Cubic Boron Nitride Wheel Research Articles

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.

Grinding Force in Creep Feed Grinding of Titanium Alloy with Monolayer Brazed CBN Wheels

In this paper, grinding forces of titanium alloy Ti-6Al-4V are measured during creep feed grinding with brazed cubic boron nitride (CBN) wheels. The effects of process parameters on grinding force, force ratio and specific grinding energy are investigated in detail. The grinding force is low and force ratio is about 1.5, and the specific grinding energy of titanium alloys Ti-6Al-4V is about 65J/mm3. Also, CBN wheels brazed with composite filler of Ag-Cu-Ti and 0.5wt.% lanthanum show better grinding performance than the counterpart brazed with Ag-Cu-Ti filler in this investigation.

Research on surface integrity of grinding Inconel718

Inconel718 is widely used in the aerospace industry; the finished surface quality has significant effect on service performance of component. The surface integrity in grinding Inconel718 respectively by using a vitrified bond single alumina (SA) wheel and a resin cubic boron nitride (CBN) wheel were investigated. First, effects of different grinding parameters on grinding temperature and grinding force and grinding chips feature by using a SA and a CBN wheel respectively were investigated. Then, the surface roughness and topography by using a SA and a CBN wheel through single factor experiment were compared, and in the grinding parameters range of the present study, the better surface can be obtained by a SA wheel. Finally, surface integrity by using a SA wheel and the different grinding depth was studied and analyzed by the grinding temperature and the grinding force. It was possible to conclude that better surface can be achieved by using a SA, and taking a p = 0.005 mm, v w = 16 m/min, v s = 25 m/s for grinding Inconel718. In this grinding case, the surface roughness was Ra0.112 μm, the surface residual stress was +700Mpa, and the surface hardness was 440 HV; the depth of residual stress layer was 40∼60 μm, the depth of softened layer was 30∼40 μm and the depth of plastic deformation layer was 10∼15 μm.

Development of a Phenolic Resin-Bonded CBN Wheel for Precision Grinding of Ferrous Materials

A phenolic resin-bonded cubic boron nitride (CBN) wheel was designed and manufactured for precision grinding ferrous materials. The resin was determined to be a linear phenolic resin pre-polymer added with hexamethylenetetramine by infrared spectrum and the curing reaction, which characterized by an exothermic peak at about 180°C with release of NH3, was analyzed by differential scanning calorimeter and thermogravimetry. Based on thermal analysis, a hot press forming process and a post thermal treatment were employed for fabricating the resin-bonded CBN wheel. Grinding experiment results showed that normal grinding forces vary from 7 to 11 N and fluctuate slightly with 1~2 N. The grinding ratio of 585 and the surface roughness of 0.18 μm were obtained under an appropriate grinding condition.

Performance of a cutting tool made of steel matrix surface nano-composite produced by in situ laser melt injection technology

Steel-matrix (105WCr6 steel) surface nano-composites with (Ti,W)C micron-sized and (Fe,W) 6C nano-sized carbide precipitates were produced by in situ laser melt injection technology with subsequent heat treatment. The microhardness of a 1 mm thick nano-composite layer was found to be higher than that of the initial matrix. The machinability of the surface nano-composite by a cubic boron nitride (CBN) wheel was found lower, but still reasonable compared to the initial matrix. Cutting tools produced from our new nano-composite by the CBN wheel were found to have higher wear resistance, longer tool life and provided lower cutting forces against a C45 steel workpiece compared to the initial matrix of the nano-composite.

Dimension Accuracy and Surface Integrity of Creep Feed Ground Titanium Alloy with Monolayer Brazed CBN Shaped Wheels

Titanium alloy tenon is creep feed ground with monolayer brazed cubic boron nitride (CBN) shaped wheels. The dimension accuracy of the tenon is assessed and the results indicate that it completely meets the requirement of blade tenon of aero-engine. Residual stresses, surface roughness, microstructure and microhardness are measured on ground surfaces of the specimen, which are all compared with that ground with vitrified CBN wheels. Under all the circumstances, compressive residual stress is obtained and the depth of the machining affected zone is found to be less than 40 μm. No phase transformation is observed at depths of up to 100 μm below the surface, though plastic deformation is visible in the process of grain refinement. The residual stress and microhardness of specimens ground with brazed CBN wheels are observed to be lower than those ground with vitrified ones. The arithmetic mean roughness (Ra) values obtained are all below 0.8 μm.

Grindability and Surface Integrity of Cast Nickel-based Superalloy in Creep Feed Grinding with Brazed CBN Abrasive Wheels

The technique of creep feed grinding is most suitable for geometrical shaping, and therefore has been expected to improve effectively material removal rate and surface quality of components with complex profile. This article studies experimentally the effects of process parameters (i.e. wheel speed, workpiece speed and depth of cut) on the grindability and surface integrity of cast nickel-based superalloys, i.e. K424, during creep feed grinding with brazed cubic boron nitride (CBN) abrasive wheels. Some important factors, such as grinding force and temperature, specific grinding energy, size stability, surface topography, microhardness and microstructure alteration of the sub-surface, residual stresses, are investigated in detail. The results show that during creep feed grinding with brazed CBN wheels, low grinding temperature at about 100 °C is obtained though the specific grinding energy of nickel-based superalloys is high up to 200-300 J/mm3. A combination of wheel speed 22.5 m/s, workpiece speed 0.1 m/min, depth of cut 0.2 mm accomplishes the straight grooves with the expected dimensional accuracy. Moreover, the compressive residual stresses are formed in the burn-free and crack-free ground surface.

Grinding Forces and Grinding Energy in High Speed Grinding for Quenched Steel

Grinding experiments for quenched high-speed tool steel by resin bonded CBN (cubic boron nitride) wheel were conducted with a surface grinder. The grinding forces were measured under different grinding parameters. The effects of grinding parameters on grinding forces and grinding force ratio are discussed. Specific grinding energy and heat flux over the grinding zone are computed according to grinding parameters and grinding forces. The effects of grinding parameters on specific grinding energy and heat flux are investigated.

Virtual high performance grinding with CBN wheels

The development of future products requires designing, manufacturing, and testing components in a virtual environment before hardware parts are actually made. This paper presents a generalized process simulation and multi-constraint optimization strategy for five-axis grinding with cubic boron nitride (CBN) wheels to increase material removal rates while avoiding process problems such as damage to the machined surfaces and premature wheel failure. The wheel–workpiece engagement conditions under five-axis grinding are extracted from a CAM system by geometrically processing the NC program, the wheel geometry and the part geometry. The interpreted geometric contact data are used in combination with empirical grinding models to predict physical process parameters such as forces, power, heat flux, and temperature. These parameters are then used as the decision variables in a multi-constraint optimization to optimize process parameters such as workspeed to reduce cycle time.

Friction studies on surface grinding of granite with a vitrified CBN wheel

AbstractAn investigation was undertaken to elucidate the interactions at the wheel–workpiece interface in the surface grinding of natural granite with a vitrified cubic boron nitride (CBN) wheel. During grinding, the spindle power and temperature responses were measured. Wear of the CBN wheel after grinding was followed using a digital imaging system. Specific energy was calculated according to the net grinding power and was found to increase with the depth of cut, indicating the action of sliding friction prevailing in the grinding. The ratio of the length of grinding zone to maximum undeformed chip thickness was proposed to include the effects of both size effect and sliding friction. Coupled with the grinding power and temperature responses, energy partitions to the workpiece were obtained and the grit tip temperature was estimated. Wear flats were found to dominate the wear of CBN in the grinding. In some cases, grit tip temperatures were found to be above the temperature of thermal stabilization of CBN. Copyright © 2008 John Wiley & Sons, Ltd.

Brazed CBN Grinding Wheel with Ag-Base Filler Alloy

In this paper, the disadvantages of the current CBN (Cubic Boron Nitride) grinding wheels were firstly introduced briefly, for indicating that it was very urgent and important to develop new kinds of grinding wheels with excellent performance to replace the conventional wheels. Then high temperature brazing experiments of monolayer CBN wheels with Ag-Cu-Ti filler alloy were carried out. The result shows that the filler alloy has good wetting capability towards CBN grits. The results of scanning electron microscope (SEM) and energy dispersion spectrometer (EDS), as well X-ray diffraction (XRD) analysis show that, just because during brazing titanium atoms in filler alloys segregated preferentially to the surface of the CBN to form Ti-nitride or Ti-boride layer by reaction between titanium atoms and nitride and boron atoms at elevated temperature, strong chemical joining was formed in the interface between CBN grits and filler alloys. Finally, the contrastive grinding experiments were performed between the monolayer brazed CBN grinding wheels and the electroplated ones. The results show that the brazed wheels have more excellent performance than the latter.

Mechanics of Loading for Electroplated Cubic Boron Nitride (CBN) Wheels During Grinding of a Nickel-Based Superalloy in Water-Based Lubricating Fluids

The mechanics of wheel loading of the nickel-based superalloy onto electroplated CBN wheels during grinding with water-based lubricants is proposed. Wheel loading was the primary cause for the significant decrease in grinding wheel life for the current formulation of water-based lubricants tested. Evidence of the specific sequence in the deposition process has been captured through extended evaluation and characterization of the grinding wheel surface and adherent alloy material. The proposed mechanism provides a phenomenological understanding of wheel loading for grinding operations using water-based lubricants, aiming to promote testing of future generation grinding lubricants and advanced fluid delivery methods specific to these operations.

Fluid Performance Study for Groove Grinding a Nickel-Based Superalloy Using Electroplated Cubic Boron Nitride (CBN) Grinding Wheels

The performance of three water-based grinding fluids was analyzed and compared to a neat oil tested under the same process conditions. Light optical and scanning electron microscopy observations show the mechanism of metal deposition that leads to CBN wheel failure for water-based fluids. To improve the performance of the water-based fluids, a new nozzle layout is proposed that would prevent metal deposition on the CBN wheels. The proposed solution is not chemical, but mechanical in nature and the presented setting should be optimized in the future to assure satisfactory performance of the CBN wheels with water-based fluids.

The laser dressing of resin-bonded CBN wheels by a Q-switched Nd: YAG laser

Resin-bonded cubic boron nitride (CBN) grinding wheels are widely used in industry due to their good grinding ability. There is, therefore, a need to find a good method suitable for the dressing of these wheels. This paper presents a new method dressed by an acoustic-optic Q-switched Nd: YAG laser based on thermal interaction, which is unlike the conventional mechanical dressing methods based on force interaction. The mechanism of the selective removal of the bond was analysed. Experiments of a single pulse ablation on the resin bond and the CBN grains, and the laser dressing of resin-bonded CBN wheels with different dressing parameters have been carried out. The grinding force has been compared for the conventional mechanical dressed wheel and the laser dressed wheel. It is shown that the resin-bonded CBN grinding wheel is suitable for an acoustic-optic Q-switched Nd: YAG laser dressing with radial irradiation, which is better than a continuous wave (CW) laser dressing with radial irradiation and conventional mechanical dressing methods.

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This paper presents a review of researches on CBN (cubic boron nitride) grinding wheels with the purpose of identifying the state of art in abrasive machining and serving as the basis for future researches and laboratory tests. The scientific studies investigated here report on interesting results involving grinding, published by Brazilian and foreign authors. The methods and the results are presented and discussed. In addition, a grinding setup is presented which provides more reliable experimental results about the surface integrity of fragile materials. This setup was obtained for grinding tests in several grinding conditions during the wheel service life, using alumina and vitrified and resin bond CBN grinding wheels. Results of cutting force, surface roughness and G ratio are also presented and discussed. They confirm the excellent machining capacity of the CBN wheel, with stable behavior in cutting force and roughness results during the tests. The G ratio values are in agreement with the results found by other researchers.

Mechanisms of abrasive wear in the grinding of titanium (TC4) and nickel (K417) alloys

The present investigation was dedicated to elucidate abrasive-wear mechanisms during surface grinding of a titanium alloy (TC4) and a nickel-based superalloy (K417) by using silicon carbide (SiC), alumina (Al 2O 3), and cubic boron nitride (CBN) wheels. The temperature at the wheel–workpiece contact zone was measured using a workpiece–foil thermocouple. SEM and EDS were used to examine the morphological features of ground workpiece surfaces and worn wheel surfaces. It is shown that the grinding with either SiC or Al 2O 3 is characterized by the high temperatures reached in the grinding zone since either of them is easily worn during the grinding processes. Along with the presence of high temperatures, strong adhesion was found between the abrasives and workpieces, which might be attributed to the chemical bonding between the abrasives and workpieces at the elevated temperatures. The increasing ductile deformation of both TC4 and K417 at the elevated temperatures may also be a factor. Therefore, the wear of SiC or Al 2O 3 is both chemical and physical. In the grinding with CBN wheels, however, the wear of abrasive grits is mainly physical since CBN is more stable to higher temperatures. At extremely high temperatures, CBN was found to undergo dislodging prior to being gradually worn. In order to reduce the grinding temperatures, a segmented wheel was incorporated into the grinding with CBN wheels.

Precision grinding using CBN wheels

The paper systematically reviews experimental research on the performance of cubic boron nitride (CBN) grinding wheels and discusses advantages and difficulties experienced in the application of CBN wheels particularly for internal grinding with fine-grain wheels. The hardness of CBN grains potentially increases re-dress life and improves dimensional stability. The problem is that increased re-dress life increases the importance of avoiding wheel loading, particularly for small-grain wheels. This paper highlights the importance of touch dressing for improved dimensional stability and other operational techniques to maintain an open surface topography of the wheel. The paper also demonstrates the benefit of an open-structured small-grain CBN wheel for precision grinding. Effects on grinding temperature are also illustrated.

A Tooth Surface Finishing Method with a New Tool of a Vitrified Cubic Boron Nitride Wheel for Involute Internal Spline.

For highly accurate and highly efficient tooth surface finishing, a vitrified cubic boron nitride (CBN) wheel or an electro-deposited CBN wheel exhibits superior performance. Honing by an involute spline tooth meshing is effective due to the generating motion. However, a lack of wheel rigidity and an inadequate feed motion of the wheel tend to reduce the finishing performance. As a result, it is difficult to keep the tooth surface smooth. In this study, the finishing with a vitrified CBN wheel is carried out using a new honing tool. The finishing performance is compared with that obtained using an electro-deposited wheel, and the finishing is carried out by braking an internal spline axis. The influence of different feed methods is investigated on the roughness of the finished tooth surface. The finishing using a vitrified CBN wheel and braking an internal spline axis shows superior performance.

Energy Partition and Cooling During Grinding

High temperatures in grinding can cause thermal damage to the workpiece. This paper presents an overview of quantitative methods to calculate grinding temperatures and the energy partition to the workpiece. It is shown that the energy partition, and consequently the grinding zone temperature, depends on the type of abrasives, fluid application conditions, and grinding process parameters. For regular grinding with conventional aluminum-oxide abrasive wheels, the energy partition typically ranges from 60% to 85%. However, for creep-feed grinding with slow work speeds and large depths of cut, cooling by the fluid at the grinding zone reduces the energy partition to less than 5%. For grinding with cubic boron nitride (CBN) superabrasive wheels, the energy partition is about 20% due to the high thermal conductivity of the CBN abrasive. However, this may be reduced from 8% to 5% for grinding with porous vitrified CBN wheels at high removal rates due to the combined effect of the high thermal conductivity of CBN abrasive and cooling by the fluid at the grinding zone.

A Tooth Finishing Method with A New Tool of a Vitrified CBN Wheel for Involute Internal Spline.

In high accurate and high efficient tooth finishing, a vitrified CBN (cubic boron nitride) wheel or a electro-deposited CBN wheel shows superior performance. And honing by a involute spline tooth meshing is profitable due to the generating motion. However, a lack of wheel rigidity and an inadequate feeding motion of the wheel trend to reduce finishing performance. As a result, it is difficult to keep the tooth surface smooth. In this study, the finishing with a vitrified CBN wheel is carried out using a new honing tool. The finishing performance is compared with that obtained using a electro-deposited wheel. And the finishing by braking a internal spline axis is carried out. The influence of different feeding methods is investigated on the finished tooth surface roughness. The finishing by using a vitrified CBN wheel and braking a internal spline axis shows superior performance.