Abstract Both the topics of Computer Aided Process Planning and Production Planning in the contex... more Abstract Both the topics of Computer Aided Process Planning and Production Planning in the context of sheet metal air bending have been presented as standalone topics previously. This paper will focus on the interaction between both modules. Choices made by the ...
It is explained how 'one-to-many' fasteners can contribute to achieve cost-efficient disa... more It is explained how 'one-to-many' fasteners can contribute to achieve cost-efficient disassembly. These fasteners use advanced materials or structures as a catalyst for disassembly, allowing multiple assemblies to separate simultaneously after exposure to specific, external triggering conditions. In this paper the emerging techniques in this area are sketched and evaluated, according to their generic applicability and the degree of imbedded
Life Cycle Assessment (LCA) is a preferred technique for assessing the environmental impact of pr... more Life Cycle Assessment (LCA) is a preferred technique for assessing the environmental impact of products considering all environmental aspects over the full product life cycle. However, a number of drawbacks limit a continual and pro-active application of LCA in the design process. Indicators have been proposed as an alternative approach to LCA. This paper provides a brief survey of indicator
Energy consumption is responsible for a substantial part of the environmental impact generated by... more Energy consumption is responsible for a substantial part of the environmental impact generated by industrial production (1). Currently, minimising the energy consumption is hardly a priority for many machine designers, since they concentrate primarily on improving functionality, accuracy and safety. Nevertheless, alternative machine designs with improved energy consumption are emerging. This paper investigates the case of a laser cutting machine
This paper presents a methodology to assess the economic potential of a Product-Service System fo... more This paper presents a methodology to assess the economic potential of a Product-Service System for manufacturers of investment goods. The methodology is based on an analysis of the cost and value improvement potential per functional result, over the lifecycle of the investment good. In the theoretical description of the methodology, the importance of choosing a functional result as reference basis for the quantification is highlighted. The value-price-cost framework is proposed as the theoretical foundation of the economic ...
ABSTRACT The ability to manufacture accurate parts in single point incremental forming is depende... more ABSTRACT The ability to manufacture accurate parts in single point incremental forming is dependent on the capability to properly predict accuracy response surfaces of individual features and feature interaction combinations formed using uncompensated tool paths. Recent studies show that the accuracy profiles obtained are dependent on the choice of material used for forming, in terms of magnitude, geometric shape and nature of errors (under forming and over forming). In this paper, an attempt is made to capture the effect of material properties on the accuracy response surfaces. The response surfaces are modeled using Multivariate Adaptive Regression Splines (MARS), which is a non-parametric multivariate regression technique that helps generating continuous response surfaces. The MARS functions are based on process and feature specific geometric parameters. A set of features and feature interactions for which the response surface dependence on material properties is well predicted is used to illustrate the applicability of the MARS method for predicting the accuracy. An in-process stereo camera system is used to measure the displacement fields for different materials using digital image correlation (DIC) and understand the material dislocation mechanism. Improvements in accuracy for different sheet metal materials based on the predicted response surfaces are then discussed.
The idea generation phase is considered an important, although fuzzy, step in product development... more The idea generation phase is considered an important, although fuzzy, step in product development. Supporting methods and tools have been developed. However, their effectiveness has only been studied in sporadic attempts, and the few controlled experiments only share little similarity in conditions. Measuring the effectiveness of idea generation methods and tools requires replicable evaluation methods and suitable metrics, wh ich have recently been developed. This paper proposes a refinement of an existing novelty metric used in these evaluation methods. Furthermore, it is proposed to incorporate the variation on novelty scores in the analysis of the effectiveness of idea generation tools. Based on the analysis of the results from controlled experiments, it is shown that these refinements allow for mo re fine-grained analyses of the effectiveness of an idea generation method.
There is a need to create an awareness of Life Cycle Engineering and EcoDesign in Engineering stu... more There is a need to create an awareness of Life Cycle Engineering and EcoDesign in Engineering students. Topics covered in an LCE/EcoDesign course will create an awareness of environmental impacts, especially in other design course projects. This paper suggests that an awareness of product impact upon the environment must be created at an early stage in undergraduate education. Deciding what to include in an LCE/EcoDesign Course can be difficult because there are many different views on the subject. However, there are more similarities than differences. All LCE/EcoDesign Engineering courses have the ultimate objective of decreasing the environmental impact of a design. It has been observed that 70% of product costs are decided at the design stage. This can be extended to environmental impact, where it can be observed that, the design is correct, at the beginning, the environmental impact can be reduced by an estimated 70%. An LCE course does not need a high mathematical content and c...
ABSTRACT Solid state recycling techniques allow the manufacture of high density aluminium alloy p... more ABSTRACT Solid state recycling techniques allow the manufacture of high density aluminium alloy parts directly from production scrap. In this paper the environmental impacts associated with ‘meltless’ scrap processing routes based on three different techniques, namely hot extrusion, screw extrusion and spark plasma sintering (SPS), are compared with the corresponding remelting route as reference. Analysis of the obtained results allows clear conclusions on the perspectives offered by solid state recycling for systematic environmental impact reduction of aluminium recycling with material and energy savings as most important influencing factors. An overall impact reduction with a factor 2 for the SPS route and 3–4 for the extrusion routes is found to be realistic.
Single Point Incremental Forming (SPIF) has been developed as a new dieless process for forming m... more Single Point Incremental Forming (SPIF) has been developed as a new dieless process for forming metal sheets. This technique appears very promising in view of the current requirements for rapid prototyping and/or small series production [1]. However, inaccuracies in the shape of the processed part and material failure constitute important limiting factors for applications. In the present research, a numerical approach, based on the damage model proposed by Gurson [2], has been chosen to analyse and optimise the process, predict the material rupture and the process limit. From experimental observations of plastic deformation and ductile fracture, damage is related to the nucleation, growth and coalescence of microvoids [3]. Gurson’s model uses the volume fraction of these voids as a main variable. Hence the determination of this value is a key factor for a correct identification and validation of the model. More particularly, the present work focuses on two different methods used to ...
The International Journal of Advanced Manufacturing Technology, 2015
ABSTRACT This paper presents a number of novel active fasteners developed to significantly lower ... more ABSTRACT This paper presents a number of novel active fasteners developed to significantly lower disassembly costs during reconditioning, remanufacturing, and recycling of products. In the initial stage of the fastener development process, the applicability of distinct trigger signals for active disassembly (AD) is evaluated. Based on this evaluation, the high robustness of using a pressure increase or decrease as a nondestructive trigger for AD is demonstrated. Since previously proposed pressure-sensitive fasteners face considerable drawbacks upon implementation in electronic products due to the ongoing trend of miniaturization, a second generation of pressure-based active fasteners is developed. Evaluation of these fasteners by means of axiomatic design techniques and prototyping demonstrates that the presented snap-fits, which make use of a closed-cell elastomer foam, are most robust. Subsequently, the contraction forces that closed-celled foams can exert as a function of an increase in ambient air pressure are experimentally determined. Furthermore, the implementation of pressure-sensitive foam-based snap-fits in both a modem and a payment terminal is described. Results of these experiments demonstrate that the contraction force of a cross-linked metallocene polyethylene closed-cell foams can reach up to 6 N/cm2 at an overpressure of 2 bar and that the foam-based snap-fits can be released at a pressure increase of 2 bar.
ABSTRACT Taking into account the expected growth of the world's population and increasing... more ABSTRACT Taking into account the expected growth of the world's population and increasing welfare level in developing countries, the global energy and material resource demand can be expected to increase significantly. Therefore, the environmental burden per unit produced should be strongly reduced in order to assure a sustainable impact level [1,2]. This paper describes the environmental assessment and comparison of two alternative metal coating techniques: i.e. electrostatic powder coating and fluidized bed sintering. The paper starts with a general description of both investigated metal coating processes. Subsequently the life cycle inventory data collection effort is described and an environmental impact assessment is performed for both processes. The environmental performance of both processes is compared taking into account the differences in expected life time of both coatings. Finally, an overview of potential improvement measures is provided.
Finally, a procedure for estimating dimensional errors in bent parts is suggested and illustrated... more Finally, a procedure for estimating dimensional errors in bent parts is suggested and illustrated with an example to show the applicability of the method.
The International Journal of Advanced Manufacturing Technology, 2014
Intensive appeal for energy saving has driven the production industry towards more environmentall... more Intensive appeal for energy saving has driven the production industry towards more environmentally benign manufacturing. Diverse process settings in manufacturing can result in a high variance of energy consumption. Regarding process chains, the allocation of machining stock to each process is very crucial in terms of energy use. Optimization of material stock allowance and process parameters can effectively reduce the production energy. In this study, two cylindrical machining processes-turning and grinding-are compared at machine level with respect to energy intensity and surface roughness. A systematic energy-efficient approach, based on minimizing the production energy while complying with the required surface roughness, has been developed and validated to optimize the grinding stock for the turning-grinding process sequence. Compared to conventional stock allocation method, the developed approach results in more than 16 % of energy reduction for the turning-grinding process.
Single point incremental forming (SPIF) is an emerging application in sheet metal prototyping and... more Single point incremental forming (SPIF) is an emerging application in sheet metal prototyping and small batch production, which enables dieless production of sheet metal parts. This research area has grown in the last years, both experimentally and numerically. However, numerical investigations into SPIF process need further improvement to predict the formed shape correctly and faster than current approaches. The current work aims the use of an adaptive remeshing technique, originally developed for shell and later extended to 3D "brick" elements, leading to a Reduced Enhanced Solid-Shell formulation. The CPU time reduction is a demanded request to perform the numerical simulations. A two-slope pyramid shape is used to carry out the numerical simulation and modelling. Its geometric difficulty on the numerical shape prediction and the through thickness stress behaviour are the main analysis targets in the present work. This work confirmed a significant CPU time reduction and an acceptable shape prediction accuracy using an adaptive remeshing method combined with the selected solid-shell element. The stress distribution in thickness direction revealed the occurrence of bending/unbending plus stretching and plastic deformation in regions far from the local deformation in the tool vicinity.
Abstract Both the topics of Computer Aided Process Planning and Production Planning in the contex... more Abstract Both the topics of Computer Aided Process Planning and Production Planning in the context of sheet metal air bending have been presented as standalone topics previously. This paper will focus on the interaction between both modules. Choices made by the ...
It is explained how 'one-to-many' fasteners can contribute to achieve cost-efficient disa... more It is explained how 'one-to-many' fasteners can contribute to achieve cost-efficient disassembly. These fasteners use advanced materials or structures as a catalyst for disassembly, allowing multiple assemblies to separate simultaneously after exposure to specific, external triggering conditions. In this paper the emerging techniques in this area are sketched and evaluated, according to their generic applicability and the degree of imbedded
Life Cycle Assessment (LCA) is a preferred technique for assessing the environmental impact of pr... more Life Cycle Assessment (LCA) is a preferred technique for assessing the environmental impact of products considering all environmental aspects over the full product life cycle. However, a number of drawbacks limit a continual and pro-active application of LCA in the design process. Indicators have been proposed as an alternative approach to LCA. This paper provides a brief survey of indicator
Energy consumption is responsible for a substantial part of the environmental impact generated by... more Energy consumption is responsible for a substantial part of the environmental impact generated by industrial production (1). Currently, minimising the energy consumption is hardly a priority for many machine designers, since they concentrate primarily on improving functionality, accuracy and safety. Nevertheless, alternative machine designs with improved energy consumption are emerging. This paper investigates the case of a laser cutting machine
This paper presents a methodology to assess the economic potential of a Product-Service System fo... more This paper presents a methodology to assess the economic potential of a Product-Service System for manufacturers of investment goods. The methodology is based on an analysis of the cost and value improvement potential per functional result, over the lifecycle of the investment good. In the theoretical description of the methodology, the importance of choosing a functional result as reference basis for the quantification is highlighted. The value-price-cost framework is proposed as the theoretical foundation of the economic ...
ABSTRACT The ability to manufacture accurate parts in single point incremental forming is depende... more ABSTRACT The ability to manufacture accurate parts in single point incremental forming is dependent on the capability to properly predict accuracy response surfaces of individual features and feature interaction combinations formed using uncompensated tool paths. Recent studies show that the accuracy profiles obtained are dependent on the choice of material used for forming, in terms of magnitude, geometric shape and nature of errors (under forming and over forming). In this paper, an attempt is made to capture the effect of material properties on the accuracy response surfaces. The response surfaces are modeled using Multivariate Adaptive Regression Splines (MARS), which is a non-parametric multivariate regression technique that helps generating continuous response surfaces. The MARS functions are based on process and feature specific geometric parameters. A set of features and feature interactions for which the response surface dependence on material properties is well predicted is used to illustrate the applicability of the MARS method for predicting the accuracy. An in-process stereo camera system is used to measure the displacement fields for different materials using digital image correlation (DIC) and understand the material dislocation mechanism. Improvements in accuracy for different sheet metal materials based on the predicted response surfaces are then discussed.
The idea generation phase is considered an important, although fuzzy, step in product development... more The idea generation phase is considered an important, although fuzzy, step in product development. Supporting methods and tools have been developed. However, their effectiveness has only been studied in sporadic attempts, and the few controlled experiments only share little similarity in conditions. Measuring the effectiveness of idea generation methods and tools requires replicable evaluation methods and suitable metrics, wh ich have recently been developed. This paper proposes a refinement of an existing novelty metric used in these evaluation methods. Furthermore, it is proposed to incorporate the variation on novelty scores in the analysis of the effectiveness of idea generation tools. Based on the analysis of the results from controlled experiments, it is shown that these refinements allow for mo re fine-grained analyses of the effectiveness of an idea generation method.
There is a need to create an awareness of Life Cycle Engineering and EcoDesign in Engineering stu... more There is a need to create an awareness of Life Cycle Engineering and EcoDesign in Engineering students. Topics covered in an LCE/EcoDesign course will create an awareness of environmental impacts, especially in other design course projects. This paper suggests that an awareness of product impact upon the environment must be created at an early stage in undergraduate education. Deciding what to include in an LCE/EcoDesign Course can be difficult because there are many different views on the subject. However, there are more similarities than differences. All LCE/EcoDesign Engineering courses have the ultimate objective of decreasing the environmental impact of a design. It has been observed that 70% of product costs are decided at the design stage. This can be extended to environmental impact, where it can be observed that, the design is correct, at the beginning, the environmental impact can be reduced by an estimated 70%. An LCE course does not need a high mathematical content and c...
ABSTRACT Solid state recycling techniques allow the manufacture of high density aluminium alloy p... more ABSTRACT Solid state recycling techniques allow the manufacture of high density aluminium alloy parts directly from production scrap. In this paper the environmental impacts associated with ‘meltless’ scrap processing routes based on three different techniques, namely hot extrusion, screw extrusion and spark plasma sintering (SPS), are compared with the corresponding remelting route as reference. Analysis of the obtained results allows clear conclusions on the perspectives offered by solid state recycling for systematic environmental impact reduction of aluminium recycling with material and energy savings as most important influencing factors. An overall impact reduction with a factor 2 for the SPS route and 3–4 for the extrusion routes is found to be realistic.
Single Point Incremental Forming (SPIF) has been developed as a new dieless process for forming m... more Single Point Incremental Forming (SPIF) has been developed as a new dieless process for forming metal sheets. This technique appears very promising in view of the current requirements for rapid prototyping and/or small series production [1]. However, inaccuracies in the shape of the processed part and material failure constitute important limiting factors for applications. In the present research, a numerical approach, based on the damage model proposed by Gurson [2], has been chosen to analyse and optimise the process, predict the material rupture and the process limit. From experimental observations of plastic deformation and ductile fracture, damage is related to the nucleation, growth and coalescence of microvoids [3]. Gurson’s model uses the volume fraction of these voids as a main variable. Hence the determination of this value is a key factor for a correct identification and validation of the model. More particularly, the present work focuses on two different methods used to ...
The International Journal of Advanced Manufacturing Technology, 2015
ABSTRACT This paper presents a number of novel active fasteners developed to significantly lower ... more ABSTRACT This paper presents a number of novel active fasteners developed to significantly lower disassembly costs during reconditioning, remanufacturing, and recycling of products. In the initial stage of the fastener development process, the applicability of distinct trigger signals for active disassembly (AD) is evaluated. Based on this evaluation, the high robustness of using a pressure increase or decrease as a nondestructive trigger for AD is demonstrated. Since previously proposed pressure-sensitive fasteners face considerable drawbacks upon implementation in electronic products due to the ongoing trend of miniaturization, a second generation of pressure-based active fasteners is developed. Evaluation of these fasteners by means of axiomatic design techniques and prototyping demonstrates that the presented snap-fits, which make use of a closed-cell elastomer foam, are most robust. Subsequently, the contraction forces that closed-celled foams can exert as a function of an increase in ambient air pressure are experimentally determined. Furthermore, the implementation of pressure-sensitive foam-based snap-fits in both a modem and a payment terminal is described. Results of these experiments demonstrate that the contraction force of a cross-linked metallocene polyethylene closed-cell foams can reach up to 6 N/cm2 at an overpressure of 2 bar and that the foam-based snap-fits can be released at a pressure increase of 2 bar.
ABSTRACT Taking into account the expected growth of the world's population and increasing... more ABSTRACT Taking into account the expected growth of the world's population and increasing welfare level in developing countries, the global energy and material resource demand can be expected to increase significantly. Therefore, the environmental burden per unit produced should be strongly reduced in order to assure a sustainable impact level [1,2]. This paper describes the environmental assessment and comparison of two alternative metal coating techniques: i.e. electrostatic powder coating and fluidized bed sintering. The paper starts with a general description of both investigated metal coating processes. Subsequently the life cycle inventory data collection effort is described and an environmental impact assessment is performed for both processes. The environmental performance of both processes is compared taking into account the differences in expected life time of both coatings. Finally, an overview of potential improvement measures is provided.
Finally, a procedure for estimating dimensional errors in bent parts is suggested and illustrated... more Finally, a procedure for estimating dimensional errors in bent parts is suggested and illustrated with an example to show the applicability of the method.
The International Journal of Advanced Manufacturing Technology, 2014
Intensive appeal for energy saving has driven the production industry towards more environmentall... more Intensive appeal for energy saving has driven the production industry towards more environmentally benign manufacturing. Diverse process settings in manufacturing can result in a high variance of energy consumption. Regarding process chains, the allocation of machining stock to each process is very crucial in terms of energy use. Optimization of material stock allowance and process parameters can effectively reduce the production energy. In this study, two cylindrical machining processes-turning and grinding-are compared at machine level with respect to energy intensity and surface roughness. A systematic energy-efficient approach, based on minimizing the production energy while complying with the required surface roughness, has been developed and validated to optimize the grinding stock for the turning-grinding process sequence. Compared to conventional stock allocation method, the developed approach results in more than 16 % of energy reduction for the turning-grinding process.
Single point incremental forming (SPIF) is an emerging application in sheet metal prototyping and... more Single point incremental forming (SPIF) is an emerging application in sheet metal prototyping and small batch production, which enables dieless production of sheet metal parts. This research area has grown in the last years, both experimentally and numerically. However, numerical investigations into SPIF process need further improvement to predict the formed shape correctly and faster than current approaches. The current work aims the use of an adaptive remeshing technique, originally developed for shell and later extended to 3D "brick" elements, leading to a Reduced Enhanced Solid-Shell formulation. The CPU time reduction is a demanded request to perform the numerical simulations. A two-slope pyramid shape is used to carry out the numerical simulation and modelling. Its geometric difficulty on the numerical shape prediction and the through thickness stress behaviour are the main analysis targets in the present work. This work confirmed a significant CPU time reduction and an acceptable shape prediction accuracy using an adaptive remeshing method combined with the selected solid-shell element. The stress distribution in thickness direction revealed the occurrence of bending/unbending plus stretching and plastic deformation in regions far from the local deformation in the tool vicinity.
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Papers by Joost R Duflou