ASTM G65 standard Rubber wheel abrasive wear test

Introduction The wear damage carries to replace machine parts causing a lost in the valuable time of productions. Therefore should be proposed serious studies related with the tribology. Thus, is possible predict future flaws when an appropriate evaluation method adopted for the different materials and machines according to its work cycle, in this manner is conserving the productivity, the industrial security and the decrease of costs. Laboratory modelings of tribological behaviors are very importance, because facilitates the correct selection of the materials to use in frictional constraints and contributes to materials saving and increment its durability. With this perception of necessities required in the industry, have been developed methods able to perform reproducible tests in any place. Due to this, organizations like ASTM, DIN, ISO, among others, have standardized these techniques, achieving with this, the general knowledge of the conditions of operation of the machines, of their dimensions and of all the operation parameters during the realization of the rehearsals. ASTM G 65 standard for abrasive wear test is widely used by industry to assist in selecting materials for abrasive wear service. This test involves loading a specimen against a rotating rubber-rimmed wheel while a flow of abrasive sand is directed at the contact zone. Choices of loads and sliding distances are detailed in the test method. In Mechanical Engineering Faculty of the Central University "Marta Abreu de la Villas" of Cuba isn’t had a tribologic laboratory that allows to make waste rehearsals in tribosystem. To will make this laboratory is necessary the design and production of the machines that will conform it. Then is performed the design and fabrication of a machine type "dry sand - rubber disk" for test in abrasive wearing according to the ASTM G 65 Standard. Results According to the ASTM carrying out the rehearsal it’s parameters of work. Firstly was verified the rate wheel, for this was used a SHIMPO Tachometer (See Fig. 6). It was to 204 rpm like it was foreseen. Lastly, was verified that the weights placed in the hook of the distal end of Lever Arm that cause the force established in the contact point of the specimen with the rubber wheel. This can be verified placing a KRAFTMESSGERATE HALLE Dynamometer in this point such as shown in the Fig. 8. It was verified that in that point was applied 45 N like it establishes by the ASTM G 65 [6] Standard for the D procedure. Also are carried out the rehearsal to a cast iron specimen. Then was used the method B of ASTM G 65 Standard [6] (See Table 1). Chemical analysis of the material was done, obtaining a chemical composition shown in Table 2. As a result of the metallographic analysis was determined that the specimen material has a ferritic structure containing lamellar graphite inclusion with long straight between 60 and 120 ?m, has a uniform distribution and the amount between 5 and 8% (See Fig. 9) The hardness measuring was performed to the specimen material resulting of 165 HV. For tests, four specimens were made according to the standard [6] with the dimensions of 7.62 x 2.54 cm (3 x 1 in). After performing the tests can be observed the results in one of the specimens (See Fig. 10) and a microscopic image of the wearing surface (See Fig. 11). Traces produced by the abrasive particles to slide along the surface of the cast iron specimen are clearly shown in both images. To process the results, the mass loss was measured in each specimen subtracting the final weighing to the initial weighing. As established in ASTM G 65 Standard [6] the final report of this test should be shown in terms of volume loss according to the mass loss measured. These results are reported in Table 3. Conclusions The design and construction of the dry sand - rubber wheel apparatus complies with the established work parameters in the ASTM G 65 standard, allowing abrasive wear testing with good results. The design and construction of the machine is much economical than importing it. In his manufacturing were used recycled materials, including the transmission and engine. The cost of this kind of machine outside the country hovers around 8000 USD without considering his transportation and other costs. The manufactured machine is very important in Tribology Laboratory of Mechanical Engineering Faculty of the Universidad Central "Marta Abreu de Las Villas", it can be used for teaching and research purposes related with knowledge consolidating in abrasive wear that can acquire students on various materials.