Micromechanical model of dry friction hybrid polymer composite clutch facings

Modelling the complex coupled thermomechanical and tribological contact of a dry friction clutch system between cast iron flywheel and scatter-wound hybrid composite clutch facing requires a thought through investigation of the friction material properties and behaviour. Challenges of the creation of a mechanical stiffness matrix for such a complex material are described in this paper along with simplification ideas and solutions

Friction Behavior of Engineering Polymers Treated by Atmospheric DBD Plasma

The frictional behavior of (PA6 E and PETP) engineering polymers commonly used in the industry were investigated implying 3D surface topography due to Dielectric Barrier Discharge (DBD) source, atmospheric cold plasma surface treatment and compared to the pristine surface results under the same test conditions. The 3D surface topography shows a decrease in the surface roughness after treatment and keeps good topographical stability with the function of time. The friction coefficient of treated samples were lower than the pristine one under “run-out” lubrication conditions in line with surface characterization results

Abrasive sensitivity of engineering polymers and a bio-composite under different abrasive conditions

Two different test systems were designed to evaluate the tribological behavior of five engineering plastics (Polyamide-PA grades and Ultra High Molecular Weight Polyethylene-UHMW-PE) and a fully degradable bio-composite (Polylactic Acid-PLA/hemp fibers) targeted to agricultural machinery abrasive conditions. Pin-on-plate tests were performed with different loads, sliding velocity and abrasive particles. The material response was further investigated in a slurry containing abrasive test system with different sliding velocities and distances, abrasive media compositions and impact angles. The abrasive wear, the change of the 3D surface roughness parameters, the friction force and contact temperature evolution were also analyzed as a function of the materials' mechanical properties (H,E,sigma(y),sigma(c),epsilon(B),sigma(F),sigma(M)) and the dimensionless numbers derived from them. Using the IBM SPSS 25 software, multiple linear regression models were used to statistically evaluate the measured data and to examine the sensitivity of the material properties and test system characteristics on the tribological behavior. For both test setups, the system and material characteristics influencing the dependent variables (wear, friction, heat generation) and the dimensionless numbers formed from the material properties were ranked using standardized regression coefficients derived from the regression models. The abrasion sensitivity of the tested materials were evaluated taking into account a wide range of influencing parameters

New method for dynamic tribological test of engineering polymers

In this article, tribological tests of Polyamide 6 (PA 6), Ultra High Molecular Weight Polyethylene (UHMW PE) and Polyoxymethylene copolymer (POM C) by a new testing method is introduced. The tribometer used in the test is capable for pin-on-disc measuring within all possible layout known in tribology practice, otherwise can be modified into special model of fatigue sliding test. The pin was a specimen made from examined materials, always in contact with a rotating metal disc under a normal load, which is usually static. However, since vibration exists in every practical scene as an important phenomenon, for instance in turning process, we added vibration load into the test. The supplement load is generated by a special-designed vibrating machine. Then properties of examined materials can be studied more profoundly under vibration load. As a result, different value of friction coefficient in static and vibration load have been discovered and taken into comparison

Analysis of Vibration During Turning Process of Different Materials

In this article, we would like to introduce the problems caused by vibrations in case of polymer turning processes. Nowadays there is a lot of research in this topic, to avoid the unnecessary phenomena of vibrations. The two most common methods are the Spindle Speed Variation (SSV), and the Vibration Assisted Machining (VAM). In case of SSV, the CNC machine can increase and decrease the speed of spindle continuously during turning which can significantly reduce the effects of chatter. This method is beneficial for longer workpieces when there is not any support except the chuck. Vibration-assisted machining can be used to minimise the problems caused by vibrations. VAM combines precision machining with small-amplitude tool vibration to improve the fabrication process. It has been applied to some processes ranging from turning, drilling to grinding. Based on the enumerated above we made some trial measurements about the basic vibrations of the turning tool shank. The tests were done on an NCT EUROturn-12B CNC machine which can found in the workshop of our institute. The tested material was Polyamide 6 because this is the most commonly used polymer in the industry. In the future, we would like to test some other basic and composite polymer materials too. The equipment was served by a specialist from SPM Budapest Kft. With these tests, our goal was to make sure that the equipment and the measuring setup are suitable for our future research

Hőre lágyuló műszaki műanyag fogaskerekek élettartama: Lifetime of the engineering thermoplastic gear

Nowadays, plastic gears are gaining more and more space within the field of power transmission systems due to their advantageous properties. However, their applicability has limitations such as load carrying capacity and temperature sensitivity. Design standards are currently incomplete and only properly developed for specific materials (e.g., polyoxymethylene (POM) or polyamide (PA), etc.). In this work, the lifetime and the surface temperature of the polyvinyl chloride (PVC) gears are investigated at a given speed, and variable load under non-lubricated conditions, applicable and what forms of failure are expected. The obtained results are compared with the results of the POM and PA gears found in the literature. Thus, there is a comprehensive picture of the load range in which the examined gears can be used and what forms of failure are expected. Kivonat Napjainkban a teljesítményátviteli rendszereken belül a műanyag fogaskerekek egyre nagyobb teret hódítanak előnyös tulajdonságaik miatt, azonban alkalmazhatóságuknak megvannak a korlátjai, mint például a terhelhetőség és a hőmérsékletre való érzékenység. A teljesítmény adatok, valamint a tervezési szabványok jelenleg hiányosak, valamint csak adott anyagokra (pl. polioximetilén (POM), vagy poliamid (PA) stb.) vannak megfelelően kidolgozva. A munkánkban a kevésbé elterjedt polivinil-klorid (PVC) fogaskerekek élettartamát és hőmérséklet alakulását tanulmányoztuk adott fordulatszám, illetve változó terhelés mellett kenés nélküli körülmények között A kapott eredményeket összehasonlítjuk a szakirodalomban fellelhető POM és PA fogaskerekek eredményeivel, így átfogó képet kapunk arról, hogy a vizsgált fogaskerekek milyen terhelhetőségi tartományban alkalmazhatók, valamint milyen tönkremeneteli formák várhatóak

The Effect of Crystallinity on the Toughness of Cast Polyamide 6 Rods with Different Diameters

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