Thermal Optimization of Injection Molds Produced by Layered Manufacturing Techniques

Producing injection tooling with cooling channels of almost any form seems to be one of the most promising advantages of Layered Manufacturing Techniques (like Selective Laser Sintering). It could be efficiently exploited to achieve higher productivity or better quality parts in injection molding. Unfortunately, at the present time, the lack of data-processing tools to design optimal cooling systems still prevents us from fully benefiting from this new potential. The first objective of this paper is to present a methodology for the optimal design of cooling systems in three-dimensional injection molds. Our optimization process is based on a finite element model of the mold and on the standard gradient method. In the second part of this paper, we compare a conventional mold and a mold equipped with a cooling system optimized by means of the proposed methodology. The comparison is carried out thanks to an appropriate protocol. The conclusion is that the optimization of the cooling system doubled the productivity of the mold.Mechanical Engineerin

An innovative method to build support structures with a pulsed laser in the selective laser melting process

In selective laser melting machines, continuous laser are usually used to melt the powder. The support structures, which are inevitable when dealing with elaborated pieces, necessitate a complex design by CAD in order to be easily removed. This paper propose an innovative laser manufacturing method by combining pulsed and continuous modes of radiation. Continuous radiations are used for the object-to-build itself, in order to guarantee the requested mechanical properties. Pulsed radiations are used to build the support structures. The resulting support structures have sufficient mechanical properties to withstand the deposition system and to evacuate heat, and are easy to remove from the denser parts. This building method reduces drastically time to market since the same laser can be used in two modes and because pulsed radiation allows very high scanning speed with high power during the building of support structure

Ant Methaheuristics with Adapted Personalities for Vehicle Routing Problem

At each generation of an ant algorithm, each ant builds a solution step by step by adding an element to it. Each choice is based on the greedy force (short term profit or heuristic information) and the trail system (central memory which collects information during the search process). Usually, all the ants of the population have the same char- acteristics and behaviors. In contrast in this paper, a new type of ant metaheuristic is proposed. It relies on the use of ants with different per- sonalities. Such a method has been adapted to the well-known vehicle routing problem, and the obtained average results are very encouraging. On one benchmark instance, new best results have been found

An innovative method to build support structures with a pulsed laser in the selective laser melting process

In selective laser melting machines, continuous laser are usually used to melt the powder. The support structures, which are inevitable when dealing with elaborated pieces, necessitate a complex design by CAD in order to be easily removed. This paper propose an innovative laser manufacturing method by combining pulsed and continuous modes of radiation. Continuous radiations are used for the object-to-build itself, in order to guarantee the requested mechanical properties. Pulsed radiations are used to build the support structures. The resulting support structures have sufficient mechanical properties to withstand the deposition system and to evacuate heat, and are easy to remove from the denser parts. This building method reduces drastically time to market since the same laser can be used in two modes and because pulsed radiation allows very high scanning speed with high power during the building of support structures

Clustering Human Decision-Making in Production and Logistic Systems

Part 3: Knowledge Based Production ManagementInternational audienceHuman decisions play an essential role in Operations and Supply Chain Management. However, these decisions are rarely integrated in simulation models of Production and Logistic Systems. One main reason for this fact is the strong dispersion of human decisions among a population, as well as the variability of a single individual’s decision over time. This work presents an experimental study of a human decision consisting in the dynamic selection of suppliers in a well-controlled laboratory environment. The analysis of the results obtained on a large population shows that individual decision behaviors can be grouped into representative clusters typifying different decision behaviors. The results obtained from this study opens up the prospect to significantly reduce the number of decision models required to simulate Production and Logistic Systems including human decisions and could also allow categorizing human decision behavior based on a set of known criteria

Estimate Supply Chain robustness using asymmetric loss functions

Supply Chains have to be designed and managed holding simultaneously into account many different performance measures. Moreover, modern Supply Chains have to ensure satisfying performances despite an increasing degree of complexity and market uncertainty as well as be capable to limit the negative impacts of disruptive events. A multi-criteria robustness evaluation framework is proposed to deal with these challenges. The proposed approach allows to separately assessing the impact of various performance measures specifying tailor loss functions, being able to deal with non-linearity and asymmetric impacts. Moreover, an original Robustness Index is defined, in order to provide reliable estimations even in the presence of outliers and integrating information about kurtosis and skewness in the robustness estimation. The proposed framework is applied to a fictive industrial case to demonstrate its utilization and show the kind of analysis that can be done on the basis of the obtained results. The approach, simply requiring the definition of some parameters and the description of the characteristics of the Supply Chain configurations to be evaluated, is meant to be easily used by practitioners

Ant Metaheuristics with Adapted Personalities for the Vehicle Routing Problem

At each generation of an ant algorithm, each ant builds a solution step by step by adding an element to it. Each choice is based on the greedy force (short term profit or heuristic information) and the trail system (central memory which collects information during the search process). Usually, all the ants of the population have the same characteristics and behaviors. In contrast in this paper, a new type of ant metaheuristic is proposed. It relies on the use of ants with different personalities. Such a method has been adapted to the well-known vehicle routing problem, and even if it does not match the best known results, its performance is encouraging (on one benchmark instance, new best results have however been found), which opens the door to a new ant algorithm paradigm