Tribology of dust‐stop seals of mixing machines

Abstract

Dust stop seals are widely used in powder and rubber mixing industries.Design of the sealing system requires a continuous supply of pressurised lubricant, which is not recycled because of the risk of contamination. There is also the potential of large volume leakage of oil due to poor sealing, increasing operational costs and necessitating remedial measures to avoid environmental protection. Furthermore, the seal faces are prone to failure in relatively short periods of time due to reduced gap and lubricant leakage. The paper presents an analytical method and numerical predictions based on Reynolds equation under combined hydrodynamic and hydrostatic conditions with the entrant lubricant through hydraulically loaded feedholes. The validity of these methods is ascertained through comparison with a more complex but timeconsuming solution of Navier-Stokes equations. The numerical predictions allow for determining the prevailing tribological contact conditions and assessing its suitability for evaluating the sealing performance of mixing machinery.

Application of Load-Sharing Concept to Mechanical Seals

“…In this regime, a thin lubricant layer known as the lubrication film carries most of the applied load. The contact of asperities also contributes to carrying the total load, which raises the surface temperature and causes wear, and on the other hand, changes the topography of the surface due to the plastic or elastoplastic deformation of asperities [29].…”

“…Based on this equation, it can be concluded that the asperity pressure throughout the asperity region is equal to the overall contact pressure p m . If N a is considered the number of asperities on the surface with a nominal area A n , then the contact number of asperities can be achieved using the following relationship [29]:…”

“…A t is the overall actual contact surface, and total load, w t , is achieved from the total distribution of each of the asperities in all its small contacts. Therefore, for a certain distance between two surfaces, the contact surface and the total actual load are obtained from the following equation [29]:…”

“…They demonstrated the efficacy of the developed approach for predicting seal performance and determining leakage. However, it should be noted that it is difficult and time-consuming to solve the Reynolds equation in the mixed lubrication regime [29].…”