Superabrasive Diamond Research Articles

Investigating a novel and highly efficient approach for the fabrication of diamond profile rollers using Wire Electrical Discharge Conditioning (WEDC)

The fabrication of high-precision and high-performance profile rollers represents the main challenge of utilizing profile rollers as dressers to condition conventional grinding wheels. This results in high demands for an efficient process to manufacture profile rollers (form dressing wheels). Conventionally, diamond profile rollers have been produced through infiltration or negative electroplating methods. Nevertheless, these manufacturing methods suffer significant drawbacks, including extended production times and substantial costs. This study presents an innovative approach to fabricating diamond profile rollers using Wire Electrical Discharge Conditioning (WEDC). The WED-Conditioning emerges as an effective alternative to profile metal-bonded rotary diamond dressing tools. This innovative method leads to the production of diamond profile rollers in significantly shorter timeframes and at a more economical cost compared to the conventional manufacturing method with comparable quality. The research delves into the influence of profile roller specifications and conditioning strategies on the achievable profile accuracy and topography of the profile rollers. Also, the wear behavior of the WEDC-conditioned profile roller over long-term conditioning of conventional grinding wheels was studied. The findings highlight the significant contribution of the appropriate selection of WEDC strategies to the profile accuracy, with the potential to achieve profile accuracies comparable with conventional profile rollers. As well, grain size emerges as the primary determinant of achievable profile accuracy for profile rollers. The findings of this study could provide insights into optimizing the manufacturing process for super abrasive diamond profile rollers, thereby enabling their widespread use in the grinding industry.

Surface damage characteristics and identification based on acoustic emission in diamond point grinding carbon/carbon ceramic matrix composites

This study mainly investigated the effect of machining parameters on acoustic emission (AE) characteristics in grinding three-dimensional carbon/carbon ceramic matrix composites with superabrasive diamond grinding points. Signal processing techniques including fast Fourier transform (FFT) and short-time Fourier transform (SWFT) were applied to evaluate frequency features of AE signals. The RMS values were used as an indicator to detect grinding energy releasing characteristics. Results indicated that grinding speed and grinding depth were the main influencing factors on RMS values, while feed speed presented limited effects. The maximum undeformed chip thickness hmax and active grits number were two key factors affecting RMS variation of the AE signals, which corresponded to the intensity of single AE source and the number of total AE ones, respectively. The material removal mechanisms were studied via detailed SEM micrographs of machined surfaces, revealing that fiber fracture and debonding were the main material removal modes in point grinding carbon/carbon composites. The material removal mode can be possibly identified from the frequency of AE signal, as the band of 12–35 kHz mainly corresponded to fiber fracture, 35–70 kHz referred to debonding between the fiber and matrix, 70–90 kHz indicated the frictions, and the fourth band (90–120 kHz) was related to the matrix cracks.

Surface integrity and acoustic emission characteristics during slot milling 3D carbon/carbon composites using superabrasive diamond grinding point

This study mainly investigated the effect of machining parameters on surface morphology and defects in three-dimensional carbon/carbon ceramic matrix composites during slotting with superabrasive diamond grinding points. Specifically, it discussed the mechanisms of burr and uncut fiber formation based on the relationship between grinding and fiber directions. The experimental work was conducted under different spindle speeds and feed speeds, revealing that the poor machining surfaces and severe defects occurred at the minimum spindle speed (2000 rpm) with maximum feed speed (160 mm/min), and most uncut fiber defects occurred when the fiber cutting angle exceeded 90°. Acoustic emission (AE) signals were analyzed via signal processing techniques to capture the energy and frequency characteristics of slotting process under various machining parameters. Results indicated that spindle speed had a significant impact on the frequency band distribution of AE signals, while feed speed primarily influenced the stability of signal profiles. The material removal and tool wear mechanisms were examined through SEM micrographs of machined surfaces and grinding points, revealing that fiber debonding and fracture were the primary material removal mechanisms, and were highly dependent on the fiber cutting angle. Abrasive particles with relatively lower cutting velocity at the center of the grinding tool suffered severe damage/wear.

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.

Characterizations of Carbon Fibres Behavior during Cutting CFRP, Using Superabrasive Diamond Tools

Characterizations of Carbon Fibres Behavior during Cutting CFRP, Using Superabrasive Diamond Tools

Improvement of rough finishing process in multistage superfinishing of sapphire with superabrasive diamond stones

Improvement of rough finishing process in multistage superfinishing of sapphire with superabrasive diamond stones

Обоснование механизма доминирующего государственного участия в освоении ресурсов высоколиквидных полезных ископаемых Арктики

For a scientific discussion the authors present proposals on the formation in Russia of a new form of effective mineral resource base development of the strategic solid mineral resources in the Arctic zone of Siberia and the Far East. The mechanism is based on the prevailing govenmental participation in projects of development and exploitation of highly liquid metals (rare earth elements, Tomtor ore cluster in Yakutia) and minerals (diamond abrasive materials, Rock Popigai meteorite crater deposit in Krasnoyarsk region) in the Siberian Arctic, carried out under conditions of high risk. Shown, that due to the unique parameters of both rare earth and diamond ores flow of hi-tech products and semi-products is formed. With the extension of the technological and value chain - delivery to the domestic and the global markets of highly liquid products (oxides of rare earth metals and high-purity metals, technical super abrasive diamond powders and products for the treatment of materials). Thus, a cluster for the production of final products based on rare-earth metals and super abrasive rough diamonds with high added value can be created. Milestones and additional exploration operations, preparations for the operation and development of deposits are carried out by the State Corporation for Mineral Resources with the joint participation, investment, technological cooperation of private companies and research organizations. The Corporation could be considered as a platform for international cooperation and foreign investment in technological chains of a presented mega-project of development of two closely located deposits. Introduced organizational and economic mechanism allows to: a) carry out public administration of complex resource projects in the Arctic and to develop them to an economically efficient level with a gradual sale of business projects to the private sector; b) to initiate and stimulate long-term scientific and technological development in conditions of high risk; c) to form a system of preferences for the development of Russian high-tech exports; d) ensure Russia’s economic presence and increased geopolitical and geo-economic interests in the Arctic.

A new hybrid oscillatory orbital process for drilling of composites using superabrasive diamond tools

Abstract A new hybrid oscillatory orbital process, using superabrasive diamond tools, was developed for drilling FRP composites. Effects of grain size and tool geometry on forces, temperatures, and surface integrity were experimentally investigated. With proper selection of cutting conditions and process variables, the limitations of conventional orbital drilling using carbide tools can be eliminated by significantly reducing the forces and surface roughness, while increasing tool life by an order of magnitude. This is comparable to PCD tools, at a fraction of the cost. A force model based on process kinematics and chip formation mechanism was developed and validated.

Improvements of the Dressing Process of Super Abrasive Diamond Grinding Wheels

Improvements of the Dressing Process of Super Abrasive Diamond Grinding Wheels

Influence on Diamonds During the Spraying of Diamond-Bronze Abrasive Coatings

Detonation spraying provides the opportunity to produce diamond grinding tools for the machining of stone, cement, and concrete. Especially the atmospheric conditions of the spraying process yield in a high production flexibility. However, during detonation spraying, the oxygenic atmosphere as well as the thermal and kinetic energy have an impact on the processed diamond. Despite its importance for the tools’ performance, the influence of the spraying process on the superabrasive diamond is predominantly unknown. The potential decrease of the diamond durability and strength due to degradation effects during the production of sprayed diamond-CuSn 85/15 composites has not yet been determined. X-ray diffraction and Raman spectroscopy were used to verify thermally initiated surface reactions of the sprayed diamonds after exposure to the spraying process. Additionally, reference measurements on the degradation of diamonds in oxidizing and inert conditions were carried out to compare the spraying results. Differential thermal and thermogravimetric analyses were employed. To validate the mechanical properties of the diamond superabrasives, friability tests and fracture force tests were performed. It was found that under optimized detonation spraying conditions the thermal and mechanical impact remains low enough to ensure a good reliability of the processed diamonds. The diamond crystal structure endured the spraying process without detectable graphitization or oxidation. Deterioration indicators were not observed in SEM micrographs, x-ray diffraction patterns or Raman spectra. Furthermore, a high durability and strength of the sprayed diamonds were confirmed by mechanical testing.

Ultra-precision ductile grinding of BK7 using super abrasive diamond wheel

In this paper, a novel conditioning technique using copper bonded diamond grinding wheels of 91 μm grain size and electrolytic in-process dressing (ELID) is first developed to precisely and effectively condition a nickel-electroplated monolayer coarse-grained diamond grinding wheel of 151 μm grain size. Under optimised conditioning parameters, the super abrasive diamond wheel was well conditioned in terms of a minimized run-out error and flattened diamond grain surfaces of constant peripheral envelope. The conditioning force was monitored by a force transducer, while the modified wheel surface status was in-situ monitored by a coaxial optical distance measurement system. Finally, the grinding experiment on BK7 was conducted using the well-conditioned wheel with the corresponding surface morphology and subsurface damage measured by atomic force microscope (AFM) and scanning electric microscope (SEM), respectively. The experimental result shows that the newly developed conditioning technique is applicable and feasible to ductile grinding optical glass featuring nano scale surface roughness, indicating the potential of super abrasive diamond wheels in ductile machining brittle materials.

Ultraprecision Ductile Grinding of Optical Glass Using Super Abrasive Diamond Wheel

In this paper, a novel conditioning technique features using copper bonded diamond grinding wheels of 91μm grain size assisted with ELID (electrolytic in-process dressing) as a conditioner to precisely and effectively condition nickel electroplated monolayer coarse-grained diamond grinding wheels of 151μm grain size was firstly developed. Under optimised conditioning parameters, the super abrasive diamond wheel was well conditioned in terms of a minimized run-out error and flattened diamond grain surfaces of constant peripheral envelope, with the conditioning force monitored by a force transducer as well as the modified wheel surface status in-situ monitored by a coaxial optical distance measurement system. Finally the grinding experiment on BK7 was conducted using the well conditioned wheel with the corresponding surface morphology and subsurface damage measured by AFM (atomic force microscope) and SEM (scanning electron microscope) respectively. The experimental result shows that the newly developed conditioning technique is applicable and feasible to ductile grinding optical glass featuring nano scale surface roughness, indicating a prospect of introducing super abrasive diamond wheels into ductile machining of brittle materials.

Ultra-precision lapping of machinable ceramic Si3N4-BN by in-process electrolytic dressing

The machinable ceramic Si3N4-BN is a material which is increasingly being employed for automobile bearings and machinable ceramics. This material is very hard and has high resistance against volatile temperature and wear. It's efficient quality and accurate surfaces have always been of high demand for many applications in the industrial field. Besides, this material is varied by the percentage of BN contained in it, and the characteristics of lapping also varies according to this percentage of BN. Hence, in-process electrolytic dressing for ultra-precision lapping was introduced and used to experiment with the differing BN percentages in machinable ceramic Si3 N4. Metal-bonded super-abrasive diamond lapping wheels have superior qualities such as high bond strength, high stability and high machinability. The major problems encountered are wheel loading and glazing, which impedes the effectiveness of the cast-iron bonded diamond lapping wheel and, therefore, dressing should be considered. In this respect, in-process electrolytic dressing (IED) is proposed as an effective method regarding continuous protruding abrasives on the surface of wheels, whereby loading and glazing phenomena can apparently disappear. In this paper, the machining characteristics of machinable ceramic Si3N4-BN have been studied by adapting the IED lapping process in terms of the percentage of h-BN material.

A Study on the Optimization of Grinding Operation with Super Abrasive Wheel using Vibration Sound (1st Report)

This study deals with the optimization of grinding operation with super abrasive diamond wheels. In this paper, the developed equipment extracts the vibration sound of the wheel using the microphone. And, the discrimination of the quality of wheel conditioning, truing finished and of dressing interval is discussed based on signals obtained from vibration sound of diamond wheel. As a result, it is clarified to identify whether truing and dressing operations are completed or not, by detecting the sound pressure level at the specific frequency of the wheel. And, the sound pressure level at the specific frequency of the wheel can replace the evaluation for the cutting quality of the wheel.

Sintering study of the materials used in the manufacturing of diamond grinding wheels

The pencil edging diamond wheels used for lateral automotive glass grinding are composed of a mixture of metal powders (bond) and dispersed super-abrasive diamond grits (having a 100 μm average size). The metallic bond consists of a ductile alloy (sintered Ag+Cu+Ti powder mixture) and a hard skeleton (W and cast iron). The principal characteristics expected are a good wear resistance as well as a good cutting quality. In order to reproduce the industrial thermal cycle of the sintering manufacturing process in a traditional furnace, this cycle was simulated by dilatometric tests on green pellets of simplified metal powder mixtures. The aim was to determine the sintering behaviour of each component of the metallic bond.

Nano finish grinding of brittle materials using electrolytic in-process dressing (ELID) technique

Recent developments in grinding have opened up new avenues for finishing of hard and brittle materials with nano-surface finish, high tolerance and accuracy. Grinding with superabrasive wheels is an excellent way to produce ultraprecision surface finish. However, superabrasive diamond grits need higher bonding strength while grinding, which metal-bonded grinding wheels can offer. Truing and dressing of the wheels are major problems and they tend to glaze because of wheel loading. When grinding with superabrasive wheels, wheel loading can be avoided by dressing periodically to obtain continuous grinding. Electrolytic inprocess dressing (ELID) is the most suitable process for dressing metal-bonded grinding wheels during the grinding process. Nano-surface finish can be achieved only when chip removal is done at the atomic level. Recent developments of ductile mode machining of hard and brittle materials show that plastically deformed chip removal minimizes the subsurface damage of the workpiece. When chip deformation takes place in the ductile regime, a defect-free nano-surface is possible and it completely eliminates the polishing process. ELID is one of the processes used for atomic level metal removal and nano-surface finish. However, no proper and detailed studies have been carried out to clarify the fundamental characteristics for making this process a robust one. Consequently, an attempt has been made in this study to understand the fundamental characteristics of ELID grinding and their influence on surface finish.

A study on wear mechanism and wear reduction strategies in grinding wheels used for ELID grinding

Metal-bonded superabrasive diamond grinding wheels have superior qualities such as high bond strength, high stability and high grindability. The major problems encountered are wheel loading and glazing, which impedes the effectiveness of the grinding wheel. Electrolytic in-process dressing (ELID) is an effective method to dress the grinding wheel during grinding. The wear mechanism of metal-bonded grinding wheels dressed using ELID is different form the conventional grinding methods because the bond strength of the wheel-working surface is reduced by electrolysis. The reduction of bond strength reduces the grit-depth-of-cut and hence the surface finish is improved. The oxide layer formed on the surface of the grinding wheel experiences macrofracture at the end of wheel life while machining hard and brittle workpieces. When the wheel wear is dominated by macrofracture, the wheel-working surface is free from loaded chips and worn diamond grits. When the oxide layer is removed from the wheel surface, the electrical conductivity of the grinding wheel increases, and that stimulates electrolytic dressing. The conditions applied to the pulse current influence the amount of layer oxidizing from the grinding wheel surface. Longer pulse ‘on’ time increases the wheel wear. Shorter pulse ‘on’ time can be selected for a courser grit size wheel since that type of wheel needs high grinding efficiency. Equal pulse ‘on’ and ‘off’ time is desired for finer grit size wheels to obtain stable and ultraprecision surface finish.

Surface characteristics in the precision grinding of Mn–Zn ferrite with in-process electro-discharge dressing

Mn–Zn ferrite is used as a material of hard disk magnetic heads, but is difficult to grind because of its high hardness and brittleness. Therefore, a super-abrasive diamond wheel is used for the precision surface grinding of this material. However, the conventional dressing method cannot be applied to a super-abrasive diamond wheel. This study describes a newly proposed method for carrying out effective in-process electro-discharge dressing (IEDD) of a super-abrasive diamond wheel. Using IEDD, the surface roughness of Mn–Zn ferrite was improved, and the grinding force was reduced. IEDD is a good method to obtain efficient grinding and surface grinding of ferrite .

Precision Grinding of Mn-Zn Ferrite with In-Process Electro-Discharge Dressing

Ferrite is widely used as a material for magnetic heads for hard disks, but it is difficult to grind because its high hardness and brittleness. Therefore, a superabrasive diamond wheel is used for precision surface grinding of this material, However, the conventional dressing method cannot be applied to a superabrasive diamond wheel. This study describes a new method for carrying out effective in-process electro-discharge dressing (IEDD) of a superabrasive diamond wheel. Using IEDD, the surface roughness of the Mn-Zn ferrite was improved, and the grinding force was reduced. IEDD is a good method for obtaining efficient surface grinding of ferrite.

Surface characteristics on the ductile mode grinding of MgO single crystal with optimum inprocess electrolytic dressing system

MgO single crystal is widely used as a material of high-temperature resistance, but is difficult to grind because of brittleness and crack generation. Superabrasive diamond wheels are therefore required for ductile mode grinding of this material. This study describes a newly proposed optimum in-process electrolytic dressing system for carrying out effective dressing of superabrasive diamond wheels. Using this system the ground surfaces of MgO single crystals were improved, the grinding force was reduced and cracks were eliminated. In conclusion, this system enables efficient and ductile mode grinding to be obtained without cracking of MgO single crystals.