Shot peening has been used in industrial applications for about 60 years. It is mainly used to improve the fatigue strength of aircraft and automotive components. On the other hand, laser peening, which uses shock waves resulting from ablation by intense short-pulse lasers, is beginning to be used in industry. Both shot peening and laser peening are methods that can induce compressive residual stresses in metal parts. This paper describes both techniques and introduces their effects on automotive transmission gear materials.

View full abstract

In recent years, there has been a strong demand to reduce the production costs of power transmission gears, and sintered metal gears are expected to play a key role. However, ordinary sintered metals have approximately 10% of porosity, which means that they are weaker than wrought steels. Therefore, the sintered metals have not been used as materials of power transmission gears. To use sintered metals as power transmission gear materials for use at high speeds and under high loads, it is necessary to increase their strength. This paper introduces recent research being conducted to increase the strength and further reduce the cost of sintered metal gears for power transmission.

View full abstract

The technological trends are explained in gear finishing processes. Polish grinding, which is one of the new surface finishing methods, is introduced and its processing performance is investigated by observing the processed gear tooth surfaces, and also the effect of improving surface roughness on contact fatigue life is confirmed through load running performance test. When standard gear oil is used, no micro-pitting or other damage occurs on the tooth surface even after 10⁷cycles, and an extremely satisfactory level can be achieved in which running can continue with the initial grinding marks still visible. Furthermore, a new processing method called elastic blasting is introduced. It is a finishing method that can produce a mirror finish that is better than that achieved by grinding.

View full abstract

With the electrification of the whole mobility such as automobiles, motorcycles, construction machinery, etc., the quality required of gears for miniaturization, high strength, quietness, and electric cost improvement has become higher than before. The management of not only the conventional tooth profile, helix, and pitch but also shape of tooth root, bottom and tip, and tooth surface roughness has become important, and this paper explains the measurement technology in response to the demand. In addition, labor shortage is also becoming a serious problem at gear manufacturing sites, and this paper also presents trends in the automation of gear measuring machines and cooperation with gear processing machines to address labor-saving. Finally, a stylus coated with diamond-like carbon to improve wear resistance is explained.

View full abstract

Resin molding technology is becoming increasingly important as it contributes to the weight reduction of automotive parts and the realization of low-cost, high-precision optical parts used in smartphones and other devices. This report focuses on “molds” and “molding,” which are important factors in resin molding, and introduces the latest ball screw technologies that contribute to the advancement of machine tools for manufacturing molds and injection molding machines for molding.

View full abstract

Industrial chains are one of the machine elements that transmit tensile force, and it is common practice toreplace them when chain exceeded its wearelongation limit, regardlessof their use. For thisreason,improving chainwear lifeis a major issue,and alot of research and studies have been conducted in the past. This article introduces basic matters such as classifications of chain wear and the measures required for each classification, as well as our history of the measures for chain wear including oil development for chain. It also explains points of attention for developing chains to improve its wear life.

View full abstract

Lubricants are essential for plastic working; however, their use raises significant environmental and health concern. Reducing lubricant consumption requires materials with high hardness and chemical stability, such as ceramics, for application in dry press working. TiC is a promising candidate due to its excellent properties, but issues such as difficult sintering and low toughness remain. TiC-Ti composite materials have been developed using mechanical alloying and spark plasma sintering, leading to improvements in both sinterability and toughness. The material demonstrated enhanced tribological properties, making it a promising die material. This report presents the fabrication methods for the TiC-Ti composite and compares its tribological properties―particularly wear resistance and anti-adhesion characteristics―with those of conventional die materials, such as SKD11 and WC-Co alloy.

View full abstract