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.

The linear motion guideway (LM guide) is one of the key parts of precision motion and positioning, and it requires high straightness, form accuracy, stiffness, and surface quality. LM guides are actively used in manufacturing facilities for automobiles, aerospace, optics, semiconductors, robots, displays, and portable communication equipment. At present, most of LM guides are based on rolling contact, using either balls or rollers. Roller LM guides have been in high demand in recent years in various industrial fields that require high rigidity. In this study, the friction characteristics of ball and roller LM guides with the same rail width were compared, and friction behavior was analyzed. An experimental setup consisting of a driving unit, specimen, force sensor, and signal acquisition unit was constructed, and signals were collected under various conditions. Three lubrication conditions were used: no lubrication (dry surface), ISO-VG 32, and 68, and a wide feed-rate range from 1 to 100 mm/s was selected. The experimental results showed that the ball LM guide and the roller LM guide had significantly different friction characteristics, which were analyzed from the aspect of Stribeck curve components. In conclusion, friction behavior differed according to lubrication conditions in the no-payload state of the ball and roller LM guides, and the effect of lubrication conditions on friction behavior was shown.

With the development of 3D printing technology, its applications are expanding. However, 3D printed parts present a challenge in achieving high-quality surface roughness because of stair stepping problems. With the recent application of 3D printing in electronics and the visibility of flow in microfluidic systems, high-quality surface roughness is needed. Chemical mechanical polishing (CMP), one of semiconductor fabrication processes, has the longest planarization length in terms of productivity among existing planarization methods. In this study, we investigate friction characteristics of polishing of ABSLike resin material printed by the Stereolithography Apparatus (SLA). At the polishing of ABS-Like resin, the friction force has a high value at the beginning of polishing, but it stabilizes as processing progresses because of the effect of waviness on the printed material. The surface roughness (Sa and Sz) reduction and the glossiness of ABS-Like resins after polishing appear to be related to the reduction of the Shore D hardness resulting from the rise in the polishing process temperature caused by friction during polishing.