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Purpose: This study evaluated the shear bond strength of repaired new and old composite resin restorations after surface treatment with diamond bur, aluminum oxide jet, and Er:YAG laser, with the aim of developing a new ultraconservative technique to repair unsatisfactory composite resin restorations, Materials and Methods: Thirty-six hybrid composite resin blocks were made. The blocks were repaired with nanohybrid composite resin and then subjected to shear bond strength testing of the repair interfacial bond strength. ANOVA and the Tukey test were used at a significance level of 5%. Results: The highest average bond strength values were found when the old composite resin restorations were repaired with the diamond bur and the surface ablated with Er:YAG laser (2.15 W/cm²). Conclusion: The results of this study suggest that the Er:YAG laser system can be used effectively for composite resin repair. [ABSTRACT FROM AUTHOR]

The drilling response of impregnated diamond (ID) bits is controlled by processes involved in the rock fragmentation, and also the wear processes that continuously change the bearing surface of diamonds and bonding matrix. Due to the co-existence of these two processes both affecting the overall drilling response but differently based on drilling conditions (operating parameters, bit, rock and drilling fluid), the response of ID bits has been found inconsistent and difficult to interpret. In this paper, wear mechanisms of impregnated diamond bits are studied using a series of precise state of the art cutting and drilling experiments conducted with impregnated diamond bits and segments. The wear responses are decomposed into three phases of polishing, fracturing and sharpening, and the response in each phase is analyzed using interface laws in terms of depth of cut, and the extents of frictional contacts. The variation of the response at various operating parameters (weight on bit and depth of cut) are obtained and conceptual models characterizing the drilling response under both weight-on-bit and depth of cut conditions are presented. [ABSTRACT FROM AUTHOR]

Two high-temperature solid lubricants, CaF 2 and hBN, were added respectively into Fe-based impregnated diamond bit matrix to fabricate self-lubricating specimens of various lubricant contents by powder metallurgy method. Mechanical and tribological tests were performed on the specimens to investigate the relationship between specimen properties and lubricant content. The microstructure of the cross sections and the morphology of the worn surfaces of the specimens were analyzed using scanning electron microscopy (SEM). The results showed that the increase in solid lubricant content had a general weakening effect on the mechanical properties of the specimens, while such effect of CaF 2 was less significant than that of hBN. The hardness of CaF 2 specimens was found increasing slightly with CaF 2 content. Improved lubricity on the sliding surfaces was observed, while the wear resistance of the two specimens behaved differently. SEM analysis showed different microstructures of the two specimens, and improved wear condition for the CaF 2 specimen. However, the worn surface of the hBN specimen was found deteriorated. [ABSTRACT FROM AUTHOR]

The Scraping-wheel Diamond Bit is a new bit technology being put forward to solve the problems such as seriously uneven wear, thermal wear on the cutters of traditional diamond bits, especially PDC bits. The essential feature of this new technology is that the bit body is configured with rotational scraping-wheels with large angular deflection meanwhile the wheels are fixed with PDC compacts or other diamond cutters. When drilling in the formation, the scraping-wheel is driven to rotate slowly so that cutters thereon scrape the bottomhole rock successively rather than continuously. In this study, basic theory of geometry and kinematics of the Scraping-wheel Diamond Bit has been established, and variation law of wheel/bit speed ratio, tracks of cutters and main structure of the novel bit have been researched. Besides, an indoor simulated rock-breaking experiment for the Scraping-wheel Diamond Bit has been conducted, in which the influencing rule of the structure type and the structural parameters on cutters during the successive cutting process has been researched. Thus, significant experiment results, especially in the aspects of the variation law of wheel/bit speed ratio and the moving tracks of cutters, are achieved through this experiment, which not only proved the theory of geometry and kinematics of the novel bit, but also provided strong support for the rationality and feasibility of this new technology. [ABSTRACT FROM AUTHOR]

The great success and widespread use of impregnated diamond (ID) bits are due to their self-sharpening mechanism, which consists of a constant renewal of diamonds acting at the cutting face as the bit wears out. It is therefore important to keep this mechanism acting throughout the lifespan of the bit. Nonetheless, such a mechanism can be altered by the blunting of the bit that ultimately leads to a less than optimal drilling performance. For this reason, this paper aims at investigating the applicability of artificial intelligence-based techniques in order to monitor tool condition of ID bits, i.e. sharp or blunt, under laboratory conditions. Accordingly, topologically invariant tests are carried out with sharp and blunt bits conditions while recording acoustic emissions (AE) and measuring-while-drilling variables. The combined output of acoustic emission root-mean-square value (AE), depth of cut ( d), torque (tob) and weight-on-bit (wob) is then utilized to create two approaches in order to predict the wear state condition of the bits. One approach is based on the combination of the aforementioned variables and another on the specific energy of drilling. The two different approaches are assessed for classification performance with various pattern recognition algorithms, such as simple trees, support vector machines, k-nearest neighbour, boosted trees and artificial neural networks. In general, Acceptable pattern recognition rates were obtained, although the subset composed by AE and tob excels due to the high classification performances rates and fewer input variables. [ABSTRACT FROM AUTHOR]

In this study, the finite element and cohesive zone technique are used to analyse the failure mechanisms of impregnated diamond bits. The bit consists of diamond particles randomly distributed within a metal matrix. Investigations are carried out using a three-dimensional numerical model of a single diamond particle embedded in a metal matrix. This study is mainly focused on the interfacial debonding behaviour between the diamond particle and the matrix for an assessment of diamond retention capacity of these drilling bits. A zero thickness surface based cohesive zone modelling technique is used to simulate the failure at the interface. In order to validate the present model, few example problems are solved by the model and the results obtained are compared with the published results which show a good performance of the model. The effects of diamond particle shapes, orientations and the interface properties on the retention capacity of diamond particles in the bit are studied by conducting a parametric study. [ABSTRACT FROM AUTHOR]

The failure analysis of diamond impregnated bits, which are found as particulate composite materials consist of diamond particles randomly distributed within a metal matrix, is conducted to study the pull out behaviour of diamond grits for an assessment of diamond retention capacity of these drilling bits. The finite element technique is used to model the diamond-matrix system where a zero thickness surface based cohesive zone modelling technique is used to simulate the failure at the interface between the matrix and the diamond particle. For the validation of the model, few numerical examples are initially solved and the results produced by the model are compared with the published results which show a good performance of the model. Finally, a parametric study is conducted to show the effects of shapes, orientations and protrusions of diamond particles as well as interface properties on the retention capacity of diamond particles. [ABSTRACT FROM AUTHOR]

We studied the effects of sintering temperature on FeCuCo based pre-alloyed powder for diamond bits. The FeCuCo composite was fabricated by co-precipitation method. With the addition of tungsten carbide (WC), sintering under different temperatures was investigated. Mechanical properties of the FeCuCo based matrix were systematically studied. The structure of the composite was evaluated by X-ray diffraction (XRD) and scanning electron microscope (SEM) was used to analyze the surface of the powder and matrix. The suitable sintering temperature was determined through differential scanning calorimeter (DSC). Micro drilling experiments were performed, and 820 °C was identified to be the ideal sintering temperature, at which the matrix shows the best mechanical properties and drilling performance. [ABSTRACT FROM AUTHOR]

In many mining engineering applications such as prospecting, development, production and grouting, diamond bit drilling is widely used due to high penetration rate, core recovery and its ability to drill with less deviation. It has been well known that the operational parameters of diamond bit drilling are closely related with rock mass strength properties. One of the most widely discussed subjects in drilling is the possibility of using diamond drill bit operational parameters for preliminary estimation of rock mass strength and deformability properties used in many mining engineering design projects. Once such rock properties are estimated, it will be possible to make tactical planning decisions as mining progresses. In this study two different techniques, multiple regression and adaptive neuro-fuzzy inference system (ANFIS) were used to develop the models for preliminary estimation of rock mass strength. The variables used in the models are widely known and recorded operational parameters of diamond bit drilling such as bit load, bit rotation and penetration rate. To develop the models, a database covering the rock properties and the machine operational parameters collected from seven different drill holes in Turkey was constructed. Results indicate that both regression and ANFIS-based models can successfully be used to predict the rock mass strength. Adaptive neuro-fuzzy inference model exhibits better performance according to statistical performance indicators. By means of the developed models it is possible to estimate the strength of rock mass during drilling operation, especially in weak and highly fractured rock masses. The estimated strength parameters can be related to further mining engineering applications such as the assessment of excavatability, blast design and even mine design studies. [ABSTRACT FROM AUTHOR]

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Technology of rotary drilling with diamond bits requires expert knowledge and experience. Drilling modes i.e. combination of pressure on the bit, the rotational speed of the bit, and the quantity and quality of lavage has a decisive influence to achieve maximum drilling speed with minimum consumption drilling bits with diamonds. Optimal setting of the operating mode of technological parameters pressure force, speed and lavage is a fundamental prerequisite to achieving maximum productivity and overall streamlining of the drilling. When talking about the use of diamond bits the careful handling is necessary since assembly operations till drilling process. The shedding of diamonds from the cutting rim and related premature wear, destruction of the entire drilling tool results in inefficient drilling and high cost of labor and drilling tools. This paper deals with the dynamic faults of diamond core bits in drilling of selected rock. We analyze the causes and consequences of developing these faults. The frequency spectra of vibro-acoustic signal of drilling tool with water flush, without water flush, with the bit for drilling of the rock and without bit no-load are presented. Obtained knowledge about the failure causes contributes to the prediction of possible emergency conditions, to the prevention of the operating mode faulty setting. The paper points out possibilities for efficient use of the drilling process from both energetic and economic point of view. [ABSTRACT FROM AUTHOR]

A diamond drill bit is usually considered to be an inadequate seismic vibration source. To detect and use weak drillbit- generated seismic wavefields in hard-rock drilling, we compared different coherency measures between a conventional method of semblance and a generalized multiple signal classification (MUSIC) algorithm. We tested the detectability and resolution differences between semblance and MUSIC with synthetic examples. MUSIC coherency has the advantage of higher resolution over semblance measurement when the source wavefronts are accurately predicted. In addition, we applied both methods to detect the coherent moveout of a diamond drill-bit signal from a hard rock seismic-whiledrilling experiment at Hillside, South Australia. We used the coherent moveout to estimate the overburden velocity around the borehole.We also performed interferometry migration using the coherency measurements to image the drill-bit position. Our analysis determined that the direct waves generated from a diamond drill bit at shallow depths can be successfully detected, allowing drill-bit imaging and the determination of formation velocity around the borehole. [ABSTRACT FROM AUTHOR]

Abstract: In many mining, civil, and petroleum engineering applications diamond bit drilling is widely used due to high penetration rate, core recovery and its ability to drill with less deviation. Recently, many research have been conducted to estimate the penetration rate of diamond drilling which can be considered as one of the most important parameters in project planning and cost estimation of the operation. A database covering the rock properties and the machine operational parameters collected from seven different drilling sites in Turkey is constructed. Construction of an adaptive neuro-fuzzy inference system and the multiple regression models for predicting the penetration rate of diamond drilling is described. In the models, rock properties such as the uniaxial compressive strength, the rock quality designation, and the equipment operational parameters like bit load and bit rotation are considered. Although the prediction performance of multiple regression models is high, the adaptive neuro-fuzzy inference model exhibits better performance based on the comparison of performance indicators. By using the models, penetration rate of diamond bit drilling can be predicted effectively. [Copyright &y& Elsevier]

The article focuses on the research "Cost-Effective Ultralarge-Diameter Polycrystalline-Diamond-Compact (PDC)-Bit Drilling in Deepwater Gulf of Mexico." Topics include use of PDC drill bits on rotary-steerable-system (RSS) drilling assemblies for cost savings on drilling fluid, the success in drilling due to bottomhole-assembly (BHA) design, efficient operating parameters, and improved hydraulics, and discusses two case studies of British Petroleum on planning of thunder horse oil field.

Abstract: Bionics is a subject which can interact with many disciplines including the drilling engineering. On the basis of analyzing the properties of bionic non-smooth surface, the non-smooth theory is applied in the bit design to develop the bionic diamond bit. The dung beetle is selected as bionic prototype in this paper to design the working layer of an impregnated diamond bit, which makes the bottom surface always keep the same non-smooth shape and makes the bionic bit maintain a high penetration rate and long-life to underline their high efficiency, wear and resistance reduction properties. Tests show that the bionic bit improves the drilling speed and lifetime by 44% and 74%, respectively, compared with a common bit. In addition, the bionic non-smooth surface structure has an extensive application prospect in drilling engineering, due to its properties of wear, anti-sticking and resistance reduction. It can be applied to improve the wear performance of bit, pipe joint, cylinder liner and piston of mud pump, and to solve the bit balling and reduce the resistance of spiral drills and impact spearhead. [Copyright &y& Elsevier]

Abstract: Dental implants replace the damaged teeth, including the root, in a surgical procedure that begins with the drilling of the bone to create a hole of adequate dimension, before placing the implant. The temperature rise during drilling is a major factor, because overheating above 42–47 °C leads to tissue death and implant failure. Commercial steel drill bits are inefficient at low speeds and cause overheating at high speeds. To overcome these limitations, a novel CVD diamond coated tool is hereby presented consisting of a bilayer coating of micro/nanocrystalline diamond (MCD/NCD) on silicon nitride (Si3N4) ceramic drill bit. The hot filament CVD technique was employed for the diamond deposition, using H2/Ar/CH4 gas mixtures. For the drilling experiments a variable speed drill was coupled to a universal mechanical testing machine. A laminated test block formed by a solid rigid polyurethane foam with a 2 mm thick upper layer of E-Glass-filled epoxy sheet was used to simulate the human mandible and maxilla. The feed force, spindle speed and temperature rise during drilling, which are key parameters for the success of the implant, were monitored during the experiments. The spindle speed varied in the range 50 to 1400 rpm, and the infeed rate between 7.5 and 30 mm/min. The temperature oscillation during cutting was evaluated by two thermocouples placed in the polymer at different levels. By using the MCD/NCD bilayered coating it was possible to drill with significantly lower forces (fourfold smaller), lower rise in temperature (4 °C less), lower spindle speeds (100 rpm) and higher infeed rates (30 mm/min), when compared to the commercial steel (AISI 420) drill bit. [Copyright &y& Elsevier]

Abstract  A new diamond-hard alloy macrocomposite material consisting of diamond grits (0.5–0.8 mm or more in size) and a WC-Co matrix has been developed. The material is characterized by high mechanical properties of the matrix (the same as for WC-Co monolithic hard alloys) while diamonds remain completely intact (no graphitization or dissolution in cobalt melt). This process does not require superhigh pressures. Hard-alloy samples sintered beforehand in conditions that ensure the maximum mechanical properties (1450–1500°C, 30–60 min holding) are used as initial materials. Hollows (cells) or ditches of specific sizes (depth, width) are made in these samples with mechanical or electrophysical methods, and then diamond crystals (grits) commensurate with the hollows, cells, or ditches are placed in them. Vacuum infiltration (brazing) at moderate temperatures (900–1150°C) with adhesion-active alloys (or metallized diamonds) is the final stage in the formation of the composite. Therefore, strong adhesion-mechanical fixation of diamond grits in the hard-alloy matrix is ensured. The new material is efficiently used in diamond bits. [ABSTRACT FROM AUTHOR]

Diamond bit drilling is one of the most widely used and preferable drilling techniques because of its higher rate of penetration and core recovery in the hardest rocks, the ability to drill in any direction with less deviation, and the ability to drill with greater precision in coring and prospecting drilling. Conventional bit analysis techniques include mathematical methods such as specific energy and formation drillability. In this study, artificial neural network (ANN) analysis as opposed to conventional mathematical techniques is used to estimate major drilling parameters for diamond bit drilling, i.e., weight on bit, rotational speed, and bit type. The use of the proposed methodology is demonstrated using an ANN trained with information obtained from 45,000 m of diamond bit drilling operations conducted on several formations and locations in Turkey. The studied formations include shallow carbonates as well as sandstones in the Zonguldak hard coal basin. The neural network results are compared to those obtained from conventional methods such as specific energy analysis. It was observed that the proposed methodology provided satisfactory results both in relatively less documented and drilled formations as well as in well-known formations. [ABSTRACT FROM AUTHOR]

Discusses the results of a field trial on the use of disc bit, a technology for hard-rock drilling, at the GRI Catoosa Test Facility in Oklahoma. History of development of the disc-cutter technology; Geotechnical description of the Catoosa lithology; Comparison of performance between conventional insert tricone and polycrystalline diamond compact bits.

Examines the directional behavior of polycrystalline diamond compact (PDC) bits according to walk tendency and steerability. Bit design; Cutting structure of PDC bit; Lateral drillability; Effect of the back-rake angle of the PDC cutters on the steerability.

A new technique to measure wear and profile of impregnated diamond drill bit for mineral exploration is presented. A three-dimensional surface mapping of worn diamond drill bit surface is obtained by the laser triangulation method. With adequate algorithms all relevant data can be obtained. Consequently, the volume loss between two distances cored can easily be measured with a great precision. Moreover, computerized cross sections of the worn surface give relevant information about the profile resulting from the drilling process. [ABSTRACT FROM AUTHOR]

A drilling procedure for obtaining superconducting rings from top seeded melt grown samples is reported. The method described is based on the use of a column drilling machine with a copper–diamond drill bit. Modifications have been made in order to avoid structural damage to the superconductor during drilling. The success of the technique was assessed by measuring the critical current of samples before and after machining, with similar values obtained in both cases. [ABSTRACT FROM AUTHOR]

Introduces a series of articles about petroleum drilling and completion. Directional characteristics of polycrystalline diamond compact drill bits; Buckling of drill pipe and tubing in oilfields applications; Role of specialized reservoir drilling fluids in controlling formation damage; Horizontal well productivity; Reliability of electric submersible pump.