The Possibilities of Improving the Fatigue Durability of the Ship Propeller Shaft by Burnishing Process

Abstract

Heavily loaded structural elements operating in a corrosive environment are usually quickly destroyed. An example of such an element is a ship propeller operating in a seawater environment. This research presents a fatigue resistance test performed on elements operating in seawater. Different processing parameters applied on the samples in particular were compared with the specimens whose surface had been burnished differently and they were compared to specimens with a grinded surface. The research shows that the structural elements whose surface has been burnished can have up to 30% higher fatigue strength in a seawater environment than the elements whose surface has been grinded. During burnishing, an important feature of the process is the degree of cold rolling of the material. The resistance of the component to fatigue loads increases only to a certain level with increasing the degree of the cold rolling. Further increasing the degree of cold rolling reduces the fatigue strength. Introducing additional stresses in the components (e.g., assembly stresses) reduces the fatigue strength of this component in operation and these additional stresses should be accounted for while planning the degree of the cold rolling value. A device that allows for simultaneous turning and shaft burnishing with high slenderness is presented in the appendix of this article. This device can be connected to the computerized numerical control system and executed automatic process according to the machining program; this solution reduces the number of operations and cost in the process.

Numerical Simulation and Experimental Validation of Surface Roughness by the Smoothing Small Ball-Burnishing Process

“…The ball-burnishing process gives many advantages in comparison with chip removal processes. In addition to the benefit of producing a smoother surface [3,4], the burnishing process induces compressive residual stresses on the surface of a working piece and, therefore, the resistance to wear and fatigue also increases [2].…”

“…The ball-burnishing process gives many advantages in comparison with chip removal processes. In addition to the benefit of producing a smoother surface [3,4], the burnishing process induces compressive residual stresses on the surface of a working piece and, therefore, the resistance to wear and fatigue also increases [2]. In order to conduct the small ball-burnishing process, a tool embedded with a spring or a load cell system to set and maintain the burnishing force is designed to clamp the small burnishing ball.…”

“…Despite the compelling achievements reported in previous experimental works [2][3][4][5][6], universal application of these methods is not attainable. The validity of each empirical model is limited to a particular operating condition.…”

Fatigue enhancement and hardening effect through ultrasonic vibration‐assisted ball‐burnishing process on AISI 1045 steel

“…Conventional cutting processes have converged into more sophisticated processes by adding new trends, like laser‐assisted milling, 2 nano‐cutting fluids in turning, 3 ultrasonic machining, 4 or cryogenic machining 5 that allowed enhancing the superficial properties of a non‐treated material, improving the final roughness or hardness increase. However, these processes have shown a poor improvement in terms of fatigue life enhancement, compared to other finishing technologies such as shot or laser peening, 6 deep rolling, 7 or burnishing, 8 which demonstrated a fatigue enhancement through an increase of the compressive residual stresses, roughness decrease, and hardness improvement.…”

Advances and Trends in Non-Conventional, Abrasive and Precision Machining

“…The effect of burnishing on heavily loaded structural elements operating in a corrosive environment is the subject of [4]. The research presents a fatigue resistance test performed on elements operating in seawater, namely, a ship propeller, where various processing parameters of burnishing applied to samples are compared to specimens with a grinded surface.…”