Browsing by Author "Lunt, Alexander J. G."

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Evaluation of the performance variation of porous air pads on discontinuous surfaces
    (Elsevier, 2019-10-31) Sanz, Claude; Morantz, Paul; Lunt, Alexander J. G.; Shore, Paul; Chérif, Ahmed; Schneider, Jürgen; Mainaud-Durand, Hélène; Steffens, Norbert
    A new high accuracy position measurement system has been developed. It measures the position of a 0.1 mm diameter copper-beryllium wire that informs alignment of energy beams in advanced particle accelerators. This new measurement system employs air pads to provide precision and friction free rotation of a sensor. To enable the measuring system to be positioned over the wire, a slot is required in the measuring device rotor. To optimise the design of this measuring system it was necessary to understand the performance of the air pads as they pass over the gaps (slots) in the rotor. This paper describes modelling and experiments that were performed to gain understanding of air pad performance when encountering such a surface gap. Particularly, an analytical model of the variation of load of a 20 mm × 40 mm porous air pad during the passing of a 1.5 mm wide slotted surface. Subsequent experimentation revealed that the general behaviour of the load variation had been captured effectively. The results of this analysis reveal that air pads of this size can reliably pass above an opening of this size with about 14% reduction in force. The results and the methodology presented in this paper can be used as an effective basis for future designs and studies
  • Thumbnail Image
    ItemOpen Access
    Micro-scale finishing of the surface and form of a Ti-6Al-4V lightweight rotor obtained by laser powder bed fusion used for air bearing
    (Elsevier, 2018-07-26) Sanz, Claude; Gerard, Romain; Morantz, Paul; Chérif, Ahmed; Shore, Paul; Mainaud-Durand, Hélène; Lunt, Alexander J. G.
    The European Organisation for Nuclear Research, CERN, is in the process of designing and testing parts for the next generation of linear accelerators. In order to operate the experiments, the pre-alignment precision of the components of the two opposing accelerating complexes has placed increased demands on part tolerances, which are now approaching the micrometre. In order to meet these demanding requirements, improvements are necessary to the build processes, machining parameters and post-manufacture characterisation stages. One of the most promising methods for the production of these parts is Laser Powder Bed Fusion, and as such, this paper focuses on the manufacture of the lightweight air bearing rotor component and the micro-scale tolerance machining required by this part. The results demonstrate that despite being able to initially machine the part to a form tolerance approaching 2 μm, subsequent notch cutting and the release of residual stresses from the part obtained by Laser Powder Bed Fusion induces an 18 μm part misalignment which is larger than the tolerance limits of 5 μm required for operation. This demonstrates that further minimisation and understanding of the residual stresses induced during machining are required to facilitate the effective manufacture of high precision components of this type.