This paper addresses the issue of over-constrained assembly in mechanical designs using hole-pin patterns. When two hole-pin pairs are used, they can cause interference between components, leading to assembly failures. To mitigate this, designers often enlarge holes relative to pins to have a large float. However, when functional requirements do not permit significant float, field design engineers tend to add more assembly features, hoping them to mutually limit the float allowed by others. This numerical study employed two commercial tolerance analysis programs to demonstrate that these design changes could not sufficiently reduce float to justify added costs. Instead, this paper proposed an exactly-constrained design by replacing one of the holes with an elongated hole. Numerical analysis showed that this approach significantly reduced float compared to current design practices. This paper logically explains why this must be the case. It is hoped that this study contributes to the advancement of mechanical assembly design practices by adopting the exact constraint concep.

In this paper, we introduce a recently built screwing robotic system for the bolt assembly of elastic steel plates. The screwing robotic system consists of two vision cameras (having narrow and wide fields of view), a collaborative robot with a 10 kg payload, and a motorized screw drill with a pneumatic bolt supplier. Due to the elasticity of the steel plates, they tend to statically deform and dynamically vibrate during tasks under the conventional setting of automatic screwing, often resulting in screw failures. Thus, we designed a compliant connector device to be attached between the robot end-effector and screw drill that can absorb vibration and shock during the bolt assembly to improve the screwing quality and success rate of the bolt assembly. Upon adopting this screwing robotic system with the compliant connector, the success rate of the bolt assembly was improved from 56% to 100%.

In this study, the effects of repetition of assembly and disassembly of polymer electrolyte membrane fuel cells on electrochemical performance were systematically investigated. Additionally, the effects of additional activation on polymer electrolyte membrane fuel cells were evaluated. All fuel cells were measured every three days. For the disassembled polymer electrolyte membrane fuel cells, membrane electrode assemblies were stored in a vacuum desiccator. For the maintained assembly, fuel cells were stored at room temperature. The performance and electrochemical characteristics of the fuel cell were analyzed by electrochemical impedance spectroscopy. As a result, the addition of activation to maintained assembly fuel cells showed the best performance among fuel cells with other assembly and activation conditions. Repetition of assembly and disassembly, as well as insufficient activation, caused degradation of the performance of fuel cells.

In this paper, a multi-material non-assemble 3-DOF Force-Sensor was proposed and developed to improve the efficiency in the manufacturing. The PLA-Filament was used to produce the frame-structure and the elastic-deformation, and the conductive-PLA-filament, to produce a transducer. A dual-nozzle 3D-Printer was applied to produce the monolithic-structuretype force-sensor with the multi-materials simultaneously in single-manufacturing-process. The sensor was designed in a tripod-structure to detect the 3-DOF force-components in an external-force and a mechanical-interpretation was conducted on the elastic-deformation, which acts as a load-cell. The output model of a Wheatstone-bridge circuit-based transducer serving as a strain-gauge was also produced. A calibration-testing device, comprising a rotating stage, which turns with 2- DOF (θ, ϕ), was also developed to apply force in every direction. By conducting the calibration test, the relations between the input and output were computed in as a matrix and the resolution of the sensor was determined through the evaluation of linearity and stability deviations.

The assembly misalignment of a high maneuver precision guidance missile such as anti-air interceptor could have poor influence on the performance of the system and lead to fatal mission failure. Thus, several methods to minimize the assembly misalignment of missiles have been suggested, including assembly guiding tools and measuring devices. However, previously suggested solutions have disadvantages in versatility and cost. In this study, the low cost and universally applicable solution based on inclinometers for measuring assembly misalignment of a missile is introduced. The comparison between measurement data of the suggested system and a three-dimensional laser tracker for a missile assembly misalignment was conducted. The results show the suggested system can quantify a missile assembly misalignment with comparable precision and accuracy.

A simple and rapid method of fabricating Mg(OH)2 layer by chemical immersion was developed to improve the corrosion resistance of the magnesium alloy AZ31. The fabricated surface was superhydrophobic with a self-assembled monolayer coating of silane. The surface characteristics were evaluated by Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Photoelectron Spectroscopy (XPS). The average water contact angle and sliding angle were determined to be 160° and 7° respectively as a result of wettability test. Potentiodynamic polarization indicated that both Mg(OH)2 layer and the thin layer of air were effective in improving anti-corrosion. This method which is efficient with regard to time and cost would be useful for magnesium industries and its application

Automation of electronic connectors has been in demand, based on automation of assembly of electronic products. In this study, we propose a new classification of electronic connector, for grasping and assembling. We analyze characteristics of electrical connectors often used at actual industrial sites, from the perspective of the robot, not a person. As a result, it is appropriate to classify the grasp, according to the shape of the electric connector. For the assembly, we suggested that classification should be based on directions are different, because of interference of the electric wire and peripheral parts. We hope that this research will become a new basis, for electrical connector assembly.

Super-wettability surface has various applications and actively studied in many fields. However water droplet transmissivity on super-wettability mesh was not be studied. This work is about water droplet transmissivity of an aluminum mesh with super-wettability on its surface. The mesh which fabricated surface structures with semi-permanent and non-etching process has super-wettability without strength drop of mesh structure. With this process, water droplet transmissivity was measured along various mesh pore per inch and dropping angle. Also water droplet transmissivity along dropping height was measure with super-hydrophobic mesh. As a result, super-hydrophilic mesh shows similar transmissivity behavior with bare mesh which has hydrophilic surface at high pore per inch and high dropping angle, super-hydrophobic 120 mesh shows lowest water droplet transmissivity in various situation.

In this study, we developed a convenient method to achieve superoleophobic surfaces on zinc substrates by using anodization and self-assembled monolayer coating, and to facilitate the fabrication of superoleophobic surfaces having reentrant structures, even for lower surface tension liquids than 30 mN/m- including hexadecane (γ = 27.5 mN/m). The liquid repellency of the structured surface was validated through observable experimental results; contact angle measurement. The optimal anodizing condition was determined as a critical parameter in building the superoleophobicity. The re-entrant had nanowire/microball structures formed by anodization with a high voltage. Under an optimized morphology by re-entrant structures with fluorination treatment, the contact angle over 150o is achieved, even for hexadecane.

A study about superhydrophobic surface started from the analysis of lotus leaf, and superhydrophobic surface fabrication methods have been researched. These methods cannot be used on various metals because the fabrication methods have complex and material-selective processes. In this work, we report a simple fabrication method using abrasive blasting and a self-assembled monolayer coating to produce a superhydrophobic surface. Abrasive blasting was used to create microstructures on metal surfaces. Random peak and valley microstructures were created after abrasive blasting, and a surface profile was measured to analyze the relationship between blasting pressure and a roughness parameter. A hydrophobic material coating was performed by a self-assembled monolayer method. Six kinds of metal surfaces displayed superhydrophobic properties. This utilitarian method could be applied to diverse applications.

This paper proposes a new improved methodology to assess reconfiguration manufacturing system (RMS) adaptability in small and medium manufacturing industries. The evaluation of scenarios and alternatives for a reconfigurable design in manufacturing systems requires efficient and convenient methodologies to confirm the comparative evaluation metrics of the assigned KPI. Customizable factors are extracted and mapped for the design structure matrix and the analytic hierarchy processes. Reconfiguration event information is visualized as bill of resource. Evaluation format of KPI choice is then suggested. The reconfiguration control manager is designed to extract and combine the objects and the resource library of the reconfigurable assembly module and line. This paper first proposes the improved evaluation modeling frame and format with the newly refined KPI for the assessment of reconfiguration adaptability. Second, it shows the applicable suitability through a partly designed domain at the real automotive components manufacturing and assembly factory. Finally, it discusses the issues related with the customization and case results by the suggested evaluation methods.