Diamond Cutting Research Articles

Theory and Experiment on Rock-Cutter Interfacial Friction and Rock Mohr-Coulomb Parameter Estimations

Summary The Mohr-Coulomb (M-C) failure criteria is by far the most widely used model for granular materials (including rocks and soils) in many geotechnical industries due to its simplicity. Its parameters are conventionally obtained by performing a series of pressurized triaxial compression tests (TCTs). The peak stress from each confining pressure is plotted at a single point as the maximum vs. the minimum principal stresses. The M-C parameters are obtained by the best linear fitting through the failure envelope formed by the peak stress points of interest. The TCT is time-consuming, costly, and destructive. Is there an experiment that can provide the failure envelope with one single test, even at the atmospheric pressure? This seems impossible, at least has never been rigorously reported. In this work, we present our finding of such a test. The paper first provides the experimental setup and the theoretical solution for a hemispherical scratch test of a polycrystalline diamond cutter (PDC) at low rate of cut (ROC) and low depth of cut (DOC); the theoretical characteristic response of the test is identified and validated. Next, the formula for the rock-cutter interfacial coefficient of friction (COF) is derived, which provides a theoretical guide for the friction measurement for shaped cutters. Then, the nominal average drag and thrust stresses are evaluated, which are observed experimentally and then proved theoretically to behave in a linear relation, analogous to the M-C envelope from the TCTs. We also provide a first method that can self-consistently evaluate the M-C parameters for the crushed zone, which plays a very important role in rock cutting. By comparing the M-C results for three rocks at different loading conditions, good agreements under different scratch conditions are made against the M-C parameters for several rocks from the TCTs.

Mechanism and characterization of laser-assisted hybrid processing for chemical vapor deposited diamond micro milling cutters

The fabrication of superhard micro milling cutters with extreme sharpness is highly demanded to meet the strict requirements of micro structures in terms of machining accuracy, surface roughness and burr height. In this study, nanosecond laser induced graphitization assisted grinding was proposed by considering machining efficiency and machining quality simultaneously for chemical vapor deposited (CVD) diamond micro flat-end milling cutters. An optimal cut-section was obtained by adopting moderate laser cutting energy and avoiding unstable thermodynamic coupling effect. The following laser induced graphitization mechanism on the cut-section was studied by analysing the different graphitization behaviours. The extensive graphitization caused sintered and banded graphite while the weak graphitization could not eliminate the defects caused by laser cutting. The uniform and dense graphitization resulted from appropriate energy distribution contributed to the smooth transition layer which was the significant factor in subsequent grinding. Moreover, the subsequent grinding behaviours of different transition layers were investigated, the grooved defects on transition layer caused the unstable grinding and fracture removal model, leading to the cracked ground surface and blunt cutting edge. Nevertheless, the grinding model of smooth transition layer was scratching without transcrystalline cracks, resulting in the smooth ground surface and sharp cutting edge. Thus, the laser parameters were finally optimized based on the feedback. Furthermore, the even graphitization, undamaged transition layer, scratching, as well as less material stress resulted in the extreme sharpness. In this way, the CVD diamond micro flat-end milling cutter (CVDM) with a diameter of 200 μm, surface roughness Sa of 30 nm, aspect ratio of 3, and edge radius of around 0.12 μm was prepared, the extreme sharpness was indicated by comparing with the edge radius of 1–5 μm reported heretofore. Finally, the micro grooves with surface roughness Sa of 17.8 nm and tiny burrs were machined on Ti-6Al-4 V by the homemade CVDM, which thereby indicated the outstanding cutting performance of the CVDM in micro-milling.

Development of a system for controlling a diamond drilling mode in terms of rock fault resistance

Relevance. Resistance to rock-cutting elements in rock destruction largely determines the effectiveness of drilling results. Information about the drag coefficient allows you to correctly and timely adjust the intensity of a drilling tool impact on the bottom of the well. To control the force contact of the drilling tool cutters with the bottom of the well, it is necessary to have a methodological apparatus that allows determining the rock destruction mechanism, taking into account the resistance forces. The existing methods for selecting combinations of diamond drilling mode parameters according to the known RPI index or according to the criterion of energy intensity of rock destruction N/vm , where N is the bottomhole power to overcome the resistance during rock destruction at the bottom hole; vm – mechanical drilling speed, have a number of disadvantages. They consist, for example, in occurrence of tool wear or the need to obtain a bottomhole power value in the current time mode, which is difficult under modern drilling conditions. Therefore, the study of rock resistance to destruction by a diamond cutter, based on application of the full factorial experiment method with obtaining mathematical models of factors and their graphical interpretation in combination with process control systems using computer technology in the current time mode, is a relevant topic. The disclosure of this topic will determine the direction of increasing technical and economic indicators of drilling. Aim. To develop a methodological apparatus that allows determining the mechanism of rock destruction taking into account the resistance forces to ensure optimal control of diamond drilling. Objects. Mechanism of rock resistance to destruction by a diamond cutter. Methods. Analysis, analytical research, full factorial experiment. Results. The paper presents an analytical analysis of the possibility of controlling drilling modes in order to achieve the greatest effect from drilling by estimating the drag coefficient as a function of the intensity of destruction or deepening per one revolution. Based on the analytical studies and the mode of drilling control by a computer in the real time mode, the authors have proposed a method for selecting the parameters of the drilling mode according to a given optimal value of the resistance index during drilling, and a way for its automatic implementation.

Enumerating Diamond Cuts

We present an algorithm for enumerating all possible faceting arrangements of dihedrally symmetric diamond cuts. We first separate the question into enumerating crowns and pavilions. In each case, the method involves enumerating all plausible graphs within a fundamental domain, and then checking for planarity and triconnectivity using the Tutte spring embedding. Such graphs can be lifted to three dimensional convex crowns or pavilions via the Maxwell-Cremona correspondence.

The Casting and Hot Forging of Low-Carbon Copper-Bearing Steel and Its Substructural Characterization

The casting of metal alloys followed by hot forging is a widely used manufacturing technology to produce a homogeneous microstructure. The combination of mechanical and thermal energy envisages the microstructural properties of metal alloys. In the present investigation, a metal alloy of composition 0.05C-1.52Cu-1.51Mn (in weight %) was cast in an induction furnace using a zirconia crucible. The melt pool was monitored using optical emission spectroscopy (OES) to maintain the desired composition. The as-cast block was then subjected to forging under a pneumatic hammer of 0.5 t capacity so that any casting defects were eliminated. The as-cast block was reheated to a temperature of 1050 °C and held at that temperature for 6 h to homogenize, followed by hammering with a 50% strain using a pneumatic hammer. The microhardness was calculated using a Vickers microhardness testing apparatus. The microstructure characterization of the processed alloy was carried out using an optical microscope, electron backscattered diffraction (EBSD), energy-dispersive X-ray spectroscopy (EDXA), and a transmission electron microscope (TEM). The sample for optical microscopy was cut using a diamond cutter grinding machine and surface polishing was carried out using emery paper. Further, mechanical polishing was performed to prepare the samples for EBSD using a TEGRAPOL polishing machine. The EBSD apparatus was operated at a 20 kV accelerating voltage, 25 mm from the gun, and with a 60 µ aperture size. HKL Technology Channel 5 Software was used for the post-processing of EBSD maps. The procedure of standard polishing for OES and TEM sample preparation was followed. Recrystallization envisages equiaxed grain formation in hot forging; hence, the strain-free grains were observed in the strained matrix. The lower distribution of recrystallized grains indicated that the driving force for recrystallization was not abundant enough to generate a fully recrystallized microstructure. The fractional distribution of the misorientation angle between 15 and 60° confirms the formation of grain boundaries (having a misorientation angle greater than 15°) and dislocations/subgrain/substructures (having a misorientation angle less than 15°). The fraction of misorientation angle distribution was higher between the angles 0.5 and 6.5°; afterwards, it decreased for higher angles. The substructure was observed in the vicinity of grain boundaries. The softening process released certain strains, but still, the dislocation was observed to be deposited mostly in the vicinity of grain boundaries and at the grain interior. The fine precipitates of the microalloying element copper were observed in the range of size in nanometers. However, the densities of these precipitates were limited and most of these precipitates were deposited at the grain interior. The microhardness of 210.8 Hv and mean subgrain size of 1.61 µ were observed the enhanced microhardness was due to the limited recrystallized grains and accumulation of dislocations/subgrain/substructures.

Effect of tool wear on machining quality in milling Cf/SiC composites with PCD tool

Carbon fiber reinforced silicon carbide ceramic matrix (Cf/SiC) composites have great application potential in aerospace. But their high hardness and anisotropy cause rapid tool wear during machining, which affects machining quality and efficiency. However, tool wear mechanisms in milling Cf/SiC composites are still unclear. There is a lack of research on the relationship between tool wear and cutting performance. In this paper, milling experiments on 2.5D Cf/SiC composites were conducted using polycrystalline diamond (PCD) cutters. The tool wear mechanisms and effect of tool wear on surface roughness, milling force, burr damage, surface microstructure and chips were explored. The results show that abrasive wear caused by chips continuously scraping tool material and diamond particle fragmentation and falling off caused by sprouting and expansion of cracks inside grain were primary causes of tool failure. The formation mechanism of burr damage was analyzed. It was proved that the peak radius of cutting edge Rpeak and flank wear VB could reflect cutting capabilities. It was found that increasing flank wear had regrinding effects on the cutting edge, which affects the peak radius. The degree of burr damage was related to these two parameters. Tool wear changed the surface formation mechanism. Before tool wear, carbon fibers were primarily removed through the micro-brittle fracture, with low surface roughness. The flank face and chips scratched the workpiece like abrasive grains after tool wear, leaving scratches on the surface and increasing surface roughness from 1.27 μm to 2.25 μm.

Cutting Power, Temperature, and Surface Roughness: A Multiple Target Assessment of Beech during Diamond Milling

Beech wood is a material commonly used for furniture, and cutting performance is the key to improving product quality and enterprise benefits. In this work, beech milling experiments using diamond cutters were carried out, and the changes in cutting power, temperature, and surface roughness were examined using the factor analysis method. The main results of this work are listed as follows: Firstly, a higher cutting speed and depth led to higher cutting power, temperature, and surface roughness. Meanwhile, cutting power and surface roughness were negatively related to the rake angle; however, cutting temperature first increased and then decreased with the increase in rake angle. Furthermore, cutting depth had greatest impact on the cutting power and surface roughness, followed by rake angle and cutting speed. Cutting speed had the greatest contribution to the cutting temperature, followed by cutting depth and rake angle. Only the cutting depth had a significant contribution to both cutting power, temperature, and surface roughness. Finally, optimal cutting parameters were determined to be a rake angle of 15°, cutting speed of 54 m/s, and depth of 0.5 mm. These values best meet the multiple objectives of lower cutting power, temperature, and surface roughness, which relate to superior product quality and enterprise benefits.

Effect of Low-Thermal Treatment on the Particle Size Distribution in Wood Dust after Milling.

The thermal treatment of wood can improve the appearance of the wood product's surface, its dimensional stability, and resistance to fungal attacks. However, the heat treatment changes the technological properties of wood, making it a new engineering material. This work investigates the effect of the low-thermal treatment of birch wood (Betula pendula Roth.), European beech wood (Fagus sylvatica L.), and alder wood (Alnus glutinosa L.) on the fine dust particles creation during woodworking. The samples of thermally treated wood with temperatures commonly used for the change of wood colour (105, 125, and 135 °C) were compared with reference samples made of natural wood. All 12 variants of the tested woods were milled using the 5-axis CNC machining center (20 mm diamond cutter, rotational speed 18,000 rev·min-1, the depth of cut 3 mm, feed rates of 2, 4 and 6 m∙min-1). A sieving analysis method allowed measuring the dust particle size distributions in all dust samples. The experiment's result analysis points out that wood type, thermal treatment, and feed rate meaningfully affect the size distribution of dust particles. Compared to birch wood and beech wood, the milling of alder wood samples created a much higher content of the finest dust particles, with particle sizes smaller than 0.032 mm. Increased temperatures in thermal treatment increase the share of fine dust particles with sizes smaller than 0.125 mm, compared to wood in its natural state. Milling with a lower feed rate (2 m·min-1) creates finer dust than processing with higher feed rates (4 and 6 m·min-1). Generally, the milling of alder in a natural or thermally treated state is a source of fine dust particles, particularly at low feed speed-rate milling, compared to birch and beech wood. In general, these results indicate that the low temperature thermal treatment parameters attribute new technological properties to all thermally modified types of wood tested.

Machining Properties of Stone‐Plastic Composite Based on an Empirically Validated Finite Element Method

High‐cutting performance is an essential metric for improving the suitability of materials for industrial applications. Herein, the machining properties of stone‐plastic composite are assessed through a finite element method to explore orthogonal cutting behavior by diamond cutters. The key aspects examined in this work are the effects of tool geometry and cutting parameters on the cutting force, temperature, chip formation, von Mises stress, and surface quality finish. Primary findings show that chip continuity increases proportionally with increase in rake angle but decreases with cutting speed and depth. Meanwhile, both cutting stability and surface quality are negatively correlated with cutting speed and depth but positively correlated with rake angle. These results support the adoption of cutting conditions using greater rake angle, higher cutting speed, and shallower cutting depth to obtain higher cutting performance, that is, greater cutting stability and surface quality in the finishing machining of stone‐plastic composites.

Novel technique to study the wet chemical etching response of multi-crystalline silicon wafers

The current work aimed to demonstrate the application of a technique where white light interferometry (WLI) and Laue X-ray crystallography scanner characterisation were combined to study the chemical etching response of diamond cut multi-crystalline Si (mc-Si) wafers. Using this technique, the effect of different texturing additives (isopropyl alcohol, natrium hypochlorite) was evaluated by examining the topography of the mc-Si surfaces before and after etching. The etching responses of monocrystalline Si wafers of (100), (110) and (111) orientations were used as reference for comparison with the multi-crystalline wafers investigated. The texturing results illustrated the influence of different crystal-orientations on the etching rate. It was revealed that for the mc-Si wafers, the etching speed of the different crystal grain-planes is increasing with their crystallographic similarity with the main (hkl) planes (100, 110,111). The comparison of isopropyl alcohol (IPA) and sodium hypochlorite (NaOCl) additives to KOH solutions showed that NaOCl additive is favourable for the polishing of mc-Si wafers, while IPA can be used as polishing only for crystal grains close to the (111) orientation.

Diamond Cuts Diamond: News Co-mention Momentum Spillover Prevails in China

Diamond Cuts Diamond: News Co-mention Momentum Spillover Prevails in China

Study on tool wear mechanism of single-crystal diamond in ultrasonic vibration elliptical cutting of tungsten heavy alloy

Tungsten heavy alloy has been widely used in the nuclear industry, military, and other fields due to its excellent material properties. In this paper, the wear of single crystal diamond tool and its influence on surface roughness were studied by ultrasonic elliptical vibration cutting experiment of tungsten heavy alloy and compared with conventional cutting. The experimental results show that under ultrasonic elliptical vibration cutting, the flank wear of a single crystal diamond cutter is reduced by 74.5%, and the retreat of the cutting edge is reduced by 70.6%. After the cutting experiment, the elements on the cutting surface, chip surface, and diamond tool adhesion were detected and analyzed by Raman spectroscopy and X-ray photoelectron spectroscopy. The results show that compared with conventional cutting, ultrasonic elliptical vibration cutting can effectively inhibit the graphitization of single-crystal diamond tools and avoid chemical wear. This is an essential reason why single-crystal diamond tools can be used for tungsten heavy alloy processing under ultrasonic elliptical vibration cutting.

Functional, antioxidant, and sensory properties of a ready‐to‐eat wheat flour snack incorporated with germinated legume flour

AbstractThe present study aimed to develop a protein‐rich product by increasing the nutritional properties of a ready‐to‐eat snack known as “diamond cuts.” Diamond cuts, also known as “papad,” is a crunchy savory snack of South and South‐East Asian countries, typically served between meals in India and Pakistan. In this research three legumes, namely, lentils (Lens culinaris), green gram (Vigna radiata), and black gram (Vigna mungo) were sprouted in a jute bag for 24 h. These were ground to form legume flour and were then used in the preparation of diamond cuts. These products were analyzed for moisture content, percentage expansion, pH, textural characteristics, oil content, peroxide value, total phenolic content, total antioxidant capacity, and sensory characteristics. The results showed that diamond cuts containing germinated lentils, green gram, and black gram containing to have higher total phenolic content (2.29 and 1.25 mg/100 g, respectively) and antioxidant activity (90%, 87%, and 84%, respectively) with improved moisture content. It was also observed that diamond cuts with germinated legumes exhibited significantly harder texture compared to their non‐germinated counterparts. Also, oil uptake was positively correlated to moisture loss is an important parameter in characterizing the physical properties of fried products. In terms of overall acceptability, all germinated fried snacks were liked significantly higher 7.4 than the snacks containing non‐germinated legumes. From the results of sensory evaluation, it is concluded that the incorporation of germinated legumes in diamond cuts would give acceptable color, flavor, and appearance. Therefore, diamond cuts supplemented with germinated legumes could improve the textural, sensory, and nutritional properties of the product.

Numerical Analysis of Dynamic Properties of an Auxetic Structure with Rotating Squares with Holes.

In this paper, a novel auxetic structure with rotating squares with holes is investigated. The unit cell of the structure consists of four units in the shape of a square with cut corners and holes. Finally, the structure represents a kind of modified auxetic structure made of rotating squares with holes or sheets of material with regularly arranged diamond and square cuts. Effective and dynamic properties of these structures depend on geometrical properties of the structure. The structures are characterized by an effective Poisson's ratio from negative to positive values (from about minus one to about plus one). Numerical analysis is made for different geometrical features of the unit cells. The simulations enabled the determination of the dynamic characteristic of the analyzed structures using vibration transmission loss, transmissibility, and mechanical impedance. Numerical calculations were conducted using the finite element method. In the analyzed cases of cellular auxetic structures, a linear elasticity model of the material is assumed. The dynamic characteristic of modified rotating square structures is strongly dependent not only on frequency. The dynamic behavior could also be enhanced by adjusting the geometric parameter of the structure. Auxetic and non-auxetic structures show different static and dynamic properties. The dynamic properties of the analyzed structures were examined in order to determine the frequency ranges of dynamic loads for which the values of mechanical impedance and transmissibility are appropriate.

Effects of cutting speed and fiber orientation on tool wear and machining quality in milling CFRP with PCD cutter

Milling carbon fiber reinforced polymer (CFRP) composites faces significant challenges, such as rapid tool wear leading to machining damage, even for a polycrystalline diamond (PCD) cutter. However, the effects of the milling conditions on the tool wear of PCD cutters remain unclear. This study investigated the effects of the cutting speed and fiber orientation on the tool wear of a PCD cutter and the corresponding machining quality in milling CFRP. These effects were analyzed by considering fiber and cutter interactions, and milling experiments with a PCD cutter were conducted for validation based on the analyses of cutting-edge profiles, cutting forces, burr area, and machined surface of CFRP. The worn cutting edge profiles were found to be elliptical in shape for cutting CFRP in different fiber orientations owing to the more severe wear on the flank face and cutting edge. Tool wear decreased with increasing cutting speed under a consistent feed per tooth, which further led to a reduction in the cutting force, burr area, and surface roughness. In addition, the maximum and minimum variations of worn cutting edge profiles were found in the cutting of 45° and 135° CFRP, respectively, suggesting that frequently changing the tool working position at 45° could suppress burr damage and increase tool life.

Jazz Feminism is to Soul as Purple is to Lavender

Jazz Feminism is to <i>Soul</i> as Purple is to Lavender

Fabrication of a diffractive optical element by the precision diamond micro-turning method

The paper considers the manufacturing process of a diffractive optical element by precision diamond micro-turning using a diffractive lens as an example. The process consists of a preparatory stage and the stage of manufacturing a given diffractive element on specialized equipment with computer program control. The preparatory stage includes selection of a special diamond cutter with a response offset of the cutter angle relative to the calculated microstructure of the diffractive element, the preparation and manufacture of the necessary equipment, including fasteners, with the help of which the optical part is installed and adjusted, on the surface of which a diffractive lens is formed. After that, the specified values of the parameters of the lens zones, the values of the parameters of the diamond cutter are entered into the computer software, and the process of manufacturing a diffractive lens is started.

Preventive measures to fight with COVID-19 through environmental parameters with the help of Ayurveda: A literary research article

COVID-19 is an emerging virus of now-a-days which causes severe lung infection. This mutated virus is very contagious in nature. Ayurveda since ancient times is serving humanity in a positive way. Rasa Shastra (pharmaceutics) is the branch of Ayurveda which deals with the manufacturing of different types of Aushadhies (medicines). By the process of Shodhana (purification) , Marana (incineration) and Moorchhna (manufacturing) along with the help of cow dung cakes , many medicines are prepared. There are a lots of complicated and untreatable diseases which are possible to treat with the help of Rasa Shastra a branch of Ayurveda.There are many more processes by which diseases are treated indirectly by killing microorganisms outside the body of the host. This article is an attempt in a same way for dealing with the present threat of pandemic. According to the popular proverb “Diamond Cuts Diamond”, this animal virus can be controlled by another animal antidote. In old sacred religious books importance of almost every animal is described. New generations must follow the instructions given by the ancient sages in all the said ways to stay healthy.

Wear mechanism and quantification of polycrystalline diamond milling cutter in high speed trimming of carbon fiber reinforced epoxy

The use of polycrystalline diamond cutters (PCD) in machining of composite material is increasing. Understanding their wear mechanism and clarity on wear measurement methodology will lead to their productive usage and cost justification. This study focuses on understanding wear in PCD milling cutters at the micro, macro level, and its physical characterization when employed for fibrous composite machining. This leads to the development of a proposal for a clear methodology on consistent wear measurement, which includes a suitable selection of techniques and identification of wear parameters. Continuous diamond skeleton structure made during binder infiltration is captured in worn out PCD edge with the help of scanning electron microscopy. Overall wear process appears to be a complex mixture of losing binder, smaller grains, and pieces of continuous diamond skeleton. This results in cavities of various shapes and forms on the cutting edge making substantial variations in edge recession and edge width. After analyzing, different tool parameters, it was found out that the distance from apex to edge roundness of clearance or rake face is a reliable and repeatable wear parameter. These are shown to be comparable between different wear locations, flutes, and tools suggesting higher wear predictive capabilities. Among different techniques, three-dimensional high-resolution profile scanning of the cutter has been identified as the most efficient tool for tracking wear at regular intervals in tool life prediction studies.

Intense Cooling during Composite Rock Breaking of High-Pressure CO2 Jet-Polycrystalline Diamond Cutter

SummaryIn deep well drilling, rock breaking has some problems, such as low rock breaking efficiency, serious thermal wear of cutters, short service life, and high cost. It is noticed that the application of CO2 drilling fluid in the oil and gas underbalanced drilling is an efficient approach to achieve the reduction of CO2 emissions. Thus, based on the rock-breaking advantages of CO2 jetting, a new rock-breaking method of combing high-pressure CO2 jet and polycrystalline diamond cutter (PDC) is proposed in our study. The cooling mechanism and influencing during rock breaking by using the high-pressure CO2 jet-PDC are conducted. With the test system during composite rock breaking of the high-pressure CO2 jet-PDC, the composite rock-breaking experiment of the high-pressure CO2 jet-PDC was carried out. In the experiment, the comparison of the CO2 jet, N2 jet, water jet, and without a jet was conducted and analyzed. And based on the numerical simulation analysis, the intense cooling mechanism was expounded. In the process during composite rock breaking of the high-pressure CO2 jet-PDC, the intense cooling mechanism was mainly attributed to three main reasons: the thermal effect of the jet flow, the expansion endothermic effect of the jetted flow, and the phase transformation cooling effect of the CO2 jet. The effects of rock samples, jet temperatures, jet flow pressures, and rock temperatures on the cutting temperature were experimentally explored, and finally, the intense cooling rules of composite rock breaking were obtained. The experimental results showed that the CO2 jet had a stronger cooling effect on granite than that of the sandstone. In a certain range, jet pressure was positively correlated with the cutting temperature, whereas jet temperature and heating time were negatively correlated with cutting temperature. The study provides the theoretical support for the CO2 application as a drilling medium in underbalanced drilling.