Molecular dynamics simulation study of interface stability of spiral magnetic fluid seals of cone bit

Purpose The purpose of this paper is to investigate the interfacial stability between the magnetic fluid and the grease during the drilling process of a spiral magnetic fluid seal in a tooth wheel drill bit. Design/methodology/approach In this study, the actual working conditions of a tooth wheel drill bit in downhole operation are simulated by means of molecular dynamics, so as to observe the microscopic state of the interface between the magnetic fluid and the grease of the tooth wheel drill bit helical magnetic fluid seal during the actual operation. Findings Through the molecular dynamics simulation carried out under five working conditions, respectively, it can be obtained that with the increase of temperature and pressure, the magnetic particles diffuse more and more slowly in the system, and the interaction force between the magnetic particles and the grease molecules becomes weaker and weaker. And there is only a slight fusion of the interface between the magnetic fluid and the grease, and the overall performance of the magnetic fluid is not affected by the grease. Originality/value In this study, to the best of the authors’ knowledge, the spiral magnetic fluid sealing structure of a tooth wheel drill bit is proposed for the first time, which is highly innovative. And the study of using molecular dynamics to simulate the interfacial stability between the magnetic fluid and grease analyzes the feasibility of the spiral magnetic fluid sealing structure of the tooth wheel drill bit. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2024-0065/