Alumina Abrasive Wheel Research Articles

Effects of intermittent cutting behavior on wear characteristics of alumina abrasive wheels during grinding ultra-high strength steels

Effects of intermittent cutting behavior on wear characteristics of alumina abrasive wheels during grinding ultra-high strength steels

Alumina abrasive wheel wear in ultrasonic vibration-assisted creep-feed grinding of Inconel 718 nickel-based superalloy

Blade root with a special fir-tree shape is a critical connection part in an aero-engine. This part has high requirements on the surface finish and geometrical accuracy. At present, the tangential ultrasonic vibration-assisted profile grinding (UVAPG) is an effective method for machining the blade roots. During UVAPG, the wheel wear degrades the surface finish and geometrical accuracy. However, the characteristics of the wheel wear in UVAPG are not fully revealed. This study proposes an analytical wear model by considering the intermittent grinding behavior of a grinding edge, the number of active grinding edges, and the effects of wheel profile on the tool wear. The model is experimentally demonstrated to be applicable to predicting the wear volume in UVAPG with a maximum error of 4.2 %. Based on the model, the tangential ultrasonic vibration increases the average unchanged chip thickness and the number of active grinding edges. UVAPG causes an approximately 22 % increase in wear volume at the steady wear stage compared with the conventional grinding. The wear speeds vary at different regions of a profile wheel. The convex regions represent higher wear speeds than the concave regions on the wheel.

Mechanical and Abrasion Resistance Properties of Concrete Containing Recycled Abrasive Waste as Partial Replacement of Fine Aggregate

In grinding wheel, the stub portion is unused and dumped after end of its primary purpose. The portion, which is considered as waste, has unused abrasives in it. The present work deals with reusing this abrasive waste as the replacement material for sand in concrete production. Reuse of the crushed vitrified brown alumina abrasive wheel which passes through 80 mesh can be used as a partial replacement for sand in concrete production. Structural properties of the crushed abrasive waste were analysed using X-ray diffraction and scanning electron microscopic analysis. Concrete samples were made with five different replacement ratios of 10%, 20%, 30%, 40% and 50% to replace the fine aggregate(sand) in concrete. Mechanical properties such as compressive, split-tensile, flexural strength and water absorption properties of the prepared concrete were determined. It was found that partial replacement of sand by abrasive waste was able to increase the compressive by 32%, tensile strength by 17% and flexural strength by 14%. Abrasive resistance of the concrete was measured using sand blasting equipment. Concrete with 40% abrasive waste shows around 83% improvement in abrasive resistance. The reuse of abrasive wastes as a partial replacement of sand in concrete is seen to enhance its mechanical properties and enable proper utilisation of these non-biodegradable solid wastes for better environment.

Investigation of the wear characteristics of microcrystal alumina abrasive wheels during the ultrasonic vibration-assisted grinding of PTMCs

As newly developed metal matrix composites, particulate-reinforced titanium matrix composites (PTMCs) have been eliciting increasing attention in the fields of aviation and aerospace due to their superior temperature durability and mechanical properties. Grinding is an important method for achieving high-efficiency and precision machining of PTMCs. However, the service life of abrasive wheels is severely affected under the action of alternating loads due to the existence of hard–brittle TiC particle reinforcements embedded into PTMCs materials. Ultrasonic vibration-assisted grinding (UVAG) is widely used at present for machining difficult-to-cut materials, particularly for improving the wear performance of abrasive wheels. In this work, comparative experiments on the conventional grinding (CG) and UVAG of PTMCs were conducted to investigate the wear properties of microcrystal alumina abrasive wheels. Moreover, characterisation of tool wear morphologies was performed. On the basis of the standard deviation of the Gaussian distribution of workpiece profile, active cutting edge density was evaluated. Lastly, grinding force and machined surface quality were analysed in detail. Results showed that CG caused severe adhesion and macrofractures, whereas UVAG produced slight adhesion and microfractures. UVAG also achieved lower grinding force and better surface quality than CG. Furthermore, UVAG provided a longer steady tool wear region than that in CG because ultrasonic vibration can enhance the self-sharpening characteristics of microcrystal alumina abrasive wheels during grinding.

Tool wear behavior of alumina abrasive wheels during grinding FGH96 powder metallurgy nickel-based superalloy

The tool wear behavior of microcrystalline alumina (MA) and brown alumina (BA) abrasive wheels were comparatively studied during grinding FGH96 powder metallurgy nickel-based superalloy. The grinding ratio, radial wear and grinding force were quantitatively analyzed. The influences of tool wear on surface morphology were discussed. The results suggest that grinding force and radial wear of MA wheel is lower than that of BA wheel. Serious tool wear occurs on both the MA and BA wheel from grinding ratio which is less than 1.8 because of the material adhesion and pores clogging. Meanwhile, several defects were found on the ground surface.

An investigation on machined surface quality and tool wear during creep feed grinding of powder metallurgy nickel-based superalloy FGH96 with alumina abrasive wheels

In this study, the machined surface quality of powder metallurgy nickel-based superalloy FGH96 (similar to Rene88DT) and the grinding characteristics of brown alumina (BA) and microcrystalline alumina (MA) abrasive wheels were comparatively analyzed during creep feed grinding. The influences of the grinding parameters (abrasive wheel speed, workpiece infeed speed, and depth of cut) on the grinding force, grinding temperature, surface roughness, surface morphology, tool wear, and grinding ratio were analyzed comprehensively. The experimental results showed that there was no significant difference in terms of the machined surface quality and grinding characteristics of FGH96 during grinding with the two types of abrasive wheels. This was mainly because the grinding advantages of the MA wheel were weakened for the difficult-to-cut FGH96 material. Moreover, both the BA and MA abrasive wheels exhibited severe tool wear in the form of wheel clogging and workpiece material adhesion. Finally, an analytical model for prediction of the grinding ratio was established by combining the tool wear volume, grinding force, and grinding length. The acceptable errors between the predicted and experimental grinding ratios (ranging from 0.6 to 1.8) were 7.56% and 6.31% for the BA and MA abrasive wheels, respectively. This model can be used to evaluate quantitatively the grinding performance of an alumina abrasive wheel, and is therefore helpful for optimizing the grinding parameters in the creep feed grinding process.

Grinding force and surface quality in creep feed profile grinding of turbine blade root of nickel-based superalloy with microcrystalline alumina abrasive wheels

Creep feed profile grinding of the fir-tree blade root forms of single crystal nickel-based superalloy was conducted using microcrystalline alumina abrasive wheels in the present study. The grinding force and the surface quality in terms of surface topography, subsurface microstructure, microhardness and residual stress obtained under different grinding conditions were evaluated comparatively. Experimental results indicated that the grinding force was influenced significantly by the competing predominance between the grinding parameters and the cross-sectional root workpiece profile. In addition, the root workpiece surface, including the root peak and valley regions, was produced with the large difference in surface quality due to the nonuniform grinding loads along the root workpiece profile in normal section. Detailed results showed that the surface roughness, subsurface plastic deformation and work hardening level of the root valley region were higher by up to 25%, 20% and 7% in average than those obtained in the root peak region, respectively, in the current investigation. Finally, the superior parameters were recommended in the creep feed profile grinding of the fir-tree blade root forms. This study is helpful to provide industry guidance to optimize the machining process for the high-valued parts with complicated profiles.

Morphological evolution and grinding performance of vitrified bonded microcrystal alumina abrasive wheel dressed with a single-grit diamond

Abstract Dressing experiments under different conditions were carried out on a vitrified bonded microcrystal alumina abrasive wheel with a single-grit diamond dresser. The grinding performance of the as-dressed abrasive wheels was investigated. The dressing force, grinding force and the surface morphology of abrasive wheel and machined workpiece were studied to shed light on the relationship among the dressing processing vectors, morphology of abrasive wheel and the grinding performance. The results obtained show that the dressing forces increase with the increasing volume of the abrasive wheel material removed per unit time. The sensitive analysis reveals that the dressing feed speed take a greater effect than the single dressing depth on the dressing force. The self-sharpness of vitrified bonded microcrystal alumina abrasive wheel brings into some functions under certain dressing conditions, but a deep dressing depth would lead to an excessive abrasive self-sharpness, i.e. abrasive grits fall off and embed into the workpiece surface.

Comparative investigation on wear behavior of brown alumina and microcrystalline alumina abrasive wheels during creep feed grinding of different nickel-based superalloys

This study investigates the comparative wear behavior of brown alumina (BA) and microcrystalline alumina (MA) alumina abrasive wheels and its effect on the creep feed ground surface of different nickel-based superalloys, such as wrought alloy GH4169, directional solidified alloy DZ408 and single crystal solidified alloy DD6. The abrasive wheel wear topography was characterized and an analytical model was developed to evaluate the abrasive wheel wear comprehensively. Finally, the effects of tool wear on the grinding performance and ground surface were discussed. Results obtained indicate that, compared with BA abrasive wheel, the MA wheel performed better in terms of the grinding ratio and tool wear behavior. Strong adhesion wear and attritious wear of the abrasive wheels were generated during grinding of GH4169 and DZ408 alloys, while great wheel clogging occurred during grinding of DD6 alloy. Moreover, DZ408 alloy produced the most severe tool wear and largest grinding forces, followed by GH4169 and DD6 alloys. The defects pattern of ground surface with BA wheel was unparallel to the grinding direction due to the grain dislodging and fracture; however, when grinding with MA wheel, groove defects were created along the grinding direction due to high ductility and hardness of grains.

Grinding of Ti2AlNb intermetallics using silicon carbide and alumina abrasive wheels: Tool surface topology effect on grinding force and ground surface quality

Ti2AlNb intermetallics have the potential to replace some of the nickel-based superalloys application in aero-engine components due to their outstanding high-temperature mechanical properties. As a result of high strength, they are difficult to grind and can induce rapid tool wear. The current study compares the grinding performance of Ti2AlNb intermetallics by using green silicon carbide (GC) and pink alumina (PA) wheels. The wheel wear and topology evolution have been assessed. The wear effect on the grinding force and ground surface quality has also been analyzed. It has been found that the adherent area on the abrasive grains of PA is 8 times larger than that of GC wheel, which dulls the PA wheel cutting tips. The plowing and chip formation power occupy about 40–60% of the total power for the PA wheel, and this value is above 80% for the GC wheel. In addition, the GC wheel shows less white etch layer issue which renders better surface finishing and it is preferred in the Ti2AlNb intermetallics grinding.

In-situ TiC-TiB2 coating on Ti-6Al-4V alloy by tungsten inert gas (TIG) cladding method: Part-II. Mechanical performance

TiC-TiB2 composite coating was produced on Ti-6Al-4V alloy by TIG cladding method (an economical alternative of laser cladding process) through in-situ reactions between Ti and B4C pre-deposited powder mixture. The experimental results revealed significant variation in the hardness value along the depth of the coatings for the alteration of processing conditions, which mainly occurred due to discrepancy in the dilution of substrate material and consequent change in the percentage of hard TiC and TiB2 phases. The fracture toughness of the coatings measured by indentation method are found (5.65–6.97 MPa·m1/2), much higher than that of individual TiB2 or TiC. The sliding abrasive wear test performed against alumina abrasive wheel revealed that abrasion wear is predominant for removal of the coating. However, adhesive wear due to plastic deformation and brittle fracture resulted from the stress induced due to cyclic loading by the abrasive particles are also effective to remove the coating material subjected to the concentration of hard TiC and TiB2 phase in the coating. The produced coating exhibited up to four times higher hardness and three times higher wear resistance as compared to Ti-6Al-4V alloy substrate, which makes the coating a suitable candidate for application in wear resistance components.

Sliding abrasive wear characteristic of TIG cladded TiC reinforced Inconel825 composite coating

TiC reinforced Inconel 825 alloy matrix composite coating with different weight percentage (20, 40, and 60) of TiC has been produced by TIG cladding process. With the increase in TiC percentage in the produced coating a drastic alteration in the coating morphology perceived predominantly due to the degree of melting of pre-deposited TiC particles. The sliding abrasive wear measured through the height loss of the coated pin extracted from the TiC-Inconel825 composite coatings executed against alumina abrasive wheel show the effect of TiC percentage as well as the sliding velocity during the test. The worn surfaces characterized by SEM suggested that the abrasion wear is predominant for removal of the coating along with delamination through oxidation. The coefficient of friction of the coating assessed against harden steel plate (HRC58) indicated a gradual reduction from 0.71 to 0.60 with the increase in TiC content in the TiC-Inconel825 composite coating.

Grinding temperature and wheel wear of porous metal-bonded cubic boron nitride superabrasive wheels in high-efficiency deep grinding

High-efficiency deep grinding experiments of Inconel 718 nickel-based superalloy was carried out with the porous metal-bonded cubic boron nitride superabrasive wheel, in which the uniform and large pores were formed by the broken alumina bubble particles in the working layer after wheel dressing. Grinding temperature, energy partitioning into workpiece, and wheel wear were investigated. Results obtained show that long maintenance of low grinding temperature, that is, 50 °C–170 °C, is obtained in high-efficiency deep grinding with the porous metal-bonded cubic boron nitride wheel. The energy partitioning into the ground workpiece is ranged from 2% to 6%, which is smaller than that with the conventional vitrified cubic boron nitride wheels and alumina abrasive wheels. Sufficient storage space for chips and coolants contributes to the excellent performance of the porous metal-bonded cubic boron nitride wheel in high-efficiency deep grinding. Abrasion wear and grain fracture are the dominant wear patterns of the porous cubic boron nitride wheel in the steady wear stage, while chips loading and grain pullout play a critical role in the final dramatic wear behavior of the porous wheel.

Effect of Cryogenic Cooling on Spindle Power and G-ratio in Grinding of Hardened Bearing Steel

Cryogenic coolants like liquid nitrogen (LN2) is being recognized as a promising cutting fluid to meet the requirements of sustainable manufacturing, due to its extraordinary ability to dissipate heat from machining zone temperatures and to offer environmental friendliness. In the present work, an attempt was made to explore the capability of LN2 in surface grinding of hardened AISI 52100 steel using alumina abrasive wheel. Unlike the reported literatures the present work observed and identified few adverse effects of LN2 besides its beneficial effects. A suitable power measurement setup was used to monitor the power consumption under cryogenic machining and simultaneously compared with that under dry and conventional soluble oil medium. Application of LN2, as cooling medium, was found to improve grinding ratio but adversely results into significantly higher power consumption as compared to dry and conventional soluble oil. Dimensional inaccuracy was observed to be higher with LN2. Scanning electron microscope (SEM) images of chip morphology indicated the effective cooling of grinding zone under cryogenic environment compared to other dry and wet environments.

Experimental Investigation on Grinding Performance of Microcrystalline Alumina Abrasive Grinding Wheel for Superalloys

Superalloys are widely used in the aeronautic and astronautic industries owing to their excellent properties in aspects of high-temperature strength, heat stability and thermal fatigue resistance. However, the severe loading of grinding wheel and the poor integrity of grinding surface usually become the problem in grinding of superalloys with conventional grinding wheels. In this paper an experimental study was carried out to investigate the grinding characteristics of superalloys with microcrystalline alumina abrasive wheel. The roughness of grinding surface was tested, on which the effects of the grinding parameters were analyzed. Study results indicated that low loading of grinding wheel and high quality of grinding surface (Ra 0.2 μm) were obtained. The grinding parameters were optimized based on the experiment results.

Effect of grinding temperatures on the surface integrity of a nickel-based superalloy

An experimental study was carried out to investigate the influence of temperatures on workpiece surface integrity in the surface grinding of a cast nickel-based superalloy with alumina abrasive wheels. The temperature response at the wheel–workpiece interface was measured using a grindable foil/workpiece thermocouple. Specimens with different grinding temperatures were obtained through changing the grinding conditions, including the depth of cut, the workpiece feed, and the coolant supply. Changes in the surface roughness, residual stress, metallography, ground surface morphology, and micro-hardness of the specimens were then analyzed. Bending fatigue tests were separately conducted at room temperature and at 950 °C in order to evaluate the influence of temperatures on the service life of the ground specimens. A different burning color was found on the ground workpiece surfaces when grinding temperatures are over a critical value. Along with the emergence of a burning color, the roughness of the ground workpiece surface increased greatly compared with the surfaces without burning color, which was attributed to plastically deformed coatings on the workpiece surface occurring with elevated temperatures. Excepting the surface roughness, surface integrity of the ground workpiece was not affected by temperature, provided that grinding temperature is not high enough to cause grinding cracks. Based on the findings in this study, the grinding of nickel-based superalloy can be divided into two stages in order to increase production efficiency, in which case the first stage is to reach high material removal rate without concern for the presence of a burning color, whereas the second stage is to remove the plastically deformed coatings in order to decrease the surface roughness.

Study on grinding wheel manufacture. Vitrified bonded alumina abrasive wheel.

The relation between the manufacturing conditions and the resulting properties of grinding wheel was studied using the vitrified bonded grinding wheels with white fused alumina abrasive grains as a model. The manufacturing conditions studied included molding pressure, bond content and firing time. The properties studied were bending strength, Young's modulus and apparent density. The wheel properties were affected markedly by the manufacturing conditions. The results were explained through the microstructural consideration. An uniform green density after pressing was required for making a reliable grinding wheel with uniform quality.