Tribology in Industry

11-23

Authors: H.P. Khairnar, V.M. Phalle, S.S. Mantha

In the present work, a comparative frictional behaviour of drum brakes and disc brakes in automobiles has been investigated. The influential factors; contact force and friction radius were modeled for the estimation of the friction coefficient for drum as well as disc brakes. The effect of contact force and friction radius is studied with varying conditions of parameters; longitudinal force, caliper force and torque on piston side as well as non-piston side. The numerical results obtained have been compared with the similar obtained from virtual Matlab/Simulink models for drum and disc brakes. The results evidenced that friction radius predominantly affects brake pressure and thus the friction coefficient, also the increase in contact force resulted with decrease in friction coefficient both for drum and disc brakes. Further it has been found that disc brakes exhibit gradual decrease of friction coefficient due to the equitable distribution of braking effort while drum brake presents sudden variations in friction coefficient. It can be revealed that frictional behaviour of disc brake is more consistent than drum brake.

33-44

Authors: S. Bhaumik, S.D Pathak

The present work aims to carry out a comparative experimental analysis of tribological properties of 372cSt mineral oil and 229cSt castor oil. The antiwear and extreme pressure properties of both the oils have been analysed according to ASTM G 99 and ASTM D-2783 standards. The surfaces of the balls and pins after tribo tests have been analysed using Scanning Electron Microscope (SEM) images. The present test results predict that the antiwear and extreme pressure properties in case of the selected commercially available mineral oil are better than neat castor oil. Both coefficient of friction and frictional force increased by 16-42 % and 16-35 % respectively in case of neat castor oil as compared with that of the mineral oil. The load carrying capacity in case of mineral oil has been found to be 250 kg while in case of castor oil it has been found to be 126 kg. SEM images show a higher plastic deformation in case of castor oil as compared to the mineral oil. Both mineral oil and castor oil showed surface deteriorations and increase in roughness after 40 hrs of intermittent running during scuffing test. Thus, the present investigation indicates that the tribological properties of neat castor are inferior to that of mineral oil although close observation of the results shows that both AW and EP properties of neat castor oil are much closer to that of commercial mineral oil. Thus, the present work would help in formulating castor oil based new bio lubricants with better anti wear and extreme pressure properties

57-65

Authors: G.M. Deheri, J.R. Patel, N.D. Patel

An attempt has been made to analyze the performance characteristics of a Shliomis model based ferrofluid lubrication of a rough porous convex pad slider bearing. Regarding roughness, the stochastic method adopted by Christensen and Tonder finds the application here in statistical averaging of the associated Reynolds equation. The graphical representation suggests that the adverse effect of surface roughness can be reduced to certain extent by the positive effect of Shliomis model based ferrofluid lubrication. Further, for this type of bearing system, this model remains more effective as compared to Neuringer-Rosensweig model.

74-82

Authors: A. Singla, A. Chauhan

The present study is aimed at experimental evaluation of both oil film pressure and temperature at the central plane of finite elliptical journal bearing configuration. These parameters have been obtained by running the machine at various speeds under different applied loads ranging from 500 N to 2000 N using three different grades of oil (HYDROL 32, 68 and 150). The data has been obtained through a test rig which is capable of measuring both pressure and temperature at the same location on the elliptical bearing profile. An elliptical journal bearing with journal diameter=100 mm, L/D ratio=1.0, Ellipticity Ratio=1.0 and radial clearance=0.1 mm has been designed and tested to access the pressure and temperature rise of the oil film at the central plane of the bearing. Two different lobes of positive pressure have been obtained for elliptical bearing which results in smaller area for cavitation zone and accounts for better thermal stability. Also, with the increase in load both pressure and temperature of an oil film increases for all the three grades of oil. Experimentally, it has been established that the HYDROL 68 is suitable grade of lubricating oil which gives the optimum rise of pressure and temperate under all operating conditions among the lubricating oils under study.

90-101

Authors: K.P. Lijesh, H. Hirani

In the present research work Failure Mode and Effect Analysis (FMEA) of an Active Magnetic Bearing (AMB) has been presented. Various possible failures modes of AMBs and the corresponding effects of those failures on performance of AMBs have been identified. The identified failure modes of AMBs will facilitate designer to incorporate necessary design features that would prevent the occurrence of the failure. The severity, occurrence and detection of the failures modes are determined based on a rating scale of 1 to 5 to quantify the Risk Priority Number (RPN) of the failure modes. The methods to eliminate or reduce the high-risk-failure modes are proposed.

108-114

Authors: L.V. Priyanka Muddamsetty, N. Radhika

Aluminium alloy reinforced with boron carbide (10 wt.%) was fabricated using stir casting method followed by centrifugal casting and the cylindrical specimen with dimension 150 x 150 x 15 mm was obtained. The composite specimens were heat treated at various aging temperatures and aging time for property improvement. Solution treatment was done at 525 ℃ for 5 hrs. Taguchi’s method was used for designing the plan of experiments and L27 orthogonal array was formulated for the analysis of data. The wear test was conducted on the outer periphery of centrifugally cast Functionally Graded composites using pin-on-disc tribometer. Optimization of parameters such as applied load (10 N, 20 N, 30 N), agingtemperature (150 ℃, 175 ℃, 200 ℃) and aging time (2 hrs, 6 hrs, 10 hrs) was done using Signal-to-Noise ratio. “Smaller-the-better” criterion was used for analyzing the results. Results ended up with a conclusion that aging time (92.19 %) had major influence on tribological behavior followed by aging temperature (5.36 %) and applied load (1.95 %). Scanning Electron Microscope (SEM) analysis was performed to understand the wear mechanism in heat treated specimens.

121-126

Authors: F.A. Elshukri, R. Lewis

In this study the effect of sliding speed, applied load and period of time on the wear resistance of end post materials of Nylon12 (N12), Nylon66 (N66), Nylon66a (N66a), Epoxy Glass (EG) and Phenolic Resin Bonded Fabric materials were investigated. Wear tests were implemented in dry and wet conditions on a Block-on-Ring apparatus. The tests were carried out at different sliding speeds of 1.5 m/sec., 3.3 m/sec., and 7.2 m/sec., applied loads of 10 N, 30 N and 50 N, and three periods of time 5 min., 30 min. and 60 min. The obtained results in dry condition tests showed that the wear resistance of Nylon and composite materials used in this study decreases with an increase in applied load and sliding speed due to increase in contact temperature. But the impact of these increases in sliding speed and applied load was less on the wear resistance of composite materials. Unexpected results were that in wet test condition for Nylon66 materials where the wear resistance was less compared with the same material in a dry test.