Purpose

The question of resource scarcity and emerging pressure of environmental legislations has brought a new challenge for the manufacturing industry. On the one hand, there is a huge population that demands a large quantity of commodities; on the other hand, these demands have to be met by minimum resources and pollution. Resource conservative manufacturing (ResCoM) is a proposed holistic concept to manage these challenges. The successful implementation of this concept requires cross functional collaboration among relevant fields, and among them, closed loop supply chain is an essential domain. The paper aims to highlight some misconceptions concerning the closed loop supply chain, to discuss different challenges, and in addition, to show how the proposed concept deals with those challenges through analysis of key performance indicators (KPI).

Methods

The work presented in this paper is mainly based on the literature review. The analysis of performance of the closed loop supply chain is done using system dynamics, and the Stella software has been used to do the simulation. Findings The results of the simulation depict that in ResCoM; the performance of the closed loop supply chain is much enhanced in terms of supply, demand, and other uncertainties involved. The results may particularly be interesting for industries involved in remanufacturing, researchers in the field of closed loop supply chain, and other relevant areas. Originality The paper presented a novel research concept called ResCoM which is supported by system dynamics models of the closed loop supply chain to demonstrate the behavior of KPI in the closed loop supply chain.

Purpose: The transition from linear to circular product systems is a big step for any organization. This may require an organization to change the way it does business, designs product and manages supply chain. As these three areas are interdependent, bringing change in one area will influence the others, for instance, changing the business model from conventional sales to leasing will demand changes in both product design and the supply chain. At the same time, it is essential for an organization to anticipate the economic and environmental impact of all changes before it may decide to implement the circular product systems. However, there is no tool available today that can assess economic and environmental performance of circular product systems. The purpose of this research is to develop a multi-method simulation based tool that can help to evaluate economic and environmental performance of circular product systems. Method: The conceptual models that are used to develop the tool have been formulated based on review of the state-of-the-art research. System Dynamics (SD) and Agent Based (AB) principles have been used to create the simulation model which has been implemented in Anylogic software platform. Originality: This research presents the first multi-method simulation based tool that can evaluate economic and environmental performance of circular product systems. Findings: Multi-method simulation technique is useful in designing dynamic simulation model that takes into consideration mutual interactions among critical factors of business model, product design and supply chain. It also allows predicting system's behaviour and its influence on the economic and environmental performance of circular product systems.

The main drivers for adopting product multiple lifecycles are to gain ecological and economic advantages. However, in most of the cases it is not straight forward to estimate the potential ecological and economic gain that may result from adopting product multiple lifecycles. Even though many researchers have concluded that product multiple lifecycles result in gain, there are examples which indicate that the gain is often marginal or even none in many cases. The purpose of this research is to develop system dynamics models that can assist decision makers in assessing and analysing the potential gain of product multiple lifecycles considering the dynamics of material scarcity. The foundation of the research presented in this paper is laid based on literature review. System dynamics principles have been used for modelling and simulations have been done on Stella iThink platform. The data used in the models have been extracted from different reports published by World Steel Association and U.S. Geological Survey. Some of the data have been assumed based on expert estimation. The data on iron ore reserves, iron and steel productions and consumptions have been used in the models. This research presents the first system dynamics model for decision making in product multiple lifecycles which takes into consideration the dynamics of material scarcity. Physical unavailability and price of material are the two main factors that would drive product multiple lifecycles approach and more sustainable decisions can be made if it is done by taking holistic system approach over longer time horizon. For an enterprise it is perhaps not attractive to conserve a particular type of material through product multiple lifecycles approach which is naturally abundant but extremely important if the material becomes critical. An enterprise could through engineering, proper business model and marketing may increase the share of multiple lifecycle products which eventually would help the enterprise to reduce its dependency on critical materials.

The transition towards a circular economy has become important. Manufacturing industry being a major stakeholder in this transition has started exploring the potential of this transition and challenges in implementation. Ambitious companies such as Gorenje d.d. has taken the circular economy transition seriously and aims to become a pioneer in implementing circular manufacturing systems. One vital step in this transition is the business model shift from the linear (sales model) to a circular model such as 'product as a service'. This brings new challenges to Original Equipment Manufacturers (OEMs) that have never been experienced in their conventional businesses. One of the challenges is to establish an information communication and technology (ICT) infrastructure that enables information management and sharing as well as establishes a real-time communication between relevant stakeholders. Outlining such an ICT infrastructure is the objective of this paper.

This chapter presents a guiding framework for circular economy implementation in supply chains. Closing the loop for resource efficiency is a well-known practice in the industry. To concretize the circular economy implementation strategies, closed-loop thinking requires innovation and adaptation. Circular supply chains (CSCs) are one of the key enablers in closing the loop by design or intention for value recovery and profit maximization. CSC is an emerging area, and the view of CSC where forward and reverse supply chain is seamlessly integrated with the overall aim to achieve system-wide circularity is missing in the academic debate. By offering a cross-functional and systemic perspective of circular supply chains, we present a guiding framework to structure and understand the underlying complexities and highlight the crucial elements of circular supply chain implementation. The framework categorizes the circular supply chain into four building blocks: systemic approach, main drivers, levels of decision making, and mechanisms to manage the full loop closure and minimize the inherent uncertainties of a complex system. We conclude the chapter by illustrating the applicability of the circular supply chain framework using two industrial cases that are transitioning toward the circular economy.

Closing the loop for resource efficiency is a well-known practice in the industry. Toconcretize the circular economy implementation strategies, closed-loop thinkingrequires innovation and adaptation. Circular supply chains (CSCs) are one of the keyenablers in closing the loop by design or intention for value recovery and profit maxi-mization. CSC is an emerging area, and the view of CSC where forward and reversesupply chain is seamlessly integrated with the overall aim to achieve system-wide cir-cularity is missing in the academic debate. By offering a cross-functional perspectiveof CSC, this paper presents a CSC guiding framework to structure and understandthe underlying complexities and highlight the crucial elements of the CSC implemen-tation. Thus, this framework lays the basis for CSC within the systemic implementa-tion of CE by closing the loop by design or intention. The framework categorizes theCSC into four building blocks, namely, systemic approach, main drivers, levels of deci-sion making, and mechanisms to manage the full loop closure and minimize the inher-ent uncertainties of a complex system. The building blocks of the framework aresynthesized from various streams of supply chain literature and recurring concepts inthe circular economy literature. The CSC framework applicability is illustrated usingtwo industrial cases that are transitioning towards the circular economy.

Additive manufacturing (AM) has recently been accorded considerable interest by manufacturers. Many manufacturing industries, amongst others in the aerospace sector, are already using AM parts or are investing in such manufacturing methods. Important material properties, such as microstructures, residual stress, and surface topography, can be affected by AM processes. In addition, a subtractive manufacturing (SM) process, such as machining, is required for finishing certain parts when accurate tolerances are required. This finish machining will subsequently affect the surface integrity and topography of the material. In this research work, we focused on the surface integrity of Ti-6Al-4V parts manufactured using three different types of AM and finished using an SM step. The aim of this study was to gain an understanding on how each process affects the resulting surface integrity of the material. It was found that each AM process affects the materials’ properties differently and that clear differences exist compared to a reference material manufactured using conventional methods. The newly generated surface was investigated after the SM step and each combination of AM/SM resulted in differences in surface integrity. It was found that different AM processes result in different microstructures which in turn affect surface integrity after the SM process.

Ultraprecision (UP) components have become common in everyday life products such as mobile phones or compact high resolution digital cameras. Thus the need of producing such components with high accuracy and low production cost. UP machine tools are capable of extremely high accuracy in tool positioning but still today the workpiece is positioned by hand, hence the high production cost of UP components. A fully automated chain of production has been developed within the EU-IP project “Production 4 micro”. This paper describes the active alignment chuck for workholding in UP machining. The chuck has been provided with a high damping interface (HDI) and to evaluate its efficiency the chuck has undergone an experimental modal analysis (EMA) as well as machining tests. The chosen operation was grooving by fly cutting using a diamond tool. The EMA showed that the HDI was effective for those modes where there was relative displacement between one side and the other of the HDI. This result was confirmed by the machining tests as well. The HDI resulted being effective in damping high frequency modes (around 4 – 5 kHz), hence one expected benefit would be a longer tool life.

Vibration phenomena are a main consideration during the material removal operation, as it has prominent effects on the product quality, cutting tool life, and productivity of that machining operation. Within the context of machining performance, role of enhanced stiffness and damping on the dynamic behaviour of machining systems such as turning and milling is well established. In this experimental analysis, investigations have been conducted for identifying the natural characteristics and dynamic responses of a milling process with the application of a novel carbon based (CNx) nano-composite damping material. TheCNx material has been applied into the joint interface of a workholding device with adaptive dynamic stiffness. Prior investigations of this material, produced by theplasma enhanced chemical vapor (PECVD) process, showed inherent damping capacity via interfacial frictional losses of its micro-columnar structures. For thisstudy, natural characteristics of the workholding system have been characterized bythe modal impact testing method. Dynamic responses during the machining processhave been measured through the vibration acceleration signals. The ultimate objective of this study is to comprehend the potentiality of CNx coating material forimproving machining process performance by analyzing the frequency response functions and measured vibration signals of the investigated milling process with varying stiffness and damping levels.

A main consideration in the operation of machine tools is vibrations occurring during the cutting process.Whether they are forced vibrations or self-excited ones, they have pronounced effects on surface quality, tool lifeand material removal rate. This work is an experimental study of interactions between natural characteristics,control parameters and process parameters of a machining system designed with adaptive dynamic stiffness. Inorder to comprehend these interactions, the effect of changes in dynamic stiffness on the system’s response isexamined. The system under study consists of an end-milling tool, a steel workpiece and a work holding devicewith controllable stiffness. Natural dynamic characteristics of the system components are determined throughmodal impact testing. Then the behaviour of the whole machining system is examined under both high and lowcutting speed conditions by analysing vibration levels using acceleration signals acquired through a tri-axialsensor mounted on the workpiece. Cutting is performed in both directions of the horizontal plane of a CNCmilling machine. In both cases the results are presented for two extremes of stiffness and damping in the workholding device. The effect of control parameters on the system’s natural characteristics could be identifiedtogether with a relation between these parameters and the system’s response in high and low cutting speedconditions. The high-damping configuration reduces the vibration amplitudes significantly, while the increaseof pre-stress has a different effect depending on the cutting conditions.

Machining vibrations and dynamic instability of machine tools is an important consideration in machining systems. Common approaches for improving their dynamic performance target either the process, or intelligent, yet complex control systems with actuators. Given that machine tools' dynamic characteristics are largely defined by the characteristics of the joints, this article proposes a novel concept, attempting to create a new paradigm for improving the dynamic behaviour of machine tools-introducing modular machine tools components (Joint Interface Modules-JIMs) with joints deliberately designed for increasing dynamic stiffness and enhancing damping with the use of viscoelastic materials. Through a systematic model-based design process, a prototype replicating a reference tool holder was constructed exploiting viscoelastic materials and the dynamic response of the machining system was improved as a result of its introduction; in machining experiments, the stability limit was increased from around 2 mm depth of cut to 4 mm depth of cut, without compromising the rigidity of the system or changing the process parameters. The article also includes the results of investigations regarding the introduction of such prototypes in a machine tool and discusses the shortcomings of the stability lobe diagrams as a method for evaluating the performance of machine tool components with viscoelastically treated joints.

Machine tool joints have significant influence on the dynamic characteristics of the machine tool and therefore on the response of the machining system to excitations from the cutting process. In cases of unstable response, generally described as chatter, surface quality of a machined workpiece and tool life deteriorate significantly. This paper presents a novel way of exploiting joints in order to control the dynamic response of the system, by integrating a mechatronic tool holder (Joint Interface Module - JIM) in the machine tool. This system has a purposely designed joint interface with controllable natural characteristics (stiffness and damping). These characteristics are controlled by altering the applied pre-load on the internal joint interface of the tool holder. The preload on the joint interface is controlled by pneumatic means. In doing so, a milling process during which the stability limit was exceeded became stable during the machining process, without alteration of the process parameters.

A hybrid joint interface module (HJIM) was developed using viscoelastic materials’ (VEM) “incompressible” property. The HJIM composes VEM layers compressed by screws. Its static stiffness and damping had been characterized by inverse receptance method. The analysis result showed that its static stiffness increases by nearly 50 % with increasing compression preload without compromising its loss factor. A comparison study of HJIM with a viscoelastic material joint interface module (VJIM) revealed that the change of the screws mechanical contact conditions affected the HJIM’s stiffness. Compression preload by fastening the screws, however, did not significantly affect the damping property of the HJIM. On the contrary to shear pre-strain, compression preload did not affect the VEM’s properties shown by studying the VJIM case. A workpiece was studied while fixed on the HJIM. Varying compression preload affected the stiffness of HJIM and that resulted in increased shear strain in VEM for certain modes while decreased shear strain in VEM for other modes. The affected shear strain in VEM altered the vibrational strain energy distribution and changed the receptance amplitude of different modes. In addition to apply the VEM where it is significantly strained, the analysis revealed that constraining the shear strain in VEM resulted in reduced receptance amplitude for different modes. The changes of receptance will further affect the vibration conditions in machining.

A computation model based on inverse receptance coupling method is presented in this paper aiming for obtaining the joint interface's stiffness and damping properties using frequency response functions measured on assembled structures only. In the model, it is emphasized that the joint stiffness and damping should be modeled with frequency dependency. The model's validity is checked both through finite element (FE) simulation and experimental analyses. In the FE simulation example, the computation model gives more accurate results with noise-free data. In the experimental example, where noise in the data is unavoidable, the computation model is explored further for its applicability in the real industrial environment. Results from applications of the computational model show that it is even capable of obtaining the joint interface stiffness and damping values over the structure's resonance frequency. A viable process of predicting behaviors of workpiece with receptance coupling method through identifying the joint interface properties is presented in the end of the paper. The applicability of this computation model and the factors that influence the accuracy of the model are discussed in the end of the paper.

Chatter in machining process is one of the common failures of a production line. For a cantilever tool, such as a boring bar, the rule of thumb requires the overhang length of the tool to be less than 4 times the diameter. The reason is because longer overhang will induce severe tool vibration in the form of chatter during machining. When a longer overhang than 4 times diameter is necessary for performing special machining operations, damping methods are needed to suppress tool chatter. One of the methods is the constrained layer damping method. Materials, such viscoelastic material, are applied in the vibration node regions of the structure to absorb the concentrated vibration strain energy and transform the mechanical energy to heat. With a cantilever tool clamped in a tool holder, the clamping interface is usually the vibration node region. The friction in the joint interface with low normal pressure became another source of damping and can be used for tool chatter suppression in mechanical structures. Joint interfaces are well known to possess normal pressure dependent stiffness and damping. The normal pressure’s effect on the structures frequency response function had been observed by H. Åkesson [1] et al, and L.Mi [2] et al. However, the direct effect of the joint interface normal pressure on machining process stability hasn’t been investigated. In this paper, a cantilever tool with 6.5 overhang length to diameter ratio is investigated. The direct effect of the tool clamping interface’s normal pressure on the machining process stability is studied. Three different levels of clamping normal pressure are tested with an internal turning process. The machining results indicate another adaptable solution on shop floor for suppressing tool chatter.

As the Global South shifts towards increased manufacturing, the negative effects on climate change and environmental pollution raise serious concerns. These global effects are increasingly felt locally, as reflected in health surveys throughout the Global South. The world cannot afford to wait for a natural development process to take place in which rising incomes might curb pollution. This article examines the challenges of reforming manufacturing in the Global South towards more sustainable practices. It also focuses on the lessons of the Sustainable Manufacturing and Environmental Pollution Program (SMEP) which has funded a series of environmental improvement projects across sub-Saharan Africa and South Asia aimed at reducing pollution in the manufacturing process. The lessons learned from these projects include the need to improve the tracking of the negative effects of the environmental damages caused by manufacturing and analyze the manufacturing supply chain processes to better identify potential points of intervention; as well as the need for more external financial and technical resources to expand these projects. 

Additive manufacturing (AM) using powder bed fusion is becoming a mature technology that offers great possibilities and design freedom for manufacturing of near net shape components. However, for many gas turbine and aerospace applications, machining is still required, which motivates further research on the machinability and work piece integrity of additive-manufactured superalloys. In this work, turning tests have been performed on components made with both Powder Bed Fusion for Laser Beam (PBF-LB) and Electron Beam (PBF-EB) in as-built and heat-treated conditions. The two AM processes and the respective heat-treatments have generated different microstructural features that have a great impact on both the tool wear and the work piece surface integrity. The results show that the PBF-EB components have relatively lower geometrical accuracy, a rough surface topography, a coarse microstructure with hard precipitates and low residual stresses after printing. Turning of the PBF-EB material results in high cutting tool wear, which induces moderate tensile surface stresses that are balanced by deep compressive stresses and a superficial deformed surface that is greater for the heat-treated material. In comparison, the PBF-LB components have a higher geometrical accuracy, a relatively smooth topography and a fine microstructure, but with high tensile stresses after printing. Machining of PBF-LB material resulted in higher tool wear for the heat-treated material, increase of 49%, and significantly higher tensile surface stresses followed by shallower compressive stresses below the surface compared to the PBF-EB materials, but with no superficially deformed surface. It is further observed an 87% higher tool wear for PBF-EB in as-built condition and 43% in the heat-treated condition compared to the PBF-LB material. These results show that the selection of cutting tools and cutting settings are critical, which requires the development of suitable machining parameters that are designed for the microstructure of the material.

Stretchable electronics is a new innovation and becoming popular in various fields, especially in the healthcare sector. Since stretchable electronics use less printed circuit boards (PCBs), it is expected that the environmental performance of a stretchable electronics-based device is better than a rigid electronics-based device that provides the same functionalities. Yet, such a study is rarely available. Thus, the main purpose of this research is to perform a comparative life cycle analysis of stretchable and rigid electronics-based devices. This research combines both the case study approach and the research review approach. For the case study, a cardiac monitoring device with both stretchable and rigid electronics is used. The ISO 14044:2006 standard's prescribed LCA approach and ReCiPe 2016 Midpoint (Hierarchist) are followed for the impact assessment using the SimaPro 9.1 software. The LCA results show that the stretchable cardiac monitoring device has better environmental performance in all eighteen impact categories. This research also shows that the manufacturing process of stretchable electronics has lower environmental impacts than those for rigid electronics. The main reasons for the improved environmental performance of stretchable electronics are lower consumption of raw material as well as decreased energy consumption during manufacturing. Based on the LCA results of a cardiac monitoring device, the study concludes that stretchable electronics and their manufacturing process have better environmental performance in comparison with the rigid electronics and their manufacturing process.

Nanofluids could be used to provide cooling and lubrication action and to control thermo-physical and tribo-chemical properties of material processing. It is foreseen that properly designed nanofluids could surpass conventional cutting fluids with respect to thermal conductivity, convective heat transfer coefficient, critical heat flux, viscosity, and wettability. These properties have a promising potential to lead to the development of new coolants and lubricants with applications in a wide variety of materials processing technologies. This paper analyses the developments in research on the properties of nanofluids and evaluates their potential for applications in machining, focusing on their thermal and tribological aspects. The increasing use of nanofluids leads to a need for information on their sustainability in order to recognize and avoid risks. Sustainability is discussed in view of occupational health and safety and toxicity of nanoparticles.

A nanoparticle-based cooling-lubricating fluid (nCLF), designed and fabricated by suspending engineered nanoparticles (ENPs) in biodegradable vegetable-based fluids, has been developed for integration into material processing technologies. This new product exhibits tribological properties superior to those of conventional metalworking fluids. The major innovation is the ability to create a stable nCLF through the modification of ENP surfaces. Functionalized MoS2 nanotube ENPs were successful used as low friction additives. The experimental work, required for the proof-of-concept and technology validation, was carried out on three different levels to quantify the improved tribological behavior of nCLF. These experiments include standard tribological tests, mock-up tests to simulate machining, and actual machining tests. It is demonstrated that the specific properties of ENPs, fluid design and composition, as well as specific lubrication mechanisms, exhibit superior performance of nCLF in terms of friction and wear. The objective of this paper is to demonstrate how recent nanotechnology developments support innovation needed for transitioning to sustainable production via new product development and integrated industrial applications.

This paper introduces an agent-based approach to study customer behavior in terms of their acceptance of new business models in Circular Economy (CE) context. In a CE customers are perceived as integral part of the business and therefore customer acceptance of new business models becomes crucial as it determines the successful implementation of CE. However, tools or methods are missing to capture customer behavior to assess how customers will react if an organization introduces a new business model such as leasing or functional sales. The purpose of this research is to bring forward a quantitative analysis tool for identifying proper marketing and pricing strategies to obtain best fit demand behavior for the chosen new business model. This tool will support decision makers in determining the impact of introducing new (circular) business models. The model has been developed using an agent-based modeling approach which delivers results based on socio-demographic factors of a population and customers’ relative preferences of product attributes price, environmental friendliness and service-orientation. The implementation of the model has been tested using the practical business example of a washing machine. This research presents the first agent-based tool that can assess customer behavior and determine whether introduction of new business models will be accepted or not and how customer acceptance can be influenced to accelerate CE implementation. The tool integrates socio-demographic factors, product utility functions, social network structures and inter-agent communication in order to comprehensively describe behavior on individual customer level. In addition to the tool itself the results of this research indicates the need for systematic marketing strategies which emphasize CE value propositions in order to accelerate customer acceptance and shorten the transition time from linear to circular. Agent-based models are emphasized as highly capable to fill the gap between diffusion-based penetration of information and resulting behavior in the form of purchase decisions.

The recent circular economy movement has raised awareness and interest about untapped environmental and economic potential in the manufacturing industry. One of the crucial aspects in the implementation of circular or closed-loop manufacturing approach is the design of circular products. While it is obvious that three post-use strategies, i.e., reuse, remanufacturing, and recycling, are highly relevant to achieve loop closure, it is enormously challenging to choose “the right” strategy (if at all) during the early design stage and especially at the single component level. One reason is that economic and environmental impacts of adapting these strategies are not explicit as they vary depending on the chosen business model and associated supply chains. In this scenario, decision support is essential to motivate adaptation of regenerative design strategies. The main purpose of this paper is to provide reliable decision support at the intersection of multiple lifecycle design and business models in the circular economy context to identify effects on cost and CO2 emissions. The development of this work consists of a systematic method to quantify design effort for different circular design options through a multi-method simulation approach. The simulation model combines an agent-based product architecture and a discrete event closed-loop supply chain model. Feasibility of the model is tested using a case of a washing machine provided by Gorenje d.d. Firstly, design efforts for reuse, remanufacturing, and recycling are quantified. Secondly, cost and emissions of different design options are explored with different business model configurations. Finally, an optimization experiment is run to identify the most cost-effective combination of reused, remanufactured, and recycled components for a business model chosen on the basis of the explorative study results.

Background: Transitions from a linear (take-make-dispose) to a circular product system (consideringreuse/remanufacturing/recycling) require changes of business models through new value propositions.Therefore, the focus for industrial businesses shifts from selling physical products to, for example,providing access to functionality through business innovation. In this context it is particularly challengingto understand what complexity a new concept like circular economy (CE) brings to establishedbusinesses where the success and the failure of the business is dependent on customer’s acceptance ofnew value propositions.Objective: The objective of this paper is to develop an algorithm based on gathered survey data to “learn”choice behavior of a small customer group and then replicate that choice behavior on a larger populationlevel.Purpose: This paper explores the opportunities of different circular business offers in the city of Stockholmby embedding support vector machine classifiers, which are trained on CE survey data, in asimulation model to quantify and study choice behavior on city level.Method: Stated choices from CE surveys including unique demographic data from the respondents, i.e.age, income, gender and education, are used for algorithm training. Based on the survey data, supportvector machine algorithms are trained to replicate the decision-making process of a small sample ofrespondents. The example of a washing machine is used as a case study with the attributes price andpayment scheme, environmental friendliness as well as service level. The trained support vector machinesare then implemented in a simulation model to simulate choice behavior on population level(Stockholm city).Originality: This paper is the first of its kind to use both machine learning and simulation approaches in aCE market acceptance context.Findings: Based on the washing machine-specific survey and Stockholm-specific customer data, resultsindicate that larger share of the Stockholm population would be willing to opt for circular washingmachine offers compared to the existing linear sales model. Given the data-driven nature of machinelearning algorithms and the process-oriented structure of simulations programs allows for generatinglarge amounts of data from small samples. This supports exploration of new emerging areas like CE inaddition to saving time and expenses.

Background: In industrial practice a transition from a linear (take-make-dispose) to a circular product system (considering reuse/remanufacturing/recycling) requires the change of business models through new value propositions. In doing so the focus of the value proposition shifts from selling a physical product to providing access to functionality through business innovation. One key factor related to circular business transitions is market acceptance. It is particularly challenging to understand what complexity a new concept like circular economy (CE) brings to established businesses where the success and the failure of the business is dependent on customer's acceptance of new value propositions. Purpose: This paper empirically explores the opportunities of a circular business approach for washing machines in the city of Stockholm by quantifying and assessing customer preferences for CE value propositions for a business to customer (B2C) scenario. Method: This study uses the method of choice-based conjoint analysis to investigate preferences based on the attributes price and payment scheme, environmental friendliness as well as service level. Originality: This paper is the first of its kind to assess customer preferences from the CE market acceptance point of view using a conjoint approach and provides insight to what extent new CE value propositions may be adopted. Findings: Results indicate that there is general interest in paying for access rather than for ownership. Service levels have the strongest impact on customer utility of a washing machine offer. If associated with reduction in CO2 emissions the number of remanufacturing cycles can increase purchase probability. As a method choice-based conjoint analysis is highlighted as beneficial to break down CE value propositions and to identify to what extent particular service-related attributes and product-related attributes contribute to overall customer utility. (C) 2017 Elsevier Ltd. All rights reserved.

The concept of circular economy (CE) is to an increasing extent treated as a solution to series of challenges such as waste generation, resource scarcity and sustaining economic benefits. However the concept of circularity is not of novel as such. Specific circumstances and motivations have stimulated ideas relevant to circularity in the past through activities such as reuse, remanufacturing or recycling. Main objectives of this work are: to provide a comprehensive review of research efforts encompassing aspects of resources scarcity, waste generation and economic advantages; to explore the CE landscape in the context of these three aspects especially when they are considered simultaneously; based on an idea of a comprehensive CE framework, propose an implementation strategy using top-down and bottom-up approach in a concurrent manner. To fulfill this objective a comprehensive review of state-of-the-art research is carried out to understand different ideas relevant to CE, motivation for the research and context of their recurrence. Main contributions of this paper are a comprehensive CE framework and a practical implementation strategy for a regenerative economy and natural environment. The framework emphasizes on a combined view of three main aspects i.e. environment, resources and economic benefits. It also underlines that joint support of all stakeholders is necessary in order to successfully implement the CE concept at large scale. The proposed framework and implementation strategy also identify new avenues for future research and practice in the field of CE.

Electron beam powder bed fusion (PBF-EB) is used to manufacture dense nickel titanium parts using various parameter sets, including the beam current, scan speed and post cooling condition. The density of manufactured NiTi parts are investigated with relation to the linear energy input. The results implies the part density increases with increasing linear energy density to over 98% of the bulk density. With a constant energy input, a combination of low power and low scan speed leads to denser parts. This is attributed to lower electrostatic repulsive forces from lower number density of the impacting electrons. After manufacturing, densest parts with distinct parameter sets are categorized into three groups: i) high power with high scan speed and vacuum slow cooling, ii) low power with low scan speed and vacuum slow cooling and iii) low power with low scan speed and medium cooling rate in helium gas. Among these, a faster cooling rate suppresses phase transformation temperatures, while vacuum cooling combinations do not affect the phase transformation temperatures significantly. All the printed parts in this study exhibit almost 8% pseudoelasticity regardless of the process parameters, while the parts cooled in helium have a higher energy dissipation efficiency ( ), which implies faster damping of oscillations. 

Since electron beam (EB) is the main additive manufacturing (AM) tool in electron beam melting (EBM), EB spot size plays a significant role in the parts quality, surface roughness as well as the microstructure and corresponding properties. So far, the research on the relationship between the machine parameters and the EB spot size has been mainly based on the single track and powderless single track printing on a metal plate such as stainless steel. However, this method, due to material thermal properties as well as the melting phenomena, cannot reveal the actual value for the EB spot size. This research is carried out to establish a simple methodology on measuring the EB spot size in a more accurate way with a low cost. To do so, a ceramic surface coating was applied to the surface of a metal copper starting plate and stainless steel plate. Afterwards, the EB applied the tracks onto the coatings and regular metal plate. The analysis showed that the EB tracks on ceramic coated stainless steel plates could be the best replica for the electron beam among those materials tested in this work.  

The increasing demands for precision and efficiency in machining call for effective control strategies based on the identification of static and dynamic characteristics under operational conditions. The capability of a machining system is significantly determined by its static and dynamic stiffness. The aim of this paper is to introduce novel concepts and methods regarding identification and control of a machining system’s dynamics. After discussing the limitations in current methods and technologies of machining systems’ identification and control, the paper introduces a new paradigm for controlling the machining system dynamics based on design of controllable structural Joint Interface Modules, JIMs, whose interface characteristics can be tuned using embedded actuators. Results from the laboratory and industrial implementation demonstrate the effectiveness of the control strategy with a high degree of repeatability.

Titanium alloys are labeled as difficult to materials because of their low machinability rating. This paper presents an experimental study of machining Ti-6Al-4V under turning operation. All machining tests were conducted under dry, mist and flood cooling approaches by using a TiAlN coated carbide cutting inserts. All cutting experiments were conducted using high and low levels of cutting speeds and feed rates. The study compared surface finish of machined surface and flank wear at cutting edge under dry, mist and flood cooling approaches. Scanning electron microscopy was utilized to investigate the flank wear at cutting edge under various cooling approaches and cutting conditions. Investigation revealed that TiAlN coated carbides performed comparatively better at higher cutting speed.

Pocket milling operation is one of the widely used milling operations. CAM packages offer different tool path strategies to execute a machining operation. In the presented work zigzag, constant overlap spiral, parallel spiral and oneway tool path strategies were compared in terms of power and energy consumption for pocket milling of Al 6061 aluminum alloy. All pocketing operations were conducted using 8 mm diameter High Speed Steel (HSS) end milling cutters. Energy utilization was analysed for all tool path strategies. This work aims to develop better understanding towards sustainability concept in core machining phase.

Titanium alloys exhibit extraordinary characteristics such as excellent strength-to-weight ratio, superior corrosive and erosive resistance and capability to operate at high operating temperatures. These alloys show poor machinability rating due their low thermal conductivity and high chemical reactivity. This study investigates the machinability of Ti6A14V using TiAIN coated tools by analyzing cutting forces and cutting temperatures. The simulated cutting force data was used to predict the total energy utilized by the process. Cutting tool temperatures during the machining operation were measured by an Infrared (IR) camera with cutting forces experiments. Finite element simulations can offer a cost effective solution when evaluating the machining performance of difficult to cut materials such as Titanium alloys. The study incorporated modified Johnson-Cook constitutive equation and friction model to develop the finite element simulations of the machining process. The finite element simulated results of forces and tool temperature presented good agreement with the experimental results. Copyright

This article is concerned with the experimental and numerical investigation of energy consumption involved in the turning of Ti6Al4V titanium alloys. Energy consumption of a machining process is considered as an important machining performance indicator. This article aims to propose an approach for the prediction of energy consumption and related environmental implications using finite element modeling simulations. Machining experiments were conducted using uncoated carbide tools under dry cutting environment. DEFORM-3D software package was utilized to simulate finite element–based machining simulations. Experimental validation was mainly conducted by focusing on the cutting forces and power consumption measurements. Simulated results of the cutting force and power consumption were found in a good agreement with the experimental findings. The amount of CO2 emission resulting from energy consumption during the machining phase is highly dependent on the geographical location. This study also incorporated the energy mix of United Arab Emirates for the environmental calculations. Finally, in the light of proposed methodology, possible future directions and recommendations have also been presented.

Titanium alloys generally show low machinability ratings. They are referred as difficult-to-cut materials due to their inherent properties such as low thermal conductivity, high chemical reactivity and high strength at elevated temperatures. Cooling strategies play an important role to improve the machining performance of the cutting process. In order to facilitate the heat dissipation from the cutting zone, generous amount of coolant is used when machining highly reactive metals such as titanium alloys. Generally, cutting coolants are nominated as pollutants due to their non-biodegradable nature. This article presents experimental evaluation of a minimal quantity cooling lubrication system. The study investigates a combination of sub-zero-temperature air and vegetable oil-based mist as possible environmentally benign alternative to conventional cooling methods. The results are compared with the dry and flood cutting environments as well. Machinability was evaluated experimentally by considering the surface finish, cutting forces, tool life and their associated tool wear mechanisms. It was concluded from the results obtained from the surface roughness, cutting force and tool life investigation that minimal quantity cooling lubrication (internal) cooling strategy has encouraging potential to replace the conventional flood cooling method.

The paper presents an innovative methodology of coupling the conventional finite element machining simulations with computational fluid dynamic (CFD) model to analyse the temperature distribution at the cutting tool. The conventional finite element machining simulations were conducted using DEFORM 2D to predict the heat generation and tool tip temperature during the cutting action. Machining simulations were conducted using Ti6Al4V and uncoated carbide as a workpiece and tool material respectively. Modified version of Johnson-Cook constitutive model was incorporated in the conventional finite element based machining simulations to predict the behavior of flow stresses for Ti6Al4V titanium alloy. Computational fluid dynamics (CFD) simulations were performed using ANSYS (R) CFX. CFD model has incorporated air as a cooling media to simulate the dry cutting and temperature distribution at the tool surface was obtained. The coupled numerical modeling methodology showed encouraging potential of predicting precise temperature distribution on the cutting tool. The approach can be further evaluated to predict temperature distribution under flood cooling and minimum quantity lubrication (MQL).

This study deals with the conjugate heat transfer problem of a single point cutting tool under turning operation dissipating heat in the tool material and streams of the surrounding air. In order to estimate the cutting temperature during the turning operation, the DEFORM-3D finite element package was utilized. A machining simulation material model for Ti6Al4V was utilized using a modified Johnson–Cook equation. The maximum cutting temperature value was obtained from the finite element model. The temperature was then used as a constant heat source on the tool tip, and the conjugate heat transfer (CHT) approach was used to develop a computational fluid dynamics (CFD) model. The CFD model utilized a 3D heat and fluid flow analysis using ANSYS ® CFX. A cutting insert with a constant heat source was exposed to the stream velocities of the dry air. The numerical equations governing the flow and thermal fields in the fluid domain and energy equation in the solid domain were solved in parallel by maintaining the continuity of temperature and heat flux at the solid–fluid interface. The presented conjugate heat transfer (CHT) approach provided a very useful understanding of the temperature profile development at the cutting tool that is still a complex challenge for the existing experimental and numerical techniques.

During the metal cutting operation, heat generation at the cutting interface and the resulting heat distribution among tool, chip, workpiece, and cutting environment has a significant impact on the overall cutting process. Tool life, rate of tool wear, and dimensional accuracy of the machined surface are linked with the heat transfer. In order to develop a precise numerical model for machining, convective heat transfer coefficient is required to simulate the effect of a coolant. Previous literature provides a large operating range of values for the convective heat transfer coefficients, with no clear indication about the selection criterion. In this study, a coupling procedure based on finite element (FE) analysis and computational fluid dynamics (CFD) has been suggested to obtain the optimum value of the convective heat transfer coefficient. In this novel methodology, first the cutting temperature was attained from the FE-based simulation using a logical arbitrary value of convective heat transfer coefficient. The FE-based temperature result was taken as a heat source point on the solid domain of the cutting insert and computational fluid dynamics modeling was executed to examine the convective heat transfer coefficient under similar condition of air interaction. The methodology provided encouraging results by reducing error from 22 to 15% between the values of experimental and simulated cutting temperatures. The methodology revealed encouraging potential to investigate convective heat transfer coefficients under different cutting environments. The incorporation of CFD modeling technique in the area of metal cutting will also benefit other peers working in the similar areas of interest.

During the machining operation, elevated temperatures are achieved at the cutting interface due to the presence of high plastic deformation and friction in between the tool and chip contacting area. Efficient heat dissipation from the cutting interface is required to achieve better machining performance. Elevated temperature in the cutting area results in lower tool life as it facilitates different types of wear mechanisms. Metal working fluids (MWFs) are employed to reduce heat and friction in the cutting zone, simultaneously to help in the flushing of waste particles. The MWFs are based on either water or petroleum oil and include several additives which make them non-biodegradable and toxic in nature. The minimum quantity lubrication (MQL) method offers a feasible substitute to the MWF-based conventional flood cooling method. In this study, a vegetable oil-based MQL system was mixed with sub-zero temperature air to design a new minimum quantity cooling lubrication (MQCL) system. The study investigates the machinability of Ti6Al4V using an MQCL system under various oil flow rates and compared its machining performance with both dry cutting and conventional flood cooling. For further evaluation, the study investigated surface roughness, flank wear, and associated wear mechanisms. It was found that in the MQCL system (60–70 ml/h), oil supply rates provided reliable machining performance at higher feed levels.

Titanium and nickel alloys are the most commonly used in the demanding industries like aerospace, energy, petrochemical, and biomedical. These highly engineered alloys offer unique combination of heat resistance, corrosion resistance, toughness, high operating temperature, and strength-to-weight ratio. These alloys are termed as "Difficult to cut materials" because of their low machinability rating. They are difficult to machine because of properties like low thermal conductivity, high strength at elevated temperatures, and high chemical reactivity. Machining of titanium- and nickel-based alloys causes problems of surface integrity and selection of cutting tool materials that is always a challenge for manufacturers. In this work, machinability studies for titanium and nickel alloys are reviewed with reference to cutting tool materials, associated wear mechanisms, failure modes, and novel tooling techniques. It also discusses major surface integrity defects like carbide cracking, white layer formation, work hardening layer formation, residual stresses, and microstructural alterations. Major aim of this work is to evaluate the challenges involved in improving machinability of the titanium- and nickel-based alloys, and determine the future research direction for productivity improvements in machining these alloys.

The products and the business models developed for conventional open-loop product systems are unable to cope with the requirements for resource efficiency. This paper redefines the conventional paradigm of closed-loop product systems and outlines the novel concept of multiple lifecycle products. The newly developed conceptual framework considers the conservation of energy, material and value added with waste prevention and environment protection as integrated components of the product design and development strategy. It also presents innovative ideas regarding designing products with multiple life cycles, business model for closed-loop supply chain, empowering customers, and multi-stakeholder approach required for the transition towards resource efficient production and consumption.

For sustainability of our future societies we need sustainable manufacturing strategies with resource and environment conservation as their integral part. In this perspective closed-loop supply chains are considered as the most feasible solution. However, their implementation within the paradigm of prevailing open-loop product systems seems extremely complicated and practically infeasible. This paper argues for a radical shift in thinking on the closed-loop systems and presents the novel concept of Resource Conservative Manufacturing (ResCoM). The ResCoM concept considers the conservation of energy, material and value added with waste prevention and environment protection as integrated components of the product design and development strategy. It also presents the innovative idea of products with multiple lifecycles where several lifecycles of predefined duration are determined already at the product design stage thus demanding for new design strategies and methodologies. To succeed with this concept ResCoM advocates for new approach to supply chain design and business models as well, where the customers are integral part of manufacturing enterprises and the product design is effectively connected with the supply chain design. This work concludes that the products, supply chains and the business models developed for open-loop product systems are unable to cope with the dynamics of closed-loop systems. The uncertainties associated with product returns are inherent to the conventional concept of lifecycle and closed-loop systems. The ResCoM concept has much better capability in dealing with these uncertainties while developing sustainable closed-loop systems. The presented work outlines and discusses the conceptual framework of ResCoM. A comprehensive work on the strategic and tactical issues in the implementation of the ResCoM concept will follow.

The paper present theoretical and experimental studies of the energy dissipation performance of a composite structure composed in a multilayer nano-composite damping coating applied on a tungsten carbide shim and placed beneath the cutting insert. The coated shim placed closed to the cutting zone is subjected to high compressive and shear stresses as well as high temperature. Therefore, apart from high damping capacity it requires high stiffness and high thermal resistance. The coated shim dissipates the high frequency oscillations produced at the tool-chip and tool-workpiece interfaces during the chip forming process. The use of coated shims demonstrates that the tool life is considerably extended, while the machined surface integrity is improved. The Reuss model of the composite structure composed of a phase with a stiff, low loss factor and a phase with high loss factor is used to calculate the optimal coating thickness that gives high loss factor combined with high stiffness. The synthesis process of the coating material using HiPIMS process is discussed. The physical characteristics of the coating and the machining performance are presented in the experimental section.

This paper presents the development implementation and testing of an active controlled palletised workholding system for milling operations. The traditional approach to controlling vibration in a machining system is to develop control systems for cutting tools or machine spindles as in the case of milling machines. This work is a deviation from the traditional approach and targets a workholding system for the control of unwanted vibration. Palletised workholding systems, due to their compact design, offer an opportunity to design active control systems that are economical and easier to implement in the case of milling machines. The active control system developed here is based on an adaptive filtering algorithm, the filtered X-LMS, and employs piezo-actuators for dynamic control force. The system has been tested experimentally to demonstrate the reduction in dynamic force due to vibration. Extensive testing has been carried out to validate the performance of the system in terms of parameters of practical importance such as improvement in surface finish and increase in tool life.

Passive means of vibration attenuation have been employed successfully and efficiently in machining systems such as turning and milling. Traditional approach to controlling vibration in a milling system is to develop control mechanisms for cutting tools or machine spindles. However, due to the nature of milling operations where the cutting tools rotate at high speed, the passive vibration control methods find very limited application with the traditional approach. In order to utilise the potential of the passive vibration control methodology in milling applications, the milling operation should be viewed as a system comprising an elastic structure and operation parameters. Dynamics of this closed-loop system should improve with improvement in dynamics of any of the system components, especially within the elastic structure that comprises the cutting tool, the machine tool, the workholding system and the workpiece. Although the level of improvement will vary depending on which component of the elastic chain is targeted for this purpose. This paper presents the development and testing of tuned viscoelastic dampers (TVDs) for vibration control through their application on a workpiece in milling operations. This work targets workpiece held on a palletised workholding system for the control of unwanted vibration and thus deviates from the traditional approach where cutting tool and/or machine spindles are targeted for vibration control strategies. Palletised workholding systems, due to their compact design, offer an opportunity to design passive damping mechanisms that are easier to implement in the case of a milling system. The TVD developed through this research is based on a commercially available viscoelastic damping polymer. Advantage of such materials is their high damping performance over a wide range of excitation frequencies. The TVD design process has used a unique combination of analytical modelling with experimental FRF data. Modal impact testing showed that the application of the TVD reduced the amplitude of vibration acceleration by 20dB for the target mode. Since the target mode corresponded to torsional vibration, the TVD was effective in two planar coordinates, i.e. X and Y. In addition, the TVD also significantly reduced the amplitude of a vibration mode far from the mode it was designed for. The system has been tested experimentally to demonstrate significant reduction in vibration amplitudes during a milling process. The milling tests with different combinations of cutting parameters show that multi-TVD approach is always valid regardless of the parameters being used. The only requirement for TVDs to function effectively is that the natural frequency of the system, for which the TVDs are designed, is excited during the milling process.

Role of structural damping in the machining systems is well established andit is known that higher damping in machine tool structures extends the limits ofunconditional process stability regime in the stability lobes diagrams. Despite itssignificant contribution in process improvement the research on damping-basedimprovement in machining performance has been very limited in comparison toadaptive control of dynamic instability through optimum process parameters based onstability lobes’ characteristics of the machine tools. Conventional solutions forimproving damping in machining systems usually target one component at a time, e.g.cutting tools in case of boring bars, machine spindles in case of milling etc. Thisapproach has its limitations as the damping in single components can’t be increased tolevels for a significant contribution at the system level and very often withoutworsening their rigidity. An alternate to this conventional approach is to consider allcomponents of the elastic chain of the machining system- the machine, the cutting toolsand the workholding- for addition of damping, simultaneously. In this way a muchhigher amount of damping can be added into the system without deteriorating structuralrigidity of a single component. This research investigates the potential of high dampingin a milling system added through a workholding system, in this case. A High DampingInterface (HDI), based on a composite of metal-viscoelastic polymer is developed andintegrated in a palletized workholding system and analyzed experimentally. Theexperimental modal analysis and lab-machining tests show more than 50% reduction invibration amplitudes of natural frequency modes of the workpiece held on theworkholding system. The system is further tested in industrial machining environmentshowing up to 17x increase in metal removal rates and 100% improvement in surfacefinish in end milling operations. Ultimate objective of this research is to develop amachining system with its critical joint-interfaces replaced by HDIs with knowncharacteristics. The HDIs should be designed and distributed throughout the system in amanner that they play a dominant role in defining the dynamic behavior of themachining system.

It is estimated that the adaptation of the Circular Economy approach can yield material cost savings of hundreds of billions of dollars per year for the EU and can result in huge environmental benefits. To tap this potential, the manufacturing industry needs to take a circular approach, where the products are designed intentionally to be used for multiple lifecycles. However, there is a lack of methodologies to date that can support such an approach. To fill this gap, this research has proposed a novel methodological approach that can support designing products for multiple lifecycles to keep the products as well as the components and the materials at their highest utility and value at all times. This research has identified that there is a strong synergy among the concepts of product design strategies, product obsolescence and product end-of-life options. Taking this synergy as the foundation and adopting modular architectures in the product design and development process, lifecycle planning can be performed for products that will sustain multiple lifecycles. This research is performed in two steps: first, the research review process is used to explore the knowledge base in the field of product design methodologies and based on the insights from the literature a novel methodological approach is proposed; second, a case example is used to demonstrate the applicability and effectiveness of the proposed methodological approach.