Papers by Keyword: Friction

Abstract: Abrasive processes are influenced by many different parameters. For a systematic investigation of these influencing parameters, a test bench for abrasive tools has been developed and set up on a 3-axis milling machine. The test bench is capable to control the machining parameters, such as the cutting speed and the feed speed, regulate the lubrication conditions, such as the temperature or the flow rate, and measure the cutting force during the process. Impacts of the single force components are investigated by means of the abrasive tools in contact with the rotating workpieces and the calculation of the tangential force coefficient. In this paper, the set-up of the test bench is explained and the systematic proceeding in investigating the impacts is exemplified by cooling lubricants because the surface of the workpiece, the wear of the tool, the temperature and the friction forces are often influenced by the type of cooling lubricant and its composition. The aim of the test bench for tools is to understand the correlations of the single influencing parameters in abrasive processes. The first results of comparative investigations with cooling lubricants of different viscosities are presented and discussed.

Abstract: In this paper the frictional and tensile properties of stainless-steel fiber, cotton fiber, polyester fiber and rayon fiber, as well as the tensile and surface hairy properties of stainless-steel yarn, cotton yarn and wool yarn were tested and compared. Experimental results shown that the stainless-steel fiber has greater density, friction coefficient and tensile breakage strength but smaller breaking elongation. On the basis of summarizing the differences between stainless-steel fiber (yarn) and conventional textile fibers (yarns), difficulties occurred during knitting process were analyzed and the corresponding solutions were proposed.

Abstract: The characteristics, structure and applications of polyetheretherketone (PEEK) composites are introduced briefly. The research progress of friction and wear resistance properties of PEEK composites, modified by carbon fiber, other nanometer and micro-particles, are summarized. Suggestions for further research are put forward.

Abstract: To study the friction and wear properties of S136/WC-Co friction pair, friction and wear tests in air jet, nitrogen jet and nitrogen cold plasma jet atmospheres are carried out. The morphology and composition of friction surface are analyzed by camera, scanning electron microscope and energy-dispersive X-ray spectroscope. The wear behaviors and mechanism of anti-wear of the three jets to S136 are also discussed. The experiment results prove that the reactive species in the nitrogen plasma jet contribute to the generation of oxidation film on the friction surface quickly to reduce the wear of S136/WC-Co friction pair in real-time.

Abstract: The force of the concrete pumping work of mine rotor wet spraying machine is analysis in this paper, focusing on the piston assembly and cylinder bore rotor stress analysis during nesting, selecting the important structural parameters and optimizing the structure, to ensure the normal and efficient function of wet spraying working to improve the stability of wet spray machine work and life, and providing an important reference for the structural design of the piston assembly.

Abstract: The effects of acrylamide modified liner on bonding properties and tribological properties of self-lubricating spherical plain bearings were explored by used of Instron5944 electronic universal testing machine and homemade spherical plain bearings friction and wear tester. The results showed that the bonding properties of bearings modified by acrylamide modified liner were much more improved than those of the unmodified bearings; Self-lubricating spherical plain bearing friction and wear properties and oscillating frequency obvious correlational dependence. With the increase of the oscillation frequency, the friction coefficient and the wear loss increased, while the friction temperature rose. The friction coefficient, wear loss and friction temperature of bearings modified were much more improved than those of the unmodified bearings. It showed that the liners after modification treatment can improve the tribological properties of self-lubricating spherical plain bearings.

Abstract: The Skewed–Roller Slipping Clutch (SRSC) produces resistant torque which depends on the relative rotation and sliding between askew arranged cylindrical rollers and specially curved races. In this paper, the surface contact stress and von Mises stress distributions between the dub-off profiled rollers and races are calculated, with consideration given to the frictional contact and dynamic equilibrium of the rollers. The effects of the profiled roller’s parameters on the von Mises stress are investigated and the optimal modification parameters are calculated. In addition, the limiting resistant torque characteristics of the slipping clutch with optimal profiled rollers are discussed in detail.

Abstract: Cu-based powder metallurgy friction materials were prepared by varying of Fe and C (% weight) in the friction components. The samples were compacted under the load of 24 metric tonnes and sintered at a temperature of 950 °C for 45 minutes. The friction and wear characteristics the materials developed were studied using Chase machine. The results show that Fe and C have different friction and wear characteristics. The friction coefficient of Cu-30%Fe-15%C sample maintained to be high and slightly increased after the drum temperature of 350°C and subsequently stable throughout tests. The friction of Cu-20%Fe-10%C stable until the drum temperature of 450°C and then its start to decay slightly until the end of the test. On the hand, the friction of Cu-10%Fe-5%C start to decay after sliding a few minutes at the drum temperature of 230°C. Thus, it could be postulated that the friction coefficient increased with increasing weight percentage of Fe and C in the friction components. However, the volume loss shows that there is no direct correlation with the Fe and C content. The volume loss of Cu-10%Fe-5%C was higher than the two samples which had the lowest hardness. On the hand, the volume loss of the Cu-30%Fe-15%C was slightly higher than Cu20%Fe-10%C as result of higher porosity and lower hardness. Wear mechanisms of abrasion, adhesion and thermal were observed to be operated during sliding process.

Abstract: This paper presents a comparative study upon tribological behavior of polybutylene terephthalate (PBT) and a blend of PBT + This paper presents a comparative study upon tribological behavior of polybutylene terephthalate (PBT) and a blend of PBT + 10% aramid fibers, in dry regime. Some of the properties of PBT grade CRASTIN 6130 NC010^®. The tested materials they were obtained by molding at ICEFS Savinesti Romania. The aramid fibers added into PBT were supplied by Teijin, and have an average length of 125 mm. Tests were done with the help of a block-on-ring tribotester. The tests parameters were: three normal forces (F = 5 N, F = 15 N and F = 30 N), three values of sliding speed (v = 0.25 m/s, v = 0.50 m/s and v = 0.75 m/s) and a sliding distance of L = 5000 m, in dry regime, each test characterized by (F, v, L) being done twice. The conclusion of this research was that adding short aramid fibers in PBT improves the wear resistance, but slightly increases the friction coefficient. Also, the recorded temperatures near the contact are higher for the blend with aramid fibers. SEM investigation revealed particular processes within superficial layers of polymeric blend.

Abstract: The paper studies the cold-hardening phenomenon of material in high precision stamping. Level of material cold-hardening can be evaluated with thickness of cold-hardening stratum Δg (that may reach 0.2mm) and with its toughness (that may increase up to 1.8 times). For a correct conducing of high precision stamping process, is need to know, from designing stage, the way that different factors influence the piece material cold-hardening.The paper proposes the cold-hardening index IE that characterizes global and correct the cold-hardening level of stamped material. It was studied, for a large range of metallic materials (non-ferrous, carbon steels and allied steels), the way that tool-piece friction which varies from dry friction (μ=0.5) to limit friction (μ=0.05) influences value and evolution of cold-hardening index IE. The remark is that a reduced tool-piece friction goes to cold-hardening index IE increasing.