Micro-Analysis of the Contact Zone of Tribologically Loaded Second-Phase Reinforced Sol-Gel-Abrasives

2014

This article presents the results from a traverse internal cylindrical grinding process conducted using grinding wheels with sol-gel alumina abrasive grains and varying volumes of glass-ceramic vitrified bond. The aim was to determine how changing the bond volume within the range of V b =11.5-14.5 % influenced the wear phenomenon of the microcrystalline sintered corundum abrasive grains and the ceramic bond bridges with glass-crystalline structure. The paper presents grinding wheels with conic chamfer and the most important wear phenomena of the grinding wheel components occurring in the area of contact between the tool and the workpiece material. The work includes the methodology of the experimental tests on the traverse internal cylindrical grinding of bearing rings made from steel 100Cr6 (62±2 HRC). A wide range of test results were analyzed, including machined surface roughness parameters (Ra, Rz, Sm, Δa), grinding power, grinding wheel volumetric wear V s , material removal V w , G-ratio, root-mean-square roundness deviation from mean circle (Δ, rms), grinding wheel edge wear, grinding wheel microtopography parameters (Sa, St, Sdr, Sds), and SEM images of the wear marks on the grinding wheel active surface. The dominant wear phenomena of the grinding wheels with conic chamfer and the influence of the bond volume share on its intensity were experimentally determined. The results show that the decrease in bond volume from V b =14.5 to 11.5 % increases the grinding wheel life by twofold. This was due to a decrease in abrasive wear and plastic flow phenomena and to a greater fracture wear (mostly fatigue and thermal-fatigue). These events led to a periodic shedding of the oxide layer and the plastically deformed grain layer and also revealed the crystals' sharp edges, located below the plastically deformed surface layer.

Section: Discussion Of the Test Resultsmentioning

confidence: 99%

Section: Discussion Of the Test Resultsmentioning

confidence: 99%

Wear phenomena of grinding wheels with sol–gel alumina abrasive grains and glass–ceramic vitrified bond during internal cylindrical traverse grinding of 100Cr6 steel

2014

“…The efficiency of grinding with abrasive tools from various abrasive materials is highly dependent on the conditions in which the grains work and on the dominant wear processes, including the comprehensive system of phenomena that combine chipping, plastic deformations and chemical reactions [40,41]. The microfractures present in the abrasive develop into fracture systems when the strains reach their critical values, which leads to chipping of grain microfragments [42].…”

Section: Working Conditions and The Phenomena Of Microcrystalline Sinmentioning

confidence: 99%

“…8 Microscopic view of the SG™ grains microstructure: a magnification×1,000; b magnification×10,000 Works [40,41] were the first ones to present in detail the processes of grinding and wear of Al 2 O 3 grains with microcrystalline structure. They prove that the excellent cutting capacity of these grains is closely connected with the tribological properties of the smoothed out surfaces of cutting apexes in the zone of contact with the machined material.…”

Section: A)mentioning

confidence: 99%

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State of the art in production, properties and applications of the microcrystalline sintered corundum abrasive grains

2014

The following article presents the current state of knowledge about technologies connected with microcrystalline sintered corundum against the backdrop of present abrasive products and the contemporary grains market. The complementary presentation of issues related to the microcrystalline sintered corundum abrasive grains, which constitute an important group of abrasives used in modern grinding technology, was given. The most important stages in the development of sintered corundum grains production technology, from the 1960s to current developments (nanocrystalline sintered corundum) in this field, were presented in chronological order. The production technology, properties, working conditions, wear phenomena and most important areas of application of such abrasive grains were described. Particular attention was paid to the wear phenomena of microcrystalline sintered corundum abrasive grains occurring during the grinding process. The collection of phenomena affecting the extension of the life of these types of grain in comparison with the white fused alumina grains were described. Moreover, forecasts concerning the development of abrasive grains of micro-and nanocrystalline sintered corundum were presented.

The effect of wear phenomena of grinding wheels with sol-gel alumina on chip formation during internal cylindrical plunge grinding of 100Cr6 steel

Kapłonek

2016

The article presents the results of experimental investigations to determine the effect of wear phenomena of grinding wheels with sol-gel alumina abrasive grains on chip formation during internal cylindrical plunge grinding of 100Cr6 steel. Basic wear phenomena conducted during the grinding process using microcrystalline sintered corundum abrasives are described. In order to expand our knowledge of this phenomena, experimental tests were conducted in two stages. In stage 1, only one opening was machined, which corresponded to the removal of 464 mm 3 of workpiece material. In the second stage, the process was carried to machine 100 subsequent openings (material removal V w = 46, 400 mm 3). Such methodology allowed one to observe changes in the form of chips resulting from the progressive wear of the grinding wheel components. The form and size of the chips were identified by recording and analyzing the SEM micrographs of the chips for both grinding stages, respectively. Conducted studies have shown that the dominant type of chips, shaped in the initial period of the grinding wheel's life, are large (several hundred μm in length) flowing-type chips resulting from material removal by sharp cutting edges of abrasive grain active vertices. At the end of the grinding wheel's life, when active vertices of abrasive grains have clear signs of large fatigue and thermo-fatigue wear, only in the near-edge zones of the wheel can flowing-type and shearingtype chips (usually less than 100 μm in length) be observed, while knife-type and slice-type microchips were predominately registered on the whole grinding wheel surface.