Rémy Glardon

Sintering of commercially pure titanium powder with a Nd:YAG laser source

To understand the process of pulsed selective laser sintering, two different energy coupling mechanisms have to be considered. In a first step, the energy is absorbed in a narrow layer of individual powder grains determined by the bulk properties of the material. This leads to a high temperature of the surface of the grains during the interaction. After thermalization of the energy, heat flows mainly towards the center of the grains until a local steady state of the temperature within the powder grain is obtained. Afterwards, the surrounding powder properties have to be considered for the further thermal development. According to these model assumptions, a numerical simulation of the heat flow equation has been performed and compared with experimentally obtained titanium plates, which allowed to obtain a process map.

Direct rapid tooling: a review of current research

Rapid prototyping technologies are now evolving toward rapid tooling. The reasons for this extension are found in the need to further reduce the time‐to‐market by shortening not only the development phase, but also the industrialization phase of the manufacturing process. The present state of rapid tooling is reviewed and the direct rapid tooling concept, aimed at developing direct and rapid tool manufacturing processes, is presented, along with three promising methods. Their intrinsic properties are outlined and compared. Necessary research and development are described in terms of direct rapid tooling requirements.

UECML: Unified Enterprise Competence Modelling Language

This paper introduces the principles of a unified language devoted to the area of competence-based enterprise modelling. The language, named UECML, for Unified Enterprise Competence Modelling Language, is intended to provide a neutral interface to enterprise modelling based on competences. Therefore, it is built on previous languages, especially Unified Enterprise Modelling Language (UEML) and provides constructs to cover process, resource, competence and enterprise entities. An example of the implementation of the proposed UECML is provided with its application to a producer of railway vehicles.

Influence of Nd:YAG Parameters on the Selective Laser Sintering of Metallic Powders

Compared with CW CO2 laser sources, Nd:YAG lasers with Q-switching capability offer a wider parameter range, with improved sintering control, due to the short pulsed energy delivery. In particular, thermal diffusion being strictly limited by the nanosecond interaction between the energy pulse and the powder, higher accuracy can be achieved, while caking can be minimized. By systematically varying average power, scan velocity and repetition rate, process maps are established, for various materials, such as nickel and cobalt alloys, and titanium. Sintering depth and macrostructures are determined for different parameter sets. Basic models and physical explanations are given, for the various phenomena and consolidation processes. This mapping provides a correlation between the process parameters and the structure and properties of the produced parts. Results show that roughness and density are related to the pulsed energy delivery. For example, it is shown that multi-layer Ti samples can be sintered to a density close to 80 %.

On the effect of scanning strategies in the selective laser melting process

In the selective laser melting process, one has to strike a balance between power and scan speed. When a small scan speed is used, thermal gradients are important and local solidification can lead to cracks. On the other hand, when high speed is used, the power has to be huge and phenomena due to heat transfer, like delamination or balling, arise. In this paper, we study different possible scanning strategies and we indicate those that lead to homogeneous heating of the part until its melting point. The results are compared to numerical simulations.

ERP data sharing framework using the Generic Product Model (GPM)

Nowadays, all product life cycle processes are investigated deeply in order to get an advantage over competitors. To support these processes, several software applications are available. However, this wide range of heterogeneous applications leads to a large variety of hardware and operating systems, data management software, data models, schemas, and data semantics that hinder the information sharing process. To tackle this problem, Hitachi Company has developed a modeling language called Generic Product Model (GPM) in addition to several translators from native formats to GPM for storing, sharing and visualizing product data in a single data warehouse. In order to broaden the range of application data able to be stored and shared using the GPM data warehouse, this paper presents a methodology and a translator that allow management data to be included in a GPM data warehouse. Given the fact that most management data are stored in Enterprise Resource Planning (ERP) software, and that the latter allows extraction of database contents into Excel files, we propose a translator that handles Enterprise Resource Planning management data that are already extracted into Excel Format. The proposed framework enables data management contained in flat Excel Files to be translated into structured GPM data. Translation methodologies are given for the translation of mass production and customized product data through two case studies, one in the computer retail sector and the other in the extrusion machine industry.

A Markovian model for the hybrid manufacturing planning and control method 'Double Speed Single Production Line'

In this paper, the hybrid production planning & control method Double Speed Single Production Line (DSSPL) is presented, modelled and its performances evaluated and compared to classical Production Planning and Control methods (PPC). DSSPL combines JIT/kanban and Material Requirement Planning for the production of different classes of products (A- and B-items based on a market or customer oriented analysis) on one single production line. By the use of a Markovian birth-death queuing model of a single-stage, two-product production system, the performance and the behavior of the basic DSSPL concept are analyzed and compared to the classical MRP concepts. Its capability to cope with limited resources is illustrated with an industrial case study where DSSPL has been implemented to solve coordination problems between a plastic molding feeder shop and the final assembly line of a micromotor producer.

Competitor Based Strategic Networks of SME

Small subcontracting companies have difficulty getting in touch with large customers which drastically reduce the number of their suppliers to those able to provide a complete service. Setting up strategic networks is a new way of doing business where companies which are normally competitors can successfully cooperate to address new markets they will never be able to address alone. This paper presents a methodology for creating competitor based strategic networks as well as a case study showing how this methodology has been applied to set up Swiss Microtech, the first network in the screw machining domain.

Study of the inter-particle necks in selective laser sintering

Purpose – Since pulsed lasers are mainly used in selective laser sintering (SLS) – contrarily to selective laser melting (SLM) – only the exterior of the powder particles is molten while their core stays solid. The purpose of this paper is to investigate the binding mechanism between two particles of titanium powder.Design/methodology/approach – A dedicated experimental setup is used to isolate the particles. They are then irradiated by the laser. SEM micrographs are taken at each step and image analysis is performed. The obtained results are compared with the predictions of a thermal model allowing for the incorporation of the latent heat of fusion and for a realistic surrounding. The absorbed laser intensity is modeled by means of the Mie theory.Findings – The growing of the interparticular necks and the volume of liquid formed for different repetition rates are measured and compared with numerical simulations. A good agreement is found. A new method to easily find the absorption coefficient of the lase...

Combining JADE and Repast for the Complex Simulation of Enterprise Value-Adding Networks

This paper describes how to combine the JADE agent platform with Repast-provided simulation functions for rapidly developing an environment for the simulation of complex agent model. The main motivation comes from our requirements concerning the simulation of enterprise Value-Adding Networks, whose ultimate objective is to analyse management performance. JADE is useful for creating and deploying a distributed agent organisation modelling enterprise workflow model and supply chain network, as well as for system monitoring at the level of agents and communications. Integrating dynamically human interaction during the simulation is relatively easy. Repast was developed as a general purpose framework for agent based simulation with appropriate graphic interfaces. Their combination makes it possible to construct complex model of multi-agent organisation whose execution states can be observed from users and the global simulation results can be used for performance analysis. Their extension and composition mechanisms are described using a case study of a manufacturing enterprise.