Conventional Diamond Grinding Research Articles

Ultra-low damage processing of silicon wafer with an innovative and optimized nonwoven grind-polishing wheel

Silicon is essential to the production of integrated circuits and optical components. Grinding is a commonly used method of silicon surface machining, but it often leads to surface and subsurface damage. These damages need to be removed by subsequent processes, typically through polishing. The surface quality generated by grinding directly impacts the cost of polishing. To enhance the quality of the grinding surface and reduce the time and cost of polishing, a grind-polishing wheel with a different structure from the conventional diamond wheel was developed. This wheel utilized ultrafine zirconia with grit size of 200 nm as abrasives and nonwoven as substrate to support the abrasives. Furthermore, to optimize the wheel and achieve better grinding performance, various wheels with different abrasive mass fractions and elastic moduli were fabricated and grinding experiments were conducted. The surface integrity of processed silicon and the material removal rate (MRR) were used to compare the grinding performance of the various wheels. After optimization, the MRR of the grind-polishing wheel reaches its peak at 0.81 μm/min. The silicon wafer ground with the grind-polishing wheel exhibited a surface roughness Sa of 0.51 nm and a subsurface damage depth of 74 nm, which is close to the effect of chemical mechanical polishing processing. Compared to conventional diamond grinding wheel (mesh size of #5000), the optimized grind-polishing wheel is better suited for semi-fine finishing and can significantly reduce the cost and time of polishing.

Grain wear properties and grinding performance of porous diamond grinding wheels

Conventional diamond grinding wheels present challenges such as poor self-sharpening and difficulties in achieving ductile domain machining when processing hard and brittle materials, reducing machining quality and efficiency. This paper introduces a novel grinding wheel composed of porous diamond abrasive grains for better ultra-precision machining. Thermochemical etching is used to produce porous diamond grains of varying corrosion levels, and the cutting and wear mechanisms of these grains are investigated through molecular dynamics simulations and single-grain scratch tests. Compared to conventional diamond grains, the increased "micro-edge" and "multi-edge" features of porous diamond grains effectively reduce cutting force and heat. Notably, corrosion pore sizes ranging from 2 μm to 5 μm reduce cutting damage. Conventional diamond abrasive grains primarily incur damage through crystal surface dissociation and block crushing, whereas porous diamond abrasive grains experience damage mainly due to micro-crushing and micro-fracture. Ultra-precision grinding tests on 4H–SiC revealed that conventional abrasives produced cracks and pits on the grinding surface. In contrast, abrasives with a 2 μm eroded aperture exhibited predominantly ductile removal with minimal cracks and pits present. Abrasives with a 5 μm eroded aperture displayed desirable characteristics. This research offers valuable technical insights for enhancing the grinding performance of diamond wheels.

Mechanical properties of ZrB2 ceramics determined by two laboratories

AbstractThe mechanical properties for zirconium diboride (ZrB2) were measured at two laboratories and compared. Two billets of ZrB2 were prepared by hot‐pressing commercial powder. The relative densities of the billets were >99% and with an average grain size of 5.9 ± 4.5 µm. Both laboratories prepared American Society for Testing and Materials (ASTM) C1161 B‐bars for strength and ASTM C1421 bars with notch configuration A for fracture toughness. Specimens were machined by diamond grinding at the Army Research Laboratory (ARL) and electrical discharge machining (EDM) at Missouri S&T. Strength bars tested at Missouri S&T were polished to a .25 μm finish while the bars were tested as‐ground at ARL. Strengths were 473 ± 79 MPa for the Missouri S&T bars and 438 ± 68 for the ARL bars while the fracture toughness values were 3.9 ± .7 MPa•m1/2 for the Missouri S&T bars and 4.4 ± .6 MPa•m1/2 for the ARL bars. Vickers hardness was measured by both laboratories over a range of indentation loads. The resulting hardness values were on the low end of previously reported values and were quite different from each other especially at indentation loads ≤20N. The study demonstrated that the properties of materials tested to ASTM standards at different laboratories can be compared directly. In addition, strength and fracture toughness were nearly identical for bars prepared by conventional diamond grinding or EDM.

Experimental investigation of rotary ultrasonic face milling on red granite: A comparison with conventional grinding

Long-term sustainability with cost-effective machining and materials are used in many companies these days. Also, precise machining on brittle and hard materials is becoming a challenge for production engineering. Rotary ultrasonic face milling (RUFM) is an unconventional milling process that is preferred to perform precise surface machining on such materials. The research work aims to analyse the enhancement in conventional diamond grinding (CG) due to the addition of ultrasonic vibration and compare both processes (RUFM and CG). Analysis of variance (ANOVA) technology was applied for the analysis. The scanning electron microscopy (SEM) technique was used to analyse the tool wear after milling operation. The controlling factors used for the study were feed rate, depth of cut, and ultrasonic power. The outcomes of the study showed an increment in material removal rate during RUFM compared to CG. Material removal rate (MRR) also increases with increment in each level of controlling factors. Surface roughness (SR) increases with the addition of ultrasonic vibration during RUFM. Also, SEM technology shows the complete removal of diamond grits at the bottom surface of the tool. The research concluded that tool life and material removal rate get improved but the reduction in surface finish during RUFM while comparing to CG.

Theoretical and Experimental Investigation on Inclined Ultrasonic Elliptical Vibration Cutting of Alumina Ceramics

Alumina (Al2O3) is an extremely hard and brittle ceramic that is usually used as an abrasive or a cutting tool insert in manufacturing. However, its growing applications in industrial products make it necessary to conduct a study of the machinability of alumina themselves with a cost-effective and flexible method, rather than conventional diamond grinding or laser-assisted processing methods. In this paper, polycrystalline diamond tools are used to investigate the machining of nonporous pure alumina by applying an inclined ultrasonic elliptical vibration cutting (IUEVC) method. First, a theoretical analysis is presented to study the effects of the machining parameters on cutting performances during raster cutting procedures from the prospective of the material removal rate (MRR), tool-chip contact area, cutting edge angle, etc. Then, experiments are carried out to investigate the cutting forces and the areal surface roughness (Sa) in connection with the theoretically established relationships. The results show that the cutting forces are remarkably reduced, by up to more than 90%, and that the machined surface finish is also improved compared with conventional methods.

Effect of Method of Sample Preparation on Strength of Zirconium Diboride (ZrB2)

Different surface finish of ZrB2 was generated by machining the hot pressed monolithic ZrB2 by wire-electrical discharge machining (EDM) as well as conventional diamond grinding. The effect of surface finish on strength was studied. Our results showed that wire-EDM produced very high roughness (Ra = 1.2) as compared with diamond grinding (Ra = 0.2 and 0.33) which resulted into lower strength of ZrB2 for EDM machined sample as compared to diamond ground samples.

Virginia Quieter Pavement Demonstration Program

This paper summarizes findings from Virginia’s recent quieter pavement research. It reviews overall condition; functional performance (ride, noise, and friction); winter maintenance and use characteristics; and other important observations made about a series of demonstration projects constructed in 2011 and 2012. The lower-noise pavement technologies included porous asphalt, conventional diamond grinding, and Next Generation Concrete Surface. The paper also summarizes results from the accelerated trafficking of Virginia materials at the National Center for Asphalt Technology Pavement Test Track. Finally, the paper reviews current federal policy and the pertinent ramifications for Virginia’s program. As of spring 2015, the difference in measured tire pavement noise between control surfaces and the most successful (lowest noise) quiet asphalt technology was no longer detectable with normal human hearing (<3 dB). The lowest-noise concrete surface continues to have a noticeable (~4 dB) advantage over the standard concrete finish. Although none of the quiet pavement technologies tested thus far provide sufficient noise reduction to satisfy federal regulations for noise abatement, the Virginia Department of Transportation is encouraged to continue monitoring federal policy for changes that may incorporate pavement type as a tool for mitigating noise. The department is also encouraged to continue to monitor (and to test as warranted) products of national and international research and development that show promise for reducing or eliminating traditional sound barriers.

Acoustic enhancement of concrete pavement surface through diamond grinding

Functionality of concrete pavements can be restored through conventional diamond grinding (CDG) that improves ride quality and friction. Recently, an alternative diamond grinding configuration was proposed by the Institute for Safe Quiet and Durable Highway at Purdue University as part of a nationwide interest in quiet pavements. This paper discusses the field-testing of the CDG and alternative (innovative) diamond grinding as well as the pre-existing transverse tined (TT) texture at the MnROAD research facility. Acoustic properties, ride quality and friction performance of the diamond ground surfaces are compared to data obtained in the pre-existing TT surface. The initial performance of the innovative grind over a period of 3 years is also compared to that of the conventional grind and the TT surface. Test results, analysis, merits and demerits of the grinding types are also accentuated.

Comparison of EDG, Diamond Grinding, and EDM Processing of Conductive Alumina Ceramic Composite

The ceramic materials are widely used in various industrial applications nowadays as they possess excellent properties like high hardness, low fractural strength, and brittleness, which makes machining very difficult and costly. Therefore, in the present work, the processes like conventional diamond grinding, electric discharge machining (EDM), and electric discharge grinding (EDG) are compared on the basis of material removal rate (MRR) and surface finish (Ra). EDG is the hybrid process of EDM and grinding and hence utilizes the benefits of both processes to give better MRR and surface finish than the parent processes. The MRR achieved in the EDG process is up to 50 times higher, and the surface roughness is at least 4 times better than the EDM process. The surface finish obtained by the EDG process is at least 4.5 times better than the conventional diamond grinding process and 3 times lower than cryogenically cooled conventional diamond grinding process. Surface and subsurface cracks, pit formation, and micropores were observed after conventional diamond grinding and EDM, but no such drawbacks were found on the selection of proper process parameters in case of the EDG process. Hence, surface finish and MRR obtained in EDG are better than EDM and the conventional diamond grinding process.

EXPERIMENTAL STUDY ON THE CUTTING FORCE DIFFERENCE BETWEEN ROTARY ULTRASONIC MACHINING AND CONVENTIONAL DIAMOND GRINDING OF K9 GLASS

A comprehensive experimental study on the cutting force differences between rotary ultrasonic machining (RUM) and conventional diamond side grinding, drilling and face grinding is conducted on K9 glass. By analyzing the experimental results and the kinematics of diamond grits, it can be seen that the reasons for the cutting force differences between with and without ultrasonic vibration are not same for the three machining processes. The cutting force difference of conventional diamond side grinding and RUM can be explained by analyzing the trajectory of diamond grits, while the cutting force difference of conventional diamond drilling and RUM is mostly dependent upon the difficulty level of removing chips. As a transitive form, the cutting force difference between conventional diamond face grinding and RUM is affected by both the diamond grits' trajectory and the difficulty level for removing chips. In addition, it is also noticed that different cutting tools have different reduction percentages of cutting forces in RUM compared with conventional diamond grinding. The findings are helpful for researchers to have a further understanding in RUM.

Edge Sharpening and Surface Modification of PcBN Cutting Tool by Pulsed Laser Grinding

PcBN cutting tools have excellent characteristics such as high degree of hardness and low chemical reactivity, so they have potential to replace high precision grinding of hardened steel with high precision cutting. PcBN might be more efficient tool material if improvement in formability, and good surface modification can be achieved. In order to solve these problems, Pulsed Laser Grinding (PLG) is applied to a shape cutting edge and to finish a rake face. After processing by the PLG, shaped cutting edges were observed with a scanning electron microscope (SEM) and measured with contact- type profilometer. As a result, cutting edges processed by the PLG are similar or shaper than that by conventional diamond grinding. In addition, as a one of effects of surface modification, The Vickers microhardness of rake faces increases by about 10 present after PLG. On the other hand, according to frictional test with lateral force microscopy, the coefficient of friction of rake face decreases by half of ordinary surface. Depending on these advantages of PLG, high precision turning of hardened steel with 58HRC in hardness by use of the tool processed by PLG can demonstrate good performance rather than a commercial tool with diamond grinding finish.

Ultrasonic slot machining of a silicon carbide matrix composite

Rotary ultrasonic slot machining (RUSM) of ceramic matrix composites is explored. A comparison is made between RUSM and conventional diamond grinding by studying the effects of material removal rate (MRR) on process forces, tool wear and surface roughness. It was shown that RUSM leads to a significant decrease in process cutting forces and tool wear in comparison to the conventional machining process. Furthermore, the influences of diamond tool characteristics on surface roughness and tool wear are also ascertained.

Ordered diamond micro-arrays for ultra-precision grinding—An evaluation in Ti–6Al–4V

The surface topography of a conventional diamond grinding wheel can be characterised as having a perplexity of abrasive particles with random crystallographic orientations resulting in different heights of protrusion from the bond and inherent varying inter-particle spacing. The number and effectiveness of the abrasive particles during grinding depends on factors such as the abrasive concentration, the crystallographic shape and the extent of particle protrusion from the wheel’s surface. The consequence of this random layout inhibits the optimal performance of individual abrasives in the process of material removal, and where particles are clustered, chip flow is negatively affected. This paper reports on the evaluation of purpose designed precision diamond micro-arrays for the grinding a case-study material, Ti–6Al–4V and compares their performance against conventional diamond electroplated micro-cutting elements of D91 and D46 abrasive size in an imitated grinding setup. The precision diamond micro-arrays, produced from thick film CVD diamond utilising energy beam ablation offer an optimised layout of abrasive elements, each having a cutting width of 100 μm of identical crystallographic orientation, protrusion height and regular spacing to provide chip flow paths. In addition, the primary/secondary rake angles γ=−32°/+1° and clearance angle α=4.5° of each abrasive cutting element have been controlled in order to provide an enhanced cutting action. The precise layout of the abrasive cutting elements of the micro-arrays produced superior chip flow compared with the diamond electroplated grinding elements; this has been proven by in-depth scanning electron microscopy of the clogged workpiece material on the studied abrasive elements. The results show a 3.5 times improvement to surface finish and a 21.5 times improvement to flatness of the Ti–6Al–4V workpieces when ground with the proposed innovative diamond micro-arrays.

Brittle-Ductile Transition in the Two-Dimensional Ultrasonic Vibration Grinding of Nanocomposite Ceramics

Based on impulse theories and indentation fracture mechanics, the motion model of the contact between abrasive particle and workpiece in workpiece two-dimension ultrasonic vibration grinding (WTDUVG) was analyzed, and the critical condition of ultrasonic vibration grinding brittle-ductile transition was analyzed theoretically, furthermore the critical cutting depths of a grain under different grinding conditions were obtained by Matlab programs. In this work, the ultrasonic vibration and conventional diamond grinding of Al2O3/ZrO2 nanoceramics were performed in order to investigate the effect of workpiece ultrasonic vibration on the brittle-ductile transition mechanism, the effect of grit size, worktable speed and grinding depth on the critical depth of cut were studied by grinding experiments. the micro-topography of the grinding surface was observed by AFM and SEM. Experiment indicated that only when the grinding depth less than critical grinding depth, ductile regime grinding of ceramics can be realized, the appropriate grinding parameter on surface finish are suggested.

Analysis of effect of voltage on surface texture in electrochemical grinding by autocorrelation function

The major difficulty faced in electrochemical grinding (ECG) of composite materials is poor surface integrity because of differential dissolution rates of different ingredients present in those materials. In the present investigation an experimental study, organized by statistical procedure, was made to evaluate the effect of the major controllable parameter ‘voltage’ on the surface finish of P-20 grade cemented carbide. The surface roughness data were analyzed for different voltages. The values of autocorrelation function for different values of lag period were calculated. The periodicity and randomness of surface roughness were identified. They are compared with the similar observations on the conventional diamond grinding of the same material in ECG environment with no application of voltage. A non-dimensional parameter was introduced for that purpose and was termed as ‘periodicity to randomness index’. An attempt was made to find out the relative contribution of the electrolytic dissolution under the chosen experimental conditions.

Development of Vitrified Diamond Grinding Wheel for Engineering Ceramics

Newly developed engineering ceramics are very difficult to be ground using conventional diamond grinding wheel because of their poor dressability and low cutting ability. In this study, a rigid and porous vitrified diamond grinding wheel was made so that a diamond grain might not deteriorate and it might be tightly bonded to the bond bridge using proper frit bond at lower firing temperature. According to the grinding test results, the grinding force was very low and dimensional accuracy of ground ceramics was very excellent.