Analysis of the tribological interaction of a polytetrafluoroethylene-lined radial lip oil seal, shaft and lubricant sample

To investigate the tribological interaction and wear mechanisms of polytetrafluoroethylene-lined radial lip oil seals in service, a sleeve, seal and lubricant sample taken off a rotating rig are studied. The test was terminated at 72 h, after severe leakage in the final 15 h of the test. All three components are studied using a coherence scanning interferometer and environmental scanning electron microscopy to investigate wear after testing. Results show a wear band on the aerospace grade case-hardened sleeve, appearing as a ‘polished in’ area by the seal. A study of the filler content of the polytetrafluoroethylene coating uncover glass fibres, calcium carbonate, carbon and graphite layers present, assumed responsible for the wear to the sleeve. The polytetrafluoroethylene coating is a 300 μm coating, distinct from the bulk elastomer. This finding is confirmed after observing this layer on both, the tested and new seal lip. Wear of the seal lip is measured and facilitated by comparison to the identical new seal. Lastly, debris from the seal and sleeve wear are found in the lubricant sample.

ANALYSIS OF REPLACEMENT PART TIME INTERVAL DETERMINATION OF CRITICAL IN ENGINE WATER COOLANT PUMP TYPES KRI FPB57

Maintenance management is required and has a very vital role for a KRI types FPB57, considering the type KRI is one Alutsista Navy who have a high frequency activity, as well as the broad range of operations support capabilities are varied so that the automatic machine is also high activity and in the end reliability will decrease. Methodology Failure Mode Effects and Criticality Analysis (FMECA) is a widely recognized tool for the study and analysis of the reliability of the design or process. Many authors in the field have emphasized specifically the usefulness of this method and its limitations. At this writing considering the lifetime of the machine and the elements therein specifically the components of the water coolant pump has had a lifetime of more than 20 years, because it can be said that the components have entered a critical period. Based on the steps Failure Mode Effects and Criticality Analysis (FMECA) through the calculation of Risk Priority Number (RPN), so we can determine the critical components of acquired 9 of 19 chances damage that has critical component is Angular Bearings, Cylindrical Bearings, Spacer Ring, Water Seal, shaft Seal, Seal Slip Ring, Impeller, O'Ring and shaft. These components if damaged can lead to engine breakdown. From the optimization results indicate that the component replacement Cylindrical Bearings have the fastest time, ie 98 days. While the replacement of components with the longest time, which is a component Impeller 134 days. Besides obtain the most optimal replacement time of each component, also produced the cost of replacement is effective, it is proved by the value of the optimal CBR. CBR value for all types of components is less than 1 (CBR <1).Keywords : FMECA, Risk Priority Number, Reliability, Replacement Intervals,CBR.

Diagnostic Model of Crankshaft Seals

The paper presents a research stand being a diagnostic model of radial lip seals used, among others, on crankshafts of piston combustion engines in order to identify the correctness of their operation. The possibility of determining the technical condition of lip seals on the basis of the proposed coefficient of correctness of operation has been described. The basic features of seals influencing their correctness of operation were also described, along with examples of determining the durability limits of lip seals. A modified version of the friction node of the T-02 four-ball apparatus is presented. It allows to check the correctness of sealing lips operation as well as to test the compatibility between the steel shaft, sealing lip and sealed lubricating oil. It was shown that the test results con-firmed the usefulness of the hypothesis that the quality of oil affects the durability of sealing lips and their coefficient of correctness. Additionally, attention was paid to the possibility of analyzing the pumping effect affecting the transition of the seal-shaft system from the state of partial suitability S2 to the state of full suitability S1 or to the state of unfitness S3, and because the change in the state of such a system is random, it requires a probabilistic analysis.

ANALISIS TERJADINYA SLIP PADA KOPLING DI UNIT SCANIA P 124 CB 8x4 NZ 420

In the operation of the unit whose successor does not use a hydraulic system, the role of the clutch is very important in transmitting power from the engine to the transmission. However, the clutch can only slip so that it can no longer function to forward power from the engine to the transmission. This can be caused by several things, including: wear on the clutch material, the presence of oil in the field of clutch surface, and spring damage to the clutch. On Scania P 124 CB 8x4 NZ 420 units this slip on clutch problem also occurs so research needs to be done to find the main cause. The method used in this study is to carry out checks and measurements and then the results are compared with the standard values that have been determined. The result shows that the cause of the slip on the clutch on the Scania P 124 CB 8x4 NZ 420 unit is 1) the presence of oil that wet the coupling surface is caused by a damaged seal shaft; 2) wear on clutch components namely clutch disc and pressure plate. To keep the seal shaft in good condition, regular and regular oil changes must be made and when the replacement of the seal shaft must be in accordance with the part number so that the possibility of the same problem can be reduced.

An Experimental and Theoretical Study of Brush Seal and Shaft Thermal Interaction

This paper presents a detailed experimental study and theoretical analysis of the thermal interactions of brush seal, shaft and airflow. The tests were performed in the Oxford University Brush Seal Test Facility. The facility, which was originally designed for the brush seal aerodynamic study, has been enhanced for thermal measurements. A variety of brush seals, typically applicable to aero and power generation gas and steam turbines, have been tested. The thermal interaction caused by changes in rotor and housing alignment was also studied. In the tests, in addition to the conventional aerodynamic parameters, such as the pressure, mass flow and torque, the temperatures of the rotor were measured and heat generated in the bristle/rotor contact were deduced using the finite element analysis. A theoretical analysis of the system was developed which predicts the heat transfer to the airflow from the bristle pack. This analysis is used to give a correlation to predict heat input to the rotor. The study provides valuable design information for the use of brush seals.

Numerical Analysis of Temperature Distribution at the Lip Seal-Shaft Interface

A numerical model has been developed to investigate thermal effects at the lip seal shaft interface. The thermal Reynolds, film thickness, and energy equations with appropriate boundary conditions were discretized according to the control volume finite difference approach and solved using the multigrid multilevel technique. The pressure distribution at the lip seal shaft interface for both isothermal and thermal cases are obtained. The temperature effects on leakage rates are obtained for various operating conditions. The results indicate that temperature effects within the film are significant and increase the side leakage rate as compared to the isothermal case.

Visco-Elastohydrodynamic (VEHD) Lubrication in Radial Lip Seals: Part 1—Steady-State Dynamic Viscoelastic Seal Behavior

In general, most analyses of radial lip seal behavior assume a static deformation state in the seal lip. Nevertheless, a dynamic excitation of the seal lip always occurs in practice, due to unroundness of the shaft or motions of the shaft center. In this first part of a two part paper the influence of dynamic excitation on the occurrence of clearances in a dry seal-shaft contact is studied, taking into account viscoelasticity and inertia of the seal material. The ultimate goal is to determine whether viscoelastic seal behavior can result in a continuous fluid film or not. First, attention is paid to the mechanical behavior of synthetic rubber under an oscillating load. The seal elastomer shows a glass transition, resulting in a strong increase in stiffness with frequency. Next, a FEM analysis of the seal-shaft contact under dynamic conditions is presented. The steady-state response of the seal is represented by a transfer function approach. It is shown that clearances develop due to viscous and inertial seal material behavior. In practice, these clearances are filled with fluid. Due to entrainment and squeeze effects a fluid film is generated. This phenomenon is designated visco-elastohydrodynamic (VEHD) lubrication, and is subject of Part 2.