Cubic Boron Nitride Grinding Wheel Research Articles

Influence the effect of balancing the grinding set on the accuracy and roughness of the machined surface

The article examines the effect of balancing the grinding wheel set on the accuracy and roughness of the machined surface during the production of cutting tools. Screw drills with a diameter of 12 mm were manufactured as well as test specimen in the shape of a recess with a width of 20 mm and a diameter of 18 mm. The workpiece material was sintered carbide (WC+Co). Properly balanced and unbalanced sets of cubic boron nitride (CBN) and synthetic diamond grinding wheels were used in the production of the tools and test specimens. A WZS 60 Reinecker tool grinder was used as the machine. The parameters of surface roughness and dimensional accuracy were measured in the experiment. Surface roughness was evaluated on a Zeiss Surfcom 5000 shape and contour measuring machine. Dimensional accuracy measurement was performed on an optical measuring machine Zoller Genius 3. In terms of dimensional accuracy, tools and test specimen s produced by wheel balancing to a lower level of balance quality G show greater dimensional inaccuracy than tools and test specimen s produced by wheel sets that were balanced to a higher quality level of balance G. From the point of view of evaluating the surface roughness, the results were not clear, but the tools and test specimens produced by CBN grinding wheels showed better surface roughness, regardless of the quality level of balance G.

Double-sided deep grinding of gas turbine engine blades with highly porous CBN tool

The results of the implementation of high-porous cubic boron nitride (CBN) grinding wheels in the operation of double-sided deep grinding of the fir-tree profile of the locking element of the turbine blade are presented. The features of designing the working layer of the CBN wheel for this operation are described. Recommendations for the selection of the characteristics of diamond dressing rollers are formulated. The principles of organizing an efficient production process when introducing CBN grinding wheels are described. Keywords: deep grinding, part, gas turbine engine, working turbine blade, grinding wheel dressing, diamond profile roller, highly-porous CBN grinding wheels. d_i_volkov@rsatu.ru, boris_tsvetkov@mail.ru

Study on Preparation and Grinding Performance of Vitrified Bond CBN Grinding Wheel with Controllable Porosity.

Vitrified bond cubic boron nitride (CBN) grinding wheel specimens with controllable porosity were prepared by regulating the pore former dextrin content and varying the forming pressure, and the performance of the grinding camshaft was studied. The porosity of the specimens increases with the increase in dextrin content, and decreases first and then increases with the increase in the forming pressure. The grinding experiments show that the dextrin content is negatively correlated with the grinding force and grinding temperature, while the grinding force and grinding temperature of the specimens increase and then decrease with the increase in the forming pressure. When we observe and measure the grinding surface of the specimen and workpiece, we see that the surface roughness of the specimen after grinding is smaller than that before grinding. In addition, the greater the porosity of the specimen, the rougher the surface of the workpiece after grinding.

Pulse laser precision truing of the V-shaped coarse-grained electroplating CBN grinding wheel

The machining difficulty has limited the further application of ultra-hard materials. For V-shaped coarse-grained electroplated cubic boron nitride (CBN) grinding wheel, a precise and efficient pulse laser truing method was proposed. Firstly, a theoretical model of the pulse laser truing process was established in order to optimize the laser truing energy distribution. Secondly, the effects of truing depth, grinding wheel speed, laser power and truing time were analyzed. Finally, the grinding performance of laser trued wheels were evaluated. The results showed that larger grinding wheel speed n would bring higher energy value and more stable energy distribution, truing depth h would not affect the value and stability of energy. CBN would not undergo phase transition and could bear more laser power Pavg. With the increase of truing time t, the geometric precision of V-shaped grinding wheel could be improved. The angle of V-shaped grinding wheel could reach 90.15° (deviation 0.02°), the bottom fillet radius was 53 μm (less than 100 μm). The surface roughness and grinding force corresponding to laser truing were less than that of mechanical truing, the truing time required was reduced by 72%∼83%, and the corresponding tooth profile angle and bottom fillet were basically the same.

Process limits in high-performance peel grinding of hardened steel components with coarse CBN grinding wheels

Recent developments in the production processes for cubic boron nitride (CBN) abrasive grains have led to commercially available grain sizes larger than lg > 300 µm. These superabrasive grains allow higher material removal rates during grinding of hardened steel components. Currently, these components are pre-machined by turning processes before being hardened and eventually finished by grinding. However, the turning process can be substituted by grinding with coarse CBN-grains since higher depths of cut are achievable when machining hardened components. This paper investigates the process behaviour of vitrified and electroplated grinding wheels with large grain sizes during the machining of hardened steel components. Process forces, wear behaviour and workpiece surface roughness are investigated for three different grain sizes, and the process limits of both bond types are examined. The investigations show that vitrified tools do not fully suit the demands for peel grinding process with high material removal rates since wear by bond breakage occurs. The electroplated tools on the other hand are capable of very high material removal rates. Their wear behaviour is characterized by clogging of the chip space if the process limit is reached. Even so, both tools outperform a standard hard-turning process in terms of process time by 74% and 94% respectively. This process time reduction in combination with the possibility to use the same (machine) tool to machine both soft and hard sections of a workpiece adds flexibility to current process chains.

High performance peel grinding of steel shafts using coarse electroplated CBN grinding wheels

Grinding is widely known for its low material removal rates and high surface quality. However, recent developments in production processes for cubic boron nitride (CBN) abrasive grains have led to commercially available grain sizes larger than 300 µm. These superabrasive CBN-grains allow higher material removal rates during grinding of hardened steel components. Currently, these components are pre-machined with turning processes before hardening and finishing the work piece by grinding. However, the turning process can be eliminated by grinding with coarse CBN-grains since higher depths of cut are achievable when machining hardened components. This paper explores the limits of grinding wheels using grains with a size of B602 during soft and hard machining in comparison to conventional B252 grains. It is shown that the use of coarser grains leads to lower process forces, higher (tensile) residual stress and higher surface roughness. Residual stress and surface roughness are of less importance as these grains are to be used mainly in roughing operations with ensuing finishing operations for the required surface properties. Over all investigations, especially in hard machining, neither grain nor tool wear was observed for the B602 grains, whereas the B252 tool was severely clogged during the experiments. Additionally, the grinding force ratio indicates that the coarse grain tools have not yet reached their productivity limit as it increases over all investigated feeds. This indicates improving tool performance with lower amounts of rubbing for increasing feed rate during hard grinding and shows the potential for the industrial use of higher feed rates with larger grains.

Effects of grinding α–β Titanium with 3% CNTs in CBN grinding wheel: An Experimental Study

Carbon Nano Tubes (CNTs) have found an immovable niche in the world of manufacturing in the form of reinforcements in composites. Their many advantageous properties have allowed their usage in innumerable ways and this has led to a plethora of innovations in engineering. In advanced manufacturing of very-hard-to-machine materials like titanium, where surface integrity is of prime importance, the presence of multi-walled CNTs even as less as 3% alongside Cubic Boron Nitride (CBN) in grinding wheels, has demonstrated improved surface finish on Titanium alloy (Ti-6Al-4V). This proposed grinding wheel for use on Titanium, reduces surface roughness and improves Material Removal Rate (MRR) on the Titanium work pieces. It also shows slight improvement in the contour of the wheel.

Prediction of Surface Roughness When Surface Grinding C45 Steel Using CBN Grinding Wheel

This paper presents a study of the roughness prediction of the workpiece when using CBN (Cubic Boron Nitride) grinding wheel to process C45 steel on a surface grinder. On the basis of inheriting the previously published studies on modeling surface roughness of workpiece when grinding, this study was conducted to develop one of these models and build a new model of surface roughness that consider many factors affecting surface roughness. Cutting parameters, parameters of grinding wheel, characteristics of materials, characteristics of contact of grinding wheel with workpiece have been included in the roughness model of the surface roughness of workpiece. This new surface roughness model was used to predict surface roughness of workpiece when grinding C45 steel with CBN grinding wheel. The results showed that the surface roughness value when predicting was very suitable for the experiment and the average deviation between the predicted results and the experimental results was only about 9.84%. The surface roughness model proposed in this study also confirms that the roughness can be predicted more accurately than the previous surface roughness models. And then, the development direction for further research is also mentioned in this paper.

Influence of Electroplated CBN Wheel Wear on Grinding Surface Morphology of Powder Metallurgy Superalloy FGH96.

The electroplated cubic boron nitride (CBN) wheel has perfect precision retention and high-temperature grinding performance, which is widely used in the field of grinding difficult-to-cut materials, such as nickel-based superalloy. However, the research on the influence law and mechanism of grinding surface morphology affected by the wear state of small-size grinding wheel is insufficient, which limits the further promotion and application of electroplated CBN wheel in the field of precision grinding of superalloy materials. Based on the in-depth analysis of the structure of FGH96 turbine disk, and combined with the actual processing requirements, the electroplated CBN wheel was designed, and the abrasive grains size selection experiments and CBN wheel wear experiments were then carried out for the powder metallurgy superalloy FGH96 in turn. The influence law of the abrasive grain size of CBN grinding wheel and the wear state of grinding wheel on the surface morphology was investigated, respectively. The obtained results showed that under the given processing parameters, the surface roughness Ra using 400# and 600# electroplated CBN wheels are around 0.66 μm and 0.53 μm during the normal wear state of grinding wheels, respectively, which can meet the requirement of surface quality less than Ra 0.8 μm in engineering application of turbine disk, and prove the feasibility of small-size CBN wheel grinding FGH96. In addition, the failure form of electroplated CBN wheel is mainly the accumulation and adhesion of abrasive debris, and the crushing and shedding of abrasive grain are hard to appear.

Transfer of Cubic Boron Nitride Grinding Wheel Wear Products to the Nickel Alloy Surface

The article summarizes the results of microscopic and x-ray spectral studies of objects embedded in the surface layer of a nickel alloy after grinding with a wheel of cubic boron nitride (CBN) on a ceramic bond. In the introduction, the authors analyzes the results of research on the use of CBN as an abrasive material. Unlike silicon carbide wheels, CBN tools are a more complex and multi-component structure, which has a significant impact on the self-sharpening of the abrasive tool and the transfer of material. The purpose of this article is to detect and identify the wear products of a CBN grinding wheel on the treated surface of a nickel alloy. As a result of studying the morphology of the alloy surface after grinding with CBN wheels, foreign objects embedded in the metal were detected with a scanning two-beam electron microscope. The chemical composition of the objects was studied by x-ray spectral microanalysis. Based on the obtained spectrograms, the objects were divided into three groups, including peaks of x-ray characteristic radiation: boron and nitrogen characteristic of CBN grains; aluminum and oxygen characteristic of corundum; oxygen, silicon, aluminum, and some elements characteristic of a ceramic bond. Tables of the chemical composition of the studied objects are provided. Conclusions. The transfer of CBN grinding whee wear products from to the treated surface is experimentally proved.

Effect of CBN grain friability in hardened steel plunge grinding

Nowadays, modern technology allows engineers to create tools with more adequate properties depending on the application. Currently, a lot of components require dimensional and geometric precision with tolerances increasingly tight. Grinding is the most suitable machining process in many cases and is currently applied in large scale in the machining business. Since it is a complex process due to its stochastic nature, there is a wide-open field of study and data collection to obtain the most efficient combination of tool/workpiece material depending on what is desired, always seeking improvements and optimization of the process. Besides this, a new parameter that can recently be considered to select the grinding wheel is the abrasive grains’ friability level within cubic boron nitride (CBN) material. Since there is scarce information about the influence of this specific parameter in the performance of the wheel, this work aims to fill this gap. This work analyzes the cylindrical grinding of the AISI 4340 steel using two types of vitrified-bonded CBN grinding wheels. Their only significant distinction is the difference in the abrasive grains’ friability. The performance of each wheel was analyzed taking into account the results obtained from the parameters’ surface roughness, roundness error, micro hardness, acoustic emission, and average power. Regarding the average surface roughness, the more friable wheel produced values of 0.31, 0.40, 0.44, and 0.53 μm, respectively, for the 0.25, 0.50, 0.75, and 1.00 mm/min feed rates. On the other hand, the average surface roughness values obtained from the workpieces ground with the less friable wheel were: 0.22, 0.29, 0.35, and 0.40 μm, respectively, for the 0.25, 0.50, 0.75, and 1.00 mm/min feed rates. This means that when using the less friable abrasive grain, the surface roughness is better, which suggests that in the friability range analyzed, the use of a less friable wheel produces workpieces with better quality.

Surface integrity of quenched steel 1045 machined by CBN grinding wheel and SiC grinding wheel

PurposeThe purpose of this paper is to evaluate surface integrity of quenched steel 1045 ground drily by the brazed cubic boron nitride (CBN) grinding wheel and the black SiC wheel, respectively. Surface integrity, including surface roughness, sub-surface hardness, residual stresses and surface morphology, was investigated in detail, and the surface quality of samples ground by two grinding wheels was compared.Design/methodology/approachIn the present work, surface integrity of quenched steel 1045 machined by the CBN grinding wheel and the SiC wheel was investigated systematically. All the specimens were machined with a single pass in the down-cutting mode of dry condition. Surface morphology of the ground specimen was observed by using OLYMPUS BX51M optical microscopy. Surface roughness of seven points was measured by using a surface roughness tester at a cut-off length of 1.8 mm and the measurement traces were perpendicular to the grinding direction. Sub-surface micro-hardness was measured by using HVS-1000 digital micro-hardness tester after the cross-section surface was polished. The residual stress was tested by using X-350A X-ray stress analyzer.FindingsWhen the cut depth is increased from 0.01 to 0.07 mm, the steel surface machined by the CBN wheel remains clear grinding mark, lower roughness, higher micro-hardness and higher magnitude of compressive stress and fine microstructure, while the surface machined by the SiC grinding wheel becomes worse with increasing of cut depth. The value of micro-hardness decreases, and the surface roughness increases, and the surface compressive stress turns into tensile stress. Some micro-cracks and voids occur when the sample is processed by the SiC grinding wheel with cut depth 0.07 mm.Originality/valueIn this paper, the specimens of quenched steel 1045 were machined by the CBN grinding wheel and the SiC wheel with various cutting depths. The processing quality resulted from the CBN grinding wheel is better than that resulted from the SiC grinding wheel.

Investigation on heating temperature characteristics during rotating induction brazing of monolayer CBN grinding wheels: Numerical simulation and experimental verification

This article mainly carries out the numerical simulation and experimental verification of heating temperature characteristics during fabrication of monolayer brazed cubic boron nitride (CBN) grinding wheels using the rotating induction brazing technique. Effects of the critical heating factors in t he rotating induction brazing process, such as induction current, current frequency, heating gap and scanning speed are analyzed, respectively. It was found that, the maximum value of heating temperature increases nonlinearly with the increasing induction current and current frequency, and with decreasing of the heating gap and scanning speed. The empirical formula of heating temperature is established, and the rotating induction heating parameters are accordingly optimized to control the brazing temperature range of 880-940°C, which has been confirmed valid during the rotating induction brazing operation of monolayer CBN grinding wheels.

Behavior and quantitative characterization of CBN wheel wear in high-speed grinding of nickel-based superalloy

This work aims to clarify the wear behavior and quantitatively characterize the wear in cubic boron nitride (CBN) wheels during the high-speed grinding of the nickel alloy, Inconel 718. Grinding experiments were performed first to qualitatively investigate the wear behavior of CBN wheels. To simplify the grinding process, single-grit grinding experiments were carried out to quantitatively characterize the degree of wear on the CBN grain afterwards. The influence of maximum chip thickness on the wear and grinding ratio of CBN grains was studied. Finally, the wear of the CBN wheel was quantitatively characterized by using the wear flat area percentage. It was found that the wear of a single CBN grain increases dramatically at first and then varies little with the increase in the accumulated material removal. The wear flat area percentage of the CBN grinding wheel is able to remain at a low level, and a high and stable grinding ratio can be achieved for CBN wheels. This demonstrates the feasibility of CBN wheels in the high-speed grinding of nickel alloys.

Effects of Abrasive Types on Grinding of Chopped Strand Mat Glass Fiber-Reinforced Polymer Composite Laminates

A grindability study of chopped strand mat glass fiber reinforced polymer laminates (CSM GFRP) has been carried out to evaluate the effects of abrasive types on grinding force ratio and area roughness at varying grinding parameters such as speed, feed and depth of cut. Performances of alumina (Al2O3) and cubic boron nitride (CBN) wheels were compared. Both wheels delivered the maximum grinding force ratios at low speed, high feed and low depth of cut. Alumina wheel produced smoother surface when grinding at low speed, low feed and high depth of cut. CBN wheel, on the other hand, gave smoother surface at high feed and low depth of cut conditions, regardless of speed. With CBN wheel, it is likely that a single grinding condition exists that maximizes grinding force ratio and minimizes area roughness. The findings indicate that CBN wheel exhibited higher grinding force ratio than alumina grinding wheel in general. CBN grinding wheel also outperformed alumina grinding wheel by producing smoother ground surface in most cases.

Effect of Grinding Conditions of a TC4 Titanium Alloy on its Residual Surface Stresses

The grindability of titanium alloys that are classified as hard-to-machine materials is studied in high-speed cylindrical grinding using a cubic boron nitride (CBN) wheel. The investigation is concerned with residual surface stresses, including the construction of its empirical model, orthogonal experiments with a CBN grinding wheel at a speed of 45–150 m/s, and prediction with the back propagation (BP) network. The results of residual surface stress measurements obtained in grinding experiments and simulation analysis for five sets of grinding conditions are compared, it can be seen that the empirical model is partially applicable to a Ti-6Al-4V titanium alloy (TC4) under examined grinding conditions. Generally, the calculation results with the empirical model exhibit a significant deviation from the data of actual measurements in some cases. The BP network possesses the function of complex nonlinear mapping and adaptive learning. So the BP network is adopted to predict the relation between residual surface stresses and three key grinding conditions accurately enough. The accuracy of the network is verified, which lays the foundation for its in practical application.

Research on Grinding Ti6Al4V Alloy with Inner-Lubricating Wheel

The new wheel could reduce grinding friction and prevent of chip adhesion by lubrication between wheel and workpiece surface. Investigation of the simulation dry grinding Ti6Al4V alloy with monolayer brazed CBN (cubic boron nitride) and diamond grinding wheels, and systematically studies the effect of process parameters on the microstructure of specimen. the cutting properties generated during grinding with internal lubricating wheel. Grinding simulation was carried out with this internal lubricating wheel. The machining properties were assessed in terms of grinding temperature. The results indicate that graphite significantly improve machinability during dry grinding of Ti6Al4V alloy.

Effect of granulated sugar as pore former on the microstructure and mechanical properties of the vitrified bond cubic boron nitride grinding wheels

For vitrified bond cubic boron nitride (CBN) grinding wheel, introduced pores play a very important role for its mechanical properties and performance. In this paper, granulated sugar was used as pore former of the vitrified bond in CBN grinding wheel. The effects of content and particle size of the granulated sugar on the porosity and the flexural strength of the sintered vitrified bond CBN wheel samples have been investigated. It was found that the porosity of the vitrified bond CBN wheel is positively correlated with the content of the granulated sugar. The smaller and more irregular shaped pores are uniformly distributed in the bond when the content of granulated sugar is between 1 and 3wt.%. Larger and more non-uniform pores and pore channels appear as the content of granulated sugar is increased from 5 to 7wt.%. The flexural strength of the vitrified bond CBN wheel specimens decreases with an increase in pore former’s content and the porosity. With the increase of pore former’s particle size at the content of 3wt.%, the flexural strength reaches to a peak value of 49MPa with average particle size of granulated sugar is 250μm. When the average size of granulated sugar is from 100 to 125μm, the pores’ size is similar with the size of pore former and distributed homogeneously. The larger granulated sugar with the size from 160 to 500μm can introduce different size of pores which could be smaller or larger than the size of pore former.

CBN Grinding Performance Improvement in Aircraft Engine Components Manufacture

Cubic Boron Nitride (CBN) grinding is extensively employed in the aerospace industry as it allows to effectively grind high performance aerospace metal alloys such as nickel base superalloys. With reference to a real industrial case of CBN grinding for the manufacture of aircraft engine components, the aim of this paper is to improve the CBN wheel tool life and optimize the grinding process while taking into account economic, environmental and social sustainability issues. Different types of CBN grinding wheels fabricated using diverse deposition procedures are tested to compare their behavior during grinding of Ni base superalloys and assess their tool life in terms of number of parts successfully ground by a single wheel. Tests are also performed to investigate alternative coolant type applicability as well as grain size influence on surface integrity as these factors can significantly affect process performance, final workpiece quality and grinding wheel life.

Fabrication and performance of porous metal-bonded CBN grinding wheels using alumina bubble particles as pore-forming agents

Porous metal-bonded cubic boron nitride (CBN) composite blocks and grinding wheels were fabricated using alumina bubble particles as pore-forming agents and Cu-Sn-Ti alloy as bonding material. The influence of the porosity on the mechanical strength of the porous composite blocks was examined by means of three-point bending tests. The microstructure of the blocks fracture surface was characterized. The grinding performance of the porous metal-bonded CBN wheels was investigated and compared with the vitrified CBN wheel. Results show that the bending strength of the porous metal-bonded blocks is varied from 51 to 103 MPa when the porosity is changed from 8 to 45 %. High blocks strength is mainly attributed to the firm bonding formed at the sintering interface of Cu-Sn-Ti/CBN grain and Cu-Sn-Ti/alumina particles. Porous metal-bonded CBN wheels exhibits good grinding performance during grinding nickel superalloy due to the abundant chip storage space.