Papers by Keyword: Lubrication

Abstract: High-strength aluminum alloys provide great potential for weight reduction in vehicle and aircraft production. Nevertheless, forming of these materials is limited at room temperature. Thermally supported forming operations such as hot forming and quenching (HFQ^®) allow forming of components without failure and reduced springback. Currently, the adhesive wear and high friction limit the use of HFQ^®-operations for high-strength aluminum alloys. Out of this reason, the present paper describes the tribological performance of new developed dry lubricants at elevated temperatures for the alloy AA7075. For this purpose, strip drawing tests were carried out in a modified open tribological system at temperatures between 20 °C and 400 °C. Additionally, the melting behavior of these lubricants, as well as the variation of the lubricant thickness, were investigated. The results show a reduction of the coefficient of friction at elevated temperatures.

Abstract: Surface topographies play a critical role in controlling friction, surface damage and transfer layer formation in engineering applications; hence understanding this is of great importance. In this work, experimental studies were carried out to understand the influence of surface topography on friction, scuffing and transfer layer formation in completely immersed lubricated sliding interactions. For this, sliding experiments were carried out in sphere on flat configuration using EN31 steel flats and Tungsten Carbide pin countersurface. Perpendicular and parallel surface topographies were induced onto the steel flats. Experiments were conducted at high normal loads of 1000N, 2000N and 3000N. The results show that Surface topography has a significant influence on the frictional response. When the topography directionality was perpendicular to the sliding direction, scuffing was observed only at a high load of 3000N. A ‘peak friction’ was also observed during the occurrence of scuffing. When the directionality in topography was parallel to sliding direction, scuffing and surface damage occurred from 2000N itself, accompanied by a high amount of transfer layer formation. This can be attributed to the directionality of parallel topography, which displaces away the lubricant during sliding interaction, creating metal-to-metal contact and hence leading to scuffing and higher transfer layer formation.

Abstract: The article considers the main points for choosing lubricants, taking into account the specifics of the injection molding process. The main drawbacks of modern lubricant compositions are identified, and based on them, the main requirements for lubricants for injection molding are determined. The most critical parameters of lubricants are specified, depending on the melt to be filled. The methods of applying lubricants are considered, and the most optimal ones are selected.

Abstract: In this paper, experiments are conducted on drilling AISI 316L Austenitic Stainless Steel material using minimum quantity lubrication technique under formulated environmental friendly Pongam oil as cutting fluid. Cutting torque, Thrust force and Surface roughness and Chip formation are studied for the evaluation. The experimental results show that, the Cutting torque is dropped by 36 % under modified Pongam oil as cutting oil, compared to mineral oil base cutting fluid. About 34 % drop in Thrust force and Surface roughness values are noticed under formulated Pongam oil. Further, spiral and continuous form chips are seen under vegetable oil mode of lubrication compared discontinues spiral form under mineral oil based cutting fluid.

Abstract: The paper presents studies of the Vickers hardness of various areas of steel friction surfaces, on which normal and adhesive types of wear were observed after the process of friction in the environment of the lubricant of various grades. Implemented a comparison of the friction surface hardness with the original surface. It is shown that the hardness varies in the process of friction and has different values ​​depending on the lubricating medium and the type of wear.

Abstract: Electro Sinter Forging (ESF) is a new sintering process based on Joule heating by high electrical current flowing through compacted metal powder under mechanical pressure. The whole process takes about three seconds and is based on a closed-die setup, where the sample is sintered inside a die. A near-net shape component is therefore manufactured. One of the challenges associated with this process is the ejection of the sample after sintering. Due to powder compaction and axial loading during sintering, a radial pressure is generated at the die/sample interface. Consequently, the ejection can be difficult, and the final quality of the sintered component in terms of roughness and surface defects may be affected. In the present work, four different lubricants and non-lubricated conditions were tested to investigate the effects on the final part quality. The sintered sample is a disc made of commercially pure titanium powder. The force was measured while ejecting the samples by using a speed-controlled press. The surface roughness parameter Sa was measured by using a laser confocal microscope.

Abstract: Reducing automobile weight has been necessarily accelerated to save energy and improve drivability. Accordingly, use of high strength steel and hollow sections help in weight reduction. In this study, the effect of trapped oil has been investigated to improve the metal flow in upsetting of a hollow workpiece using no mandrel. It was found that the ideal deformation without friction between the dies and the workpiece was nearly achieved when a low and thick ring with trapped oil was upset. The inner diameter of the oil-filled ring was expanded more than that of the benchmark ring. The effect of the expansion of the ring and the reduction of the friction proved helpful in trial forming of a gear preform.

Abstract: The effect of pulsed (oscillating) ram motion control on lubrication was investigated in hot forging of stainless steel workpiece with oxide glass lubricant. During the retreat in the pulsed ram motion, the workpiece was re-lubricated by flow of lubricant through the gap between the workpiece and the die. A hot spike-type forging test on a servo press with pulsed ram motions was carried out to investigate the lubrication performance of the oxide glass. In the test, the workpiece with a temperature of 1223 K was extruded into the hollow part of the upper die together with oxide glass in a manner that combined pulsed and stepwise ram operations. The re-lubrication of the workpiece with oxide glass was confirmed by the test results showing 5–10% reduction in the forging load and 5% longer length of the backward extruded part of the workpiece under an appropriate pulsed ram motion.

Abstract: Since the beginning of the 90’s, research activities focused on friction and wear in metal forming have been developed at the LAMIH UMR CNRS 8201 in Valenciennes. Specific methodologies have been designed to optimize a given forming process (bulk forming process or sheet forming process). These methodologies involve prototype benches which have been built to reproduce contact conditions encountered in manufacturing plants by taking specimens and contactors from the real industrial workpieces and tools. The evaluation of the friction coefficient added to the fine analysis of the surfaces have helped us to better understand friction and wear during processes. These facilities have been settled by numerical simulation at meso and macro scales by means of finite element methods. So, this paper is the sum up of the output of these methodologies with a specific focus on wear and lubrication, at room and hot temperatures.

Abstract: Cold forging processes enable the economical production of high quality components like joints, shafts and gears. The manufactured parts are characterized by improved properties such as hardness, surface quality and fatigue strength. For manufacturing components using cold forging, a comprehensive knowledge regarding the cold forging procedure and its process parameters is needed. One important influencing factor, which needs to be analyzed to use the potential of this kind of processes, is the tribological system, especially the used lubricant. The tribological conditions significantly influence the material flow and thus the workpiece quality. Furthermore, resource efficient and environmentally benign metal forming processes became very important within the last decade. The present study evaluates the resulting tribological conditions and their differences for various cold forging lubricants with and without a zinc phosphate based lubricant carrier. The lubricants are based on molybdenum disulphide, polymers, or both inorganic salts and waxes. The tribological conditions of the different lubricants are investigated using the Double-Cup-Extrusion-Test (DCET) as a laboratory friction test.