Diamond Grinding Wheel Research Articles

Численное моделирование температурного поля в алмазных шлифовальных кругах

A numerical simulation of the temperature field in diamond grinding wheels of a polymer matrix is carried out. The influence of various coatings on diamonds on the temperature field is studied. The properties of the matrix and the parameters of the coatings, which provide increased efficiency of the circles, are determined.

Diamond abrasive based cutting tool for processing of advanced engineering materials: a review

Abstract The use of abrasives for grinding was first noticed in ancient Egypt in 2000BC. Quartz was the only abrasive known at that time. Further, emery, garnet and diamond were used as the other abrasive materials for grinding as per the need of various manufacturing processes. Diamond has been recognized as an alternate to various other available abrasive materials for grinding and finishing processes in last two decades. The machining of advanced materials such as titanium alloys, nickel alloys, heat treated steel, high strength temperature resistant alloys etc, resulted in the development of new machining processes, known as hybrid machining processes. These processes involve various new tools such as metal bonded diamond grinding wheel, diamond drill bits etc. and these are most widely accepted nowadays by the researchers in micro-machining field. In present paper, attempts have been made to do an exhaustive review of various advancements in the machining technology using the diamond abrasive based tools. Diamond abrasive tools are widely being used by various researchers in hybrid machining processes such as EDDCG, EDDFG, EDDSG, ECDG, ECDD etc. This paper illustrates the history of diamond abrasives and its use in recent advancements in the manufacturing technology till now with an overview of various manufacturing methods of the diamond abrasive based tools

Effect of V2O5 addition on the wettability of vitrified bond to diamond abrasive and grinding performance of diamond wheels

In this paper, V2O5 was added into vitrified bond as a surfactant to improve the holding force of the vitrified bond to diamond abrasive and to improve the grinding performance of vitrified diamond grinding wheel. Results showed that the refractoriness of the vitrified bond with 4 wt% V2O5 reached 555 °C, 17 °C lower than that of the vitrified bond without V2O5. During sintering, vanadium ions in the bond was enriched on the diamond surface and combined with the unsaturated carbon atom existed on the surface of diamond to form VC bond, which can improve the wettability between vitrified bond and diamond abrasive; Li2Si2O5 phase began to precipitate in bond when addition of V2O5 content reached 2 wt%; The Flexural strength and Rockwell hardness were significantly improved from 83.7 MPa and 87.4 HRB to 112.6 MPa and 108.1 HRB, 34.5% and 23.7% higher than those of diamond composites without V2O5, respectively. The performance of the diamond grinding wheel prepared by adding 2 wt% V2O5 to the vitrified bond was improved, The roundness and straightness errors of the 50th zirconia workpiece in one dressing cycle decreased from 3.31 and 2.11 μm to 3.02 and 1.9 μm, respectively, as compared with the vitrified diamond wheel without V2O5.

Surface integrity and flexural strength improvement in grinding partially stabilized zirconia

Zirconia has been used in medical applications since last few years and an optimum and cost-effective condition in grinding zirconia has drawn industrial attention. This paper aimed to improve and control the surface integrity, flexural strength and grinding cost in grinding partially stabilized zirconia (PSZ) using a diamond grinding wheel. The phase transition and grindability of PSZ were also evaluated. Ground surfaces analysis shows that all samples subjected to the grinding presented an increase in surface integrity, and the subsurface damages 100 below the surface were reduced from 3.4% to 0.9%. The flexural strength using 3 point bending test (3PB) shows that grinding increased the flexural strength more than 29% which is the result of higher surface integrity. The ground surfaces were analyzed using X-ray diffraction (XRD) and the results shows that T-M phase transition trend is in accordance with the surface integrity. In other words, XRD analyses prove that T-M phase transition results in higher flexural strength and surface integrity. It was also observed that in the best condition, the grinding cost was reduced by 72%. It can be concluded that controlling the grinding condition in grinding PSZ will result in the increase of the surface integrity and flexural strength. A mathematical model was created to find an optimum condition using response surface method (RSM). It is observed that feed rate has greater effect on the outputs rather than depth of cut.

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.

Influence of grinding parameters on phase transformation, surface roughness, and grinding cost of bioceramic partially stabilized zirconia (PSZ) using diamond grinding wheel

The aim of this study is to evaluate the effect of various grinding parameters on the phase transformation, surface roughness, G-ratio, grinding cost, and specific grinding energy of partially stabilized zirconia (PSZ) using different diamond grinding wheels. The use of PSZ ceramic in dental applications has significantly increased in recent years due to excellent mechanical and biological properties. Considering the extreme hardness and brittleness of PSZ besides achieving dimensional and geometrical accuracies, grinding becomes an essential process. PSZ blocks are ground using four different diamond grinding wheels and grinding forces are measured during the grinding process. Next, PSZ phase transformation is analyzed using X-ray diffraction (XRD) and surface roughness; furthermore, wheel wear and grinding cost analysis are performed. All samples subjected to grinding reveal an increase in monoclinic phase content. From the surface integrity point of view, processing the images of scanning electron microscopy (SEM) from the specimens subjected to the grinding with a metal bond diamond grinding wheel shows 12% higher surface integrity. Additionally, it is shown that grinding in an optimum condition could enhance the surface roughness more than 60%. To find this optimum condition as well as to establish a mathematical relationship between inputs and outputs, response surface method (RSM) is employed. The obtained R-square value for the mathematical model is more than 0.90, which confirms the precision of the model.

On-machine electric discharge truing of small ball-end fine diamond grinding wheels

Abstract Small ball-end metal bonded fine diamond wheel (SBFDW) is mainly applied to finishing complex components with small curved surfaces. Hence, it needs to investigate the influence of electrical parameters on the on-machine electric discharge truing of the SBFDW. Material removal characteristics in SBFDW truing are studied to analyze the relationship between the electrical parameters and profile accuracy. Profile accuracy and surface characteristics of the SBFDW and surface quality of the ground workpiece are experimentally investigated to evaluate the truing quality. The relationship between the electrical parameters and profile accuracy is established, based on which sensitivity analysis is used to reveal the influence degree of different factors. Among these factors, the open voltage has the most significant influence on the profile accuracy. Single pulse discharge energy will affect the surface topography of the SBFDW and further affect the grinding quality. When the energy is high enough, burns occur, recast layer covers the grinding wheel, and graphitization of diamond grits occurs. The surface roughness value of workpiece and grinding force increase with the increase of the truing energy. Then, a truing strategy combining low energy truing and high energy truing is proposed for truing the SBFDW. The trued SBFDW is proved to be suitable for grinding the complex components.

Design of assembled substrate of electroplated diamond grinding wheel for disassembly of abrasive layer

Expensive diamond grains remaining within waste diamond grinding wheels and wheel substrate need to be recycled. Electroplated diamond grinding wheel was taken as an example. An idea of “substrate structure-induced cracks (SSIC)” was proposed to solve the disassembly problem of waste electroplated diamond wheels. An assembled substrate for electroplated diamond grinding wheel was designed. Fabrication and disassembly experiments of electroplated diamond wheel with assembled substrate were carried out. Also, finite element analysis was used to investigate the mechanism of disassembly processes. Recycling experiments of electroplated diamond wheels were carried out in three ways, namely acid corrosion method, electrolysis method and SSIC method. The experimental results show that cracks generate in the diamond abrasive layer of the assembled wheel. The simulated maximum principal stress occurs on diamond abrasive layer near the mating surface between cylindrical pins and substrate, which is consistent with the location where the crack is created. The abrasive layer can be easily peeled off from substrate after the cracks occur on abrasive layer. Compared with electrolysis and acid corrosion methods, the SSIC method has the shortest disassembly time and the lowest disassembly costs. The assembled substrate provides possibility to exert cracking forces from substrate to diamond abrasive layer. With assembled substrate, the nondestructive disassembly of electroplated diamond wheel can be fulfilled. Assembled substrate can meet the need of DFD for electroplated diamond grinding wheel.

Modified gel casting technique to fabricate honeycomb structured vitrified-bonded ultrafine diamond grinding wheels

To avoid agglomeration of ultrafine diamond particles and to improve machining precision of silicon (Si) wafers, a combination of gel casting and pore-forming agent is introduced to fabricate vitrified-bonded ultrafine diamond grinding wheel with ultrahigh porosity (~75%), honeycomb structure, and homogeneous microstructure. Moreover, the as-prepared grinding wheel possesses uniformly distributed closed pores, which are highly desirable for chip removal, heat dissipation and extended service life. In addition, influences of sintering schedules on microstructure, porosity and bending strength of the as-prepared grinding wheel are systematically investigated. Because of the honeycomb structure, the as-fabricated grinding wheel renders superior self-sharpness, which is required for continuous grinding of Si wafers without dressing, and this subsequently enhances the working efficiency. Results reveal that the surface roughness and damaged layer of the ground Si wafers are approximately 5.0 nm and 0.21 μm, respectively. The current study provides a novel pathway for efficiently processing high-quality silicon wafers.

Developments in pre- and post-treatment of thin films and their influences on surface topography and coating adhesion strength of cutting tools

Due to the increased requirements on machining of metallic and non-metallic materials, the pre- and post-treatment of hard thin films has been an important topic in several researches in the past decade. The main improvement in tool properties by a reduction of surface inhomogeneities is reached by an additional mechanical or chemical treatment before and/or after the coating process. Especially the cleaning before coating has to be considered to reduce the amount of debris of the pre-treatment which may negatively effect surface quality after the coating process. The mainly used processes of mechanical treatment to enhance surface topography before and after coating are several machining processes such as abrasive jet machining or drag finishing. This paper introduces a novel process for the pre- and post-treatment of coated cutting tools by elastically bonded diamond grinding wheels. Both the removal rate of surface inhomogeneities, the influence of surface topography before and after coating and the influence of the initial tool surfaces regarding coating adhesion strength were investigated to underline the potential of this pre- and post-treatment. Additionally, a new method for characterizing and describing the number of coating defects and proportion area of coating defects per $${\hbox {mm}}^{2}$$ is presented.

Efficient and Precise Grinding of Sapphire Glass Based on Dry Electrical Discharge Dressed Coarse Diamond Grinding Wheel.

In this paper, in view of low grinding efficiency and poor ground surface quality of sapphire glass, the coarse diamond grinding wheel dressed by dry impulse electrical discharge was proposed to perform efficient and precise grinding machining of sapphire glass. The dry electrical discharge dressing technology was employed to obtain high grain protrusion and sharp micro-grain cutting edges. The influences of grinding process parameters such as wheel speed, depth of cut and feed speed on the ground surface quality, grinding force and grinding force ratio on sapphire glass were investigated, and the relationship between grinding force and ground surface quality was also revealed. The experimental results show that the grain protrusion height on the surface of a coarse diamond grinding wheel dressed by dry electrical discharge can reach 168.5 µm. The minimum line roughness Ra and surface roughness Sa of ground sapphire glass surface were 0.194 µm and 0.736 µm, respectively. In order to achieve highly efficient ground quality of sapphire glass, the depth of cut was controlled within 7 µm, and the wheel speed and feed speed were 3000–5000 r/min and 10–20 mm/min, respectively. The influences of feed speed and wheel speed on grinding force ratio were more significant, but the influence of depth of cut was little.

Study on in-air electro-contact discharge (ECD) truncating of coarse diamond grinding wheel for the dry smooth grinding of hardened steel

Abstract Dressing is used to protrude the micron-scale grains from wheel bond, but the grain protrusion height is not identical due to the irregular grain shape and distribution. In order to assure the grain uniformity with identical protrusion height, the electro-contact discharge (ECD) truncating is proposed after dressing. In the ECD truncating, an in-air impulse discharge thermal between wheel and electrode is transferred to cutting interface of diamond grain through the cutting chip. Accordingly, the outstanding thermal conductivity of diamond is utilized to perform a mechanical and thermochemical removal of grain edge layer without any damage to its hardness. The objective is to realize an efficient truncating of coarse diamond wheel for dry smooth grinding of hardened steel. First, a constant-voltage/constant-current transform was employed to suppress the short-circuiting current between wheel and electrode and to adjust the discharge thermal to diamond grain surface. Then the grain temperature distribution was modeled with reference to the transfer of impulse discharge thermal to cutting interface for diamond graphitization. Finally, the truncated diamond wheel was used to perform a grinding in contrast to general CBN wheel. It is shown that the spark-discharge thermal transferred from the rolled-up cutting chip to the grain cutting interface contributes to truncating. In in-air ECD truncating, the spark-discharge voltage ranges 19–23 V, which increases the grain truncating rate by 95% against the general arc-discharge. The truncating temperature may be maintained as about 626 °C to induce the layer graphitization of diamond grains with the mechanical and thermochemical removal up to about 6435 μm3/min. In contrast to wet CBN grinding, the dry grinding greatly improves the ground surface with the truncated diamond wheel rather than the dressed one.

Grinding performance improvement of laser micro-structured silicon nitride ceramics by laser macro-structured diamond wheels

Silicon nitride ceramics are widely used in various industrial fields because of their excellent characteristics: high hardness, high elastic modulus, abrasion resistance, and high heat resistance. Diamond wheel grinding is the predominant and most productive method to machine silicon nitride ceramics. However, a lot of heat is generated due to high friction between a diamond grinding wheel and extremely rigid silicon nitride during grinding. This causes surface/subsurface damage, wheel wear, etc., which impairs the surface quality of silicon nitride. This impairment can restrict the use of silicon nitride ceramic components. To improve the surface quality and service life of grinding wheels, a laser macro-micro combination structured grinding (LMMCSG) method was presented. The results indicated that the grinding force ratio and surface roughness when using LMMCSG were respectively 31% and 40% lower than the grinding force ratio and surface roughness when using conventional grinding. Moreover, the LMMCSG method effectively reduced the wheel wear and workpiece subsurface damage.

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.

Developing a novel binderless diamond grinding wheel with femtosecond laser ablation and evaluating its performance in grinding soft and brittle materials

In this study, a binderless diamond grinding wheel (BDGW) is fabricated to prevent impurities embedding during the machining of soft and brittle materials by conventional grinding wheels. The ‘binder’ features, as well as the ‘grains’, are produced on a single piece of chemical vapor deposition diamond, whilst the ‘grains’ are ablated with a femtosecond laser. The performance of the novel grinding tool in terms of grinding radio, wear types, grinding forces and specific grinding energy, ground surface roughness, surface morphology, and subsurface damage is evaluated by comparing it with a resin-bonded diamond grinding wheel (RDGW). Experimental results show that the BDGW has excellent redress life with simple form of wear-abrasion wear on the top of the cutting edges and extremely high grinding radio of 103, which is nearly eight times of that of the RDGW. The benefit of the simple form of BDGW wear is that no embedded bond debris and fall-off grains appear. These conditions are essential to ensuring high ground surface quality for grinding soft and brittle materials.

Study on process and manufacturability of metal-bonded diamond grinding wheel fabricated by selective laser melting (SLM)

Selective laser melting (SLM) technology is used to fabricate metal-bonded grinding wheel based on mixed powders consisted of metal powders and diamond abrasives. Taguchi method is adopted to obtain the optimal SLM process parameters for grinding wheel considering laser power, scanning speed and layer thickness. Specimens are fabricated with different SLM process parameters for compression and three-point bending tests. Materials characterization and manufacturing limit test are performed on the specimens fabricated by the optimal SLM process. Results indicate that laser power of 250W, scanning speed of 2.5m/s and layer thickness of 20μm are determined as the optimal SLM process in terms of comprehensive mechanical property and formed surface quality. Moreover, diamond abrasives are firmly embedded into aluminium binder with good bonding condition for SLM-fabricated composite. Furthermore, manufacturability of SLM-fabricated composite is evaluated by manufacturing limits of several common structures. In summary, work in this study fully proves the feasibility of SLM-fabricated metal-bonded grinding wheel and provides a solid basis for the further investigation on the novel grinding wheel with customized porous structures.

Fiber laser CNC tangential turing V-shaped concave diamond grinding wheel system based on machine vision technology

In order to achieve high-precision V-shaped concave diamond grinding wheel by laser tangential turing, a high-precision laser-inspecting and tangential turing diamond grinding wheel system was built by utilizing high-pixel camera, double telecentric lenses, backlights, CNC grinding machine, and a fiber laser as the main hardware and adopting digital image processing technology as the processing method. The experimental results showed that the depth error rate of compensation turing was approximately 1/2 that of rough turing, and the width error rate was greatly reduced. After compensation turing, all of the evaluation indexes tended to improve. In particular, the error rate of compensation turing was approximately 1/6 that of rough turing. Under the optimized process parameters, the geometric parameters of the V-shaped concave contour and the error average difference were within 3%. Thus, the proposed approach effectively improves the shape and position error of the turing process. The experimental results showed that the system can detect the geometric profiles and size of the grinding wheel accurately and can obtain high turing precision effectively and quickly.

Design of binderless grinding wheel with positive rake angle and fabrication used femtosecond laser ablation for grinding soft and brittle crystals

Recent research has proved that precision grinding method can be used for machining the soft and brittle crystals, such as KDP, KTP, and LN et al, achieving much higher process efficiency than the single-point diamond cutting method. However, poor ground surface quality and impurity embedding are encountered when grinding these materials. In this paper, a binderless diamond grinding wheel with positive rake angle of cutting edges is innovatively designed and fabricated by femtosecond laser ablation on CVD diamond. To evaluate the effects of cutting edge rake angle on the grinding performance, two grinding wheels with 5° and 0° rake angles are fabricated. Grinding outputs of these two wheels, including ground surface roughness, surface microstructure and grinding forces for grinding KDP crystal are compared and analyzed. It is found that, positive rake angle effectively improved the ground surface quality, i.e. the ground surface roughness achieved using the wheel with 5° rake angle is about 1/10 of that obtained using the wheel with 0° rake angle. The positive rake angle wheel also effectively reduced the level of grinding forces and specific grinding energy. The grinding forces using the wheel with 5° rake angle are about 2/3 of that with 0° rake angle. It is also found that the wear depth of the binderless diamond grinding wheel with 5° rank angle is about 30 μm, with about 20 μm blade corner radius, and the wear depth of the wheel with 0° rank angle is about 20 μm, with about 10 μm blade corner radius, after removing 1000 mm3 KDP material.

Selective laser sintering and grinding performance of resin bond diamond grinding wheels with arrayed internal cooling holes

In this study, selective laser sintering was used to 3D print resin bond diamond grinding wheels with internal cooling holes. The mechanical properties and microstructures of the resin bond diamond grinding wheel were investigated. The grinding performance of 3D printed resin bond diamond grinding wheels with different internal cooling holes on the glass and cemented tungsten carbide was examined. The results show that 3D printed resin bond diamond wheels can be used to grind the glass and cemented tungsten carbide. Wheels containing internal cooling holes have lower grinding force. With increasing number and diameter of internal cooling holes, grinding forces on the glass decreased. Surface roughness up to 2–4 μm on the glass and cemented carbide was obtained by present 3D printed resin bond diamond wheel.

Studies on the grinding force, size effect, surface texture, and mechanism of material removal in the grinding of AA6061-TiB2/ZrB2 in situ composite

Machining and conversion of aluminum matrix composites into a desired shape with accuracy has been a challenge for many years. Grinding is a process aimed at achieving better-quality surface finish along with reasonable rate of material removal. The present article describes the influence of operating parameters on the tangential grinding force, size effect, and surface integrity in the grinding of in situ aluminum matrix composites using various grinding wheels. The material removal mechanism of the in situ composite under different grinding conditions is established. Experimental results show that the grinding operating parameters have significant influence on the tangential grinding force, size effect, surface integrity, and material removal. Scanning electron and atomic force microscopy findings indicate presence of numerous surface defects on the grounded surface under all grinding conditions. Diamond grinding wheel outperformed the CBN and Al2O3 wheels by requiring lower grinding force and specific grinding energy and generating lower surface defects. Surface defects, including grinding striation, delamination, and ridge formation are unavoidable under all machining conditions. However, the aforementioned surface defects indicate the ductile mode of material removal at all experimental conditions. Undeformed chip thickness under various grinding conditions plays a significant role in material removal and surface generation. These findings help to understand the mechanism of material removal in machining of in situ composites under various grinding conditions, which helps in attaining the economic production rate without compromising the surface integrity.