitates a completely different set of optimised SLM parameters compared to traditional Al alloys. After SLM, it is shown that this method can successfully reinforce the Al matrix with numerous nanometer sized oxide particles (typically ~ 50-120 nm). Despite this clear success to manufacture in situ reinforced Al composites by SLM, the applied method could not avoid partial Zn evaporation (limiting in situ alloying) and could not successfully suppress the cracking that also occurs after SLM of unreinforced Al6061. ispartof: pages:39-43 ispartof: Procedia CIRP vol:74 pages:39-43 ispartof: 10th CIRP Conference on Photonic Technologies [LANE 2018] location:Fürth, Germany date:3 Sep - 6 Sep 2018 status: published

This work investigates the influence of powder size/shape on selective laser sintering (SLS) of a thermoplastic polyurethane (TPU) elastomer. It examines a TPU powder which had been cryogenically milled in two different sizes; coarse powder (D50∼200μm) with rough surfaces in comparison with a fine powder (D50∼63μm) with extremely fine flow additives. It is found that the coarse powder coalesces at lower temperatures and excessively smokes during the SLS processing. In comparison, the fine powder with flow additives is better processable at significantly higher powder bed temperatures, allowing a lower optimum laser energy input which minimizes smoking and degradation of the polymer. In terms of mechanical properties, good coalescence of both powders lead to parts with acceptable shear-punch strengths compared to injection molded parts. However, porosity and degradation from the optimum SLS parameters of the coarse powder drastically reduce the tensile properties to about one-third of the parts made from the fine powders as well as those made by injection molding (IM). publisher: Elsevier articletitle: Effect of Powder Size and Shape on the SLS Processability and Mechanical Properties of a TPU Elastomer journaltitle: Physics Procedia articlelink: http://dx.doi.org/10.1016/j.phpro.2016.08.102 content_type: article copyright: © 2016 Published by Elsevier B.V. ispartof: pages:971-980 ispartof: Physics Procedia vol:83 pages:971-980 ispartof: Laser Assisted Net Shape Engineering 9 International Conference on Photonic Technologies - LANE 2016 location:Fürth, Germany date:19 Sep - 22 Sep 2016 status: published

© 2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license Base plate preheating is one of the recent enhancing tools added to the process of Selective Laser Melting (SLM). This tool aims at a reduction of thermal stresses in SLM parts, achieved by decreasing the thermal gradients during SLM processing. In the current study, base plate preheating up to a temperature of 400°C is applied during SLM of 4 different materials, including aluminum 7075 alloy, nickel alloy Hastelloy X, H13 tool steel and CoCr. General trends, as well as material specific effects are discussed regarding part density, crack formation, internal stresses, microstructure and mechanical properties. These show how base plate preheating can induce different influences according to each particular material category. ispartof: pages:5-11 ispartof: Procedia CIRP vol:74 pages:5-11 ispartof: 10th CIRP Conference on Photonic Technologies (LANE) location:Furth, GERMANY date:3 Sep - 6 Sep 2018 status: published

© 2014 The Authors. Published by Elsevier B.V. Due to increasing energy and resource costs at the one hand and upcoming regulations on energy and resource efficiency at the other, a growing interest of machine tool builders in the environmental performance of their machine tools can be observed today. The last decade, academic as well as industrial research groups started to assess the environmental aspects of discrete part manufacturing processes and indicated a significant potential for improvement [1]. This paper provides an overview of the environmental performance (energy and resource efficiency) of different types of laser cutting systems and derived performance improving strategies. LANE2014 - Keynote ispartof: pages:854-864 ispartof: Physics Procedia vol:56 issue:C pages:854-864 ispartof: 8th International Conference on Laser Assisted Net Shape Engineering LANE 2014 location:Fürth, Germany date:8 Sep - 11 Sep 2014 status: published

Layerwise Laser Melting (LLM) is an Additive Manufacturing process which allows producing complex metallic parts by building parts layer by layer. Monitoring and control of the melting process is needed for further development of the process and future adoption of the process by industry since it allows to monitor the quality of the building process during the actual build job. Furthermore, melt pool monitoring enables a better and more fundamental understanding of the thermal behavior of the process. This paper describes a system for monitoring of the melt pool during LLM and a data processing algorithm to map the measured melt pool data in space. With this so called mapping approach the data interpretation can be significantly reduced. It will be shown that with this system a wide range of process failures can be detected during the process. ispartof: pages:753-759 ispartof: Physics Procedi vol:39 pages:753-759 ispartof: Laser Assisted Net Shape Engineering location:Erlangen date:12 Nov - 15 Nov 2012 status: published