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• New Method for Dynamic Tribological Test of Engineering Polymers

  25-29

  Ádám Sarankó

  Róbert Keresztes

  Gábor Kalácska

  Views:

  137

  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

  200-205

  Ádám Sarankó

  Gábor Kalácska

  Róbert Keresztes

  Views:

  138

  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.

• Pin on Disc Tests of Closed Cell Aluminium Foams

  353-357

  András Gábora

  Gábor Kalácska

  Róbert Keresztes

  Sándor Beke

  Zoltán Gergő Géresi

  Views:

  222

  Metal foams have a lightweight cellular structure with excellent mechanical and physical properties and are at the forefront of materials development for the automotive and other industries. Although metal foams are popular, they are still not sufficiently characterized thanks to their extremely complex structure. The aim of the research is the tribological investigation of closed cell metal foams with different production technologies and different cell sizes. The paper introduces the closed cell aluminium foams produced by direct foaming and gas injection and those raw materials. The Pin on Disc instrument and the most important parameters of the experiments are also presented.

• The Effect of Sizes of the Cast Polyamide 6 Rods upon Tensile-Impact Strength

  21-24

  Miklós Odrobina

  Gábor Kalácska

  Róbert Keresztes

  Views:

  147

  We have studied the tensile-impact strength of the magnesium catalysed cast polyamide 6 (PA6) rods according to the EN ISO 8256:2004 standard. The purpose of our investigation was to follow: the mechanical properties of rods are mapped beside same casting technological process in case of different diameters. We have compared the received results with each other than have sought disparities. We examined cylindrical product (rod) in seven dimensional steps in diameter ranging from 40 mm to 300 mm. We have determined that the semi-finished products can be divided into two groups typically in case of their tensile-impact strengths in this size range. The tensile-impact strength is higher in case of the rods with a diameter of less than 100 mm and it is smaller in the larger dimension range. Therefore, the smallest tensile-impact strength can be established in case of the natural semifinished PA6 rods that each rod accomplishes independently of size. However, a range can be determined, which the tensile-impact strength values of product are separated according to the manufacturing size