This is the sixth special issue on Design and Manufacturing for Environmental Sustainability. As the first special issue on this topic was issued in 2009, the topic has thirteen years of history in this journal. Environmental sustainability was recognized as important for manufacturing even at that time. This is why the special issue was started in this journal. The seriousness of this topic has been increasing not only in Europe but also in Japan and other countries. One critical trend as of late has been the way that the attitude of companies regarding this issue, including their positions on carbon neutrality, circular economy, and biodiversity, has come to determine the value of the company in the eyes of, for example, environment, society, and governance (ESG) finance. Nowadays, we cannot say sustainability or business; we should pursue businesses that contribute to sustainability.

This sixth special issue includes eighteen well-written papers, with one more paper to follow. This series of special issues has focused on topics related to ecodesign, recycling, remanufacturing, low-energy and low-emission manufacturing, and circular economy. The papers in this special issue are also deeply related to these topics. As a result of the thirteen-year history of the special issue, we have been able to learn some viewpoints specific to the series in this journal. This has led this special issue to consist of four subcategories, although they are not explicitly represented in the table of contents. The first subcategory consists of seven papers, from the first paper by K. Halada et al. to the seventh paper by A. Yoshimura et al. These papers are related to design, including evaluation, business, remanufacturing, and materials. Among others, the important viewpoint common to these papers is the “flow” of product lifecycles and materials. The second category starts with the eighth paper by C. Ye et al. and ends with the eleventh paper by Y. Yamashita et al. These papers deal with manufacturing issues in the context of the environmental sustainability. For example, the eighth paper deals with the crushing of a photovoltaic panel, and the nineth paper by T. Cheng et al. deals with detecting lithium-ion battery fires, which are a serious problem for recycling plants. The application of additive manufacturing to remanufacturing discussed in the tenth paper by N. Sato et al. is also an important topic in the field of sustainable manufacturing.

The third subcategory consists of three papers, from the twelfth paper by J.-C. Tu et al. to the fourteenth by A. Y. T. Panuju et al. These are related to consumer behavior. The fourth subcategory, from the fifteenth paper by M. Kojima to the last paper by S. Tajima, deals with issues related to developing countries and locality. These two topics of consumer behavior and developing countries are indispensable to the discussion of environmental sustainability, yet they are rarely discussed in engineering journals. The editor believes that no other journal deals with these four subcategories in a special issue.

Most of the papers, revised and extended in response to the editor’s invitations, were originally presented at EcoDesign 2021: the 12th International Symposium on Environmentally Conscious Design and Inverse Manufacturing, which was held online.

The editor sincerely thanks the authors and reviewers for their devoted work in making this special issue possible. We hope that these articles will encourage further research into design and manufacturing for environmental sustainability.

This study proposes new indicator, Resource Efficiency Account (REA). REA represents the effects of eco-design efforts in achieving a circular system. The key concept of REA is “acircularity.” “Acircularity” is the distance to the ideal circular system to be achieved. REA is given as material efficiency (service per total value of constituent materials) divided by acircularity. Acircularity is the sum of the value of resources that the techno-sphere demands from the eco-sphere, and the value of resources that are dissipated within the techno-sphere. If an utterly circular state is reached, the acircularity value is zero. Additionally, this study proposes a new method to quantify the decline of the quality of scrap provided to the market as a decline in the value of the material to calculate the dissipation. The calculation focuses on the control level of impurities in scrap. The validity of these indicators is discussed using an automobile case. Differences in the current circulation level, eco-design for recycling, and refurbishment efforts can be quantitatively evaluated using REA and acircularity.

Life cycle assessment (LCA) is the internationally adopted tool to assess environmental footprint. However, as highlighted by Billstein et al. [3] and Arushanyan [4] carrying out an LCA for ICT equipment is a challenging task due, to the amount of data that should be collected to achieve accurate results. This paper describes how documents such as full materials declarations can be used to solve this issue. Furthermore, the circular economy concept is introduced by analyzing alternative business models and the ITU-T L.1023 on circular economy scoring. Even if LCA was considered as a criterion in the L.1023 the link is not always straightforward between these two methods. Hence, this paper investigates how LCA results can be linked to the L.1023 criteria and proposes new criteria, for instance on recycled metals content and modularity.

The tire industry has employed effective CO₂ reduction measures in the form of retread tires, which replace only those components that are exposed to the road’s surface. Due to safety concerns, lack of manufacturing technology, high cost, and other issues, retread tires in passenger cars are currently unavailable in Japan. This study aims to analyze the production cost and environmental impacts of retread tires in passenger cars in Japan. This study considered investments in and economies of scale of retread tires, which have lower profit margins than new tires after safety and manufacturing technology issues have been resolved; this is done when the carbon tax is equal to that in the EU. This reserach further examined the proportion of retread tires and new tires that are produced. The primary goal of this study is to determine which ratio of retread vs. new tire production is feasible for an optimal business portfolio. If a carbon tax equivalent to that in the EU was introduced in Japan and each company offered retread tires for passenger cars, this setup would not be profitable and overall costs would need to be lowered. To achieve this cost-effectiveness, it is necessary to extend the life of the equipment and to lower the initial investment. Furthermore, by calculating the costs involved using realistic production expenses, a more realistic cost for the introduction of retread tires for passenger cars can be achieved.

Manufacturing companies are expected to make decisions that achieve not only the goals of the company but also the goals of society. Each company’s decisions affect the material flow and demand of other companies. Therefore, each company can play a role in strategic management by predicting in advance the impact of its own and other companies’ decisions on the achievement of social goals. To support such strategic management, this study proposes a life cycle simulation method that can estimate the impact of strategic decisions by considering social goals. The target is a connected life cycle systems (CoLSys) consisting of multiple product life cycle systems and interactions, in which the interactions are operated according to the life cycle system of each product. A decision-making model is included in the proposed method, and changes in the interaction settings are made in each product life cycle system to achieve predefined social and individual goals. To show the effectiveness of the proposed method, a case study was conducted for a CoLSys consisting of six products: electric vehicles, gasoline vehicles, hybrid vehicles, home batteries, battery charging stands, and photovoltaic power generation systems. In the case study, the social goal was decarbonization by 2050 and the individual goal was increasing profits. The simulation results confirmed that the decision-making model would result in greater reductions in CO₂ emissions, including a faster transition from gasoline vehicles to electric vehicles. Moreover, we confirmed that the decision-making model contributed to balancing the achievement of social goals with the benefits of individual systems while adjusting the intensity of the interactions. However, it was found that decarbonization cannot be achieved by 2050 if only the assumed products and interactions are applied in the case study.

Environmental issues and increasing global demand have led to calls for sustainable production and consumption. Products deemed insufficiently environmentally friendly are beginning to be removed from the market, and manufacturers must achieve social responsibility and economic benefits. However, in a conventional linear supply chain, an increase in sales volume directly leads to an increase in waste and resource consumption, resulting in a trade-off between the environment and the economy. Closed-loop supply chains resolve trade-offs, achieve corporate social responsibility, and enhance competitiveness. Closed-loop supply chains must recover used products with a high degree of uncertainty. Uncertainty in the quantity, quality, and timing of used products can cause serious problems such as the bullwhip effect in the dynamic behavior of the supply chain. This study aims to analyze the dynamic impact of used product uncertainty on a closed-loop supply chain and propose ways to deal with it. Products deteriorate with their use and eventually become worthless for recovery and remanufacturing. This study confirms that, even when there is no demand variability and lead time, the uncertainty of used products, especially qualitative uncertainty, causes large variability in the closed-loop supply chain. The results of the numerical example using the model proposed in this study show that the policy of limiting the quantity of remanufacturing can mitigate the variability. Furthermore, the appropriate limits vary depending on the characteristics of the product, such as its lifetime. This suggests the need to control the amount of remanufacturing for the sustainability of the closed-loop supply chain rather than remanufacturing as much as possible, to reduce environmental impact.

The demand for resource circulation of heat exchangers in air conditioners is expected to grow rapidly; however, the market stocking time is relatively long. Therefore, this scenario was used as a case study for sustainable products design. A material flow analysis was conducted to estimate the balance between global relative resource consumption for shipment, waste, and installed stock from publicly available information up to 2050. Based on the projected demand through 2050, the shipment volume for each year was calculated on a cooling capacity basis. From this analysis, the waste volume was calculated. Using the shipment volume on the basis of yearly cooling capacity, the shipment volume on a resource basis was calculated considering the heat transfer coefficient. The balance between the waste volume and the installed stock was estimated. The resource circulation was simulated by defining variables such as the ratio of units that can be converted from waste to shipment and the ratio of heat exchangers using circulated resources in the total number of shipments. The results indicate that the shipment, waste, and installed stock of resources projected for 2050 were greater than those at the 2021 levels by factors of 2.2, 2.8, and 2.9, respectively. In addition, they were greater than those of the 2021 levels in the scenarios by factors of 1.8, 2.2, and 2.8 accounting for the increase of heat transfer coefficient into account, indicating the importance of improvement of heat transfer. The simulation of circulation showed that a fully closed loop in 2050 would be difficult to achieve owing to the shortage of heat exchangers for waste-to-shipment. Sensitivity analysis also indicated that even under conditions where there is no predicted shortage of circulated resources for 2050, achieving the target in a short period of time may cause a rapid increase in demand for circulating resources. This would subsequently, lead to a shortage of supply compared to demand. Thus, it is important to account for these dynamics relating resource circulation and strategy planning during analysis.

Indium is a rare metal that is an essential raw material for indium tin oxide (ITO) essential for transparent electrodes for displays. However, its supply is unstable as it is a by-product of zinc. In this research, we investigated the domestic substance flow of indium used for liquid crystal applications in Japan. Accordingly, we quantitatively evaluated the amount of indium contained in the process loss and the content of indium in end-of-life products. Through this quantification, we examined the visualization of loss in the entire flow and the usability of end-of-life products as secondary production. Consequently, it was found that the amount of indium used in the production of end-use-products in Japan has increased significantly due to the growth of liquid crystal display TVs, particularly in preparation for the transition to terrestrial digital broadcasting in 2011, and has drastically decreased after 2012. Meanwhile, some manufacturing bases have been relocated from Japan to other countries, and a certain proportion of end-use-products are imported, by which we infer the domestic input amount of end-use-products in recent years is estimated to have remained at approximately 4 t. Based on the result, after having continued to increase to the maximum value of approximately 70 t in 2014, the in-use stock has exhibited a gradually decreasing trend. Moreover, the indium content in end-of-life products has continued to increase, and in 2015, it exceeded the amount of the end-use-products input into society. Furthermore, compared with the process loss at the time of processing from ITO to a display, the gap has been narrowed from 100 times or more, and the indium content in end-of-life products in 2008 to about 15 times in 2017. These results suggest that the recycling potential of end-of-life products has increased with the spread of indium-based products.

Grinding is a unit of operation of a pure mechanical process. An attritor is a grinder able to be used for fine or selective grinding. However, few studies have reported on the optimum design for the attritor. The attritor’s grinding characteristics and grinding effect depend not only on the operating conditions, but also on the geometry of the agitator. Therefore, we investigated the effect of the agitator shape on the grinding efficiency from the viewpoint of experiments, kinetic analysis, and discrete element method (DEM) simulations. We conducted grinding experiments with two different agitators. One was Agitator A, a traditional design with two pairs of 90° staggered mixing arms at the middle and bottom of the mixing shaft. The other was Agitator B, with a lower mixing arm inclined by 10° along the horizontal direction. We found that the grinding rate constant of Agitator B was approximately 40% greater than that of Agitator A. Although the size distribution of the particles was relatively dispersed after grinding with Agitator B, the distribution was concentrated mainly within two ranges (<0.5 mm and 2–4 mm) with Agitator A. These results and an elemental analysis of each size fraction suggested that the dominating grinding mode in Agitator A was surface grinding, whereas in Agitator B, it was bulk grinding. In terms of the influence of the agitator shape, the DEM simulation results showed that the kinetic energy of the grinding media in Agitator B was 0.0046 J/s, i.e., larger than the 0.0035 J/s obtained for Agitator A. A collision energy analysis showed that the dominating collision was between the media and wall in the tangential direction for both models. The collision energy of the media in Agitator B was larger than that of that in Agitator A. The results from the DEM simulation can help us evaluate the experimental results and infer the reasons why the grinding rate constant in Agitator B is larger than that in Agitator A.

With the development of artificial intelligence, image recognition has seen wider adoption. Here, a novel paradigm image recognition system is proposed for detection of fires owing to the compression of lithium-ion batteries at recycling facilities. The proposed system uses deep learning method. The SparkEye system is proposed, focusing on the early detection of fires as sparks, and is combined with a sprinkler system, to minimize fire-related losses at affected facilities. Approximately 30,000 images (resolution, 800 × 600 pixels) were used for training the system to >90% detection accuracy. To fulfil the demand for dust control at recycling facilities, air and frame camera protection methods were incorporated into the system. Based on the test data and realistic workplace feedback, the best placements of the SparkEye fire detectors were crushers, conveyors, and garbage pits.

Remanufacturing is an industrial process of turning used products into products with the same quality as new ones. Of the processes comprising remanufacturing, the repair process poses the greatest challenge. Additive manufacturing (AM) is expected to bring innovation to the repair process of remanufacturing. Although, so far, the directed energy deposition (DED) type AM has been most frequently applied to remanufacturing and only a few studies applied powder bed fusion (PBF) type AM to remanufacturing, PBF demonstrates great potential for application in remanufacturing. This study aims to assess the feasibility of the application of PBF to remanufacturing. We conducted an experimental PBF-based repair and attempted to identify its challenges. In the experiment, 1) we used AlSi10Mg powder, 2) we first fabricated a 5 mm square cube sample by using PBF, 3) we next removed 0.4 mm of thickness from the sample with milling, 4) then we restored 0.44 mm of thickness using PBF, and 5) we observed the restored sample. The observation showed that: 1) misalignment in the restoration occurred, 2) keyhole defects and gas pores were found more in the boundary area between the original and restored parts, and 3) the microstructures showed polycrystals in the restored part. These factors impaired the quality and reliability of PBF-based repair and present challenges of enhancing the feasibility of applying PBF-based repair to remanufacturing. This study also examined the whole process of PBF-based remanufacturing, which includes not only the repair process but also the processes of component inspection, process design, pre-repair process, and post-repair process, and discussed the challenges in these processes. The challenges include the development of repair process design methods, supportless fabrication processes, and non-destructive test (NDT) techniques.

Various nondestructive testing (NDT) methods have been proposed to detect defects inside products. The hammering test is an NDT technique widely used for this purpose. In this test method, a worker judges whether a part is defective or not by listening to the sound after hitting the product with a hammer. Conventional research has shown that a classifier using machine learning can discriminate the hammering data with high accuracy. However, to use these machine learning methods, a lot of samples are needed for learning. In actual industrial situations, it is difficult to collect a lot of samples of defective products. Regarding the hammering test, a machine learning method that can correctly discriminate defective products without sample data has not been proposed. This study aims to construct a system that can correctly discriminate the hammering test data even when there are no defective samples. We propose a method using ‘transfer learning.’ We conducted case studies to demonstrate the effectiveness of the proposed method using two variants of a brazed product. First, we verified the effectiveness of normal machine learning in a hammering test. In this study, we succeeded in discriminating brazed products, which were not correctly discriminated by the workers. We then applied the proposed method to brazed products. We succeeded in discriminating a variant of the brazed products by transferring the knowledge learned from another variant of the brazed products.

Over time, consumer awareness of environmental protection has grown. From big data in the Internet of things (IoT), green advertisement has indeed made a significant impact on consumers’ awareness of environmental protection. Therefore, this research studied the impact of the IoT and green advertisements on consumers’ behavior. An investigation was conducted based on focus group interviews, and the assumption was tested using statistical methods. The research results were as follows: 1) advertisement has a significant impact on consumer behavior; 2) consumers are willing to purchase advertised products that convey positive messages, regardless of their age, educational level, or average income level; 3) consumers with higher education levels have better environmental concepts; and 4) green advertisement has a significant impact on consumers’ environmental concepts and behaviors. In summary, the study found that green advertisement can improve consumers’ awareness of environmental protection and that consumers’ behavior can effectively influence the implementation of environmental protection.

In the wake of rapid advances in design and production technologies, differentiating products based on their quality has become a challenge. Against this backdrop, design has become an important factor in determining product value. Design is a creative activity influenced by the experience and sensitivity of designers, who are required to understand the preferences and needs of customers and reflect them in their designs. Accordingly, there is a need to efficiently determine customer preferences. Although it is possible to extract customers’ apparent preferences through interviews and questionnaires, these may be arbitrary. Additionally, to respond to the recent diversification of customer preferences, it is not enough to understand apparent preferences; latent preferences must also be extracted. However, they are vague and cannot be expressed in words by the customers. Unfortunately, a practical method for extracting latent preferences has not yet been developed. In this study, we propose a method for extracting latent customer preferences. We develop a system for recommending products that customers are likely to prefer from among existing products, and develop a system for creating original product designs that customers are expected to prefer. We experimentally verify the usefulness of this method.

Sustainable design in product development has multiple roles in addressing an increased level of sustainability. This includes reducing resource consumption and modifying user behaviors to become more eco-friendly. However, these functions are typically assessed separately, despite a proposed mutual correlation. This paper proposes a framework for defining this correlation. By using the correlated functions in parallel, one can enhance the product development process, and this will strengthen the use of sustainable design as a powerful design tool for future products. A practical approach for implementation is needed, which should show the benefit of the design both from the environmental aspect and a change in the responsibility of users. The primary goal of this manuscript is to propose an approach to fill this gap, using experiments to explore the effect of a washing machine modification project in Indonesia. Resource consumption while doing the laundry is measured as a representation of the environmental impact, while the users’ predisposition for environmental responsibility inclination is analyzed by scaling the responsibility. The results show that the sustainable design strategy is effective in reducing the environmental impact, while simultaneously increasing the environmental responsibility of users. Further study is required to define the correlation between the measured factors to formulate a well-developed theory related to this correlation.

Remanufacturing policies have been gradually introduced in Asian countries, such as China, Japan, Malaysia, Singapore, and Thailand. This paper reviews the process of diffusion of remanufacturing policy in Asia. The mechanism of this diffusion is also discussed. The United States began to promote the idea of remanufacturing around the year 2000 through bilateral free trade agreements with Asian countries and international forums such as G8 and the Asia-Pacific Economic Cooperation (APEC). This paper reviews the various efforts on remanufacturing in Asian countries and discusses policy options for promoting remanufacturing. It is crucial to identify the ways to promote remanufacturing in each country in the region to improve resource efficacy and strengthen the circular economy in Asia.

There is a significant increase in plastic consumption with the growing economies of Asia, causing severe environmental issues as a large proportion of the plastic waste is not appropriately disposed due to the underdeveloped collection systems. The situation in Malaysia is particularly worrying as the total plastic waste increased by nearly 30% in 2018, becoming the second-highest of the entire household solid waste. This problem can be addressed by improving the plastic waste management system and increasing the plastic wastes recycling rate. Therefore, this study aims to investigate the current situation of plastic waste generation. Malaysia’s waste management framework is a unique integration of the formal and informal sectors. The lack of uniformity has been the main challenge for the policy implementation in improving plastic waste management. From the plastic material flow analysis, only 41.4% of the plastic wastes were recycled in 2019. The most recycled plastic types in Malaysia are high-density polyethylene (HDPE), polyethylene terephthalate (PET), low-density polyethylene (LDPE), and polypropylene (PP), as they are easier to collect and have higher density. From the identified plastic recycling process flow, the main challenge is low recyclability. Most recyclables are usually contaminated with food waste or non-recyclable plastic, which hinders the sorting process. Informing the public how to recycle plastic waste properly can increase the effectiveness of recyclables collection as well as the sorting process.

Economic development must occur alongside environmental sustainability. The circular economy (CE) in an industrial context is a critical area that has been widely studied. However, the scope of the CE is broad and involves the development of various fields, ranging from energy and production to digitalization. The areas targeted for CE development also vary according to the stage of economic development. This study focuses on identifying the potential for CE development from the perspective of developing economies by using patent and bibliometric analyses.

This research aims to visualize the social relations of a locally oriented sustainable product based on specialty product development in Nagara, Chiba. Japan’s population has declined since 2008. Sustainable regional revitalization, such as the United Nation’s Sustainable Development Goals, is an urgent issue. Developing specialty products to foster regional brands is flourishing in various places because regional brands will improve their earning power. Although various specialty products are being developed nationwide, there is no indicator of their social sustainability regarding how locally oriented products directly contribute to regional revitalization. Nagara Town is located in the central part of Chiba Prefecture and is the second-smallest town in the prefecture with a population of 6,520. Nagara Town and Chiba University signed a partnership agreement on regional revitalization in 2015 and are working on industry-government-academia collaborative community development with the theme of a continuous care retirement community (CCRC). In 2019, the university, local companies, and the town hall collaborated to develop a specialty product, “Nagara and Guarana (N&G).” Design thinking was used for the development, and the N&G prototype was completed in 2020. After prototype testing, N&G was commercialized in 2021, and 45,000 bottles were manufactured. It was sold at facilities and station shops inside and outside the town, and sold 36,510 bottles, successfully exceeding the original schedule. Unlike normal specialty product development, Nagara Town has become an N&G seller. Related studies have shown that locally oriented products contribute to social sustainability by localizing them according to the social context of the region on a global scale. However, in regional revitalization, building social connections within regions through locally oriented products contributes to social sustainability. However, there is no indicator of how locally oriented sustainable products contribute to this region. The author proposed a Socio-Relation Map (SRMap) to quantitatively measure the social relations of a product by counting the stakeholders involved. SRMap comprises stakeholders involved in product planning, manufacturing, and dissemination. Then, we applied SRMap to N&G to verify its effectiveness and limitations.

Chatter vibration is a major problem in machining. At present, chatter vibration is avoided by changing the cutting conditions based on the stability limit diagram such that chatter vibration does not occur. However, changing the cutting conditions may reduce the productivity. The stability limit is estimated from the relationship between the dynamic characteristics of the machine tool and the cutting conditions. Therefore, we propose a method for avoiding chatter vibration by changing the machine tool rigidity. The dynamic characteristics of a desktop milling machine tool developed in a previous study can be changed by changing the tensile load of the brace bar attached on the frame. We report the transition of the dynamic characteristics and stability limit diagram with changes in the rigidity of the desktop machine tool, and confirm the presence or absence of chatter vibration through machining tests.

Herein, a new milling method via an electrochemical reaction is proposed to realize the high-speed machining of sintered carbide. In this method, cobalt (Co) on the surface of the sintered carbide is eluted via an electrochemical reaction, and the sintered carbide weakened by the elution of Co is scraped off with an insulating cutting edge. Results show that the cutting resistance is significantly reduced by the electrochemical reaction. However, under the conditions of a previous machining experiment, the amount of removal was low, and the machining test was conducted within a range that did not reflect the high-speed machining of sintered carbide. In this study, the conditions required to realize the high-speed machining of sintered carbide using the abovementioned method are examined. To increase the speed of electrolysis, the facing area between the tool and workpiece must be increased, and the current used for electrolysis must be increased as well. It is shown that the electrolytic current can be increased by performing machining with a large depth of cut. Consequently, the machining speed can be increased compared with that for the case without electrolysis, although a few problems remain.

Various operations in the production sites of manufacturing industries are being automated using industrial robots instead of operators. In recent years, an offline teaching method for robot motion has been implemented, where programs are generated in a work environment that is reproduced virtually inside a computer. However, the robot program developed using the offline teaching method can pass through singularities or suddenly change the robot’s posture, making the robot incapable of performing safe operations. To achieve optimal operation, the operator must determine the workpiece placement and create a robot program through trial and error. In this study, we proposed a method that uses manipulability to generate a program that commands the robot to move without passing singularities or changing the robot’s posture. Manipulability is quantitatively evaluated as an indicator of a robot’s ability to move its end effector in arbitrary directions. We proposed another method to determine the optimal workpiece placement for robot operations that can maximize the sum of manipulability during the operation. We implemented the aforementioned methods in an offline teaching system. We applied the developed system to a welding operation and verified its effectiveness by conducting motion simulations. The developed system was able to generate a practical robot program that maintained high manipulability and did not cause sudden changes in the posture or pass singularities. The developed system was able to simultaneously determine the optimal workpiece placement for the task, thereby confirming the usefulness of the proposed method.

In wire electrical discharge machining (WEDM) that can perform 2-D or 2.5-D machining, 3-D complex shape machining is also possible via the addition of a rotary axis on the NC table. Several examples of pin-shaped machining using a rotating shaft like spindle have been previously reported. Alternatively, machining using a rotary axis as an indexing device has also been reported. In these machining processes, the rotary axis is not servo controlled. Conversely, a spiral groove is formed on the outer circumference of the round bar by gripping the round bar workpiece on the rotary axis and performing machining in synchronization with the x- and rotary axes. In this machining, the gap control in electrical discharge machining is performed along the x- and rotary axes. Furthermore, complicated shape machining becomes possible by adding a 2-axis rotary axis of rotation and tilt. When the x-axis is synchronized with the rotation and tilt axes, a spiral groove with a variable groove width is formed. In this case, servo control is synchronized with the three axes, and machining proceeds. In this study, we performed spiral groove shape machining through WEDM with the addition of 1-axis or 2-axis rotary axes, consequently verifying the machining accuracy. Moreover, two types of NC program were used for machining, direct input and CAM output, and the accuracy was compared. The results revealed that the groove width was wider in the direct input program. Therefore, there was a possibility that the wire could bend during machining and tilt along the direction of the apparent widening of the groove width. Thus, it is necessary to consider the deflection of the wire in WEDM with a rotary axis, which is different from the conventional one, to realize precision machining.

To explore the influence of the release agent on the fluidity of the aluminum alloy melt, continuous experiments were carried out. First, through a flat mold filling experiment, the aluminum alloy melt and temperature change of the flat mold were obtained via measurements under the condition in which the mold was coated with a powder mold release agent. Stable and minimal, the excellent thermal insulation performance of heat transfer coefficient. Then, fluidity measurement experiments and computer simulation were conducted to verify the influence of the density change of the powder mold release agent on the fluidity of the aluminum alloy melt during the casting process. It was found that this relationship was affected by the temperature difference between the mold and aluminum alloy melt. The experimental results showed that changes in the powder mold release agent density changed the distribution density of its components through the thickness of the coating, thereby affecting the fluidity and thermal insulation function.

Additively manufactured parts have recently been applied to products in aerospace, automobile, and tool industries in terms of design flexibility and material consumption with mechanical strength. Because the surfaces of additively manufactured parts are coarse, milling is conducted as a post-process to achieve fine surfaces within the specified tolerance. However, the microstructures and the mechanical properties of additively manufactured metals differ from those of wrought metals. Therefore, the cutting characteristics should be understood to determine the appropriate cutting parameters. The paper studies the cutting process in peripheral milling of additively manufactured maraging steel in a cutting model. The cutting force, the surface finish, the chip morphology, and the tool wear were evaluated through cutting tests. Although the hardness of the additively manufactured workpiece was higher than that of the wrought workpiece, the maximum cutting forces were approximately the same. An energy-based force model was applied to discuss the cutting force characteristics in terms of the shear area and the shear stress on the shear plane. In milling of additively manufactured workpiece, the shear stress on the shear plane becomes larger than that of the wrought workpiece. However, the shear plane length is short at a large shear angle. Therefore, the cutting force does not significantly increase. The typical change in the cutting force of the additively manufactured workpiece is also compared with that of the wrought workpiece in terms of the cutting model. The chip flow directions, then, are analyzed in the cutting force model. The chips of the additively manufactured workpiece flow more in the radial direction than those of the wrought workpiece.