Emerald | Industrial Lubrication and Tribology | Table of Contents

Materials flow for different lubricants during cold forming

Fri, 27 Jul 2012 00:00:00 +0100

Abstract

Purpose - Barreling contour variations on the free surfaces of cylindrical upset specimen are to handle measuring for different upsetting reductions and different lubrication conditions in this study.Design/methodology/approach - The materials flow for various materials using different lubricants in upsetting were investigated in this study. SAE 1020 steel, commercially pure copper and CuZn40Pb2 brass were used as the test materials. Upsetting process was applied to the cylindrical specimens using flat end dies. Three type lubricants, namely grease, graphite and SAE 40 oil were used in this study. Experiments were performed using a hydraulic press, which has 5 mm/s ram speed, and with a capacity of 150 metric tons.Findings - Variations of barrel radius change clearly with increasing deformation ratio as depend on lubricant type. Radius values are different with each other for SAE 1020, Cu and Brass specimens. It was understood that surface roughness effect is negligible at material types. The highest radius values were obtained at the brass among the all materials for the same deformation ratio. The materials flow is hard for brass specimens because of its brittleness which is due to cold drawing so its bareel radii are high. On the contrary SAE 1020 and copper are more suitable for the plastic deformation. As it is shown at the above Figures, the higher radius values were obtained especially with grease lubricant at brass specimens. Research limitations/implications - It would be interesting to search material flow for different materials and lubricants. It could be the good idea for future work could be concentrated material flow on upsetting using different lubricants. Practical implications - The friction at the faces of contact retards the plastic flow of metals and the surfaces and in its vicinity. a conical wedge of a relatively undeformed metal is formed immediately below it, while the rest of the cylinder metal suffers high strain hardening and bulges out in the form of a barrel. This demonstrates that the metal flows most easily towards the nearest free surface which is the point of least resistance. However, the use of lubricants reduces the degree of bulging and under the conditions of ideal lubrication; the bulging can be brought down to zero. Originality/value - The main value of this paper is to contribute and fulfil the detailed the dependency of barrel radius on material type by upsetting of specimen of various materials using different lubricants that are being studied so far in the literature.

Measurement of Oil Film Thickness between Piston Ring and Liner Using Strain Gauge

Fri, 27 Jul 2012 00:00:00 +0100

Abstract

Purpose - The aim of this paper is to develop a technique to measure the oil film thickness between piston ring and liner throughout the stroke, without impairing the surface properties of the piston ring and liner. Mechanical properties of the piston ring, like ring stiffness is also not altered. Effect of variation in bore on the movement of piston ring can be studied with the proposed technique. Design/methodology/approach - The gap Hmin between the cylinder liner and the piston ring is formed due to the hydrodynamic pressure generated by the presence of oil film between piston ring and liner. This gap can be inferred by measuring the movement of the inner surface of piston ring with reference to a sensor mounted on the piston at a fixed distance from the piston ring. The piston ring is connected to the sensor through reasonably rigid member. The underlying assumption here is that there is no elastic deformation of the piston ring due to the hydrodynamic pressure. The fundamental sensor to measure oil film thickness used in this setup is a set of strain gauges.Findings - 1. It is possible to measure oil film thickness by proposed arrangement for entire stroke without changing the surface properties. 2. Mechanical properties of the piston ring like ring tension is not affected. 3. The results possibly provide the correct picture of the piston ring movement throughout the stroke. 4. The measurement at near zero speed can give information on the movement of piston ring due hydrodynamic action and to the variation in the bore. 5. The measurement is not affected by engine vibrations. 6. The proposed technique can be helpful in validating the theoretical models proposed in the literature. Research limitations/implications - 1. The measurement is possible only in unfired condition. However, this attempt can be considered as the basis to measure OFT in fired condition with necessary improvements. 2. It is not feasible to measure quantity of lubricant / extent of lubricant on leading or trailing edge of piston. 3. Effect of temperature on the oil film thickness cannot be studied as the engine is not fired. 4. It is assumed that piston ring does not pass through elasto-hydrodynamic lubrication regime. 5. Debris / worn out particles in the oil may affect the indicated oil film thickness at local points. Originality/value - This manuscript is the result of the original work carried out during the PhD work at Sardar Vallabhbhai National Institute of Technology, Surat, Gujarat, India. The results are original and the test setup is available at the institute.

Friction heat conduction and entransy of friction lining

Fri, 27 Jul 2012 00:00:00 +0100

Abstract

Purpose - This paper aims to analyze the friction heat conduction and entransy of two friction linings in the high-speed slide accident of a mine friction hoist.Design/methodology/approach - Firstly, the dynamic thermophysical properties were analyzed and their fitting equations were also obtained. Additionally, the dynamic heat partition ratio was obtained according to the dynamic thermophysical properties. Then, a simple method was developed to solve the temperature rise of friction lining. Finally, based on the theoretical model of temperature rise, the entransy of friction lining with respect to T and t were gained.Findings - The error of temperature rise between simulation result and experiment result is less than 7%, which proves that the theoretical model is correct. The entransy decreases with the temperature below 40°C and it increases after 40°C. The entransy of lining K a little higher than that of lining G within 19s, but the entransy of lining G is much higher than lining K after 19s and the entransy difference gets great gradually. It is indicated that the lining K has good heat-resistant property which is of great benefit to the tribological property of friction lining.Practical implications - Our study provides fundamental basis for developing a new friction lining with good heat-resistant property, and it also bring forward a new quantitative method to evaluating the heat-transfer capability of friction materials.Originality/value - A simple method was introduced to calculate the temperature rise of friction lining with the consideration of dynamic thermophysicial properties and dynamic heat partition ratio. And the entransy of friction lining was obtained to evaluate the heat-transfer capability of friction linings quantitively.

Pattern recognition based surface roughness prediction in turning Hybrid Metal Matrix Composite using Random Forest algorithm

Fri, 27 Jul 2012 00:00:00 +0100

Abstract

Purpose - Surface roughness prediction using pattern recognition for the Aluminium Hybrid Metal Matrix Composite (HMMC).Design/methodology/approach - Hybrid composites were manufactured using liquid metallurgy technique. The cast HMMC was machined using an industrial CNC turning centre and the machining vibration signals were acquired using an accelerometer. The acquired signals were processed and used to build a machine learning model for predicting surface finish based on the tool signature. Findings - The fabricated HMMC is found to have good machinability. The online surface roughness prediction model based on vibration signature analysis was developed successfully.Practical implications - Established a technique for predicting and monitoring the surface quality during machining using a low cost accelerometer. It is capable of being integrated with the machine controller for online warning of deviations in surface roughness. The system is reconfigurable for any machining condition with a very short training period. The use of this model facilitates online surface roughness monitoring, avoiding the need for costly measuring equipment. Originality/value - The model developed is innovative and not reported widely to the best of authors’ knowledge. The use of accelerometer based surface roughness prediction and control is an innovative approach for automation of machining process monitoring. These can be integrated in to any existing machining centre as a standalone system or can be integrated in to the CNC controller like Fanuc or Siemens.

The tribological behaviour of Fe-C-Al cast iron – Effect of temperature

literatinetwork@emeraldinsight.com (M Abdul Maleque, S Shaha) — Fri, 27 Jul 2012 00:00:00 +0100

Abstract

Purpose - The aim of this paper is to study the tribological behaviour of Fe-C-Al cast iron at different temperatures using universal pin-on-disk machine. Design/methodology/approach - The cold set resin bonded sand mould casting process was employed to develop Fe-C-Al cast iron and Fe-C-Si cast iron. The microstructures of materials were studied using field emission scanning electron microscope. The wear and friction tests were conducted using universal pin-on-disk machine at 25 0C, 100 0C, 200 0C and 300 0C temperature. The wear damage surface was characterized using scanning electron microscopy. Findings - The lower wear rate was found for Fe-C-Al cast iron compared to Fe-C-Si cast iron and delamination type wear morphology was observed in both types of cast iron materials. The results also showed that the friction coeficient value of Fe-C-Al cast iron was lower than Fe-C-Si cast iron at different temperature. It can be concluded that the overall tribological behaviour of Fe-C-Al cast iron at higher temperature was better than conventional Fe-C-Si cast iron.Originality/value - The information on the development and tribological properties of the Fe-C-Al cast iron at different temperatures is scare in literature. The special type of cold set resin bonded sand mould was used for casting this Fe-C-Al cast iron material. Therefore, current study is quite new and it is hoped that it will provide a high value to the automotive and other engineering researchers for the application of this material.

Effects of non-Newtonian Rabinowitsch fluids in wide parallel rectangular squeeze-film plates

Fri, 27 Jul 2012 00:00:00 +0100

Abstract

Purpose - In the present paper, we analyze the non-Newtonian effects of Rabinowitsch fluids on the squeeze film performances between wide parallel rectangular plates.Design/methodology/approach - Based on the cubic-stress equation model, a nonlinear squeeze-film Reynolds-type equation has been derived. By using a small perturbation method, a closed-form solution of the squeeze film characteristics is derived for the parallel plates considering the non-Newtonian effects of cubic stresses.Findings - Comparing with the Newtonian-lubricant parallel plates, the effects of non-Newtonian cubic-stress flow rheology provide significant influences upon the squeeze film characteristics.Originality/value - It is shown that the non-Newtonian pseudoplastic behavior reduces the load capacity and the response time; however, the effects of non-Newtonian dilatant lubricant provide an increase in the load-carrying capacity and therefore lengthen the response time of parallel squeeze-film plates.

Static performance characteristics of hybrid journal bearings with plugged entry holes

literatinetwork@emeraldinsight.com (Hem Chander Garg) — Fri, 27 Jul 2012 00:00:00 +0100

Abstract

Purpose - This paper investigates the effect of plugging of holes on the static performance characteristics of a constant flow valve compensated hole-entry hybrid journal bearing system operating with Newtonian and non-Newtonian lubricants. The analysis considers the generalized Reynolds equation governing the flow of lubricant having variable viscosity in the clearance space and equation of flow of lubricant through constant flow valve restrictor. The non-Newtonian lubricant is assumed to follow the power law .The performance characteristics are computed for the two values of power law index (n=1.0 and 0.566). The computed results indicate that the blockage of holes during operation will not be the likely causes for the imminent failure of a well designed non-recessed hole-entry hybrid journal bearing.Design/methodology/approach - Finite element method has been used to solve generalized Reynolds equation governing the flow of lubricant having variable viscosity in the clearance space and equation of flow of lubricant through constant flow valve restrictor.Findings - The computed results indicate that the blockage of holes during operation will not be the likely causes for the imminent failure of a well designed non-recessed hole-entry hybrid journal bearing. The bearing configuration with plugged holes provides sufficient fluid film thickness and low power requirement as less lubricant is required to be pumped in the bearing. Originality/value - To the best of the author’s knowledge no study which considers the influence of plugging of holes on the static performance characteristics of a constant flow valve compensated hole-entry hybrid journal bearing system operating with Newtonian and non-Newtonian lubricant is yet available in the literature.

Study on variation of tribo-performance of commercial engine oils.

literatinetwork@emeraldinsight.com (Gananath Doulat Thakre, M R Tyagi) — Fri, 27 Jul 2012 00:00:00 +0100

Abstract

Purpose - To study the performance variability of commercially available engine oils based on Physico-chemical and Tribological performance parameters. Design/methodology/approach - By evaluation of Physicochemical parameters of Flash point, Pour point, TAN, Sulphated ash, Viscosities @ 40 & 100°C and VI. The Tribological performances in terms of friction, wear, weld load and load bearing capacity of lubricant film under the point and line contact geometries. Findings - Correlation between some of the physico-chemical properties and tribological performance parameters could be made and variation in performance of the lubricants assessed.Originality/value - The findings will be important to the engine oil producers and the users.