Procedia manufacturing最新文献

Additive manufacturing (AM) machines have developed more rapidly than standardized frameworks needed for the qualification of their geometric capabilities. While some manufacturer-specific methods exist to test capabilities and perform some calibration tasks, standardization efforts have only recently been undertaken in the form of ISO/ASTM 52902. In this study, the recommended methodology prescribed by the standard was implemented by building geometric artifacts with a laser powder bed fusion (LPBF) system and performing dimensional inspection with a coordinate measurement machine (CMM), amongst other methods. Typical dimensional capabilities of the LPBF system are identified and commentary is made on applying metrology methods, detecting geometric error, and diagnosing base causes in the LPBF system. In doing so, favored metrology practices and measurement analysis methods auxiliary to the standard are proposed. Artifact measurements were used to characterize beam positioning error and beam offset error. Methods for decoupling the effects of error sources are proposed. Difficulties in the inspection of AM components are identified, and the effects of various CMM measurement strategies are evaluated. Insights on the application of the new standard are presented, along with commentary as to its fitness for the LPBF process.

In this paper, we explore the applications and practices that Stereolithography enables for an enhanced manufacturing process of a nitrate assay chamber for an underwater Point of Care device. Features such as engraved identifiers, creating post for inlet/outlet connections, embedding electromechanical components and optimizing the spatial distribution, were tested as a case of study for an underwater vehicle component. This study is a first approach in proposing a framework for manufacturing practices toward a new generation of customized devices for the application. The case study is validated using Computational Fluid Dynamics for the design and manufacture of an array of micromixing enhanced nitrite assay sensors that employ and exploits the enabling technology of stereolithography.

The goal of this work was to determine which standard particle size metric derived from optical analysis most closely approximates the sieved weight percent of irregularly shaped powder intended to be used for directed energy deposition. In this investigation, equivalent circle diameter, maximum diameter, minimum diameter, and perimeter were used as metrics to “virtually sieve” the particles in samples of irregularly shaped powder into the following particle size bins: <45 µm, 45 µm – 150 µm, and >150 µm. The percentage in the 45 µm – 150 µm bin were then compared to the weight percent of the powder mechanically sieved into this size range. The absolute difference between the virtually sieved percentage and the mechanically sieved percentage was assessed for 81 samples of mechanically-generated stainless steel 316L powder, all produced under different processing conditions in an oscillation ball mill. This difference was found to be on average, the least with the minimum diameter assessed as an area percentage, followed by the equivalent diameter assessed as an area percentage, and then the maximum diameter assessed as a percentage of the total number of particles ranked third. These findings and the methodology used to obtain them may be used by powder production process engineers and quality assurance personnel to assist in process control as more diverse additive manufacturing feedstocks become utilized.

This paper proposes a dual function fatigue tester that can perform both the traditional four-point rotate bending and the new cantilever rotate bending fatigue test. The linear profile of the cantilever specimen, that is simplified from the theoretical cubic profile, is subjected to uniform stress along the entire gage length and alternating between tension and compression modes until fracture. The system is designed to operate at 50-60 Hz, which is much faster than the traditional 5-10Hz in traditional push-pull fatigue testing. Preliminary fatigue testing on wrought Inconel 718 cantilever specimen shows random fracture along the specimen gage length, and successfully separation of fatigue fractured surfaces for subsequent fractography analysis. The system will be utilized for studying fatigue of selective laser melted Inconel 718 and the effect of different post processing parameters.

In Additive Manufacturing (AM), auditing layer-by-layer images can detect infill defective attacks effectively. However, the auditing process itself can become a target of inside or outside attackers in Cyber-Physical Manufacturing System (CPMS) environments because pervasive connection through various types of computer networks in CPMS opens new doors for adversaries to compromise various components in an attack detection system. To maintain an effective attack detection system and prevent data from malicious data injection, this paper presents a Layer Image Auditing System (LIAS) secured by the Blockchain technology in CPMS. LIAS consists of a pre-processing system and a Multilayer Perceptron Neural Network (MLP). To evaluate the prediction accuracy of LIAS, a set of simulated infill images and physical images were used for training and testing. The effectiveness of the Blockchain implementation is demonstrated by presenting the comparative performance analysis of the proposed attack detection system with and without the Blockchain.

The manufacturing innovation that underlies advanced products comes about through rational, reasoned design, motivating the need for a manufacturing engineering curriculum within higher education that teaches methodologies for designing manufacturing processes. As an alternative to conventional manufacturing process courses, the authors propose learning outcomes and methods for teaching process design and innovation. Proposed learning outcomes for new process design courses include describing key relationships and directionality between product and process design functions, determining whether a component can be made with a process, selecting process sequences for products based on cost and/or environmental impact, specifying new process designs when needed, and choosing between product/process alternatives. Examples of instructional materials and approaches that are being developed to help meet these outcomes are discussed.

Multi-material lattice structures are used in a range of load-bearing applications for multiple conditions including mechanical and thermal loads. Additive manufacturing processes with multi-material capabilities are well suited to manufacture multi-material structures. In this paper, a multi-material topology optimization approach has been presented using variable-density lattice structures where the geometry of the lattice structure is pre-defined. The objective of the proposed topology optimization method is to design lightweight parts with minimized compliance and thermal energy or improve the heat transfer capability. To facilitate that, a novel interpolation scheme based on the stiffness matrices of the lattice structures has been proposed. This interpolation scheme, unlike the traditional Solid Isotropic Material Penalization (SIMP) interpolation, is observed to perform better in terms of approximating the structure’s load-bearing capacity, primarily due to its formulation on the lattice’s stiffness matrices. This cubic Hermite spline-based interpolation scheme makes it amenable for gradient-based optimization methods. A sequential linear programming method has been used to solve the weighted multi-objective optimization model. A Pareto-frontier study has also been carried out to fully characterize the trade-offs between the two objectives – compliance minimization and thermal energy minimization.

To facilitate the transition from a linear to a circular economy there is a need to develop digital tools that can provide comprehensive and useful data to enhance repair, remanufacturing, reuse, and recycling. This paper explains the typology of information key for such end, it discusses the current limitations and difficulties to implement methods in a digital platform, and a description of already existing digital solutions that will be further improved in the context of the DigiPrime project. A preliminary analysis of the availability and accessibility of information about electronics is required before the definition of a digital tool to support circular economy. First, the paper discusses the need of ‘digitalized’ end ‘standardized’ information of electronics to promote circular strategies. Then, diverse digitalization approaches by several teams of the Digiprime project are detailed. The paper concludes with a description of the next steps needed to align the diverse digitalization approaches and its potential contribution to improve the electronics sector.

In recent years there has been a growing interest in Circular Economy (CE), which promises to reduce waste and improve sustainability. The promise of CE is to change the conventional “take–make–dispose” that causes massive waste flows based on the integration of demanufacturing and remanufacturing processes within value chains. This integration requires breaking the ”silos” of the circular chain to establish new collaborative and sustainable value networks. The paper introduces a novel digital platform for the CE, which is currently under development in the H2020 DigiPrime project. The platform is destined to facilitate seamless and trusted information exchange across circular actors, while offering a range of value-added services that enable manufacturers, remanufactures, recyclers and other actors to gain insights in the status of recycling and waste management processes. The latter facilitates the implementation of zero waste processes, along with the assessment of the performance of the circular chain. The paper introduces the architecture of the digital platform, along with its data modelling, exchange and data traceability mechanisms. It also presents a CE use case used to validate the platform.

Managing the quality of global supply chains is critical for the success of global companies. Quality disseminates through the supply chains. Supply chain quality integration facilitates each company to use its main expertise which can lead to higher quality and cost reductions. Digital audits enhance the possibilities to ensure the production quality at the suppliers. A global supply chain quality integration is illustrated through the case of the Boeing 787 Dreamliner development. The development process was a major challenge for Boeing because not only several innovations were introduced in the 787 plane, but the supply chain quality integration reached new levels for the company. The 787-program had process, management, labor, and demand risks. The first 787 plane was delivered three years later than planned and the budget was exceeded by 10 billion USD. To solve the issues, Boeing created the Production Integration Center. It sent engineers and production workers to its suppliers in several countries of the world to smooth the supply chain quality integration. Boeing supported its suppliers with its knowledge. Onsite cameras were used as digital audits. The Production Integration Center intervened when it estimated delays in the shipments. Boeing successfully solved the issues, but they cost the company a lot. Examining this supply chain restructuring case can help supply chain managers to diagnose and overcome issues in supply chain quality integrations.