Papers by Keyword: Grinding Ratio

Abstract: This article presents preliminary investigations on the cutting ability of the singer layer metal-bonded cBN grinding wheel manufactured by electroplating method at Vietnamese laboratory. The cutting ability of the grinding wheel is evaluated by two factors: grinding ratio G and surface roughness of workpiece. These results are compared to those of the Japanese grinding wheels. The experimental results showed that the fabricated cBN grinding wheel has good cutting ability with high grinding ratio G. The value of the grinding ratio was 600 to 1800 in the grinding process of SKD11 steel (hardness of 62-63HRC) at the grinding speed V of 12.56m/s, feed rate S of 300mm/min, depth of cut t of 0.01mm. The maximum grinding ratio (1800) is equivalent to the average grinding ratio of the Japanese grinding wheel. The grinding ratio is also maintained up to 26 cutting hours. The good grinding surface was achieved with the average Ra of 2.5μm. In addition, the bonding of cBN abrasive to the wheel body was observed with scanning electron microscope (SEM) of the surface of grinding wheel after the cutting process. The SEM image shown that the cBN abrasive particles were not removed from the wheel surface.

Abstract: The majority of aero-engine components are designed and manufactured with nickel-based superalloy GH4169 in mind. There is little information available in the literature related to belt grinding processes of aero-engine components. Up to now, limited research has been reported in the use of belt for grinding aero-engine components made of nickel-based superalloy GH4169. A case study of an abrasive belt grinding performance applied on nickel-based superalloy GH4169 in manufacturing processes is presented, aiming to investigate the possibility of using belt grinding as a operation for components made of nickel-based superalloy GH4169. For the ‘optimised’ grinding conditions, the belt service life is evaluated by changing grinding parameters (grinding speed, contact force and oscillation frequency), and the following output measures are obtained: material removal, belt wear and grinding ratio. As a result, the maximum grinding ratio of G is 8.8, it could be concluded that belt grinding might be considered as a viable process for grinding aero-engine components.

Abstract: The use of GH4169 nickel-based superalloy for the manufacture of gas turbine engines components for aerospace/energy applications has become a routine exercise. However, components with complex designs specifications might pose manufacturing challenges especially when grinding processes are needed to enable their compliance with tight industrial standards for workpiece surface integrity. Information on grinding processes for such sensitive industrial applications is scarce. The paper reports on the influence of grinding methods/strategies on the quality and integrity of workpiece surfaces obtained after abrasive belt grinding methods on GH4169 nickel-based superalloy. The influences of grinding speed, contact pressure and oscillation frequency on surface roughness were discussed. The performance of the abrasive belt and surface topography were discussed. As a result, the maximum surface roughness of Ra is 0.072μm, and have a good performance of the abrasive belt, it could be concluded that abrasive belt grinding might be considered as a viable process for grinding aero-engine components.

Abstract: PCD diamond cutting tools which named sintering diamond tool is the main cutting tool of the natural granite, the cutting characteristics of that have great influence on machining efficiency and machining quality. At present, most scholars are relatively mature on the research of diamond tool wear condition by the physical attributes of the PCD diamond tool and physical components of natural stone material. This paper studies the impact of cutting parameters on the tool wear, optimization of process parameters.

Abstract: A vitrified bonded diamond wheel having electrical conductivity was manufactured on a trial basis. The electrically conductive (EC) vitrified bonded diamond wheel has enabled an electrodischarge truing and an electrical contact sensing. In this study, the EC vitrified bonded diamond wheel is applied to the EDM (Electro Discharge Machining) assisted grinding of PCD materials. The result shows that a lower and more stable grinding force can be realized and a better surface finish is attained compared with those achievable with a metal bonded diamond wheel.

Abstract: Polycrystalline Composite Diamond (PCD) is excellent in chipping resistance despite its very high hardness. However, it is not easy to EDM or grind PCD. To realize high efficiency and high quality processing of PCD simply and at low cost, the authors devised new PCD (EC-PCD) by using electrically conductive diamond particles and applied a complex electrodischarge grinding method. In this study, investigation is made on effective grinding condition to realize high efficiency, low and stable grinding force and low wheel wear in complex electrodischarge grinding. As a result, superior grinding property was obtained when the grinding wheel was set at minus polarity, and set peak current of i_P = 4 and 6 A was applied. Furthermore it also became clear that additional conventional grinding process followed after complex electrodischarge grinding improved the surface condition.

Abstract: This paper investigates the effect of the CBN abrasive types, sizes, concentration, bond amount, and porosity of a vitrified-bonded CBN wheel on grinding ratio, grinding forces, and surface roughness of grinding hardened steels. The experiment results showed that during grinding hardened steels the amount of bond with increase of the depth of cut increased, which makes the wheel to have a better bonding strength to get a better grinding ratio and surface roughness of the workpiece. The grinding forces produced increased with the increase of the depth of cut. In addition, too much porosity of a vitrified CBN wheel will cause the low bond strength, leading the wheel to wear rapidly. Hence, to obtain a higher grinding ratio and better surface roughness of the workpiece during the grinding hardened steels should select relatively a higher amount of bond, a lower porosity, and a higher grit strength and concentration, but the grinding forces produced were relative higher.

Abstract: A new PCD (electrically conductive PCD: EC-PCD) consisting of electrically conductive diamond particles has recently been developed. The authors have proposed a complex grinding assisted with electrical discharge machining (EDM) where discharge machining and grinding are used in combination during material removal to realize high efficiency, low and stable grinding force and low wheel wear for the EC-PCD. In this study, the effect of constant-force grinding in a complex grinding assisted with electrical discharge machining of EC-PCD was investigated. As a result, it was found that higher material removal rate, higher grinding ratio and better surface condition were obtained on EC-PCD compared with standard PCD (S-PCD) in the constant-force grinding.

Abstract: A new PCD material named EC-PCD (Electrically conductive polycrystalline composite diamond), which consists of electrically conductive diamond grits, has recently been developed. This paper deals with an investigation of a complex grinding assisted with electrical discharge machining (EDM) to realize high efficiency, low and stable grinding force and low wheel wear for the new EC-PCD. The effect of complex grinding assisted with EDM is compared experimentally with the standard PCD (S-PCD). The result shows that, in the complex grinding, lower and more stable grinding force is realized thanks to the material removal action in EDM and that lower wheel wear and better surface finish are attained, just when the EC-PCD is selected as a workpiece.

Abstract: In this study, the influences of carbides and alloy additives on ground surface characteristics of several high Chromium (Cr) steels and abrasive grains of working surface were discussed. In the grinding using metal bonded CBN wheel, almost constant values in ground surface roughness and high grinding ratio were shown. 5% Cr steel with Vanadium, 8% Cr steel and 10% Cr steel showed a rougher surface than Cr steels with 3%, 4% and 5% due to the carbide inclusion. The grinding ratio of 5%Cr steel could be raised considerably by adding sulfur to it.