Measurement and Analysis of Inadequate Friction Mechanisms in Liquid-Buffered Mechanical Seals Utilizing Acoustic Emission Technique

Mechanical seals play an important role in the reliability of a process. Currently, the condition monitoring of mechanical seals is restricted due to the limitations of the traditional monitoring methods, including classical vibration analysis. For this reason, the objective of the present work is the detection and analysis of friction mechanisms inside a mechanical seal that are unfavorable and induce fault conditions using the acoustic emission technique, which allows the measurement of high-frequency vibrations that arise due to material fatigue processes on a microscopic scale. For this purpose, several fault condition modes were induced on a test rig of an agitator vessel system with a double-acting mechanical seal and its buffer fluid system. It was possible to detect the presence of inadequate friction mechanisms due to the absence and limited use of lubrication, as well as the presence of abrasive wear, by measuring a change in the properties of the acoustic emissions. Operation under fault condition modes was analyzed using the acoustic emission technique before an increase in the leakage rate was evaluated using traditional monitoring methods. The high friction due to the deficient lubrication was characterized by a pattern in the high-frequency range that consisted of the harmonics of a fundamental frequency of about 33 kHz. These results demonstrate the feasibility of a condition monitoring system for mechanical seals using the acoustic emission technique.

Impact of hot molding temperature and duration on braking behavior of friction material

The manufacturing process of brake materials used for braking applications consists of a succession of steps among which the hot molding has a major impact on properties and performance of materials. In this paper, impact of hot molding temperature and duration on mechanical and thermal properties of friction materials developed with simplified formulation was investigated. Two different hot molding conditions were studied: condition 1 (low temperature associated to long duration) and condition 2 (high temperature associated to short duration). Braking behavior, thermo-mechanical phenomena and wear and friction mechanisms were also investigated. Results indicated that hot molding conditions did not significantly affect mechanical properties and tribological behavior, but they had impact on thermal properties (material molded according to condition 1, material A presented a higher thermal conductivity) and on wear mechanisms involved in the contact. In addition, results revealed that the studied hot molding conditions impacted thermal localization recorded during braking that was denser for the disc rubbed against material B (material molded according to condition 2).

Molecular dynamics simulation of microscopic friction mechanisms of amorphous polyethylene

Determining the nature of microscopic mechanism of friction and wear by experimental method is a challenge. Molecular simulation technology is an effective method for exploring microscopic friction mechanisms of polymers.