This study presents a rolling tribometer designed to quantitatively assess ball-raceway friction in ball-guided bearings, which is critical for applications such as smartphone camera actuators, where friction impacts power consumption. Following ASTM G133 standards, the tribometer was validated using LCP and PC materials under both short-cycle (10K cycles) and long-cycle (1M cycles) tests. Under short-cycle conditions, LCP exhibited an average coefficient of friction (COF) of 0.011, while PC demonstrated a COF of 0.009, both showing low variability at 2.7% and 4.4%, respectively. In long-cycle testing, LCP maintained stable friction coefficients, whereas PC experienced a significant COF increase around 200K cycles due to wear. Confocal microscopy revealed that the wear volume of PC was approximately 10 times greater than that of LCP after 1M cycles. Displacement-friction force analysis indicated increased energy dissipation in PC, attributed to wear-induced surface asperities. This rolling tribometer provides a reliable method for evaluating friction coefficients and long-term durability, yielding valuable data for optimizing actuator design and enhancing efficiency and lifespan in ball-guided mechanisms. The quantitative friction data generated can significantly improve the performance of ball-guided systems.

Additive manufacturing requires a relatively long time to fabricate complex three-dimensional (3D) structures or parts with more than one material. For additive manufacturing processes, production time and precision vary depending on the fabrication conditions. In this study, we developed a food additive manufacturing process of the material extrusion method type using a dual nozzle. In addition, we observed the change in the cross-sectional shape of the discharged food line according to each fabrication condition. By using a dual nozzle, the structure was fabricated under conditions of relatively high precision for the outer wall and relatively low precision for the infill, thereby shortening the production time. Through this process, it can be expected that the production time will be shortened in the food field, while the appearance will be of good quality.