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Purpose: In modern industry, titanium is recognised for its remarkable wear resistance and strength. However, its poor thermal conductivity poses a problem because it shortens the life cycle of cutting tools. Researchers have focused on enhancing the service life of cutting-edge tools, cutting production costs by using new coating materials, and identifying appropriate materials for these coatings. Design/methodology/approach: The experimental design involved tests with controlled cutting speeds of 150, 175, 200, and 225 m/min, feed rates of 0.2, 0.25, and 0.30 mm/rev, and cutting depths of 0.5, 1.0, and 1.2 mm. Titanium with a diameter of 25 mm and a length of 200 mm was prepared for the turning test over a machining distance of 20 mm. The chips obtained from the cutting test were observed and analysed using a scanning electron microscope to investigate the effect of the tool coating on the characteristics of the chip formation mechanism. Findings: The study revealed that inserts coated with AlCrSiTiN produced the characteristic of long twisted chips transitioning into continuous chips with shorter twisting distances than uncoated cermet inserts. The uncoated cermet inserts resulted in a greater twisting distance based on an examination of the chips with a scanning electron microscope, revealing more pronounced jaggedness in the fragments produced by the cermet turning inserts, which also possessed a larger average clearance than the inserts coated with AlCrSiTiN and TiAlSiN. Furthermore, the uncoated cermet inserts showed less wear at lower cutting speeds than the other types of inserts. Conversely, the TiAlSiN-coated inserts exhibited less wear at higher cutting speeds than the inserts of different materials. Research limitations/implications: The triangularly shaped inserts were cermet inserts coated with AlCrSiTiN or TiAlSiN via the PVD method and were used for dry turning. Practical implications: Wear of cutting-edge tools is a problem in turning of titanium. Therefore, it is crucial to identify methods to minimise wear and extend the service life considering the investment worthiness. Likewise, efforts are being made to develop new coatings tailored to the materials. Originality/value: The research could provide guidelines for reducing the wear generated in cutting tools and increasing the service life of cutting edges by adjusting the machining parameters. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to investigate the effect of fatigue behaviour on fracture in the 4th gear (helical gear) of a pick-up truck. Design/methodology/approach: Fracture on the failed helical gear is characterised through metallographic and fractographic analyses. Mechanical testing and finite element simulation are employed to assess the factors contributing to the gear failure. Findings: The microstructure observed in the case layer was martensite, leading to a hard and brittle surface due to carburising. Failure initiated at the crack origins and then propagated to the instant fracture zone in the core of the gear tooth. Multiple crack origins accelerated the development of ratchet marks, attributed to the high intensity of stress exerted on the workpiece and ultimately leading to a substantial final overload zone. Hardness decreased with increasing depth of the gear surface due to the effects of carburising and hardening treatments. Stress was initiated from the contact stress on the gear tooth surface and transformed into bending stress along the central axis of the gear. The contact stresses became critical when the torque surpassed the contact strength of the material. Research limitations/implications: Simulation samples must be experimentally validated to improve the results. Practical implications: Metallographic and fractographic analyses are crucial in elucidating the wear mechanisms in mechanical components. Additionally, finite element analysis can indicate the influence of stress on the mechanical part, providing insights that can effectively guide the limiting transmission power to ensure extended service life. Originality/value: Cost reduction, time for analysis, and finding the root causes of the problem should be conducted to improve the implementation process, leading to high product quality. [ABSTRACT FROM AUTHOR]