• A Fast New Numerical Tool for Designing Pre-stressed Dies for Backward Extrusion: Part 1: Die Behaviour

      Bonnavand, F.; Bramley, Alan N.; Mynors, Diane J. (Professional Engineering Publishing, 2001)
      Prestressed die inserts are often used in the forging of axisymmetric parts. Their use enhances overall tool economy and can enhance the quality of the finished forging. The design of tooling that incorporates prestressed die inserts is, however, complex. The complexity arises from the interrelated phenomena that occur within the dies during the forging process. As a result, it is not possible to obtain an analytical expression for critical parameters such as die stresses and deflections. This paper shows the limitations of currently used design methods, and identifies, for the backward extrusion process, which physical phenomena should be taken into account when designing prestressed tooling. (Professional Engineering Publishing)
    • A fast new numerical tool for designing prestressed dies for backward extrusion: Part 2: numerical analysis

      Bonnavand, F.; Bramley, Alan N.; Mynors, Diane J. (Professional Engineering Publishing, 2001)
      The economics of forging requires tools to be designed to ensure maximum service life. Ideally, this should be achieved by determining the maximum equivalent stress experienced by tools during service. However, the determination of the maximum equivalent stress in the dies through numerical simulations is very time consuming. For the case of a backward extrusion process, this paper proposes a method for its determination that is based on an analytical function of the process parameters. This function was obtained by generating a database that includes the maximum equivalent stress for a large range of process parameters. This database was then modelled by a function determined through statistical analysis. (Professional Engineering Publishing)
    • Applications and Capabilities of Explosive Forming

      Mynors, Diane J.; Anderson, R.; Richardson, A.; Snape, R.G.; Standring, P.M. (Amsterdam: Elsevier, 2002)
      This paper examines the unique work being undertaken in the UK to ensure the continued competitiveness and advancement in capabilities of the companies that make up the UK metalforming industry. The work is a partnership between commercial metalforming simulation package vendors, universities and the industry through its main trade association the Confederation of British Metalforming. In examining the present activities, a case is made for a National Centre for Metalforming Simulation.
    • Controlling the Cold Roll Forming Design Process

      Mynors, Diane J.; English, M.; Castellucci, M.; Bramley, Alan N. (Amsterdam: Elsevier, 2006)
      The cold roll forming process requires successive forming profiles to be determined and an appropriate number of profiled roll sets to be designed for the product to be rolled. This paper examines the design process and how one company has put in place a design-production control system that allows designs to be ranked in terms of quality and efficiency. In addition, consideration is given to the proportion of time given to each design task and how non-creative design activities can be automated.
    • Design Under the Gun

      Davies, Colin; Parrinder, Monika (F+W Publications, Inc, 2006)
      The authors were commissioned to write an article looking at Product Design post-9/11. The article questioned whether an aesthetic of violence had taken root, promoting a new criticality amongst product designers.
    • Finite Element Modelling of Multipass Fusion Welding with Application to Complex Geometries

      Jiang, Wei; Yahiaoui, Kadda (Professional Engineering Publishing, 2007)
      The current paper presents recently completed work in the development of advanced multi-pass weld modelling procedures, with the ultimate objective of predicting weld residual stress distributions in thick-walled complex geometries. The modelling technique was first developed using simple three-dimensional geometries, for which experimental data was available for validation purposes. All the non-linearities associated with welding, including geometry, material, and boundary non-linearities, as well as heat source movement were taken into account. The element removal/reactivate technique was employed to simulate the deposition of filler material. Combined with a newly developed meshing technique, the model was then applied to predict residual stress distributions for a relatively thick stainless steel piping branch junction. Finally, a parametric study was conducted to assess the effects of various manufacture-related welding parameters on the final residual stress fields. The interpass temperature and cooling rate were found to be the two most sensitive parameters affecting resultant residual stresses. The residual stress profiles can be optimized relatively easily by adjusting these parameters. This research demonstrated that the developed modelling technique has potential in multi-pass welding process optimization and wide industrial applications including weld repairs.(Professional Engineering Publishing)
    • Innovative Product Development and Supporting SMEs

      Hall, Frank Richard (Engineering Integrity Society, 2003)
      The paper examines University research support available to companies, citing as a case study the author’s contribution to work on the simulation of aluminium tube hydro-forming, which helped BMW to make the aluminium suspensions for the 5 and 7 series cars, work encapsulated in a PhD thesis (Haas, 2002). Also an invited keynote paper presented at the Engineering Integrity Society annual conference.
    • Properties of Titanium Dental Implant Models made by Laser Processing

      Laoui, Tahar; Santos, Edson Costa; Shiomia, Masanari; Morita, M.; Shaik, S. K.; Tolochko, Nikolay K.; Abe, F.; Takahashi, M. (Professional Engineering Publishing, 2006)
      This article discusses the influence of various process parameters on the characteristics of titanium dental implants made by laser-forming techniques involving both laser sintering and laser melting. The implant models have a porous surface structure to increase bone-osseointegration and a compact core to provide the required mechanical strength. Models in the shapes of rod and cone were built using a continuous wave (CW) laser yielding a threshold compressive force as high as 1000 N after a postsintering treatment in a vacuum furnace at 1200°C for 1.5 h. Using selective laser melting with the pulsed laser, the best parameters were found to be: scan speed of 6 mm/s, laser peak power of 1 kW, and hatching pitch of 0.4 mm yielding a tensile strength of 300 MPa and torsional fatigue strength of 100 MPa. To improve the surface wear resistance of the titanium models, laser gas nitriding using CW Nd:YAG laser was applied. The formed TiN layers had a sponge-like structure with a thickness varying from 30 to 60 μm. The hardness measured at ε20 μm from the surface varied from 1000 to 600 HV by changing the scan speed from 1 to 16 mm/s.
    • Rapid Manufacturing of Metal Components by Laser Forming

      Santos, Edson Costa; Shiomia, Masanari; Osakada, Kozo; Laoui, Tahar (Amsterdam: Elsevier, 2006)
      This overview will focus on the direct fabrication of metal components by using laser-forming techniques in a layer-by-layer fashion. The main driving force of rapid prototyping (RP) or layer manufacturing techniques changed from fabrication of prototypes to rapid tooling (RT) and rapid manufacturing (RM). Nowadays, the direct fabrication of functional or structural end-use products made by layer manufacturing methods, i.e. RM, is the main trend. The present paper reports on the various research efforts deployed in the past decade or so towards the manufacture of metal components by different laser processing methods (e.g. selective laser sintering, selective laser melting and 3-D laser cladding) and different commercial machines (e.g. Sinterstation, EOSINT, TrumaForm, MCP, LUMEX 25, Lasform). The materials and applications suitable to RM of metal parts by these techniques are also discussed.