Diamond Wheel Research Articles

High-Speed Sharpening and Thermo-activated Refinement of Blade Tools from Synthetic Diamonds

Processing of synthetic diamonds is accompanied by low productivity and high values of relative con-sumption of diamond wheels. The coefficient of use of diamond grains in these processes does not exceed 5-10%. Using synthetic diamonds as a blade tool, requires sharpening and refinement. This study proposes to use ultra-high-speed machining modes and the same diamond grinding wheel at all stages of tool shaping. At the first stage, i.e. at high speeds, a rough productive sharpening of dia-mond blade tool is made with a wheel on an iron-based binder. At the second stage processing speed is reduced, as a result grains cease to self-sharpen and to wear out. When the iron binder comes into contact with the sharpened diamond, the speed must be increased, so that the temperature in the contact zone of the binder with the rough surface of the cutter, increases. Due to diffusion wear, from the surface of the diamond, the height of the roughness micro-hills decreases. In other words, the process of high-quality thermally activated refinement of the working surface of the diamond cutter starts to be implemented.

Final detailed design of an all-in-one attachment-based PHC pile head cutting robot and its structural stability analysis

ABSTRACT Conventional pretensioned spun, high-strength concrete (PHC), pile head cutting process is associated with safety, quality uniformity, and labor productivity problems. However, trend analysis has revealed that no technology has been developed to address these problems as these pertain to specific Korean construction site situations. This study aims to derive the final detailed design for an all-in-one attachment-based PHC pile head cutting robot, and analyzes its structural stability. To this end, the key functions of an all-in-one attachment-based PHC pile head cutting robot have been defined, and the related core element technologies have been analyzed. This has led to the presentation of two detailed design alternatives. Both of these were then subjected to an analytical hierarchal process (AHP) and trade-off analysis that led to the final selection of the diamond wheel saw-based detailed design. In a structural stability analysis of the final detailed design, all tested parts did not surpass the threshold yield strengths of 230 MPa (SS400) and 255 MPa (AL6061 T6). If a prototype is developed based on the final detailed design derived in this study, it is expected to have improved work safety, quality uniformity, and work efficiency characteristics compared with the conventional PHC pile head cutting process.

Regression functions for determining the expression of surface Roughness at plane grinding of ceramic

The aim of the work is to determine, through mathematical modelling using regression functions, the dependency expression between the surface roughness Ra at grinding with diamond wheels of aluminum oxide ceramic (Al2O3) for plain grinding with longitudinal advance, and the values of the grinding processing.

Wear of a Diamond Wheel during Grinding of Ceramic Balls Made of Silicon Carbide

The results of an experimental study of the effect of the mode of processing on the wear of the diamond wheel surface and on the accuracy of batch processing during diamond grinding of ceramic balls made of silicon carbide are discussed. The grinding pattern and the frequency of wheel strokes have a statistically significant effect on the maintaining of the original flat shape of the wheel, while the discrete feeding of the wheel has no direct effect on its uneven wear. The condition for minimizing the difference in the diameter of the balls within a batch and maintaining the original flat shape of the wheel will be the choice of grinding pattern with the trajectory of the balls tangent from the inside to the outer edge of the wheel, as well as minimizing the discrete feed of the wheel in the investigated range when grinding and a simultaneous increase in the wheel feed frequency to the maximum. However, the variance of the ball diameter within a batch under these conditions does not reach the minimum possible value.

Supporting Body Material for Ceramic Diamond Grinding Tools

The characteristics of abrasive tools (the type of grinding wheel, granulation of the super hard grain, type of structure, hardness, and the type of binder) contain information on the type of supporting body materials used (e.g., dural, ceramic, steel). In this work, diamond wheels were obtained on ceramic supporting bodies, containing a sintered mixture of white alumina 99A granulation F320, green silicon carbide 99A granulation F320, and binder Ba23 bis, together with modifiers. The mechanical properties (hardness, bending strength) of ceramic supporting bodies were tested. The structure of the phase boundary of the ceramic supporting body–abrasive grinding tool was analyzed on a BEC (backscattered electron composition) image by using SEM (Scanning Electron Microscopy). It was found that the hardness of the supporting body was slightly lower (70–75 HRB) than the diamond wheels (76–81 HRB). The bending strength of the supporting bodies was high (85 ±2 MPa). The BEC image from the scanning microscope did not show a sharp transition between the ceramic supporting body and the grinding wheel. Preliminary operational tests showed significant improvement in grinding wheel efficiency in comparison to diamond tools with the same ceramic binder on a duralumin supporting body during machining of G30 sintered carbide bush.

An investigation on grinding mechanism of alumina ceramic using a grooved grinding wheel with inclined cross section

In this study, a type of the grooved grinding wheel with inclined cross section is designed based on trapezoidal beam. The grinding type of grooved grinding wheel with inclined cross section is used as a new structuring method to process alumina ceramic. The inclined cross-section groove of a grinding wheel can improve the wear-resistant properties of laser macro-structured grinding wheel. First, a pulse laser was used to ablate rectangular cross-section groove and inclined cross-section groove on two bronze-bonded diamond wheels. Second, a grinding test was performed by using the grooved grinding wheel with rectangular cross-section and grooved grinding wheel with inclined cross section. The experimental results showed that the grooved grinding wheel with inclined cross section presented a reduction of grinding forces between 18 and 31.7%, but the better surface was not obtained. In addition, the inclined cross-section groove could reduce stress concentration, thus improving the wear of the grinding wheel surface. This indicates that the grooved grinding wheel with inclined cross section has better grinding performance than the grooved grinding wheel with rectangular cross section owing to the inclined cross-section structures. This provides further evidence for a method of constructing grooved grinding wheel with inclined cross section based on trapezoidal beam design.

Рhysico-mechanical properties and structuralphase state of individual coatings based on nitrides W and Сr

Abstract. Problem. Ti, Zr, Mo, W and Cr nitride coatings are promising materials because they have high hardness and excellent tribological characteristics and are therefore widely used as a quick-wear protective cutter. At the same time, the structure and tribological properties of W-N coatings are poorly understood. All of the above coatings based on Ti-N, Zr-N, Mo-N, Cr-N and W-N phases are sensitive to the partial pressure of N2 used during deposition. Coatings with nanolayer configurations of pure metal and metal nitride have higher mechanical properties than single-layer ones. Therefore, the topic of the work and the problems considered are relevant. Goal. The aim of this work is to study the physicomechanical properties and structural-phase state of CrWN nanolayer coatings deposited on a steel substrate with different surface roughness. Such nanostructured CrWN coatings have different component concentrations. Methodology. In the work, samples of fixed-speed P6M5 steel of fixed size 15 mm × 15 mm × 5 mm were used as substrates, which were polished by a mechanical method combined with a diamond grinding wheel. Different surface roughness was achieved by grinding paper with different grain sizes by wet grinding, with preliminary grinding on the previous grain size. A target consisting of Cr and W with different area ratios was used: 95: 5, 75:25, 50:50. For the qualitative and quantitative analysis of the composition and structure of coatings, radiographic analysis was used, studies of the surface structure of coatings and obtaining energy dispersion spectra were performed on a scanning electron microscope. Results. Radiographic studies show that the obtained coating includes such phases as WN, W2N, CrN with a cubic (NaCl-type structure) crystalline lattice without a pronounced axis of grain orientation. Studies carried out on a scanning electron microscope of the obtained Cr-W-N coatings showed a nanocrystalline structure with a grain size of up to 50 nm. According to the analysis of the elemental composition of coatings, a clear correlation between the composition of the target and the composition of the obtained coating is observed. The main factors affecting the hardness and wear resistance of Cr, W and N coatings are the condensation parameters such as the stress applied to the substrate, the substrate temperature, the concentration of the gases in which the deposition occurs, their pressure and the composition of the target. Originality. It has been found that the main factors that influence the hardness and wear resistance of Cr, W and N coatings are the condensation parameters such as the stress applied to the substrate, the substrate temperature, the concentration of the gases in which the deposition occurs, their pressure and the composition of the target. The microhardness of the nanolayers was about 3 GPa for Cr39W11N50 coating and 5 GPa for Cr75W1N24 and was significantly dependent on the coating roughness and had a maximum value on the 1200 grit abrasive samples. Practical value. The investigated results of the dependence of the microhardness on the roughness show a decreasing nature with a decrease in surface roughness, that is, an increase in surface smoothness leads to a slight decrease in the hardness of the coating. The obtained values of microhardness of P6M5 steel with wear resistant coatings based on W and Cr nitrides allow to apply such coatings for surface hardening of machine tools and cutting tools.

Mechanical and electrolytic hybrid grinding of metal ceramic composites using coarse diamond grinding wheel

The application and development of metal ceramic composites have been restricting due to its low grinding efficiency and ground quality. In this paper, the hybrid machining technology combined mechanical with electrolytic grinding based on dressed coarse diamond grinding wheel is proposed to perform efficient and precise grinding of metal ceramic composites. First, the dry electrical discharge dressing technology was used to dress coarse diamond grinding wheel to obtain high grain protrusion and sharp micro-grain cutting edges. Next, the mechanical and electrolytic hybrid grinding process using dressed coarse diamond wheel was developed to grind metal ceramic. Finally, the effects of different process parameters on ground surface topographies and surface roughness were investigated. It is shown that the proposed hybrid grinding method was feasible and can effectively improve the ground surface quality. The experimental results show that the optimal process parameters including the depth of cut, open-circuit voltage and impulse width were 5 μm, 20 V and 400 ns, respectively. Compared with traditional mechanical grinding, the ground surface roughness by the proposed hybrid machining method was improved by about 25%.

Investigation of the surface integrity, flexural strength on the grinding of alumina for biomedical applications

This paper presents the analytical and experimental investigations on different factors such as surface integrity, flexural strength and grinding energy and cost of Alumina through the use of various diamond grinding wheels. For obtaining the analytical model for single-grit grinding, the effect of strain rate and grinding temperature are also included in the formulation. Moreover, the experimental tests are conducted with four different diamond grinding wheels to grind Alumina blocks. The applied force during grinding is measured. Then, the other important parameters, including surface roughness, wheel wear, and grinding cost are analyzed. According to the obtained results, a good agreement between the experimental and analytical results were achieved in all cases. Furthermore, it was found that controlling the grinding condition would be resulted in 11% reduction in the subsurface damages (SSD) according to the images of Scanning electron microscope (SEM) results at the distance of 150 μm under the ground surface. A converging improvement trend of the surface integrity and flexural strength was also observed. Also, approximately 29% improvement was attained for the flexural strength in optimum condition. In addition, the optimal condition for grinding was determined, in which 66% decrease in surface roughness and 75% decrease in grinding cost were accomplished.

Fabrication of silicon carbide microchannels by thin diamond wheel grinding

Silicon carbide (SiC) microchannels are attractive for their wide applications in microsensors, MOS devices, UV photodiodes, microcatalytic reactors, and microchannel heat exchangers in harsh environments. However, the machining of SiC microchannels poses many challenges because of the difficulty and cost involved in the material removal process due to the high hardness and brittleness of SiC ceramic. In the present study, we developed a thin diamond wheel grinding process to fabricate SiC microchannels in a conventional vertical milling machine. Microchannels with trapezoidal shapes were successfully processed in SiC substrates by thin diamond wheels. The formation, geometric dimensions, and surface quality of SiC microchannels were studied together with the analysis of material removal mechanism. The effects of grinding processing parameters, i.e., wheel speed, feed speed, grinding depth, and grinding tool parameters including grit size and thickness of diamond grinding wheel, on the geometric dimension and surface morphology were comprehensively explored. The top width of microchannels first increased and then decreased with the increase in wheel speed, whereas a reverse tendency was observed with increasing grinding depth, feed speed, and grit size. The surface roughness decreased continuously with increasing wheel speed, but it tended to increase with the increase in feed speed generally. The variations in geometric dimensions and surface roughness of SiC microchannels can be related to the crack or fracture propagations and material removal mechanism during the thin diamond wheel grinding process. Besides, the influential significance of the above processing and grinding tool parameters were also evaluated by analysis of variance (ANOVA).

Ultra-precision raster grinding of monocrystalline silicon biconical free-form optics using arc-shaped diamond grinding wheels

Free-form optics are becoming increasingly indispensible in a series of industries, such as aviation, aerospace, medical, digital video and audio optoelectronics, owing to its enhanced optical performance, fewer surfaces, lower mass, lower cost, smaller package-size and reduced stray-light, etc. However, the ultra-precision machining of free-form surface optics, especially the non-rotational asymmetric free-form optics is still faces a great challenge. In this study, ultra-precision grinding of the non-rotational asymmetric biconical free-form optics with raster grinding path was studied. Firstly, a novel feeding compensation truing strategy for truing the arc-shape grinding wheels with high-precision was proposed. A D46 μm metal-bonded grinding wheel and a D7μm resin-bonded diamond wheel, were successfully trued with high profile accuracy and desired surface topography. Subsequently, the influence of the significant grinding factors like grinding path, scallop height, contact arc length and the grinding wheel wear on the ground profile accuracy and surface quality of the biconical free-form optics was theoretically and and experimentally analyzed. Eventually, a larger size monocrystalline silicon biconical free-form optics with profile accuracy 6.0 μm and nanometer surface roughness was successfully manufactured by raster grinding combined the technology introduced in this paper.

Deformation-induced silicon nanostructures

Silicon (Si) has been widely used in advanced energy technologies including solar cells and secondary batteries because of its unique properties. However, up to now, the highest conversion efficiency of solar cells for silicon is just over 26%. Furthermore, during charge–discharge cycles, the Si voluminal expansion has been considered seriously, which greatly reduces the cycle life of the solar cell. Therefore, many research efforts have been focusing on the development of new phase, nanostructure, and pathways for improving the conversion efficiency and the cycle life of Si-based energy devices. In this review article, advanced methods, such as in situ transmission electron microscope nanomechanical testing, nanoscratching, nanoindentation, scratching at the nanoscale, and micrometer examination of the deformation-induced nanostructure of Si, are first presented. Subsequently, deformation-induced nanostructures in Si are proposed, in which the nanostructures are fabricated by a developed setup and novel diamond wheels. A new phase and a pathway in Si are manufactured and demonstrated by this setup. Finally, the perspectives and challenges of deformation-induced Si nanostructures for future developments are discussed.

The Abrasive Treatment Process as a Friction Interaction: The Factor of Sludge Presence on the Cutting Surface of Diamond Wheels

The distinctive features of sludge particles formed upon the grinding of tool materials on diamond wheels are presented. The element composition of the particles is presented and shown to be similar to the workpiece material composition or different from it in specific cases. The stie of sludge particle formation on the cutting surface of the wheel (bonding material or abrasive grains) was studied.

Brazing diamond grits onto AA7075 aluminium alloy substrate with Ag–Cu–Ti filler alloy by laser heating

The brazing of diamond is a promising way to fabricate grinding wheels for efficient machining and precision grinding. This work investigated the feasibility of bonding diamond grits onto Aluminium Alloy 7075 (AA7075) substrate with a Ag–Cu–Ti filler alloy via laser fusion brazing. The interfacial microstructures and the strength of the brazed diamond joints were studied. The cross-section of the brazed diamond joint consists of a molten filler alloy layer, a molten pool, a heat effect zone, a columnar crystal zone and an equiaxed crystal zone. Within the interface of the filler alloy/substrate metal, microstructures observed possibly were Ag(s.s), Al(s.s), TixAl, Al2Cu and Mg intermetallic compounds. A layer of TiC with a thickness of about 30–50 nm was found at the bonding interface of the diamond/filler alloy. The averaged peak shear force of the brazed joints was found to be approximately 39.8 N. The abrasion grinding test indicated that the diamond/AA7075 brazed joint was adequate for grinding. However, the pulled-off of grit was found to be the primary failure of this type of brazed joint. This work broadened the brazing diamond technique and the range of applications of brazed diamond wheels for efficient grinding.

Experimental Investigation on Face Grinding of 2024AI/SiCp with Electroplated Diamond Wheel

SiCw / 2024Al composite has excellent physical and chemical properties, such as high specific strength, good wear resistance, low coefficient of thermal expansion, etc. It has been widely used in the development of modern science and technology. An experimental research on face grinding of SiC particle-reinforced aluminium matrix composite 2024Al/SiCp with electroplated diamond grinding wheel was carried out. The effects of different grinding parameters on the surface morphology, grinding force and grinding quality of workpiece are analyzed. The results show that high quality ground surface can be achieved by using this technology; the residual stress on machined surface is compressive stress; grinding parameters have little effects on tangential and normal grinding forces, but have stronger effect on axial grinding force than that in other two directions, and the axial grinding force increased notablely as the increasing of grinding depth.

Influence of Li2O Addition on the Performance of Vitrified Bond and Vitrified Diamond Composites

In order to develop high-performance diamond wheels, the vitrified bond with different contents of Li2O addition and corresponding diamond composites were prepared. The experimental results show that the addition of a small content of Li2O leads the formation of the mullite phase in vitrified bond. When the Li2O content is 3wt%, the mullite content in the vitrified bond reaches the maximum. Whereas, the vitrified bond turns into a pure glass phase when the Li2O content further increases to 5wt%. The softening temperature of vitrified bond, wetting angle between the vitrified bond and the diamond film decrease with the increasing of the Li2O content. The softening point of the vitrified bond with 5wt% Li2O is 537 °C and the contact angle is 32°, which are 44 °C and 44° lower than those of the sample without Li2O. The CTE (coefficient of thermal expansion), the flexural strength and hardness of the diamond composite sample first increase and then decrease with the increasing of the Li2O content. When the Li2O addition is 3wt%, the flexural strength and hardness of the composites reaches the maximum values of 93 MPa and 98 HRB, respectively, which are 43.1% and 12.6% higher than those of the sample without Li2O.

Electrochemical cleaning grinding (ECCG) of aluminum alloy 6061 with electroconductive resin-bonded diamond wheels

A new manufacturing process named Electrochemical Cleaning Grinding (ECCG) is introduced to help reduce wheel loading in grinding of the highly ductile metals which exhibit high adhesion tendency. The key component of the ECCG system is an electroconductive resin-bonded diamond wheel, and its abrasive layer is made of phenolic resin bond and core-shell structured Ni-P alloy coated diamond abrasives. The alloy coating over diamond grains not only helps to increase the bond strength between the resin and the abrasives but improve the electrical conductivity properties of the grinding wheel. During the ECCG process, the abrasives on the wheel surface simultaneously act as micro cutting edges as well as microelectrodes where the anodic dissolution of the adherent metal materials takes place. This dissolution process is defined as “cleaning”. When the rate of accretion of adherent material is balanced by its electrochemical dissolution rate, the sharp abrasives are exposed to carry out efficient grinding, so that better grinding performance can be achieved. The grinding experiments of aluminum alloy 6061 (AA6061) were conducted to verify the effectiveness of the ECCG process. Compared with conventional grinding experiments, the most important changes brought in by the ECCG are the decrease in wheel loading degree and the improvement in machined surface quality. Additionally the electric energy consumption of the cleaning process is relative low and equal from 1.88 × 10−3 J/mm3 to 9.34 × 10-3 J/mm3.

Improvement of Grinding Fluid Supply Method in Grinding of Alumina Ceramics and Cemented Carbides with Straight Cup Diamond Wheel

Improvement of Grinding Fluid Supply Method in Grinding of Alumina Ceramics and Cemented Carbides with Straight Cup Diamond Wheel

ANALYSIS OF THE MACHINING SCHEME OF COMPLEX-PROFILES SHELLS OF ROTATION

Modern engineering products have complex geometry with high quality requirements, are made from new materials that is provoked the development and use the mechanisms of parallel structure, which are distinguished by high rigidity characteristics, as well as have wide functional capabilities. The precision problems of machining of complex-profile low-rigid parts, in particular thin-walled pyroceram shell are considered in article. Scheme of machining affect the accuracy and depends on the capabilities of technological equipment. Rationale for scheme of machining a thin-walled casing is presented in article. The accuracy of machining the outer profile of the casing was simulated for last step of diamond grinding. The simulation was performed for a traditional scheme of machining, which is performed for a lathe with an aggregate grinding head and a direct copying system, and for a scheme of machining for equipment that is fitted out with a mechanism with a parallel structure. The model of formation of the machining error is based on using the equations of relative displacement of the technological bases of the workpiece and the contact point of the working surface of the diamond wheel with the workpiece. The model takes into account the static and dynamic characteristics of the technological system and force factors during grinding. The calculations have confirmed that proposed solutions are able to provide the necessary machining precision. Changing the machining scheme of the workpiece and performing such machining on equipment with mechanisms of parallel structures eliminates the basing error, increases the rigidity of the technological system, and provides the possibility of turning the axis of the diamond wheel with the required angle.

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