Sustainable manufacturing,life cycle thinking and the circular economy

Achieving sustainable patterns of consumption and production is perhaps the biggest challenge facing our society today. The de-mand for more safe environmentally benign products is rising and many companies are looking for new ways to progressively improve the sus-tainability of their products. Moreover, there are numerous opportunities and countless innovations, technological as well as non-technologi-cal,that need to be exploited to improve the sustainability of products. Manufacturing industry is an important sector of any economy and hasthe potential to become a driving force for enabling sustainable patterns of production and consumption through introducing efficient productionpractices and developing products and services that help reduce environmental impacts. The benefits of adopting an integrated policy towardsproduct development based on life cycle thinking and eco-design to stimulate improvement of the environmental performance of each part ofproduct life cycle phases and achieve sustainable patterns of production and consumption are emphasized. The challenges in implementingsustainable manufacturing and the circular economy approaches are listed. A number of solutions are suggested to face up these challenges,for instance, increased awareness of enterprises particularly SME's of product life cycle issues and the opportunities that are available for costsavings and profit making from eco-innovation in product development for both the domestic and export markets and providing practical helpand advice directly to enterprises on integrated product development to promote enterprise led Eco-innovation. Aiming at contributing to sus-tainable manufacturing in China, Sino-UK Low Carbon Manufacturing Consortium, a multi-disciplinary research and educational partnershipbetween academia, industry and government agencies in the UK and China with interest in sustainable manufacturing issues, has been formedrecently.The vision, aims and benefits of membership of the consortium are also discussed.

Multiscale Characterization of Automotive Surface Coating Formation for Sustainable Manufacturing

Automotive surface coating manufacturing is one of the most sophisticated and expensive steps in automotive assembly. This step involves generating multiple thin layers of polymeric coatings on the vehicle surface through paint spray and curing in a multistage, dynamically changing environment. Traditionally, the quality control is solely post-process inspection based, and process operational adjustment is only experience based, thus the manufacturing may not be （highly） sustainable. In this article, a multiscale system modeling and analysis methodology is introduced for achieving a sustainable application of polymeric materials through paint spray and film curing in automotive surface coating manufacturing. By this methodology, the correlations among paint material, application processes and coating performance can be identified. The model-based analysis allows a comprehensive and deep study of the dynamic behaviors of the material, process, and product in a wide spectrum of length and time. Case studies illustrate the efficacy of the methodology for sustainable manufacturing.

APPROACHES FOR SUSTAINABLE MANUFACTURING

Sustainable development is a holistic approach harmonizing ecological, economical and socio-political needs with respect to the superior objective of enhancing human living standards. Thereby the availability of natural resources and the conservation of the ecosystems have to be considered that future generations have the possibility to meet their own needs. A long-term economical development demands the transition from a souree-sink economy to a cycle economy as a result of limited resources, limited environmental capacities to absorb waste and emissions as well as increasing needs of a growing population. A reference model for snstainability in manufacturing is presented and used to illustrate sustainable approaches with respect to management, technology, process and product. Adaptation of products and components is a vital element for supporting efficient reuse of products and components. Consequently adaptation contributes to the ambitions goals of snstainability. Technological enablers for adaptation as modularity, information and communication technology are exemplarily introduced. Moreover, approaches for disseminating knowledge in sustainability are given.

Energy Consumption Analysis and Characterization of Aerospace Manufacturing Facilities in the United States–A Step towards Sustainable Development

In this study,information on energy usage in the United States(U.S.)aerospace manufacturing sector has been analyzed and then represented as energy intensities(kWh/m2)to establish benchmark data and to compare facilities of varying sizes.First,public sources were identified and the data from these previously published sources were aggregated to determine the energy usage of aerospace manufacturing facilities within the U.S.From this dataset,a sample of 28 buildings were selected and the energy intensity for each building was estimated from the data.Next,as a part of this study the energy data for three additional aerospace manufacturing facilities in the U.S.were collected firsthand.That data was analyzed and the energy intensity(kWh/m2)for each facility was calculated and then compared with the energy intensities of the 28 buildings from the sample.Three different indicators of energy consumption in aerospace manufacturing facilities were used as comparators to assist facility managers with determining potential energy savings and help in the decision-making process.On average,aerospace manufacturing facilities in the United States spent 4 cents for each dollar of sale on energy.The energy intensity(kWh/m2)and the power intensity(W/m2)for each facility were calculated based on the actual facility energy bills.The power intensity for these facilities ranges from 34 to 134 W/m2.The energy intensity ranged from 232 to 949 kWh/m2.We found that the power intensity could be used to estimate energy consumption when the annual operating hours of the facility are considered.and to estimate the energy-related carbon dioxide emissions.

Nano-enhanced biolubricant in sustainable manufacturing:From processability to mechanisms

To eliminate the negative effect of traditional metal-working fluids and achieve sustainable manufacturing,the usage of nano-enhanced biolubricant(NEBL)is widely researched in minimum quantify lubrication(MQL)machining.It's improved tool wear and surface integrity have been preliminarily verified by experimental studies.The previous review papers also concluded the major influencing factors of processability including nano-enhancer and lubricant types,NEBL concentration,micro droplet size,and so on.Nevertheless,the complex action of NEBL,from preparation,atomization,infiltration to heat transfer and anti-friction,is indistinct which limits preparation of process specifications and popularity in factories.Especially in the complex machining process,in-depth understanding is difficult and meaningful.To fll this gap,this paper concentrates on the comprehensive quantitative assessment of processability based on tribological,thermal,and machined surface quality aspects for NEBL application in turning,milling,and grinding.Then it attempts to answer mechanisms systematically considering multi-factor influence of molecular structure,physicochemical properties,concentration,and dispersion.Firstly,this paper reveals advanced lubrication and heat transfer mechanisms of NEBL by quantitative comparison with biolubricant-based MQL machining.Secondly,the distinctive filmformation,atomization,and infiltration mechanisms of NEBL,as distinguished from metal-working fluid,are clarified combining with its unique molecular structure and physical properties.Furtherly,the process optimization strategy is concluded based on the synergistic relationship analysis among process variables,physicochemical properties,machining mechanisms,and performance of NEBL.Finally,the future development directions are put forward aiming at current performance limitations of NEBL,which requires improvement on preparation and jet methods respects.This paper will help scientists deeply understand effective mechanism,formulate process specifications,and find future development trend of this technology.

Fuzzy analytic network process(FANP)approach in formulating infrastructural decisions of sustainable manufacturing strategy

This paper explores a fuzzy analytic network process(FANP)approach in identifying the content of manufacturing strategy infrastructural decisions that integrates sustainability and classical manufacturing strategy framework with firm size component.The findings are as follows:(1)firms must ensure highquality product requirements with a make-to-order production system;(2)large firms must prioritize decentralization of functional areas but they must also provide higher systems integration of all production-related information to mobilize better communication channels;(3)large firms must employ highly skilled human resources in order to provide strong support on functional areas;and(4)small and medium enterprises must focus on product introduction to the market as a strategy priority area.The main contribution of this paper is the decision-making framework under uncertainty that holistically identifies the decisions that comprise a sustainable manufacturing strategy which may serve as guidelines in improving existing sustainable manufacturing practices or in creating new ones.

Reflection and Study on the Transfer of International Manufacturing Industries and Chinese Sustainable Development

Ever since the 1960s, especially 1980s, under the background of quickening pace of economic globalization and the regional division of labor around the world, the transfer of manufacturing industries among countries and areas gets great momentum and impetus. During 20-plus years in which China has adopted the policy of opening-up and reforming, our country has played an active role in taking part in the transfer of manufacturing industries. It advances the structural change of national manufacturing industries, accelerates national industrialism and promotes the comprehensive development of regional economics. In this paper, the author makes some initial study on the regularity of transfer of International manufacturing industries, discusses the profound impact of such shift on our national resources, environment, economics and society, and also proposes corresponding suggestions on how to implement the strategy of sustainable development in the process of the shift.

Overview of Jute Fibre as Thermoplastic Matrix Polymer Reinforcement

Recent decades have seen a substantial increase in interest in research on natural fibres that is aligned with sustainable development goals(SDGs).Due to their renewable resources and biodegradability,natural fiberreinforced composites have been investigated as a sustainable alternative to synthetic materials to reduce the usage of hazardous waste and environmental pollution.Among the natural fibre,jute fibre obtained from a bast plant has an increasing trend in the application,especially as a reinforcement material.Numerous research works have been performed on jute fibre with regard to reinforced thermoset and thermoplastic composites.Nevertheless,current demands on sustainable materials have required new developments in thermoplastic composites.In this paper,the author reviews jute plants as reinforcement materials for thermoplastic matrix polymers.This review provides an overview of the sustainability of jute plants as reinforcement material for thermoplastic matrix polymers.The overview on jute based thermoplastic composites focused on the thermal behavior and mechanical properties.Apart from physical,chemical,and mechanical properties,the study also covers the current and perspectives for future research challenges faced by the researchers on jute fibre reinforced thermoplastic composites.

Taguchi Full Factorial Design of Experiments Optimisation of Cutting Parameters for Energy Efficiency and Surface Roughness during the Dry Turning of EN19 Material

During metal machining, the satisfactoriness of cost-quality-time matrix convergence effectively depends on the supreme selection of cutting parameters. This study investigated the energy use minimisation and quality surface generation through optimised cutting parameters application, as sustainability enhancement during dry turning of EN19 material. Cutting parameter optimisation is a serious challenge confronting the machining industry as they strive to achieve low energy use and better component quality generation from their operations. The utility material, EN19, is a medium-carbon low alloy steel which typically gets applied in the manufacturing of multiple profiled cylindrical machine tool, rail locomotives and motor vehicle component parts, inter alia. Taguchi Full Factorial experimental plan was used to organise the empirical experiments. ANOVA and the main effects plot signal-to-noise ratio optimisation analysis were utilised in the study to establish the influence of process parameters on the response parameters—surface roughness and energy use. The aim was to investigate and determine the correlation of the machining strategy parameters with the outcome of low energy use and quality surface texture of the components as the cutting parameters were varied, and optimised for minimum surface roughness and energy use. Results of the extensive experimental study, produced optimum cutting speed, rake angle variation and feed rate which respectively influence the response parameters positively for energy use minimisation and improved surface quality. Validation experiments confirmed model findings.

Machinability Investigation and Optimization of Process Parameters in Cryogenic Assisted Sustainable Turning of AISI‑L6 Tool Steel

The application of cutting fluid is significantly increased in the machining sector to improve productivity.However,the inherent characteristics of cutting fluids on ecology,environment,and society shift the interest of researchers to work on environmentally friendly cooling conditions such as cryogenic cooling.Here,the effect of cutting speed and feed rate on the machining performance of the AISI‑L6 tool steel is investigated under cryogenic cooling conditions.Then,the L9 Taguchi based grey relational analysis(GRA)is conducted to investigate the essential machining indices such as cutting energy,surface roughness,tool wear,and material removal rate(MRR).The results indicate that the cutting speed of 160 m/min and feed rate of 0.16 mm/r are the optimum parameters that significantly improves the machining performance of AISI‑L6 tool steel.

Direct 4D printing of functionally graded hydrogel networks for biodegradable,untethered,and multimorphic soft robots

Recent advances in functionally graded additive manufacturing(FGAM)technology have enabled the seamless hybridization of multiple functionalities in a single structure.Soft robotics can become one of the largest beneficiaries of these advances,through the design of a facile four-dimensional(4D)FGAM process that can grant an intelligent stimuli-responsive mechanical functionality to the printed objects.Herein,we present a simple binder jetting approach for the 4D printing of functionally graded porous multi-materials(FGMM)by introducing rationally designed graded multiphase feeder beds.Compositionally graded cross-linking agents gradually form stable porous network structures within aqueous polymer particles,enabling programmable hygroscopic deformation without complex mechanical designs.Furthermore,a systematic bed design incorporating additional functional agents enables a multi-stimuli-responsive and untethered soft robot with stark stimulus selectivity.The biodegradability of the proposed 4D-printed soft robot further ensures the sustainability of our approach,with immediate degradation rates of 96.6%within 72 h.The proposed 4D printing concept for FGMMs can create new opportunities for intelligent and sustainable additive manufacturing in soft robotics.

Digital twin-based sustainable intelligent manufacturing: a review

As the next-generation manufacturing system,intelligent manufacturing enables better quality,higher productivity,lower cost,and increased manufacturing flexibility.The concept of sustainability is receiving increasing attention,and sustainable manufacturing is evolving.The digital twin is an emerging technology used in intelligent manufacturing that can grasp the state of intelligent manufacturing systems in real-time and predict system failures.Sustainable intelligent manufacturing based on a digital twin has advantages in practical applications.To fully understand the intelligent manufacturing that provides the digital twin,this study reviews both technologies and discusses the sustainability of intelligent manufacturing.Firstly,the relevant content of intelligent manufacturing,including intelligent manufacturing equipment,systems,and services,is analyzed.In addition,thesustainability of intelligent manufacturing is discussed.Subsequently,a digital twin and its application are introduced along with the development of intelligent manufacturing based on the digital twin technology.Finally,combined with the current status,the future development direction of intelligent manufacturing is presented.

Model for atomization droplet size and energy distribution ratio at the distal end of an electrostatic nozzle

Electrostatic atomization minimum quantity lubrication(EMQL)employs the synergistic effect of multiple physical fields to atomize minute quantities of lubricant.This innovative methodology is distinguished by its capacity to ameliorate the atomization attributes of the lubricant substantially,which subsequently augments the migratory and infiltration proficiency of the droplets within the complex and demanding milieu of the cutting zone.Compared with the traditional minimum quantity lubrication(MQL),the EMQL process is further complicated by the multiphysical field influences.The presence of multiple physical fields not only increases the complexity of the forces acting on the liquid film but also induces changes in the physical properties of the lubricant itself,thus making the analysis of atomization characteristics and energy distribution particularly challenging.To address this objective reality,the current study has conducted a meticulous measurement of the volume average diameter,size distribution span,and the percentage concentration of inhalable particles of the charged droplets at various intercept positions of the EMQL nozzle.A predictive model for the volume-averaged droplet size at the far end of the EMQL nozzle was established with the observed statistical value F of 825.2125,which indicates a high regression accuracy of the model.Furthermore,based on the changes in the potential energy of surface tension,the loss of kinetic energy of gas,and the electric field work at different nozzle orifice positions in the EMQL system,an energy distribution ratio model for EMQL was developed.The energy distribution ratio coefficients under operating conditions of 0.1 MPa air pressure and 0 to 40 kV voltage on the 20 mm cross-section ranged from 3.094‰to 3.458‰,while all other operating conditions and cross-sections had energy distribution ratios below 2.06‰.This research is expected to act as a catalyst for the progression of EMQL by stimulating innovation in the sphere of precision manufacturing,providing theoretical foundations,and offering practical guidance for the further development of EMQL technology.

A holistic decision support tool for remanufacturing： end-of-life （EOL） strategy planning

Remanufacturing is a key enabler for sustainable production due to its effectiveness in closing the loop on material flows, extending product life cycle and reducing production waste and emission. In this paper, a holistic decision support tool to facilitate the product end-of-life （EOL） strategy planning, specifically using remanufactur- ing as a key strategy is presented. The proposed model incorporates checklist methods to evaluate the viability of conducting remanufactufing for a product and its compo- nents. An optimization model for determining the Pareto set of optimal EOL strategies that correspond to maximum economic profit and minimum environmental impact is presented. Since determination of this Pareto set via enu- meration of all EOL strategies is prohibitively time-con- suming, even for a product with a small number of components, genetic algorithm （GA）, specifically NSGA-II has been utilized to achieve rapid calculation of the set of optimum EOL strategies. This NSGA-II method permits extensive sensitivity analysis to understand thoroughly the impact of situational variables, such as reverse logistic cost, technology and replacement part availability, etc., on the EOL decision making, i.e., Pareto front, and thus leading to improved strategy planning and better product design. The case study involving EOL treatment of two types of desktop phones is described to illustrate the utility of the proposed methodology.

Indirect approach for predicting cutting force coefficients and power consumption in milling process

Accurate energy consumption modeling is an essential prerequisite for sustainable manufacturing.Recently,cutting-power-based models have garnered significant attention,as they can provide more comprehensive information regarding the machining energy consumption pattern.However,their implementation is challenging because new cutting force coefficients are typically required to address new workpiece materials.Traditionally,cutting force coefficients are calculated at a high operation cost as a dynamometer must be used.Hence,a novel indirect approach for estimating the cutting force coefficients of a new tool-workpiece pair is proposed herein.The key idea is to convert the cutting force coefficient calculation problem into an optimization problem,whose solution can be effectively obtained using the proposed simulated annealing algorithm.Subsequently,the cutting force coefficients for a new tool-workpiece pair can be estimated from a pre-calibrated energy consumption model.Machining experiments performed using different machine tools clearly demonstrate the effectiveness of the developed approach.Comparative studies with measured cutting force coefficients reveal the decent accuracy of the approach in terms of both energy consumption prediction and instantaneous cutting force prediction.The proposed approach can provide an accurate and reliable estimation of cutting force coefficients for new workpiece materials while avoiding operational or economic problems encountered in traditional force monitoring methods involving dynamometers.Therefore,this study may significantly advance the development of sustainable manufacturing.

Preface:special issue on green chemistry

The growing up of green chemistry has now a history of more than twenty years,with a blooming development demonstrated by its great contribution to sustainable development and economical benefit to our society.It is well accepted that green chemistry is the development and utilization of a