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Magnetic-field assisted finishing (MAF) is a surface finishing process that utilizes a flexible brush composed of iron and abrasive particles typically mixed in a liquid medium. This paper presents an innovative approach to enhance the MAF performance by adding nano-scale solid lubricant into the brush. In particular, exfoliated graphite nanoplatelets (xGnPs), multi-layered graphene platelets with micro-scale diameter and nano-scale thickness, have been introduced into the brush. The modified brush consisting of iron particles, abrasives (cubic boron nitride, cBN), and xGnPs in silicone oil was applied to finish the surface of mold steel. While varying magnetic flux density, cBN particle sizes, and xGnP content in the MAF brush, a series of MAF experiments was conducted to examine their impact on the achieved surface quality on a workpiece and the life of MAF brush. For a given content of xGnPs in the brush, the quality of surface finish was improved and the life of MAF brush was extended significantly with larger abrasives in the brush. Furthermore, the effect of xGnPs with respect to abrasive size was investigated with various factors such as relative number and surface area coverage of xGnPs per abrasive, the relative size of xGnP to abrasives, and depth indented by abrasives on the workpiece, which enabled us to identify the change in the underlying mechanisms in relation to the abrasive size. The new MAF brush is also expected to improve the efficiencies of the overall MAF process in terms of energy consumption and material utilization.

Open product architecture is a key enabler for product personalization, as it allows the integration of personalized modules in a product architecture to satisfy individual customer needs and preference. A critical challenge for integrating personalized modules into a product architecture is determining the optimal assembly architecture when considering market expectations and manufacturing constraints. In this paper, an optimization method is proposed for determining the personalized product design architecture that incorporates individual customer preferences. First, a decision hierarchy is presented to describe the integrated design decisions of the product architecture, including product variety determination, module variant selection, and personalized module configuration. Next, a profit model is formulated as an overall performance metric that incorporates customer preferences and manufacturing cost. The systematic patterns and randomness of diverse customer preferences are modeled by combining conjoint analysis and market segmentation with a multivariate normal mixture model. Individual customer product utilities in the target market and their product purchase intent probability are estimated through Monte-Carlo simulation, which is incorporated into the profit calculation. Manufacturing limitations on processes and materials are included as they influence manufacturer’s planning on candidate module variants and production strategies of personalized modules. These models are used to determine a product family architecture that maximizes profit by optimally determining its offering of product variants, module combinations, and personalized module configuration through a genetic algorithm. The proposed method is demonstrated by a personalized bicycle architecture design example.

This paper introduces a new additive manufacturing (AM) process which significantly improves the productivity of the current metal AM technologies by combining binder jet printing and stereolithography principles. Three dimensional objects can be printed on a powder bed system where photopolymerization takes place by selectively curing the suspensions containing metallic powder and ultraviolet curable resin in a layer-by-layer fashion. Integration of a digital light projection module allows a high-speed production with dimensional accuracy within 100 µm. Printed parts are sintered at appropriate temperatures to attain metal parts with the final density above 97% and homogenous microstructure without residual stress.

In functionally graded materials (FGM), material property gradually changes within a product. To manufacture FGM by additive manufacturing (AM) using polymer powders, precise deposition of different powder materials is crucial. The powder deposition, however, is challenging, because process control and material choices are complicated. This paper presents a newly developed laser-based AM system using the direct deposit of poly-lactic acid powders on the target surface. This direct-writing AM system can facilitate material change even within a layer for superior material property variation. This study characterizes the optimal process conditions for deposition consistency by statistical methods. This study also identifies suitable statistical models by examining the model characteristics such as lack-of-fit and curvature. In addition, this study finds an appropriate statistical method to handle process abnormality such as no powder flow. Through these analyses, this study characterizes the optimal combination of process conditions and material choices for stable powder deposition, and verifies the best conditions for the new AM system. This study will help develop a new AM system with the optimal deposition for each material composition to produce novel material structure for FGM.

Personalization is an emerging manufacturing paradigm towards meeting diversified customer needs. This paper proposes a framework for producing personalized products efficiently. An approach for optimal mix of different module types is proposed in order to construct a proper assembly architecture. Sketch-based modeling, which facilitates easy model creation and modification by customers, is presented as a key to personalized design. A cyber physical system provides the platform for the collaborative design and co-creation of personalized products. A case study on personalized bicycles based on the proposed framework is presented. Such a framework enables open product realization through active customer participation.

Multilayered ultrasonic welding (USW) is widely used in joining of electrodes or tabs in lithium-ion batteries. To achieve quality joints and enhance the welding process robustness, an improved understanding of the joint formation is highly desirable. In this paper, USW of four-layered Ni-coated Cu is studied to investigate the joint formation at a single interface and joint propagation from interface to interface under both ambient and preheated conditions. The results indicate that joint formation involves three major mechanisms: Ni–Ni bonding with minimal mechanical interlocking, Ni–Ni bonding with moderate mechanical interlocking, and a combination of Ni–Ni bonding, Cu–Cu bonding, and severe mechanical interlocking. Results also show that joints propagate from the interface close to the sonotrode side to that close to the anvil side. It is further observed that the joint formation can be accelerated and the joint strength can be improved with process preheating, especially at the interface closest to the anvil. The effect of preheating is most significant during the early stage of the process, and diminishes as process progresses. The favorable effects of preheating improve the robustness of multilayered USW.

A reduction in silicon material consumption in the photovoltaic industry is required for cost reduction. Development of ultra-thin crystalline silicon (c-Si) solar cell (

Due to the sudden increase of energy consumption from modernization and civilization, energy efficiency has become an important issue in engineering devices. Much research effort has been made to enhance the performance of individual thermal devices. However, enhanced thermal devices are usually components in a larger thermal system such as an energy network connected by pipe networks to circulate an energy-carrying medium. Even when each component operates at maximum efficiency, the general system may not work in harmony to a full extent. Thus optimizing the full thermal system would increase the energy utilization efficiency even further and ultimately decrease the amount of CO2 emission. In this paper, we developed a numerical model for estimating heat flow and temperature variation in a complex energy network system using Simulink in Matlab. Emphasis has been made on heat pump's intermittent operation, where the system can be shut down for specific periods of time. A special thermal routine for the pipe was devised where the conduction becomes major heat transfer mode during the night. The code we developed was validated by comparing experimental data, and detailed analysis on system components' temperature variations and energy flow characteristic are provided.

This paper investigates the methodology to modify biodegradable polymers having random size, shape, and molecular weight into particles appropriate for selective laser sintering (SLS), which is a powerful technique to build arbitrarily complex objects. Polycaprolactone (PCL), which has recently drawn significant attention as biodegradable polymer for potential application in bone and cartilage repair, was used in this study. PCL powders with various sizes, shapes, and molecular weights were modified by chemical processes and resultant shape, size distribution, degree of crystallinity, and thermophysical properties were observed by optical and scanning electron microscopy (OM and SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The modified PCL as well as raw material were sintered by CO2 laser irradiation with 10.6-im wavelength, and specimens for tensile testing were fabricated. By simple design of experiment (DOE) method, macro and micro structures of the fabricated parts were observed depending on various processing parameters related with SLS. Finally, micro tensile tests were conducted, and tensile properties as a function of molecular weight and particle shape were obtained. All the procedures attempted in this study can be extensively applied to other biodegradable polymers. Since SLS has an advantage to deposit multiple materials spatially, the obtained mechanical properties can be referred to generate functionally graded material (FGM), which incorporates deliberately designed transition in materials composition and properties within a component, by SLS.

A 532nm Nd:YAG laser was applied to crystallize amorphous Si thin films in order to evaluate the applicability of Nd:YAG laser to low-temperature polycrystalline Si technology. In this study, we aim at enhancing uniformity as well as crystallinity. In order to achieve the goal, a new optical system called as a diffusing system was used to enhance the uniformity of irradiating beam profile, consequently improving the quality of crystallized microstructures. Optimal processing parameters for high crystallinity and uniformity were developed by design of experiments (DOE). To investigate crystallinity and uniformity, Raman spectroscopy and optical microscopy were utilized. Therefore, the effectiveness of Nd:YAG laser is suggested as a feasible alternative that is capable of crystallizing the amorphous Si thin films.

This paper addresses the optimization of a micro-grinding process using compressed air to minimize specific grinding forces and surface roughness while maximizing specific material removal rate (MRR). The design-of-experiments (DOE) approach and response surface methodology (RSM) are introduced to obtain the optimal grinding conditions. In the DOE approach, a central composite design approach is used for experimental design. Micro-grinding experiments are conducted, and the experimental results are used to obtain response surface models of specific grinding forces and surface roughness in terms of depth of cut, feed rate and air temperature. Multi-objective optimization is then conducted by introducing desirability functions, and the optimal values of depth of cut, feed rate and air temperature are obtained for minimum specific grinding forces and surface roughness and maximum specific MRR. The experimental results under the optimal grinding conditions are similar to those estimated from the response surface models, and thus the validity of the models is verified.

Injection molding process is a widely used manufacturing technique to massively produce the components of mobile device with various sizes and complicated geometries. However, the final part quality, especially dimension or geometry, referring to the original design specifications is not often acceptable due to various reasons. This study aims at developing the numerical model to predict the final part quality and subsequently identifying the critical reasons for existing problems. moldflow and abaqus software have been simultaneously used to simulate the injection molding process and thermal deformation arising after ejection step from the mold. In order to validate the model, the deformation predicted by the developed model was compared with experimental results, and both results showed good agreement. We also carried out design of experiment (DOE) to investigate the effect of various processing parameters that affect the final deformation of injection molded product. The developed model and information derived from DOE are expected to provide useful resources to the initial stage of mobile device design.

In this paper, we present a one-dimensional (1D) melting, evaporating, and resolidifying model describing the interaction of a scanning laser beam with a metal surface wherein the continuous and stepwise heat flux is applied. One set of 1D conduction equations, which is valid in all phases including solid, liquid, and vapor, has been developed along with two phase boundary conditions between the solid/liquid and liquid/air using an appropriate scaling law. The 1D heat equation has been solved separately in each phase using a sharp interface temperature technique based on the front tracking method. The generalized relations of nondimensional maximum melting depth, final evaporation depth, and maximum melting time related to nondimensional interaction time and heat flux factor are established.