Industry 4.0, a new industry initiative in Germany, is impacting strongly both on industry and on society. Many newspapers and technical magazines are publishing the state of the art articles on topics such as smart manufacturing based on IoT (Internet of Things), CPPS (Cyber Physical Production System), and cloud-based systems. Other parts of the world have started initiatives such as the IIC (Industrial Internet Consortium) in the US and the IVI (Industrial Value Chain Initiative) in Japan. Smart manufacturing is the key concept underlying these new initiatives.

This special issue addresses the most advanced research on smart manufacturing. Subjects cover cyber-physical product-service systems, machinery production lines, manufacturing system simulation, lot-size energy-consumption dependence per production throughput unit, additive manufacturing processes, sensor network technology, production management technology, supply chain management technology, and smart manufacturing reviews.

We thank the authors for their careful work and the reviewers for their incisive efforts without which this special issue would not have been possible. We hope that this special issue will trigger further research on smart manufacturing and its advances.

A fourth industrial revolution is occurring in global manufacturing. It is based on the introduction of Internet of things and servitization concepts into manufacturing companies, leading to vertically and horizontally integrated production systems. The resulting smart factories are able to fulfill dynamic customer demands with high variability in small lot sizes while integrating human ingenuity and automation. To support the manufacturing industry in this conversion process and enhance global competitiveness, policy makers in several countries have established research and technology transfer schemes. Most prominently, Germany has enacted its Industrie 4.0 program, which is increasingly affecting European policy, while the United States focuses on smart manufacturing. Other industrial nations have established their own programs on smart manufacturing, notably Japan and Korea. This shows that manufacturing intelligence has become a crucial topic for researchers and industries worldwide. The main object of these activities are the so-called cyber-physical systems (CPS): physical entities (e.g., machines, vehicles, and work pieces), which are equipped with technologies such as RFIDs, sensors, microprocessors, telematics or complete embedded systems. They are characterized by being able to collect data of themselves and their environment, process and evaluate these data, connect and communicate with other systems, and initiate actions. In addition, CPS enabled new services that can replace traditional business models based solely on product sales. The objective of this paper is to provide an overview of the Industrie 4.0 and smart manufacturing programs, analyze the application potential of CPS starting from product design through production and logistics up to maintenance and exploitation (e.g., recycling), and identify current and future research issues. Besides the technological perspective, the paper also takes into account the economic side considering the new business strategies and models available.

These days, manufacturers need to improve both their products and services, as well as their technological base to achieve a more sustainable value proposition, to become more efficient and effective in the market, and to satisfy user needs. Significant emerging technologies being discussed in various research studies include networked and smart-environments connected by Internet of Things (IoT), wearable technologies, tangible interfaces, human-robot collaboration, evolving tools, processes and interactions, virtual reality, the ubiquitous use of machine learning, and deep-learning algorithms. Such aspects are increasing the benefits of technology and opening the way toward technical breakthroughs, and have led to the emergence of cyber-physical systems (CPSs), which can be seen as systems of systems, requiring collaboration among different disciplines such as mechanical engineering, electrical engineering, and computer science for their realization. To enable the full potential of a CPS and generate a substantial competitive advantage, however, the service perspective cannot be neglected. Servitization of product offerings has recently accumulated in so-called product-service systems (PSSs), which describe the integrated development, realization, and provisioning of product-service bundles as a solution for customers. Thus, it is more and more important to consider both the technological and service aspects early in the development process. An integration of the two concepts will lead to product-service bundles provided on a cyber-physical basis, creating cyber-physical product-service systems (CPSSs). To base these complex systems on stakeholder needs and allow a successful and dynamic change to CPSSs in industry, multi-disciplinary requirements engineering (RE) for the hardware, software, and service components is a key aspect. The objective of this paper is to provide an introduction to the CPSS concept, understand its application in an industrial case, and elaborate on the specific challenges for systems engineering, focusing on the RE process.

Customer participation in the design stage of creating personalized products is increasing. Additive manufacturing (AM) has become a popular enabler of personalization. In this study, we evaluate the fabrication of an open-source robot arm in terms of cost, build time, dimensional and locational accuracy, end-effector accuracy, and mechanical properties. The mechanical components of the table-top robot were fabricated using two different AM processes of fused deposition modeling (FDM) and material jetting (polymer jetting or PolyJet). A reduction of infill density by 50% in the FDM process slightly decreased the building time, material cost, and tensile strength, but induced a 95% reduction in yield strength. A simulation of the mechanical assembly using the CAD models for the robot and the expected tolerances of the components estimated the end-effector positioning accuracy as 0.01–0.22 mm. The 3D printed robot arm was redesigned and fabricated using the best evaluated process in this study.

The General Aptitude Test Battery (GATB) is widely used to evaluate a subject’s cognitive ability for the purpose of selecting appropriate employment. The results of the GATB have been used to place staff in departments ranging from clerical departments to assembly lines. However, at actual manufacturing and assembly sites, workers receive mixed evaluations of “slow work” and “fast work” from the site administrators even though they all have high GATB scores for their jobs. In this study, with the aim of improving job design and employment selection, we do a detailed analysis of the existing GATB method of evaluating work characteristics and worker capacities. We conduct inspection ratings to measure each worker’s ability to adjust their working speeds and analyze the relationship between the GATB score and the worker evaluations. Next, we discover specific motions that explain the evaluation of workers by analyzing worker motions during the GATB. Lastly, we propose a method of determining whether an employee can work quickly in the field.

A quantitative evaluation and reduction of consumption energy on all production activities and a factory management with focus on consumption energy are necessary for industries. Previous studies were conducted on the formulation of lot-size dependence of energy consumption per unit of production. However, the effect of interprocess buffer capacity was not clarified in the formulation. In this study, the lot-size dependence of the energy consumption per unit of production with consideration of the buffer capacity is formulated. Furthermore, a simulation of a semiconductor production line is performed to verify the validity of the formulation.

A system concept that can guide the management method of a production system is important in the deployment of the Internet of Things (IoT) concept in manufacturing. This paper describes the concept of SIM (Simulation Integrated Manufacturing), the objective of which is to dynamically optimize production planning. The concept is based on the integration of engineering and supply chains in the preparatory stage of production, centering on the production model. Also described is the effect demonstrated in a verification experiment, in which this concept was applied to an actual manufacturing operation.

This study focuses on electrochemical machining as a method of processing sintered carbide at high speeds. Previous studies have suggested the possibility of using electrochemical machining to achieve high-speed machining of sintered carbide. However, there has been strong resistance in industry against bringing sintered carbide into contact with a conductive liquid. This is because the material quality of sintered carbide is degraded by the elution of Co when it is brought into contact with a conductive liquid.

In previous reports, the authors have shown that it is possible to control two modes of Co elution occurring during electrochemical machining: the elution from sintered carbide when it comes into contact with an electrolyte, and the selective elution of Co due to difference in the speeds of WC dissolution and elution of Co when sintered carbide is connected to an electrical source for processing. It was shown that it is possible to control the elution Co in sintered carbide when it comes into contact with an electrolyte by adding Co ions to the electrolyte to increase the concentration of Co ion, and that it is possible to prevent the excessive elution of Co by using a bipolar electrical source for machining. Although we showed that it is possible to carry out electrochemical machining of sintered carbide without degrading its quality, adding of large amounts of Co ions to the electrolyte entails a high cost. In this report, therefore, we describe the addition of Fe ions instead of Co ions to perform electrochemical machining of sintered carbide without quality degradation.

In this paper, some large automotive parts with complex shapes are produced to report the results of our efforts to develop press molding technologies for thermoplastic carbon fiber-reinforced plastic (CFRTP). Members of industry, academia, and the government collaborated to realize this project. The project includes a molding experiment, CAE analysis, and material strength measurements. In the material test, a tensile test, bending test, heat distortion test, and torsion test are carried out to produce several stress-strain curves. Applying the new analytical model in the simulation shows that accuracy is improved. As a result, by measuring the temperature change during the forming of complex shapes, a large automotive part with a complex shape was successfully molded in a short time. Other productivity improvements are also reported on.

Injection molding CAE is employed to analyze the flow process of insert molding. The goals of the analysis are to reduce the number of injection processes required in injection molding, to impart greater added value to the product, and to advance injection molding technology. The importance of an analysis for the weld lines that occur when the mold is filled with plastic and that may lead to lower product quality in addition to an displacements in the insert-molded part due to plastic shrinkage is pointed out. This paper will report about the importance of the previous injection molding CAE for actual fabrication to investigate the product shape design and molding conditions.

In this study, the authors describe the cutting characteristics of binderless CBN end mills in milling of die steel. A single flute radius end mill having a diameter of 0.5 mm and corner radius of 0.02 mm was in the experiment. Heat-treated steel, stainless steel, and high-speed tool steel were cut using a high-speed spindle, allowing for the analyses of tool wear and surface roughness. The results revealed that the wear volume increased with an increase in the hardness of the work material although the edge retreat amount after cutting 25 m was less than 5 μm. The average surface roughness of the finished surface was less than 15 nm in all the work materials. A mirror-finished surface was also obtained. This result contributes to the automation of the polishing process of metal molds and to the more efficient use of labor.

Flash is an appearance defect that arises in injection molding. In this paper, a flash generation-evaluating mold developed by the authors was improved to evaluate the ease of occurrence of flashes in resins, such as engineering plastic, molded at high mold temperatures and melt pressures in the cavity. Using the improved mold, we evaluated the occurrence conditions of secondary flash in polyoxymethylene (POM), polyamide PA6 (nylon-6), and polycarbonate (PC). The secondary flash occurred most easily for PA6, second most easily for POM, and least easily for PC. A correlation between the ease of occurrence of secondary flash and the crystallization of the resin was also clarified.

This paper describes a metal mold with permeability fabricated by metal laser sintering with high-speed milling, which is an additive manufacturing method, and discusses the improvement in permeability. In this method, the sintered body is produced with gas exhaust tubes based on the porous structure. To maintain permeability, ensuring that the gas exhaust tube is not blocked is essential. Blockages may occur because of reasons such as the deformation of the gas exhaust tube due to the milling process during fabrication and generation of mold deposits within the gas exhaust tube during injection molding. In this research, by irradiating the surface of a sintered body, with a gas exhaust tube, by an electron beam, water repellency attributed to the reduction in surface free energy and recovery of permeability are confirmed. Further, in a fundamental experiment with an injection molding machine, the permeability of a permeable sintered body irradiated an electron beam increased by approximately 2.8 times as compared to the permeability of a sintered body that was not irradiated.

A manufactured servo system has both current feedback and saturation elements in the servo driver (amplifier). The current feedback is thought to be effective only in reducing the electric time constant of the motor. However, the effects of current feedback are not only the reduction of electric time constant. In this study, the effect of current feedback is clarified by comparing it to a velocity control system without current feedback. In particular, the contribution of the current feedback to saturation elements in servo drivers is clarified. As a result, the influence of the saturation of the operation amount existing in servo drivers cannot be clarified easily, showing that the current feedback is indispensable in motor control by suppressing the flow of over-current to the motor. This demonstrates the possibility of force control that is compatible with trajectory control of a load by exploiting the characteristic of saturation of operation amount.

Burn marks are serious defects in injection-molded parts that can result in many defective products. There is thus a great demand for effective systems to reduce these defects in injection-molded products. In this study, we investigate the relationship between gas generation and molding conditions using gas sensors. The results show that gas sensors can be used to monitor burn marks.