Papers by Keyword: Solid Lubricant

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Authors: Fu Meng Li, Yi Hua Feng, Hao Sun, Hai Xia Huang
Abstract: Under the special circumstances, we cannot use the lubricating medium and want to overcome the lake of friction properties of the single material in the cutting process, we will be done mainly through two ways: prepared self-lubricating tool and preparation of coating tools, in order to work reliable under the extreme conditions.
Authors: Gabriela Górny, Roman Pampuch, Ludosław Stobierski, Paweł Rutkowski
Abstract: Frictional and mechanical properties of hot-pressed Al2O3 and Si3N4 - matrix composites containing up to 5 vol. % hexagonal BN as a solid lubricant. A very low coefficient of friction which is necessary for high-speed cutting has been observed. Fracture toughness remained constant with increase of h-BN content while flexural strength changes with the hBN content have been found to depend upon the material homogeneity. The work has been supported by EU Funds in Poland under contract UDA-POIG.01.03-12-024/08-00.and has been realized in the frame of scientific-industrial consortium.
Authors: Jian Xin Deng, Ze Wu, Yun Song Lian
Abstract: Textured self-lubricated tools were designed and fabricated. Dry cutting tests were carried out on with these self-lubricated tools and a conventional tool. The tool wear and the friction coefficient at the tool chip interface were measured. It was shown that the tool wear and the friction coefficient of the textured self-lubricated tools were reduced compared with that of the conventional tool. Two mechanisms responsible were found, the first one is explained as the formation of a lubricating film with low shear strength at the tool-chip interface, which was released from the texturing and smeared on the rake face, and served as lubricating additive during dry cutting; the other one was explained by the reduced contact length at the tool-chip interface of the textured tools, which contributes to the decrease of the direct contact area between the chip and rake face. It is suggested that the using of textured self-lubricated tools is an effective way to reduce the tool wear in dry cutting.
Authors: Bao Yu Song, Zhi Jie Xie, Dai Zhong Su, Feng Zhang, Qing Zhao
Abstract: In order to investigate the life of bearings lubricated by solid lubricant (BLSL), which are installed in the rotational parts of spacecraft, a test platform has been developed. The platform can test the life of BLSL working under the vacuum environment with high-low temperature cycle conditions. The test platform consists of three systems of loading, measurement, and power and speed control. A corresponding computer program was also developed to measure, monitor and record test data. The working life of deep groove ball bearings lubricated by MoS2 solid lubricant was tested in 5×10-4Pa vacuum. The surface observation and analysis for the damage condition of the failed bearings were also conducted.
Authors: Guang Yong Wu, Chong Hai Xu, Yong Lian Zhang, Ming Dong Yi
Abstract: The design concept of functionally graded materials was first introduced into the development of self-lubricating ceramic cutting tool materials. An Al2O3/TiC/CaF2 graded self-lubricating ceramic cutting tool material was designed and fabricated. Mechanical properties were evaluated by comparing with those of Al2O3/TiC/CaF2 homogeneous self-lubricating ceramic cutting tool material. The results showed that the Al2O3/TiC/CaF2 graded self-lubricating ceramic cutting tool material had superior performance to the counterpart. Graded self-lubricating ceramic cutting tool materials are bound to have promising prospect in the field of high speed dry machining.
Authors: Said Larbi, Said Djebali, Ali Bilek
Abstract: The aim of the present work is the investigation of the influence of graphite powder addition to an unsaturated polyester type polymer (32% styrene content in mass) on the mechanical and tribological properties. For this purpose, we conducted bending tests and wear tests with a combination of four loads and three speeds for three different compositions (0, 1 and 2% graphite). The wear tests are carried out on a dry type pin on disk tribometer. The disk is made of quenched and annealed C48 steel (540 Hv hardness). Before the rubbing process, the discs are subjected to polishing in order to obtain approximately the same initial surface roughness. The results show that the addition of graphite powder improves the tribological properties; a noticeable decrease of the coefficient of friction, the mass loss and the wear rate are achieved with the increase of the graphite powder percentage for all sliding speeds and loads. A 2% graphite content causes a drop of the friction coefficient from 0.4 to 0.2. The results of bending tests showed a significant decrease of the stress and strain at failure and a slight increase in Young's modulus. In addition, for the three compositions, the results show a clear preponderance of the influence of the load on the tribological properties.
Authors: S. Sulaiman, M.K.A.M. Ariffin, T.S. Hong, N.A. Mustafa
Abstract: Milling is widely used metal removal process in manufacturing industry that involves generation of high cutting forces and temperature. Lubricants become important to reduce the cutting force and temperature for better machining processes and performances. Conventional cutting fluid has some limitations. The applications of conventional cutting fluid create some techno-environmental problems like environmental pollution, biological problems to operators and water pollution. Application of solid lubricant in milling has proved to be a feasible alternative to the conventional cutting fluids. The present work investigates the effect of boric acid as solid lubricant towards machining performances such as tool wear and surface roughness. The results indicate that boric acid can improve the cutting processes and performance compared to conventional cutting fluid.
Authors: S. Santosh, K. Rajkumar, A. Gnanavelbabu
Abstract: The prime rationale for designers to choose titanium in their designs for aerospace applications is its relative low weight for a given strength level and its relative resistance to high temperature. Excellent biocompatibility makes titanium as ideal material for many biomedical applications. Even though the titanium products are either sintered or cast into required shape, there is a need for machining in order to produce intricate shapes. However machining of titanium alloys poses many serious problems owing to the reactivity of titanium at high cutting temperatures and rapid tool wear. An alternative method to overcome this is by reducing the cutting zone temperature. This can be achieved by the addition of solid lubricants to regular cutting liquids and using it as minimum quantity lubrication (MQL) strategy. In this study, hexagonal boron nitride (hBN) powder with different concentrations (5, 10, 15 wt %) was mixed with water and used as a lubricant. Turning experiments were performed with TiAlN coated Tungsten carbide insert for a constant speed and variable feed rates. For comparison purpose, machining was carried out under dry conditions. Results indicate that the cutting zone temperature reduced drastically on addition of solid lubricant hBN with water. MQL conditions showed that cutting zone temperature decreased by several folds when compared to dry machining. However there was no significant decrease in temperature between 10 and 15 wt% hBN additions which indicates that 10% hBN addition proves to be optimal. This type of machining thereby paves way for sustainable manufacturing.
Authors: K. Rajkumar, S. Santosh
Abstract: Al-graphite and Al-Nanographite particulate metal matrix composites were prepared by two step stir casting method. The reinforced particulates in the metal matrix composites varied from 5% to 10% by volume fraction. Tribological performances of these composites were evaluated based on graphite particle size and normal load using a pin-on-disc tribometer. Al-Nanographite composites show higher load withstanding capacity and low coefficient of friction compared to aluminium graphite composites by the way of forming a thick graphite layer at the contact surface.
Authors: Seung Ho Kim, Sung Hun Cho, Simo Pekka Hannula, Soo Wohn Lee
Abstract: Solid lubricants were suited for the applications of high temperature parts. Recently, researches for self-lubricating ceramic matrix composites using solid lubricants, such as MoS2, WS2, h-BN, and graphite etc., became active. This work is to use the spark plasma sintering (SPS) technique in order to make self-lubricating Al2O3/15wt% ZrO2 nanocomposites with higher mechanical properties. To optimize the self-lubricating Al2O3/15wt% ZrO2 nanocomposite systems were added with different solid lubricants (CaF2, BaF2, MoS2, WS2, h-BN, and graphite). The coefficient of friction of CaF2, h-BN and graphite added composites in steady-state at room temperature are below 0.3.
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