Wear Of Diamond Wheel Research Articles

Wheel wear behavior and its influence on grinding performance in electrical discharge diamond grinding of reaction-bonded silicon carbide

Diamond wheel wear is the greatest challenge for the high-efficiency grinding of SiC mirrors due to the need for the frequent dressing of the wheel. To realize the dressing of the diamond wheel in the process, the electrical discharge diamond grinding (EDDG) that combines conventional grinding (CG) and electrical discharge machining (EDM) was used to machine the mirror material of reaction-bonded silicon carbide (RB-SiC) considering its conductivity. However, the diamond wheel will experience quite different wear behaviors from those in the CG process due to the additional electrical discharge action in the EDDG process. As a result, different grinding performances will also be obtained. In this paper, the wheel wear behavior and its influence on grinding performance were investigated by a comparing test with the CG process in continuous EDDG of RB-SiC. The wear behavior and mechanism of the diamond wheel were investigated by a combination of morphology detection and spectra analysis. To explore the influence of wheel wear on grinding performance, the material removal rate (MRR), grinding ratio (GR), grinding force, and surface roughness were discussed based on the wear regulation of the diamond wheel varied with processing time. The result revealed that the electrical erosion was mainly responsible for the different wear behaviors and mechanisms of the diamond wheel in the EDDG process. Due to the dressing effect and material removal caused by discharge sparks, higher MRR, lower GR, lower grinding force, and lower surface roughness were obtained in the EDDG process.

Revealing patterns in the wear of profile diamond wheels

The electro-erosive wheel dressing exerts a significant impact on the machining accuracy of an article and the efficiency of the profile grinding process. To effectively control machining accuracy, the most important is the error due to the wear of a diamond wheel. The wheel should be dressed when wear approaches to the border but does not go beyond the tolerance field. This would reduce the number of defects at machining and bring down the utilization of diamonds. In addition, this reduces the dressing time and, therefore, improves the efficiency of profile diamond grinding. The paper reports the methodology and results of an experimental study into the wear of profiled diamond wheels. The specific utilization of diamonds was examined on the grinding wheels of the direct profile. The amount of a wheel linear wear was measured by a contactless method applying a special device based on the use of eddy current sensors. This was followed by determining the integrated amount of the worn volume of a diamond layer; after that, the weight of the used diamonds was measured. The mass of the sanded material was determined by weighing it before and after machining. A mathematical method of planning and analysis of experiments was used to establish the functional dependence of the specific utilization of diamonds on the technological machining modes and the diamond layer parameters. The result of regression analysis is the derived functional dependence of diamond specific utilization on the following factors: the concentration of diamonds in a wheel, the grit of the tool, the grinding wheel velocity, the depth of grinding, and the speed of an article. To determine the patterns of wear of the shaped diamond wheel, we received an imprint of its profile on a control plate made from a solid alloy and measured the coordinates of the points of the working part of the profile relative to the non-utilized areas. Determining the difference of coordinates before and after the experiment has helped find the amount of radial wear of the grinding wheel at the appropriate profile point

The Effect of Diamond Wheel Wear on Surface and Sub-Surface Quality in Fused Silica Optics Grinding

During the ultra-precision grinding process of fused silica optics, the micro-removal processes of brittle and hard fused silica material by diamond grits in different wheel wear states are inconsistent, which leads to the instability of the grinding quality of the components. First, the wear forms of diamond wheel in the process of grinding brittle and hard fused silica material were analysed. The main wear form of diamond grinding wheel was diamond abrasive wear. Then taking the cumulative removal volume of material as the evaluation parameter of wheel wear state, the evolution laws of surface roughness and sub-surface defects of components under different cumulative removal volume of material were studied. With the aggravation of grinding wheel wear, the surface roughness and depth of sub-surface defects layer decreased first, and then fluctuated and increased slowly. In the rapid wear stage, the falling diamond particles scratched deep grooves on the surface of components, and the roughness and sub-surface depth increased sharply. According to the results, it’s reliable to monitor the wheel wear state and predict the life of wheel.

Analysis of diamond wheel wear and surface integrity in laser-assisted grinding of RB-SiC ceramics

Laser-assisted grinding provides a promising solution for achieving cost-efficient machining of hard and brittle materials. However, the heat generated by laser may cause the wear of diamond grinding wheel, including the wear of both diamond grits and bond material. Consequently, wheel wear has a knock-on effect on the ground surface roughness. Moreover, the laser irritation may also induce damage in the machined surface. This paper focuses on the investigation of wear of diamond grinding wheel and surface integrity in laser-assisted grinding of RB-SiC ceramics. Different temperatures were obtained by setting the laser power to explore the influence of heat on wheel wear and surface integrity. The wear modes and mechanism of the diamond grits and bond material were analyzed by combination of SEM detection and energy dispersion spectrum analysis. The results revealed that adhesion and pullout of diamond grits in laser-assisted grinding were the remarkable difference from those in conventional grinding due to the thermal softening of both RB-SiC specimen and bond material of the grinding wheel. Surface roughness was then improved owing to the increase in active grits. The Raman spectra of the machined surface also revealed different stress conditions and microstructures of the Si and SiC Phase in RB-SiC ceramics. These results provided insight on quality control in laser-assisted machining of RB-SiC ceramics.

Diamond wheel wear mechanism and its impact on the surface generation in parallel diamond grinding of RB-SiC/Si

The diamond wheel wear mechanism and its impact on the surface generation of RB-SiC/Si carbide under parallel grinding were investigated. The machined surface was mainly characterized by surface fracture and diamond grits scratched plastic grooves, and the surface finish of the machined RB-SiC/Si improved with decreasing feed rate. But the non-uniform surface appeared due to the varied material removal rate at different radial position for a certain workpiece. Both macro- and micro-wheel wear occurred during grinding, and the macro-wheel wear appeared in the form of profile deviation and rapid loss of sharp edge, which contributed to the appearance of cone shape at the center of workpiece. Power spectrum analysis by Fast Fourier Transformation (FFT) confirmed the significant influence of micro-wheel wear on surface generation, which involved random diamond grit splintering, abrasive flattening, grain dislodgement and graphitization.

Surface damage mechanism of WC/Co and RB-SiC/Si composites under high spindle speed grinding (HSSG)

The surface damage mechanisms of WC/Co and Reaction-bonded SiC/Si (RB-SiC/Si) composites under high spindle speed grinding (HSSG) were investigated in the present work. Sharp edge loss and grit splintering were identified as two typical diamond wheel wear mechanisms. Plastic scratching grooves, Co extrusion and WC dislodgement were generated on the machined surface of WC/Co after grinding, while micro-pits of varied sizes at the phase boundaries and plastic scratching grooves were the main surface characteristics for RB-SiC/Si. Moreover, it was found that non-uniform surface finish at different radial positions resulted from the increase in material removal rate for both WC/Co and RB-SiC/Si, and the simulated results based on Soneys' model mostly corresponded with the measured outcomes. In addition, obvious relative wheel-workpiece vibration induced surface waviness was found, and its effect on the surface profile was analyzed for the wheel edge profile considered, which differed with that from single point diamond machining (SPDT).

Study on wear of diamond wheel in ultrasonic vibration-assisted grinding ceramic

The ultrasonic vibration-assisted grinding method has been widely used as a cost-effective machining method for hard and brittle materials. It is generally known that the ultrasonic vibration during grinding procedure causes the micro-fracture of the workpiece, which can improve grinding efficiency and provide better surface integrity. On the other hand, the ultrasonic vibration also acts on the diamond wheel surface, affecting its wear during the grinding process. In this study, the alumina ceramic was ground with and without the ultrasonic vibration-assisted grinding ceramic to investigate the wear characteristics of the diamond wheel. The changes of the diamond wheel surface topography were captured and the grinding forces were measured during the grinding process. Based on the analysis of the experimental data, it was found that the ultrasonic vibration caused great wear but at the same time improved the self-sharpening property of the diamond wheel. One can also found that as the ultrasonic vibration on the diamond grits produce micro cutting edge the diamond wheel work surface was steady kept sharpness during ultrasonic vibration-assisted grinding, and the grinding force and force ratio did not increase with the increasing of cumulative material removal volume.

Mechanical truing of V-shape diamond wheels for micro-structured surface grinding

An on-machine mechanical truing method with rotary green silicon carbide (GC) roller to precision shape and prepare V-shape diamond wheels for microstructured surface grinding was proposed. The effects of truing parameters on trued wheel profile accuracy were investigated. The experimental results showed that the feed direction of GC roller had a remarkable effect on truing accuracy. The V-tip radius of trued wheel was reduced with the increase of the GC roller speed or the decrease of the grinding wheel speed, truing depth per pass, feed rate, and the grain size of GC roller. The V-shape diamond wheel with less than 18-μm V-tip radius and 0.6-μm run-out (center zone of wheel) was produced by parameter optimization. Finally, the V-groove array was ground on silicon nitride mold material by the trued diamond wheels. Although the V-tip of diamond wheel can be trued to less than 18 μm, the smallest corner radius, which was obtained in the first ground groove, was still bigger than 46 μm due to the unavoidable wear of diamond wheel in the grinding process of hard mold material.

Wear of Diamond Wheel in Groove Grinding of Cemented Carbide - Influences of Speed Ratio and Nitrogen Gas Dissolved Coolant

This paper describes on the experimental results of diamond wheel wear in groove grinding of cemented carbide. The speed ratio of grinding was widely changed. Square grooves and 90 degree V-grooves were ground. The square grooves were ground by using a resin-bonded diamond wheel and the V-grooves were by a vitrified diamond wheel. At first, a water-based coolant was used, but afterward, to investigate a possibility of nitrogen to suppress the wear of wheel, nitrogen gas was dissolved into the water-based coolant. The main results obtained are as follows, (1) The wheel wear increases as the speed ratio decreases, (2) The average grinding forces is almost independent from the grinding conditions but those at the lowest speed ratio are fairly large, (3) The influence of nitrogen gas dissolved coolant is small, but in a case of V-shape grinding at a middle speed ratio there found a considerable decrease of wheel wear.

Micro/nano Indentation and Single Grit Diamond Grinding Mechanism on Ultra Pure Fused Silica

The existing research about ductile grinding of fused silica glass was mainly focused on how to carry out ductile regime material removal for generating very "smoothed" surface and investigate the machining-induced damage in the grinding in order to reduce or eliminate the subsurface damage.The brittle/ductile transition behavior of optical glass materials and the wear of diamond wheel are the most important factors for ductile grinding of optical glass.In this paper,the critical brittle/ductile depth,the influence factors on brittle/ductile transition behavior,the wear of diamond grits in diamond grinding of ultra pure fused silica(UPFS) are investigated by means of micro/nano indentation technique,as well as single grit diamond grinding on an ultra-stiff machine tool,Tetraform "C".The single grit grinding processes are in-process monitored using acoustic emission(AE) and force dynamometer simultaneously.The wear of diamond grits,morphology and subsurface integrity of the machined groves are examined with atomic force microscope(AFM) and scanning electron microscope(SEM).The critical brittle/ductile depth of more than 0.5 μm is achieved.When compared to the using roof-like grits,by using pyramidal diamonds leads to higher critical depths of scratch with identical grinding parameters.However,the influence of grit shapes on the critical depth is not significant as supposed.The grinding force increased linearly with depth of cut in the ductile removal regime,but in brittle removal regime,there are large fluctuations instead of forces increase.The SEM photographs of the cross-section profile show that the median cracks dominate the crack patterns beneath the single grooves.Furthermore,The SEM photographs show multi worn patterns of diamond grits,indicating an inhomogeneous wear mechanism of diamond grits in grinding of fused silica with diamond grinding wheels.The proposed research provides the basal technical theory for improving the ultra-precision grinding of UPFS.

Influence of metallic filler on the wear of diamond wheels with organic binder

The influence of metal fillers—in particular, copper—on the wear of diamond wheels is considered. It is found that the optimal copper content in the binder is 20%, ensuring minimum diamond consumption and maximum cutting-grain density at the wheel’s working surface.

Dynamic Monitoring and Intelligent Dressing of Diamond Wheel for Precision Curve Grinding

This paper deals with an application for achieving precision curve grinding by automatic dressing and compensation of diamond wheel wear through non-contact measuring method. A realtime vision measurement combined with vibration analysis method for the wear of a grinding wheel is presented. The wear condition is evaluated by analyzing the topography changes of the wheel surface and the vibration signals in the grinding process. A kind of PC-based integrated control system with dynamic monitoring and automatic dressing function is investigated, and the control algorithm is also proposed. The benefits of the proposed methods are confirmed by the grinding experiments. Dynamic monitoring of the wheel facilitates determining the optimum dressing amount and interval. A much higher abrasive machining precision and efficiency are attained by the real-time error measurement and compensation arrangement.

Wear of diamond wheels in creep-feed grinding of ceramic materials II. Effects on process responses and strength

Alumina specimens were ground with a resin bonded diamond wheel using three different work speeds in creep-feed up-cut mode. For each work speed, the wheel surfaces and the process responses were evaluated at five different wear states, which were generated by grinding 0, 29.6, 59.2, 88.8, and 118.4 cm 3 volume of a selected silicon nitride material. The mechanisms of wheel wear have been studied and reported in Part I (Wear 211 (1997) 94–103). This paper investigates the effects of wheel wear on process responses and ground ceramic quality, particularly the flexural strength. Strong relationships between the wheel surface conditions and the process responses are found. During the initial stage of wheel wear (from the as-dressed state to the first 29.6 cm 3 volume of material removal), the surface density of diamond grits, surface roughness and flexural strength decreased, and the specific normal force, specific tangenitial force, force ratio, and specific energy increased. The largest change in most of process responses, except the roughness, occurs at the lowest work speed. Right after grinding 29.6 cm 3 volume of sillicon nitride material, process responses stayed approximately the same with some degree of expected fluctuation due to the competing influence of attritious wear and the wheel's self-sharpening effect. The effect of wheel wear on the flexural strength of ground alumina specimens is found to be dominated by the effect of work speed.

Wear of diamond wheels in creep-feed grinding of ceramic materials I. Mechanisms

The main objective of this paper is to study and quantify the wheel wear mechanisms in creep-feed grinding of ceramic materials with diamond wheels. A resin-bonded diamond wheel was selected for this study. Nine different states of wheel working surface were generated by grinding specified volumes of a selected silicon nitride material. It is found that: (1) the roughness of wheel profile decreased quickly and stayed about the same after approximately 30 cm 3 volume of material removal; (2) diamond grits experienced attritious wear, grit fracture, and grit dislodgment; (3) the wheel wear mechanism was dominated by grit dislodgment in the first 2 cm 3 volume of material removal and by attritious wear thereafter; (4) grit density per unit area can be expressed as an exponential decay function of cumulative volume removal. The percentage of each wear mechanism was obtained by tracing grits in the same area after 2.1, 4.2, 7.4, and 10.6 cm 3 volume of material removal using the lead-tape imprint technique.