Alumina Grinding Wheel Research Articles

Wear Monitoring on Microcrystalline Aluminum Oxide Grinding Wheels on Profile Grinding with the Aid of Acoustic Emission

The localized wear on grinding wheel edges is a common phenomenon on profile grinding since the abrasive grains are less attached to the bond. The grinding wheel wear depends heavily on the process parameters, workpiece and wheel composition, causing changes on the process and profile deviation behaviors. In order to cope with these uncertainties, many natural and synthetic materials have been used in different grinding processes. However, the influence of mixed compositions of different types of abrasive grains on external cylindrical grinding is not well known. In order to assess this relation, a methodology procedure was developed providing an overview of the cinematic edges behavior on a progressive wheel wear. The methodology procedure is based on the acoustic emission technology, using a transducer with a 50 μm radius diamond tip. The tip, when in contact with a rotating grinding wheel, enables the evaluation of the cinematic cutting edges. The abrasive grain density was evaluated for different grinding wheel compositions and specific wear removal values. Furthermore, these results were compared to the profile deviation observed on the same tool, allowing the assessment of the influence of different microcrystalline corundum grains on the overall grinding wheel wear behavior.

Desgaste de dressadores de ponta única fabricados com diamantes cvd nacionais

Neste trabalho, buscou-se observar a atuação de três tipos de diamantes, dois naturais e um sintético, para determinar qual deles apresenta vida útil maior ou com maior desgaste em relação aos demais. A metodologia empregada nesse estudo foi o de dressar um rebolo de óxido de alumínio e, a cada vinte passadas com um avanço da profundidade de dressagem de 40 µm por passada, tirar uma imagem da ponta na posição horizontal e outra na posição vertical deste diamante num microscópio estereoscópio. Após isso, o dressador foi recolocado na retificadora para a realização de uma nova dressagem. O critério para o fim do ensaio foi o faiscamento, gerado pelo contato do rebolo com a base do dressador, que indicou o fim do contato do diamante com o rebolo. Após os ensaios, foram calculadas as áreas gastas de cada diamante de acordo com cada imagem obtida por meio do auxilio de um software gráfico. Os dados foram então dispostos em gráficos.

Characterization of grinding wheel topography using a white chromatic sensor

This paper introduces a non-contact, non-destructive three-dimensional wheel scanning system which is capable of measuring and characterizing the surface topography of grinding wheels. The scanning system employs a white light chromatic sensor that traverses across the wheel surface using motorized stages controlled by a computer. With a planer resolution of 2μm and a depth resolution of 25nm, the novel scanning system was shown to compare well with a HITACHI S-4700 Scanning Electronic Microscope and a Nanovea PS50 profiler for measuring a 60 grit aluminum oxide grinding wheel—without having to destroy the grinding wheel to take the measurements. It was shown that image processing techniques, including segmentation and “blob” analyses, were able to extract the cutting edge density, width, spacing and protrusion height from the raw topography measurements. The wheel scanning system was then used to characterize the surface of a grinding wheel that had been dressed using fine, medium and coarse dressing conditions. The resulting cutting edge width and spacing was found to be exponentially distributed over the wheel surface—regardless of the dressing condition, while the cutting edge protrusion height appeared to be approximately normally distributed. The coarse dressing condition yielded fewer, smaller and more widely spaced cutting edges than the medium and fine cases. Furthermore, for the dressing conditions used in this research, it was observed that dressing noticeably affected the grinding wheel surface to a depth of 80μm, while grain geometry and spacing dominated the surface topography beyond this depth.

Effect of cryogenic cooling and sol–gel alumina wheel on grinding performance of AISI 316 stainless steel

The ineffectiveness of conventional coolants and their adverse impact on the environment have led to the use of cryogenic LN2 (liquid nitrogen) as an alternative coolant, which is effective in reducing the grinding zone temperature, and providing better lubrication, in addition to being a clean technology. The sol–gel (SG) alumina grinding wheel, with a self-sharpening characteristic, is used for the experiment. The grinding experiments were conducted on AISI 316 stainless steel under the three environments of dry, wet and cryogenic cooling. The Cryogenic coolant delivers a reduction of about 32% in the grinding forces, 30–49% improvement in the surface roughness, and 45–49% lesser temperature even at higher material removal rates. Cryogenic cooling produces fewer surface defects compared to dry and wet cooling. The effects of the LN2 delivery pressure on the machining zone, in terms of the grinding forces, surface roughness, and grinding zone temperature, were also studied.

Experimental study of burn classification and prediction using indirect method in surface grinding of AISI 1045 steel

Grinding burn is a discoloration phenomenon according to the thickness of oxide layer on the ground surface. This study tries to establish an automatic grinding burn detection system with robust burn features that are caused by burn and not by the design parameters. To address this issue, a method based on acoustic emission sensor, accelerator, electric current transducers, and voltage transducers was proposed in an attempt to extract burn signatures. A trial-and-error experimental procedure was presented to find out burn threshold. Vitrified aluminum oxide grinding wheel and AISI 1045 steel workpiece were used in the grinding test, as they were the most commonly used wheel–workpiece combinations in conventional grinding process. With the help of fast Fourier transform and discrete wavelet transform, the spectral centroid of AE signal, the maximum value of power signal, and the RMS of the AE wavelet decomposition transform from wavelet decomposition levels d1 to d5 were extracted as burn features. The spectral centroid of AE signal was believed not to be affected by grinding parameters. A classification and prediction system based on support vector machine was established in order to identify grinding burn automatically. Results indicate that the classification system performs quite well on grinding burn classification and prediction.

The Theoretical Analysis and Application of the Ultra-Precision Machining the End Surface of Stop Valve’s Valve Flap with the Diamond Facing Tool

A new process was proposed. The disadvantage of of using brown alumina grinding wheel to grinding and lapping surface was studied in the analysis. The diamond facing tool was designed and manufactured with the solution of the key technique of the critical technical of single crystal diamond’s material selecting, grinding, welding. The face cutting parameters: “V”, “f” and “ap” were measured by experiment and academic analysis. Tt can fully meet the quality requirements of stainless steel valve flap’s surface used by one valve machinery factory; meanwhile the productivity was increased by a factor of 15, with overcoming the disadvatange of grinding and lapping valve flap’s surface.

Application of shallow circumferential grooved wheels to creep-feed grinding

A single-point diamond dressing tool was used to cut shallow circumferential groove on aluminum oxide grinding wheels. Creep-feed grinding experiments were then carried out to compare the performance of these grooved wheels with a non-grooved wheel. The results showed that, for the conditions used in this research, a grooved wheel could remove twice as much material as a non-grooved wheel before workpiece burn occurred. The results also showed that a grooved wheel can improve grinding efficiency by reducing the consumed power by up to 61%. Although the use of grooved grinding wheels caused the workpiece surface roughness to increase slightly when compared to a non-grooved wheel, the grooved wheel enabled up to 37% more material to be removed while still maintaining workpiece surface roughness values below 0.3μm (“fine quality” surface finish), and up to 120% more material to be removed while still maintaining workpiece surface roughness values below 1.6μm (“average quality” surface finish).

Economical and technological study of surface grinding versus face milling in hardened AISI D3 steel machining operations

Abstract This work deals with the technological and economic considerations required to select face milling vs. surface grinding operations in the manufacture of hardened steel flat surfaces for dies and moulds. In terms of technological considerations, factors such as component geometry, material and surface quality (dimensional tolerance and surface finish) are taken into account. The economic considerations include the cost of machine depreciation, labour and consumables (cutting tools in face milling vs. grinding wheels and dressing tool in surface grinding). A case study is presented based on the prismatic components in ceramic tile moulds and their associated manufacturing operations. Surface grinding and face milling experimentation was conducted on cold work steel AISI D3 (with hardness of 60 HRC) with aluminium oxide grinding wheels and coated tungsten carbide cutting tool, respectively. Technological attributes and economics of face milling are compared with surface grinding of this type of mould components. The main conclusion is that face milling with chamfered edge preparation in coated tungsten carbide tools is a competitive process, compared with surface grinding, in terms of product quality and economics.

Influence of Depth of Cut on Grind-Hardened Layer and Its Uniformity

The grind-hardening of steel 65Mn had been carried out on a conventional surface grinder with alumina grinding wheel, the influence of depth of cut on the microstructure and the microhardness of workpiece, the depth and its uniformity of grind-hardened layer were studied. The results show that the completely hardened zone of grind-hardened layer is composed of fine acicular martensites, residual austenites and a little carbide. The variety of depth of cut has no obvious influence on the microstructure and the microhardness of completely hardened zone of grind-hardened layer. The maximum depth of grind-hardened layer and the depth uniformity of grind-hardened layer of workpiece increases with the increase of depth of cut ap.

Research for Use Diamond Knife to Ultra-Precision Boring Gauging Pump’s Boring

In this thesis, the new process will proposed which using diamond profile boring to boring 8-shaped hole in intermediate stainless steel plate of synthetic fiber gear pump. Academic analysis was made for gear pump’s flow rate, and analysis was made for the disadvantage of using brown alumina grinding wheel to grinding 8-shaped hole in intermediate plate’s internal surface. The critical technical of single crystal diamond’s material selecting, grinding, welding were solved, and diamond profile boring was designed and manufactured. We confirmed the boring parameters: “”, “” and “” through experiment and academic analysis. The qualified intermediate stainless steel plate with 8-shaped hole was using in one spinning factory; we conquered the grinding hole’s disadvantage and productivity is increasing 15 times.

Study on Depth and its Uniformity of 65Mn Steel Grind-Hardened Layer

On the basis of orthogonal experiment method, the grind-hardening of 65Mn steel had been carried out on a conventional surface grinder with alumina grinding wheel, the influence of depth of cutap, table speedvw, grinding modegm, and interaction between depth of cut and table speedavon depth and its uniformity of grind-hardened layer of 65Mn steel were investigated. The results show that, theapis the significant factor influences the average depth of grind-hardened layer and the significance ratio of experiment factors from most to least as followed:ap>vw>gm> av; thegmand thevware the significant factors influence the depth uniformity of grind-hardened layer and the significance ratio of experiment factors from most to least as followed: gm>vw>ap>av. The fairly uniformity of grind-hardened layer with good economy can be obtained when using grinding conditions that theap= 0.6mm, thevw= 0.4m/min, and thegm=up grinding + down grinding in practical applications.

Development of a low-cost composite film technique for functional micro-tools

This study presents the development of a low-cost composite film technique for making functional micro-tools. A conductive substrate is coated with a layer of formative oily-wax to define the featured pattern for depositing a layer of nickel-matrix diamond on the substrate. Porous material, made from an aluminum oxide grinding wheel of appropriate pore size, is employed as the co-deposition tank to generate good convection of the electrolyte and maintain uniformity of the particulate-composite suspension in the electrolyte of the tank. Two experimental samples including a micro-hole structure and an ultra-thin wheel tool are manufactured and tested. The wax-pattern can be fully removed by simply immersing the substrate in hot water; the diamond film thickness varies positively with deposition time. The proposed approach should contribute significantly to the precision micro-machining industry.

Quantitive Evaluation and Modeling of Alumina Grinding Wheel Surface Topography

Grinding wheels are often characterized by the density and protrusion height of abrasive grains and cutting edges.Measurement and evaluation of grinding wheels contribute to the better understanding of grinding mechanism,which is also the necessary precondition of grinding optimization and simulation.White light interferometer are used to measure the surface topography of alumina grinding wheels.Three-dimensional surface characterization parameters from "Birmingham set" are employed to quantize the surface topography of grinding wheels,in items of grit density,shape and sharpness of grits.Mathematical models of the distribution of protrusion heights,are built based on statistical values of measured results.It is shown that the alumina abrasive grain can be simplified as a cone with tip radius.The tip radius is related with the abrasive grain size,while the cone angle is almost the same due to the same dressing and truing conditions.The result also shows that mathematical models of protrusion height of alumina grinding wheels accord with normal distribution.

Three-dimension surface characterization of grinding wheel using white light interferometer

Wyko NT9300 white light interferometer was employed to measure the surface topography of 60# and 120# alumina grinding wheels. The correlation of wheel topography and its performance was characterized through the employment of three-dimensional (3D) surface characterization parameters. Eight parameters from the “Birmingham set” were used to characterize the performance of grinding wheels, in items of grit density, grit sharpness and chip space. The effect of sampling interval on the 3D surface parameters was analyzed and the optimal sampling interval was selected to calculate the 3D surface parameters of grinding wheels.

The Application of Three-Dimensional Surface Parameters to Characterizing Grinding Wheel Topography

White light interferometer was employed to measure the surface topography of 60# and 120# alumina grinding wheel. The correlation of wheel topography and its performance was characterized through the three-dimensional (3D) surface characterization parameters of “Birmingham set”. Birmingham parameters were used to characterize the performances of grinding wheel, in items of grain density, grain shape and grain sharpness. The effects of sampling interval on the 3D surface parameters were analyzed and the optimal sampling interval was selected to calculate the 3D surface parameters.

A study of grinding wheel sharpness using neural network and fuzzy logic approaches

In this study, two different models were developed to estimate the skewness factor of an alumina grinding wheel which is a criterion for wheel sharpness. Development of the models is based on the back propagation neural network (BPNN) and the fuzzy logic approaches. Some experiments have been performed to train the BPNN to get it to estimate the wheel sharpness. Also, all membership functions and rule-bases have been presented in details for a fuzzy model. In experiments procedure, the grits of an alumina grinding wheel is dressed using a rotary diamond disc dresser. The predicted values of the skewness factor by using the neural network represented that this model has an acceptable precision in estimation of wheel sharpness. Also well acceptable performance of the fuzzy model was achieved. Comparison of two models shows that they were successful in estimation of the wheel sharpness.

ANALYSIS OF THE DISC DRESSING EFFECTS ON GRINDING PERFORMANCE—PART 2: EFFECTS OF THE WHEEL TOPOGRAPHICAL PARAMETERS ON THE SPECIFIC ENERGY AND WORKPIECE SURFACE ROUGHNESS

This article is the second of two parts which analyze and simulate the disc dressing process and its effect on grinding performance. In the first part a new stochastic model of the prediction of wheel topography by diamond disc dresser was developed. It predicted the number of active cutting points per unit area and average slope of the asperities on an alumina grinding wheel. In the second part the effects of a disc dressing parameter which affect the wheel topography, specific energy, and workpiece surface roughness are evaluated. An upper bound analysis of a pyramidal indenter which moves on the workpiece is used for evaluation of the specific energy and modification of the grain tip. Modified grain tip was then used to predict the surface roughness of the ground workpiece. Dressing conditions with various speed ratios, cross feed rates and depths of dressing were investigated. In each case, the grinding forces and the surface roughness were experimentally measured, and then the effect of changing dressing parameters on the grinding performance was analyzed.

ANALYSIS OF THE DISC DRESSING EFFECTS ON GRINDING PERFORMANCE—PART 1: SIMULATION OF THE DISC DRESSED WHEEL SURFACE

This article is in two parts describing the analysis and simulation of the disc dressing process and its effect on grinding performance. This part is concerned with the generation of the wheel surface by a diamond disc dresser. A new stochastic model of the prediction of wheel topography by diamond disc dresser is developed. It predicts the number of active grains per unit area and average slope of grains of the alumina grinding wheel. This model is based on the fracture of grits and it considers the kinematical influences of the disc dressing process on wheel surface. It is possible to analyze the effects of changing dressing parameters on the wheel topography. The topography that is generated from this model provides a basis for further prediction of the grinding performance.

Femtosecond laser dressing of the surfaces of porous alumina grinding wheels

The interaction of 180 fs, 775 nm laser pulses with the surfaces of alumina and glass under controlled gas atmospheres at ambient pressure has been investigated to study material redeposition, residual surface roughness and ablation rate. The effect of using various gases to protect the surface of the material appears to interfere with the effects of the plasma and can change the resulting microstructure of the dressed surface. By varying the combinations of fluence and laser scanning speed during ultra fast ablation at high repetition rates an optimum dressing condition can be reached. The process can be used to continuously dress porous vitrified cutting tools that are used for micro and nanogrinding processes.

EFFECT OF WHEEL WEAR ON CONTACT LENGTH, UNCUT CHIP THICKNESS AND FORCES FOR A DEFORMABLE GRINDING WHEEL AND WORKPIECE

In this paper, contact length, uncut chip thickness, and contact forces were studied as the wheel wore during dry surface grinding of 4130 normalized steel for three different depths of cut (0.0025, 0.005, 0.0075 mm). An aluminum oxide grinding wheel (Norton 38A46HVBE) was used for all the experiments and the work and wheel speeds were 0.22 and 32.3 mis, respectively. In each experiment, the wear flat area, the cutting edge density, the cutting edge width and length were determined using an automated optical measurement system. The grinding forces were measured using a force dynamometer. The contact length was determined using rigid-body, smooth­ body and rough-body contact assumptions. The uncut chip thickness was determined using a continnity analysis. In this approach, the average volume of material is lJrSt determined by dividing the total material removal rate by the number of cutting edges. Then an assumption of the shape of the chip is made. In this work, the uncut chip was assumed to have a triangular profile and a rectangular cross-section. The uncut chip thickness can then be determined by dividing the average chip volume by the average contact length and chip width. In the experiments, grinding forces, wear flat area, cutting edge density increased and uncut chip thickness decreased as a result of wheel wear. In addition, the wheel wear increased the contact length significantly in the rough-body assumption, marginally in the smooth-body. assumption but not in the rigid-body assumption. The normal contact pressure was determined by dividing the normal force by the product of the percent wear flat area and contact area. This result suggested that the rough body assumption represented the data most accurately.