Superabrasive Grinding Research Articles

Report on Research for the Use and Popularization of Super Abrasive Grinding Wheels

Report on Research for the Use and Popularization of Super Abrasive Grinding Wheels

Laser dressing process monitoring of superabrasive grinding wheel based on spectroscopy

In order to solve the problems of poor efficiency and low automation in laser dressing of superabrasive grinding wheels, the spectral monitoring research based on the automatic dressing of superabrasive grinding wheels was systematically carried out in this paper. For the first time, the characteristic element spectral lines that could respectively characterize the identity information of grain and bond were established, and by monitoring the characteristic element spectral line waveforms, the profiling/sharpening processing status identification was realized. It was the first to propose using the presence or absence of line spectrum during the laser dressing process as a monitoring indicator, which could achieve qualitative identification of the high-efficiency processing status of the laser beam focus. When the laser beam was in the positive defocus state, the material could be removed more accurately. A greater quantity of material would be eliminated when the laser beam was in the negative defocus state. The mapping relationship between the spectral characteristic waveform and the defocus amount of the laser beam during the laser dressing process was revealed, and a spectral monitoring theory of the defocus amount fluctuation of superabrasive grinding wheels was constructed. A high-efficiency automated laser profiling method for grinding wheels based on spectrum-assisted monitoring and self-adaptive feed was innovatively explored, and experiments had proven that this method could achieve self-adaptive feed for laser beam fast slow compensation, ultimately achieving high efficiency and automatic dressing of superabrasive grinding wheels.

Thermal management in grinding of superalloys – A critical review

PurposeThis paper is supposed to provide a critical review of current research progress on thermal management in grinding of superalloys, and future directions and challenges. By understanding the current progress and identifying the developing directions, thermal management can be achieved in the grinding of superalloys to significantly improve the grinding quality and efficiency.Design/methodology/approachThe relevant literature is collected from Web of Science, Scopus, CNKI, Google scholar, etc. A total of 185 literature is analyzed, and the findings in the literature are systematically summarized. In this case, the current development and future trends of thermal management in grinding of superalloys can be concluded.FindingsThe recent developments in grinding superalloys, demands, challenges and solutions are analyzed. The theoretical basis of thermal management in grinding, the grinding heat partition analysis, is also summarized. The novel methods and technologies for thermal management are developed and reviewed, i.e. new grinding technologies and parameter optimization, super abrasive grinding wheel technologies, improved lubrication, highly efficient coolant delivery and enhanced heat transfer by passive thermal devices. Finally, the future trends and challenges are identified.Originality/valueSuperalloys have excellent physical and mechanical properties, e.g. high thermal stability, and good high-temperature strength. The superalloys have been broadly applied in the aerospace, energy and automobile industries. Grinding is one of the most important precision machining technologies for superalloy parts. Owing to the mechanical and physical properties of superalloys, during grinding processes, forces are large and a massive heat is generated. Consequently, the improvement of grinding quality and efficiency is limited. It is important to conduct thermal management in the grinding of superalloys to decrease grinding forces and heat generation. The grinding heat is also dissipated in time by enhanced heat transfer methods. Therefore, it is necessary and valuable to holistically review the current situation of thermal management in grinding of superalloys and also provide the development trends and challenges.

Evaluating the performance of electrical discharge face grinding on super alloy monel 400

Conventional machining of super alloy Monel 400 is difficult due to its high strength, low heat conductivity, and gummy nature. In this work, the performance of the electrical discharge diamond face grinding (EDDFG) while processing supper alloy Monel 400 is assessed using the super abrasive diamond-coated grinding wheels of three different grit numbers. Preliminary experiments highlighted the superior performance of the EDDFG as compared to that of electrical discharge machining (EDM) and electrical discharge face grinding (EDFG); in terms of material removal rate (MRR), average surface roughness (Ra), and microscopic images of surfaces using scanning electron microscope (SEM). This work aimed to assess the influence of the diamond grit number (DG n ) of the grinding wheel along with other process parameters, viz. grinding wheel speed (GWS), peak current (I p ), and pulse-on-time (T on ) on Ra and MRR. The analysis of variance (ANOVA) confirmed that DG n and GWS significantly affect the response variables. Finally, the multi-objective genetic algorithm (GA) optimization approach was used to determine the optimal parametric settings of the EDDFG process.

Influence of wire electrical discharge conditioning on the grinding performance of metal-bonded diamond grinding tools

Wire Electrical Discharge Conditioning (WEDC) is an efficient non-conventional method for conditioning metal, resin, and hybrid bonded super-abrasive grinding tools. Since the diamond and CBN grains are not affected directly by the WEDC and only the electrically conductive bond material is eroded by the process, high grain protrusions are achievable. Therefore, unlike the common mechanical conditioning methods using WEDC, the microtopography of the grinding tool can be influenced by the process parameters, directly affecting the grinding efficiency. However, the selection of WEDC process parameters is influenced by the specifications of the grinding tool, particularly the grain size and concentration. This study aims to investigate the effects of WEDC parameters and strategies on the microtopography and material removal rate of metal-bonded grinding tools, considering different grain sizes and concentrations. Additionally, the correlation between the microtopography of grinding tools conditioned by the WEDC process and their grinding efficiency was investigated by analyzing tool wear, grinding forces, and surface roughness of tungsten carbide workpieces. The results indicate that the material removal rate of the WEDC process decreases as the grain size and concentration of metal-bonded diamond grinding tools increase. Furthermore, it was observed that employing high spark energy parameters reduces the grain protrusion of grinding wheels with small grain sizes. However, the utilization of high-energy sparks is necessary to create larger spark gaps and achieve a higher material removal rate.

Phase transformation and deformation of the high-frequency induction brazed grinding wheel based on multi-field coupling

With the characteristic of the high bonding strength to matrix, good sharpness, and large chip-storage spaces, the brazed super abrasive grinding wheels have superiorities in the machining of difficult-to-machine materials. However, thermal deformation is caused by the high temperature during the brazing process, leading to the accuracy of the brazed grinding wheel being degraded greatly. By means of local heating, high-frequency induction brazing can reduce the thermal deformation of the wheel. Aiming at the thermal deformation mechanism of the induction brazed wheel, a numerical simulation model of thermal-stress-phase multi-field coupling was established considering the temperature-dependent physical properties of the material. The simulation result indicated that the phase transformation occurred near the work surface of the wheel substrate. The depth of phase transformation layer decreased from 6.0 mm to 2.9 mm with the scanning speed increasing from 0.5 mm/s to 2.0 mm/s. The microstructure of the phase transformation layer mainly consisted of ferrite, pearlite, and bainite after brazing. An appropriate scanning speed was more important for the high accuracy of the wheel substrate during the induction brazing, since it had remarkable influence on the stress and deformation than brazing temperature. The experimental results of the microstructure morphology and deformation proved that the numerical simulation model was correct with 10.4% error.

Grain erosion wear properties and grinding performance of porous aggregated cubic boron nitride abrasive wheels

Cubic boron nitride (cBN) superabrasive grinding wheels exhibit unique advantages in the grinding of difficult-to-cut materials with high strength and toughness, such as titanium alloys and superalloys. However, grinding with multilayered metallic cBN superabrasive wheels faces problems in terms of grain wear resistance, the chip storage capability of the working layers and the stability and controllability of the dressing process. Therefore, in this work, novel metallic cBN superabrasive wheels with aggregated cBN (AcBN) grains and open pore structures were fabricated to improve machining efficiency and surface quality. Prior to the grinding trials, the air-borne abrasive blasting process was conducted and the abrasive blasting parameters were optimized in view of wear properties of cBN grains and metallic matrix materials. Subsequently, the comparative experiments were performed and then the variations in grinding force and force ratio, grinding temperature, tool wear morphology and ground surface quality of the multilayered AcBN grinding wheels were investigated during machining Ti–6Al–4V alloys. In consideration of the variations of grain erosion wear volume and material removal rate per unit of pure metallic matrix materials as the abrasive blasting parameters changes, the optimal abrasive blasting parameters were identified as the SiC abrasive mesh size of 60# and the abrasive blasting distance and time of 60 mm and 15 s, respectively. The as-developed AcBN grains exhibited better fracture toughness and impact resistance than monocrystalline cBN (McBN) grains because of the existence of metal-bonded materials amongst multiple cBN particles that decreased crack propagation inside whole grains. The metallic porous AcBN wheels had lower grinding forces and temperature and better ground surface quality than vitrified McBN wheels due to the constant layer-by-layer exposure of cBN particles in the working layer of AcBN wheels.

Cutting edge preparation with elastic bonded diamond grinding wheels: Influence of the interaction of metalworking fluid and grinding wheel on the grinding wheel properties and preparation result

The cutting edge preparation with elastic bonded superabrasive grinding wheels enables the accurate manufacture of customized cutting edges. This process necessitates highest accuracies of the machine and the kinematics. Up to now, no systematic investigations on the interaction of the metalworking fluid and the grinding wheel were done; those could alter the properties of the grinding wheel, and as a consequence the result of cutting edge preparation. The influence of this interaction on cutting edge preparation is investigated in this study using two different experimental setups. One setup where the grinding wheels interacted with the metalworking fluid in an aging chamber to speed up the aging process and one setup directly in a tool grinding machine, in which the grinding wheels were also applied for cutting edge preparation at different stages of aging. In the aging chamber, the interaction takes place under elevated metalworking fluid temperatures to accelerate possible interaction effects. The results revealed an increase in the diameter, width and weight of the grinding wheels and a reduction in hardness. These changes were more pronounced under the elevated temperatures in the aging chamber. This in turn resulted in a significant alteration in the geometry of the prepared cutting edges, which was not observed when the grinding wheels interacted with the metalworking fluid in the tool grinding machine. As a general result, to keep the properties of the grinding wheels approximately constant, continuous dressing cycles should be carried out. In addition, the grinding wheels should be stored in dry conditions when not using them. In this way, specific cutting edge geometries can be manufactured reproducibly.

In-machine data acquisition for evaluating the conditioning efficiency of resin-bonded super-abrasive grinding wheels

ABSTRACT Smart manufacturing factories rely on the Internet of Things to drive changes to the machine-tool sector. Grinding processes play a leading role in the manufacturing of high added-value components for high-tech sectors. CBN and diamond grinding wheels are leading the next generation of advanced grinding. One of the critical points is the control of mechanical dressing and truing techniques. In this context, rotating SiC tools and Ta metallic sticks have been successfully applied. However, there is a lack of industrial and easy-to-use wheel topography evaluation techniques. Indirect techniques and complex topography evaluation devices had proposed. However, it is of maximum interest to obtain direct information about grit protrusion and distribution that, could be shared with digitalization platforms. In this paper, an industrial, feasible and easy-to-use optical tool is proposed to gain direct information about the surface topography left by the truing super-abrasive grinding wheels. This information is shared with digitalization platforms. The results confirm the influence of speed ratio, with positive values being related to higher grain pull-out and protrusion of new grains. SiC rotary tool shows better performance when compared to Tantalum sticks. Future work will focus on protocols to share the generated data with existing digitalization platforms.

Effect of multi-anodes method for enhancing a Ni-D deposition characteristic on super abrasive grinding wheel

Effect of multi-anodes method for enhancing a Ni-D deposition characteristic on super abrasive grinding wheel

Micro-grooving of brittle materials using textured diamond grinding wheels shaped by an integrated nanosecond laser system

Freeform surfaces including both the aspherical and prismatic concave/convex have been widely utilized in optical, electronical, and biomedical areas. Most recently, it is reported that grinding with structured wheels provides new possibility to generate patterns on hard and brittle materials. This paper reports the latest research progress on micro-grooving glass ceramic using laser structured diamond grinding wheels. A nanosecond pulse laser is firstly integrated into an ultra-precision machine tool and used for the in-line conditioning of super abrasive grinding wheels, i.e., truing, dressing, and profiling/texturing. Meanwhile, an offset compensation method, considering the shifting depth of focus (DoF) at different laser irradiation positions, is proposed to accurately generate various profiles on the periphery of the grinding wheels. Three types of patterns (riblets, grooves, and pillars) are successfully fabricated on the ceramic substrate using the laser textured grinding wheels. The results indicate that the integrated laser system offers high flexibility and accuracy in shaping super abrasive grinding wheels, and the grinding using textured grinding wheels provides a promising solution to generate functional microstructures on hard and brittle materials.

Analysis of the grinding wheel wear and machining result during cutting edge preparation with elastic bonded grinding wheels

Cutting edge preparation can be considered as one of the most effective methods for optimizing the cutting tool life and the machining result. In this article, a preparation technique using elastic bonded superabrasive grinding wheels is applied. This method proved to be highly flexible in terms of the achievable cutting edge geometry. However, very little knowledge exists about the grinding wheel wear behavior and therefore the process reliability during cutting edge preparation. In this article, the impact of the process kinematics and parameters on the grinding wheel wear and preparation result is investigated and discussed. For this purpose, the impact of the depth of cut (20, 40 and 60 μm) was investigated, because it serves as the major setting parameter for the size of the cutting edge rounding. However, it also impacts the contact conditions and thermo-mechanical loads in the grinding wheel. The experimental results show that this preparation method achieves a high preparation accuracy and repeatability at small and medium depths of cut (20 and 40 μm). For a depth of cut of 60 μm, the preparation result became more inappropriate (increased deviation of the cutting edge shape from an ideal radius) with an increasing number of prepared cutting edges. Here, the soft grinding wheel exhibited a higher process stability in terms of repeatable machining results. The machining results correspond to the experimental findings from the grinding wheel radial wear Δrs. At a depth of cut of 20 and 40 μm, the grinding wheel radial wear for the hard bond was lower than for the soft bond. At a depth of cut of 60 μm, the grinding wheel radial wear for the hard bond exceeds the value for the soft bond by 10%. However, the grinding (G) ratios for the hard bond were higher for all investigated depths of cut. The highest difference was observed at a depth of cut of 20 μm. Here, the G ratio for the soft grinding wheel was 7.92 and for the hard one 18.53. Furthermore, an application scenario was introduced using suitable dressing cycles, so that up to 138,000 cutting edges (equals 34,500 indexable inserts) could be prepared with one grinding wheel using this preparation technique in industrial tool manufacturing applications.

Research on calculation of grinding surface roughness

In machining processes, grinding is often chosen as the final machining method. Grinding is often chosen as the final machining method. This process has many advantages such as high precision and low surface roughness. It depends on many parameters including grinding parameters, dressing parameters and lubrication conditions. In grinding, the surface roughness of a workpiece has a significant influence on quality of the part. This paper presents a study of the grinding surface roughness predictions of workpieces. Based on the previous studies, the study built a relationship between the abrasive grain tip radius and the Standard marking systems of the grinding wheel for conventional and superabrasive grinding wheels (diamond and CBN abrasive). Based on this, the grinding surface roughness was predicted. The proposed model was verified by comparing the predicted and experimental results. Appling the research results, the surface roughness when grinding three types of steel D3, A295M and SAE 420 with Al2O3 and CBN grinding wheels were predicted. The predicted surface roughness values were close to the experimental values, the average deviation between predictive results and experimental results is 15.11 % for the use of Al2O3 grinding wheels and 24.29 % for the case of using CBN grinding wheels. The results of the comparison between the predicted model and the experiment show that the method of surface roughness presented in this study can be used to predict surface roughness in each specific case. The proposed model was verified by comparing the predicted and measured results of surface hardness. This model can be used to predict the surface hardness when surface grinding

Optimizing the Sharpening Process of Hybrid-Bonded Diamond Grinding Wheels by Means of a Process Model

The grinding wheel topography influences the cutting performance and thus the economic efficiency of a grinding process. In contrary to conventional grinding wheels, super abrasive grinding wheels should undergo an additional sharpening process after the initial profiling process to obtain a suitable microstructure of the grinding wheel. Due to the lack of scientific knowledge, the sharpening process is mostly performed manually in industrial practice. A CNC-controlled sharpening process can not only improve the reproducibility of grinding processes but also decrease the secondary processing time and thereby increase the economic efficiency significantly. To optimize the sharpening process, experimental investigations were carried out to identify the significant sharpening parameters influencing the grinding wheel topography. The sharpening block width lSb, the grain size of the sharpening block dkSb and the area-related material removal in sharpening V’’Sb were identified as the most significant parameters. Additional experiments were performed to further quantify the influence of the significant sharpening parameters. Based on that, a process model was developed to predict the required sharpening parameters for certain target topographies. By using the process model, constant work results and improved process reliability can be obtained.

Novel comparison concept between CBN and Al2O3 grinding process for eco-friendly production

Minimal Quantity of Lubrication was developed to achieve green manufacturing in machining process. In this study, parameters of cutting fluid flow, grinding wheel type and wheel cleaning system were evaluated to achieve the maximum potential of this technique in grinding process. The comparison of super abrasive (CBN) and conventional (Al2O3) grinding wheel, the cutting fluid flow (30 ml/h, 60 ml/h and 120 ml/h), and the wheel cleaning system were analyzed based on: surface roughness, roundness errors, grinding wheel wear, confocal of grounded surface, grinding power, acoustic emission and workpiece microscopy. In a novel way, this study compared the costs per piece and the carbon footprint in terms of CO2 emission for both abrasive tool application. For all the parameters analyzed, the CBN grinding with MQL outperformed the Al2O3 grinding, showing a superior performance not only in terms of surface finishing, on average, 29% lower surface roughness and dimensional deviation 9% lower but also regarding tool efficiencies, such as 127% lower diametrical wear, 42% lower acoustic emission, and 13% lower grinding power. Despite that, the cost per piece was also evaluated for the different lubri-cooling conditions and tools, and the cost per piece recorded for Al2O3 grinding was substantially lower than CBN grinding, irrespective of the lubri-cooling method employed. The cost of grinding for all MQL techniques analyzed with aluminum oxide wheel was, on average, 72% less than grinding with CBN wheel. Besides, the conventional method with the CBN wheel was 7% more expensive than the aluminum oxide wheel.

Resin Bonded Diamond grinding wheels conditioning using SiC rotary dresser

Superabrasive grinding of advanced materials parts with complex geometry is a critical issue for aerospace or energy industry. Likewise, conditioning of superabrasive is a key process in order to obtain the most effective grinding. While from industrial point of view the conditioning parameters and dressers are designed from the experience, from scientific point of view the last works are focused on achieving guidelines for optimising conditioning process. In this sense, the present work is focussed on the conditioning process of diamond resin bonded grinding wheels. To this end, SiC rotary dressers of different hardness and applying down-cut and up-cut are tested in order to achieve the best conditions. On the one hand, the wheel surface is deeply analyse. A software is developed in order to analyse the grain pull out, the new abrasive grains and the size evolution and grain concentration during conditioning. On the other hand, the wheel geometry is also measured due to the importance of geometry loss during the conditioning process on profile grinding wheels. The results shown that down-cut conditions are more aggressive obtaining a better wheel surface recovery and the wheel geometry of the incidence edge is lost, requiring a subsequent truing process to obtain the wheel profile. Finally, it is noteworthy that the methodology developed for the analysis of the diamond resin bonded grinding wheels is suitable for all types of grinding wheels even rotary dressers.

Superabrasive Grinding Characteristics of Additively Manufactured Ti-6Al-4V

Superabrasive Grinding Characteristics of Additively Manufactured Ti-6Al-4V

Grinding efficiency and profile accuracy of diamond grinding wheels dressed with wire electrical discharge conditioning (WEDC)

Super abrasive diamond grinding wheels are the most promising tools for the precision machining of advanced ceramics and carbide materials. However, the efficiency of conventional conditioning of these tools is limited owing to high dressing tool wear, long process time, low form flexibility, and induced damage to the abrasive grains. Wire electrical discharge machining (WEDM) is an alternative method for conditioning of superabrasive grinding wheels with electrically conductive bonding materials. In this study, cylindrical plunge grinding of an alumina ceramic with a resin-bonded diamond grinding wheel is investigated. The assigned type of resin bond contains copper particles and is accordingly electrically conductive for wire electrical discharge conditioning (WEDC). Conventional (mechanical) and WEDC methods are used for generating the same profile on two similar diamond grinding wheels. As a result, the specific grinding energy was reduced up to 26% and 29% during rough and finish plunge grinding, respectively. Reduced specific grinding energy and forces, along with more effective grain protrusion and sharpness by using WEDC for profiling of grinding wheels, have contributed positively to the ground surface conditions despite the relatively rougher wheel surface topography in comparison to the conventional profiling. The more considerable reduction in the mean roughness depth (Rz) than in the arithmetical mean roughness value (Ra) (11% smaller Rz values in WEDC versus mechanical conditioning) verifies that the workpiece surface underwent less surface degradation in case of WEDC because of smaller grinding forces. Furthermore, the profile wear behavior of the workpiece ground with the WED conditioned grinding wheel was superior to the conventionally conditioned one.

Grinding performance and wear of metal bond super-abrasive tools in grinding of Zr-based bulk metallic glass

Bulk metallic glass (BMG) is the new class of promising materials with exceptional mechanical properties and corrosion resistance. BMG parts need grinding to obtain high dimension precision and surface finish. In present research work, Zr-BMG was ground by mono-layer metal bond super-abrasive grinding tools with different abrasive (diamond, CBN) and bond (Ni electroplated, NiCr and Cu-Sn-Ti brazed). The grinding force, surface roughness, surface crystallization status, wear of tools in grinding of BMG with different tools were examined and compared. The specific grinding energy of Zr-BMG was also compared with SS304 steel. The results showed that diamond tool produces lower grinding forces than that of CBN. Ni electroplated tools own lower grinding force than that of brazed ones. Zr based BMG produce higher grinding force and specific grinding energy than SS304 steel. Ni electroplated tools obtain lower surface roughness of Zr-BMG than that of brazed ones. A severe adhesion of Zr-BMG dominates the wear of super-abrasive grinding tools. Ni-electroplated tools produce less adhesion than the brazed tools.

High speed super abrasive grinding of sintered yttria stabilised zirconia (YSZ) using single layer electroplated diamond grinding wheels

High speed moderate depth super-abrasive grinding of sintered yttria stabilized zirconia (YSZ) using coolant was done in current experiment. Electroplated diamond grinding wheels of 151 μm grit size having grits of grade PDA878 were used in the present studies. The diameters of the wheels used in high-speed grinding (up to 200 m/sec) were 125 mm, with a width of 10 mm. Grinding forces were measured. The grinding forces and specific grinding energies were very less compared to grinding of metals and metallic alloys because of the mechanism of ceramic grinding which is by micro brittle fracture, whereas the mechanism of grinding in metals and metallic alloys is by shear deformation. X-ray diffraction data of received and ground sample showed the various lattice plane belonging to Yttria stabilized zirconia (YSZ) and no phase change was observed before and after the grinding. At low depth of cut and table speed surface roughness decreases with increase in wheel speed. But at high depth of cut it is increasing in nature.