Two important and difficult tasks during a bone drilling procedure are guiding the orientation of the drilling axis toward the target and maintaining the orientation against the drilling force. To accomplish these tasks, a remote center of motion (RCM) mechanism is adopted to align the orientation of the drilling axis without changing the entry point. However, existing RCM mechanisms do not provide sufficient resolution and rigidity to address hard tissue cases. We propose a new type of RCM mechanism that uses two sets of linear actuators and a gearless-arc guide to have a high resolution and rigidity. In addition, we designed a single motor-based drilling mechanism based on rolling friction. To achieve automatic control of the guiding and drilling process, we incorporated a computer-tomography-based navigation system that was equipped with an optical tracking system. The effectiveness of the integrated robotic system was demonstrated through a series of experiments and ex vivo drilling tests on swine femurs. The proposed robotic system withstood a maximum external force of 51 N to maintain the joint angle, and the average drilling error was less than 1.2 mm. This study confirms the feasibility of the proposed bone drilling robotic system with a high-resolution and high-rigidity RCM mechanism. This drilling system is the first successful trial based on an RCM mechanism and a single motor-based drilling mechanism, reducing the footprint and required motors with respect to previous bone surgical robots.

The recent stringent regulations on vehicle safety and reducing CO₂ emissions have led to a continuous increase in the application of press-hardened steel (PHS) in automobiles. Similar to other high-strength steels, assembling PHS components using the common welding techniques employed in automotive production lines is significantly difficult because of the surface coating layers and the additives within. This difficulty in post-processing, attributed to its high strength, also limits the mechanical fastening of PHS components. Therefore, this study aims to develop a process for forming a structure enabling mechanical fastening by sequentially applying piercing and hole-flanging operations during the hot stamping process. Our experimental apparatus was designed to perform the hole-flanging operation after the piercing operation within a single stroke at a specific temperature during the quenching process of PHS. At high temperatures of 440 °C or higher, the hole-flanging process was conducted in a direction opposite to that of the piercing operation for creating the pilot hole. An extruded collar with a height of 8.0 mm and a diameter of 17.5 mm was achieved, which is hole expansion ratio(HER) of 82.5%.

Surface whitening is a manufacturing‐induced surface defect in thermoplastic composites, resulting from non‐uniform shrinkage and near‐surface resin instability during cooling. This defect can compromise subsequent coating, bonding, and inspection processes. This study examines thermal annealing as a post‐processing strategy for mitigating surface whitening in carbon fiber/polyphenylene sulphide (CF/PPS) laminates without modifying the existing forming process. Laminates were consolidated at 300°C under 10 bar, followed by annealing at 280°C under a contact pressure of 1 bar for 30, 60, and 120 min. Morphological analysis indicated that surface whitening is associated with localized resin protrusion, fiber exposure, and surface layer discontinuity, all of which increase incident light scattering. Thermal annealing promoted near‐surface resin reflow, reducing the whitened area fraction by 71.8%–80.5% across all conditions. Surface roughness parameters Sa and Sz decreased significantly, whereas the crystallinity and bulk thickness changed only marginally by up to approximately 1.5% and 2.6%, respectively. Thus, whitening mitigation is primarily driven by surface morphological recovery rather than by bulk structural reconfiguration. More broadly, these results demonstrate that controlled post‐process annealing can decouple surface‐quality improvement from primary forming‐condition modification, providing a practical route for improving the manufacturability, inspectability, and downstream process compatibility of semi‐crystalline thermoplastic composite laminates.

This study investigates the secondary bonding of aircraft skin/stiffener assemblies using press conduction welding with carbon fiber/polyetherketoneketone thermoplastic composites and polyetherimide adhesive. Recognizing the challenges posed by conventional welding methods in maintaining material integrity and uniformity, this research explores an alternative methodology that mitigates these issues while ensuring high-strength bonds. The press conduction welding parameters were selected based on single-lap shear tests and applied in the bonding of skin and omega stiffener components. The temperature range was determined using differential scanning calorimetry. The pressure was held at 1 MPa for 180 s. The welding temperature that produced a high-bonding strength was identified experimentally; these key variables were then used in the welding process of the skin and omega stiffener. By analyzing how the fibers tear and the effectiveness of interdiffusion between the plies, we were able to gain insights into the bonding strength and fractured surface. The findings suggest that press conduction welding provides a viable route for secondary bonding in thermoplastic composite structures, highlighting its advantages in terms of processing efficiency and integrity. This study contributes to the understanding of the mechanical behaviors of bonded joints and underscores the significance of temperature control in the welding process.

Fiber-reinforced composites have a wide range of industrial applications owing to their light weight, high modulus, and good specific strength. Trimming using a mechanical punching tool is the fastest way to post process fiber-reinforced composites. However, quantitative analyses of the defects and process parameters are required to analyze the damage mechanisms and achieve high-quality cut surfaces. In this study, we quantitively investigated the defects on the sheared edge of woven glass epoxy laminates subjected to mechanical punching and explored the correlations between these defects and key process parameters, including punch-die clearance, weave alignment angle, and laminate thickness. The results demonstrate the necessity of considering glass fiber burr length and the dimensions of the cracked area simultaneously to evaluate the quality of the sheared surface. This study provides qualitative data on the interfacial damage mechanisms that occur during mechanical punching, which will help to tailor the process parameters of mechanical punching for fiber-reinforced polymers to obtain smooth cut surfaces.