Papers by Keyword: Lubrication

Abstract: The gears of a gear box were modeled and analyzed through Romax, and the effects of pressure angle on their lubrication properties were studied. The studies had shown that as the increase of pressure angle, the safety factor against micropitting had significantly increased. The gears were less prone to micropitting. The minimum film thickness and the maximum film thickness of the gears had also significantly increased, so the gear lubrication performance had been improved. It had important significance to improve the carrying capacity and prolong the service life of the gears.

Abstract: In this paper, an application of the surface plasmon resonance (SPR) method to real-time and in-situ measurements of changes in adsorption film thickness, e.g., fatty acid adsorbed films, is presented. As discussed in the previous study, the high sensitivity and overall simplicity of its optical system make the SPR method advantageous for monitoring lubricant film thickness. In order to demonstrate the high sensitivity of the SPR method, in-situ and real-time adsorption film growth processes of stearic acid (additives) in hexadecane (base oil) were monitored using the Otto configuration. Based on a comparison between experimental and model calculation results, changes in the adsorption film thickness during a series of different contact tests were measured.

Abstract: An experimental investigation was performed to study the wear of a promising dental ceramic, i.e., machinable lithium disilicate glass ceramic, under lubrication conditions, in particular, to examine effects of the surface finish and applied load on wear. Our previous work has shown that a fine finish in a dry condition did not necessarily translate to the lowest wear volume due to changes in the dominant wear mechanisms. This study tested the ceramic specimens with four average surface roughness values of S_a = 143 nm, 217 nm, 353 nm, and 692 nm on a reciprocating sliding friction rig against alumina balls with two applied forces of 5 N and 25 N in a bath of distilled water. Comparing with the results obtained in the dry conditions, this study shows that surface roughness of approximately 200 nm may be suitable for surface preparation of crowns made from the material in the wet and dry wear conditions in the oral environment.

Abstract: A great deal of effort and research has been dedicated to recycled aluminum alloys, mainly to recycling processes and to the mechanical properties of recomposed parts; however, very limited work has been oriented towards the machinability of recycled aluminum materials. Recycled and recomposed aluminum parts sometimes need machining to obtain the final usable part shape and for assembly purposes. The acceptability of using recycled materials in design and engineering applications depends not only on their mechanical properties, but also on their machinability. This paper investigates the machinability of recycled aluminum alloys based on surface finish, cutting forces and chip formation. Two recycled foundry aluminum alloys were used: one from aluminum can covers and another from aluminum chips produced during machining. The machining operations investigated included turning and drilling under dry and wet conditions. The two tested recycled aluminum alloys showed different machinability behaviors and different part quality characteristics, suggesting that it would be desirable to consider separating aluminum wastes and chips considered for recycling by origin or type prior to melting and recasting.

Abstract: In the context of high tool wear concerning machining of carbon fiber reinforced plastic (CFRP), it is desirable to study new processes and techniques which are able to lower the wear and thus induced costs. Therefore, this article presents a novel minimum quantity dry lubrication (MQDL)-process. It delivers minimal amounts of graphite powder, using compressed air as a conveying medium to its operating area between the tool and workpiece. For this purpose a prototypical fluidisation device for conditioning, dosing and conveying the graphite powder was built. The investigations have shown that the constructed prototype is already able to deliver tiniest amounts of graphite mass flows (less than 3 g/h) reliably. Furthermore, first results of drilling tests with internal MQDL-supply are presented. The cutting edge radius of the solid carbide drilling tools has been chosen as the wear measuring quantity. With the use of MQDL at drilling CFRP, a clear reduction in wear is shown, in comparison to pure compressed air. Finally the article shows further research and application areas of this new MQDL-technology.

Abstract: In flat cold rolling of steels, emulsions of rolling oil and water are normally used to cool and lubricate, i.e. up to 2.5 % oil is emulsified in water and sprayed on work rolls and sheet. In this article it is shown how the Henkel AG and ArcelorMittal Eisenhüttenstadt GmbH developed and industrialized successfully the thin film lubrication (TFL) in front of stand one of the AMEKO. With this device, pure rolling oil is sprayed onto the work rolls. This resulted in a rolling force decrease of approx. 4.5 % in the stand and a higher operating life of the work rolls. Furthermore, the FlexMix system of the Henkel AG is presented. Therewith it shall be possible to react flexibly on the lubrication conditions in the roll gap. Using two spray bars emulsion with higher concentration is sprayed onto the strip. Trial runs were carried out in front of rolling stand number two of the AMEKO. A rolling force reduction in the stand of up to 9.7 % was seen. Moreover up to 7.9 % of less current could be observed on the motors of this stand. The article illustrates the theoretical and practical basics on both developments including effects on the production of the AMEKO. Further an outlook is given of how future lubrication techniques can optimize the production of flat steel cold rolling mills.

Abstract: The continuously tightening regulations limiting the amount of exhaust gas components of internal combustion engines force the manufacturers to further increase the effectivity of their power units. Due to the already relatively highly-developed state of engines result in the need of research and development of even smaller engine parts – e.g. piston rings. The main aim of this project was to develop a tool for the computer simulation of the behavior of the piston ring pack, which could aid the optimization process of the piston ring pack towards lowered friction losses.

Abstract: The purpose of this paper is to present the influence of the casting parameters in the process of producing aluminium alloy components of gearbox housing type in automotive industry. The project has as objectives the minimization of the most common casting defects met in casting of gearbox housings through adjusting the parameters of the process. In order to minimize these defects, it was studied the casting speeds in phases I and II, multiplication pressure of phase III and the mould temperature that is influenced by both the cooling channels inside the mould and the spraying process of the mould (lubrication/cooling) that helps regulate the optimum temperature. The experimental results showed that the casting defects such as pores, cast in stages, shrinkage cavities, gas holes and tightness are significantly reduced by periodically controlling and correcting the specific casting parameters.

Abstract: The cooling systems on machine tools are particularly important; these have a positive influence on the cutting operation and the quality of machined surface. A particular importance represent finding an optimal correlation between the lubricant and coolant used, the material to be processed, processing method and the cutting regime. A high temperature in the working area over a certain value allowable can be harmful in terms of both the resulted surface quality and repercussions on the life of the cutting tool. The parameters of the cooling-lubricating fluid flow can be influenced by the nature of the fluid or fluids, or the nozzle geometry used, which generally has a convergent-divergent geometry in order to achieve a better dispersion of the coolant/lubricant on the area to be machined.

Abstract: Deep drawing is one of the most important processes for forming sheet metal parts. Besides its importance as a forming process, cup drawing also serves as a basic test for the sheet metal formability. This article investigates the influence of the die punch clearance, the average velocity in the active stage and the lubrication on the deep drawing quality expressed by the thickness evenness on the finished product surface. In order to minimize the number of experimental trials, a fractional factorial design was developed together with an orthogonal array, thus analyzing the contribution of the three parameters under study to the quality of the deep drawing process. Using TAGUCHI’s signal-to-noise ratio, we determine that ram velocity has a major influence, followed by the clearance between the active elements, while the contribution of lubrication is negligible. The results of the research are useful in developing a sensible design of experiments.