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In the interest of developing a comprehensive understanding of the drilling process using the hole saw tool, this article aims to build a three-dimensional (3D) micromechanical model representing the orthogonal cutting of CFRP using one tooth of the hole saw tool. For this purpose, a finite element model is developed using Abaqus Explicit code. The influence of various drilling parameters like rake angle, inclination angle and cutting-edge radius on the drilling quality is explored. Especially, chip formation mechanisms, cutting force and lateral damage are analyzed. Through finite element simulations and computational analyses, it is found that these outputs results are highly influenced by drilling parameters. When the fiber orientation angle is set to 0°, increasing the rake angle results in a change in the chip formation mechanism from buckling to bending. In contrast, with a fiber orientation angle of 90°, bending and shear governs the chip formation process, irrespective of the rake angle. In both cases, whether the fiber orientation angle is 0° or 90°, chips tend to fragment more favorably with increasing the inclination angle. Regarding the cutting-edge radius, when the fiber orientation angle is 0°, an increase in the cutting-edge radius leads to a transition in the chip-forming mechanism from buckling to bending. However, for a fiber orientation angle of 90°, the chip formation remains governed by bending even as the cutting-edge radius changes. Decreasing the rake angle, the inclination angle, and the cutting-edge radius contribute to a reduction of the cutting force. As the inclination angle and the cutting-edge radius increase, the lateral damage increases, while the rake angle has showed a negligible impact on the damage. These results provide a guidance on the appropriate hole saw tool parameters for a good drilling quality namely, a rake angle of 20°, an inclination angle of 5° and a cutting-edge radius of 0.03 mm. [ABSTRACT FROM AUTHOR]

Objective of current study is to examine the machining characteristics of Al6082 composites embedded with multi-walled carbon nanotubes (MWCNTs). Herein, chemical vapor deposition (CVD) technique was used to develop MWCNTs. Stir-squeeze casting method was used to develop 0.3 wt.%−1.2 wt.% MWCNTs/Al6082 composites. Morphology of MWCNTs was analyzed by field emission scanning electron microscopy (FESEM). FESEM analysis was performed for as-cast nanocomposites which showed uniform spreading of MWCNTs up to 0.9 wt.% and beyond that clusters of MWCNTs were observed. Hardness and tensile strength of nanocomposites were also measured to observe the impact of addition of MWCNTs. Al6082 composites reinforced with 0.9 wt.% of MWCNTs showed highest hardness and tensile strength. It is important to examine the drilling characteristics as CNT in tube form may become constraint if they are not uniformly distributed and may obstruct tool movement. CNC electric discharge machining (EDM) and CNC milling machine were used to perform the drilling operation on nanocomposites with varying cutting parameters. It was noticed that inclusion of MWCNTs enhanced material removal rate (MRR) and surface finish of composites owing to enhanced brittleness. Strong interfacial bonding between MWCNTs and Al6082 matrix reduced the delamination during drilling operation. [ABSTRACT FROM AUTHOR]

One of the major factors impacting on drill bit performance during rock drilling is interface temperature. The performance of the drill bit during drilling operations not only depends on operations parameters but also the properties of rock during drilling in laboratory and field investigations. Hence the present study focused on interface of bit-rock, the temperature had been determined by developing a specially grounded thermocouple. Over 500 different test conditions were performed in each rock sample's case during experimental drilling on a cylindrical block of UCS of 17.83 MPa (fine-grained sandstone grey-FG), 13.70 MPa (medium-grained sandstone-MG), and 51.67 MPa (fine-grained sandstone pink-FGP). The results revealed that the average increase in interface temperature for MG is about 53.74%, FG is about 93.26%, and FGP is about 165.22%. The significant parameters such as uniaxial compressive strength (26%), depth (33%), rate of penetration (15.2%), diameter of the bit (5.26%), and thrust (5.04%) are the most influenced parameters on temperature, followed by spindle speed (1.04%), and torque (0.23%) respectively. The proposed regression models successfully predict the temperature with an R2 value of 91.74%, 90.30%, and 90.95% for MG, FG, and FGP, respectively. Finally overall regression model is developed by considered operational parameters with rock properties to predict temperature and R2 value of 80.8% for all three types of rock samples considered. [ABSTRACT FROM AUTHOR]

The development of oil and gas infrastructure requires the development of new fields or the renewal of existing ones, which are mainly located in complex mining and geological conditions. Drilling intervals with abnormal formation pressures can cause a number of complications during cementing and subsequent well operation. The most common problem is inter-column pressures and cross-flow between formations. Gas migration may occur due to the fact that the mud has not been completely replaced by the cement slurry during cementing, and therefore there is no adhesion in the rock-cement contact zone. Understanding the process formation of cement slurry structural and rheological properties can reduce the risk of this problem and increase the casing anchoring efficiency. The study reveals that the rheological model of the same slurry can vary depending on various factors (temperature, water-cement ratio, cement slurry additives). Comparative results of laboratory studies on the effect of different concentrations of filtration loss reducer (FLR) from 0.1 to 0.5% and temperature in cement slurry are presented. As a result, the optimum concentration of FLR is selected, the range of which is from 0.2 to 0.3%. The analysis revealed that the accuracy of calculation of rheological parameters using the least squares method is higher than the industry standard. The deviation of numerical values of rheological model coefficients ranges from 7 to 60%. The approximation quality is assessed based on the sum calculation of the squared deviations. [ABSTRACT FROM AUTHOR]

Basalt fiber reinforced polybutylene succinate (BFPBS) composite offer competitive solutions for medium load applications but face significant drilling challenges. Present study seeks to perform an exhaustive machinability analysis and optimize pivotal drilling variables, to mitigate delamination and enhance machining efficacy in BFPBS laminates. Experimental exploration involved three distinct drill geometries: an 8 mm twist drill and two modified step drills, facilitating scrutiny of pilot diameter's impact on drilling behavior. Mapping force signals, morphological analysis, chip formation investigation, and specific cutting energy calculation were conducted to deepen comprehension of BFPBS machinability. Modified step drill showed superior performance with lower thrust force and torque. Feed rate primarily affected thrust force, whereas tool geometry notably influenced exit delamination. Multiple linear regression models enabled Genetic Algorithm optimization, revealing Pareto optimal sets balancing thrust, torque, and delamination. Step drills show potential for reduced energy use and improved efficiency in BFPBS composite machining, benefiting various industries. [ABSTRACT FROM AUTHOR]

Studying the drilling of a hybrid jute/palm composite material offers significant contributions to sustainable material development. Incorporating renewable jute and palm fibers represents an innovative, eco-friendly approach compared to synthetic composites. This research aims to optimize drilling parameters to reduce defects and evaluate the performance of different drilling tools, crucial for industrial applications. Drilling is performed via three different types of drills bit: High-Speed Steel, HSS-Co5 coated high-speed steel with 5% cobalt, and carbide. The drilling process involves adjusting the feed and rotational speed. Response Surface Methodology (RSM) was used to select drilling settings by validating experimentally obtained data and predicting the behavior of the structure based on cutting circumstances. The findings indicated that the most effective cutting parameters for minimizing delamination are achieved using the HSS drill bit, namely at lower feed and rotational speeds. Delamination remains below the threshold of 1.106 when the feed is 0.04 mm/rev and the rotational speed is 1592 rpm. The analysis of the results obtained using the response surface methodology indicates that the R2 coefficient for cylindricity is 0.96%. In contrast, the rate of delamination is 0.79% and the rate of circularity is 0.89%. [ABSTRACT FROM AUTHOR]

Coal is currently the most important energy source in most countries. With the advent of information intelligence, more and more intelligent technologies are being applied in coal mine detection. A new model for coal mine drilling detection, which combines improved YOLOv5 and Gaussian filtering, is proposed to address the low efficiency and poor accuracy in manual detection of coal mine drilling. This new model incorporates attention mechanism and multi-object detection model on the basis of traditional YOLOv5. Due to factors such as equipment vibration and electrical interference in drilling detection, random noise is often mixed into the image signal data obtained. In order to effectively reduce the impact of noise on data and improve signal-to-noise ratio, Gaussian filtering method is studied for data denoising. This new model's border regression loss value was 0.004 lower than the YOLOv5 loss value. This new optimization method's accuracy was improved from 0.966 to 0.982. This new model improved the detection accuracy of small cracks by about 0.05. The detection depth of the coal seam in this new model was 9.54 m, which was closer to the true value than other methods. Therefore, using the new model to detect coal mine boreholes can effectively improve the accuracy of borehole detection images, which has a good effect on the analysis of coal mine rock layers. This new model has a good guiding role in the detection images and rock analysis research of future coal mine boreholes. The research has good research value in oil drilling inspection, natural gas pipeline monitoring, and quality inspection of industrial automation systems. This provides important technical support for future coal mine drilling image detection and rock analysis research. [ABSTRACT FROM AUTHOR]

The present study focuses on the elimination of delamination during the drilling of a linen-based biocomposite material in epoxy resin used for the manufacture of sports kayaks, depending on the tool material, cutting conditions, and the use of additional wooden support plates. In the present study, HSS (high-speed steel) and Carbide cutting tools without coatings, with the same geometry and two types of cutting conditions (n = 1500 rpm, fn = 0.05 and 0.1 mm/rev) were used. A Sololite-type wooden backing plate was used to aid in reducing delamination. The results show that the additional support plates significantly reduced delamination by up to 80% both at the material inlet and especially at the drill hole outlet. In this study, the use of a lower feed rate (fn = 0.05 mm/rev) per tooth was shown to have a significant effect on reducing the delamination of biocomposite materials with flax fibers, which are generally known to be difficult to machine. The Carbide cutting tool shows significantly better results both in terms of its wear and in terms of delamination of the biocomposite material. The highest delamination was obtained without the use of a backing board at the tool exit after 50 drilled holes of 3509 µm. With the use of a backing board, this delamination decreased to 693 µm after 50 drilled holes. [ABSTRACT FROM AUTHOR]

Thin-walled carbon/carbon (C/C) composites are a typical difficult-to-machine material due to the characteristics of thin walls, low stiffness, and high strength. In this paper, three ultrasonic-assisted machining methods and surface morphology of C/C composite thin-walled small holes were studied. The influence of machining parameters on average axial force and hole surface morphology was explored by single-factor experiments and orthogonal experiments. A quantitative comparison was conducted to evaluate the machining defects of drilling, reaming, and grinding. The results of single-factor experiments showed that the surface quality of drilling initially improved and then deteriorated with the increase of spindle speed. Additionally, increasing feed rate resulted in a deterioration in surface quality, while increasing amplitude to a certain extent led to an improvement. In orthogonal experiments, the effect of ultrasonic amplitude on the average axial force of reaming and grinding was greater than that of drilling. In terms of surface quality, the minimum evaluation factor Qc of the grinding, reaming, and drilling could reach 1.0137, 1.0198, and 1.0253, respectively. Further optimized by a multivariate optimization function, the optimal parameters of grinding were obtained as the speed of 6200 r/min, feed rate of 40 mm/min, and amplitude of 8 μm and the minimum values of Qc could reach 1.0128. [ABSTRACT FROM AUTHOR]

Due to their excellent properties and low manufacturing costs, SiC particle-reinforced Al matrix composites (SiCp/Al) find extensive application in automobile manufacturing and aerospace. However, SiCp/Al is less machinable. The ultrasonic-assisted drilling (UAD) decreases tool wear and enhances the quality of drilled holes when compared to conventional machining techniques. This paper investigates the effect of drilling temperature variations induced by processing conditions on the degree of softening of the base material during UAD of SiCp/Al. It also analyses the mechanism of how drilling temperature affects the quality of the holes made from the perspective of matrix softening. The study demonstrates a regularity in the impact of spindle speed, ultrasonic supply voltage(ultrasonic vibration amplitude), and feed rate as a function of drilling temperature. The effects of temperature changes caused by each of these factors on import/export edge defects, surface scratches on the hole wall, and tool machinability vary. [ABSTRACT FROM AUTHOR]

Polycrystalline diamond (PCD) is widely used for micro tools due to its high hardness and wear resistance. However, micro PCD tools face challenges in machining with high accuracy and efficiency. Therefore, electrical discharge machining grinding (EDM-grinding) composite machining was proposed. The effects of pulse discharge parameters on surface quality and microhole drilling performance of PCD tool were investigated. The results show that the surface roughness of helix flute and flank face of the fabricated PCD tool were 0.125 µm and 0.158 µm, respectively, as well as the inner wall roughness achieved 0.331 µm after drilling of microhole. The average current displayed a greater effect on the machining quality of PCD tools, with tool breakage in excessive average current. The preferred pulse discharge parameters were determined as an open-circuit voltage of 95 V, an average current of 1400 mA, a pulse width of 400 ns, and a pulse interval of 2000 ns. [ABSTRACT FROM AUTHOR]

The section of bamboo eaten by bamboo rats is smooth and clean, which is due to the unique lower front teeth of bamboo rats. Based on this, a new tool was designed to reduce the defects in CFRP processing. The new bionic tool with a diameter of 6 mm is compared with the existing dovetail and fine-tooth tool and the new bionic tool with a diameter of 12 mm. The results indicate that, compared to the dovetail-fine-tooth tool, the biomimetic tool exhibits smaller axial forces and layering factors, with a slower defect formation rate. The biomimetic tool shows a significant inhibitory effect on defect formation, and larger diameter tools achieve better machining results. [ABSTRACT FROM AUTHOR]

This paper aims to quantitatively analyze the relationship between forces acting on the tool tip and tool movement during drilling operations. The study encompasses axial and lateral vibrations superimposed on the nominal tool movement, arising from rigid body motion (rotational and axial velocities). Specifically, only forces attributed to the cutting process are considered, excluding considerations of indentation forces around the chisel edge. The research adopts a generalized approach, spanning from tool measurements to establishing the force model. The investigation involves measuring cutting forces and correlating them with the varying rake and inclination angles of the drill's cutting edges. An analytical model is proposed to describe the distribution of all local force components along drill edges, considering the evolution of forces and geometry. The dynamic coefficient matrix is evaluated by using the identified cutting coefficient and tool geometry. Validation of the proposed methodology is demonstrated through drilling experiments on Ti6Al4V alloy, utilizing three solid carbide drills with distinct geometries. The proposed procedure allows complete identification of the dynamic characteristics from the measurements taken at the entrance stage of hole drilling operation. Moreover, the influence of tool geometry on cutting coefficients and dynamic coefficient matrices are discussed. • A novel method is developed to achieve minimized experimental effort to identify cutting coefficients in drilling process. • Experiments with industrially relevant tools validated the accurate predictions of transient drilling axial force and torque. • The method is extended to inversely obtain the dynamic coefficient matrix, for the first time, from experimentally measured forces. • Effects of geometry and dynamic interactions were demonstrated using three solid carbide drills with distinct geometries. [ABSTRACT FROM AUTHOR]

The rig state plays a crucial role in recognizing the operations carried out by the drilling crew and quantifying Invisible Lost Time (ILT). This lost time, often challenging to assess and report manually in daily reports, results in delays to the scheduled timeline. In this paper, the Naive Bayes algorithm was used to establish a novel rig state. Training data, consisting of a large set of rules, was generated based on drilling experts' recommendations. This dataset was then employed to build a Naive Bayes classifier capable of emulating the cognitive processes of skilled drilling engineers and accurately recognizing the actual drilling operation from surface data. The developed model was used to process high-frequency drilling data collected from three wells, aiming to derive the Key Performance Indicators (KPIs) related to each drilling crew's efficiency and quantify the ILT during the drilling connections. The obtained results revealed that the established rig state excelled in automatically recognizing drilling operations, achieving a high success rate of 99.747%. The findings of this study offer valuable insights for drillers and rig supervisors, enabling real-time visual assessment of efficiency and prompt intervention to reduce ILT. [ABSTRACT FROM AUTHOR]

Many factors (material properties, drill bit type and size, drill bit wear, drilling parameters used, and machine-tool characteristics) affect the efficiency of the drilling process, which could be quantified through the delamination factor, thrust force, and drilling torque. To find the optimal combination among the factors that affect the desired responses during drilling of wood-based composites, various modelling techniques could be applied. In this work, an artificial neural network (ANN) and response surface methodology (RSM) were applied to predict and optimize the delamination factor at the inlet and outlet, thrust force, and drilling torque during drilling of prelaminated particleboards, medium- density fiberboard (MDF), and plywood. The artificial neural networks were used to design four models—one for each analyzed response. The coefficient of determination (R2) during the validation phase of designed ANN models was among 0.39 and 0.96. The response surface methodology was involved to reveal the individual influence of analyzed factors on the drilling process and also to figure out the optimum combination of factors. The regression equations obtained an R2 among 0.88 and 0.99. The material type affects mostly the delamination factor. The thrust force is mostly influenced by the drill type. The chipload has a significant effect on the drilling torque. A twist drill with a tip angle equal to 30° and a chipload of 0.1 mm/rev. could be used to efficiently drill the analyzed wood-based composites. [ABSTRACT FROM AUTHOR]

Predicting the rate of penetration (ROP) is important for optimizing drilling parameters, improving drilling efficiency, and optimizing economic benefits throughout the drilling process. The current prediction model of ROP based on machine learning algorithms does not consider the interference of outliers. Therefore, in this study, we propose a method to predict ROP based on fuzzy support vector regression (FSVR). First, appropriate input parameters were selected from the controllable parameters. Second, based on the local outlier factor, a fuzzy membership degree was assigned to each sample. Finally, the sample with the fuzzy membership value was input into the model for ROP prediction. The results demonstrated that the goodness of fit (R2) of the improved FSVR model is 0.9634, and the mean absolute error is 0.1974. Compared with standard SVR and other models, the improved FSVR model has a stronger anti-interference ability, smaller prediction error for normal samples, and higher accuracy. [ABSTRACT FROM AUTHOR]

Due to excellent mechanical and metallurgical properties, metal matrix composites (MMCs) are in high demand for numerous engineering applications across multiple industrial sectors. However, presence of reinforcement particles in MMCs adversely affects their machinability leading to increased tool wear and cutting force requirement. To simultaneously achieve better product quality and higher tool life, there is a need to determine the optimal values for various drilling parameters affecting those characteristics. This paper proposes application of the Combined Compromise Solution (CoCoSo) method in five different fuzzy environments for solving the parametric optimization problems of two aluminium MMC (Al-MMC) drilling processes. Fuzzy CoCoSo, intuitionistic fuzzy CoCoSo, Pythagorean fuzzy CoCoSo, neutrosophic fuzzy CoCoSo and hesitant fuzzy CoCoSo are applied to search out the optimal combinations of the input parameters for the considered Al-MMC drilling operations. For the first Al-MMC drilling process, all the five approaches recommend higher helix angle = 40°, moderate spindle speed = 500 rpm and lower feed rate = 0.1 mm/rev as the optimal combination to simultaneously optimize surface roughness, cutting force and drilling temperature. Furthermore, a similar trend is also observed in the results of the second Al-MMC drilling process, where all these methods propose relatively moderate spindle speed = 2000 rpm and lower feed rate = 50 mm/min along with 3% mica reinforcement and a polycrystalline diamond drilling tip to achieve the best drilling performance. Finally, the results are compared with those achieved using the standalone CoCoSo and other fuzzy-based approaches. It is observed that CoCoSo method can effectively determine the optimal parametric combinations and the results are quite consistent throughout all the fuzzy environments under consideration. Furthermore, the fuzzy CoCoSo approaches can effectively deal with the subjectivity in opinions of the decision makers (stakeholders) while assigning relative importance to the responses according to their requirements. [ABSTRACT FROM AUTHOR]

This paper presents parametric analysis and optimization of a drilling operation on hybrid aluminium metal matrix composites (Al-MMCs), consisting of Al 7075 as the base material, and 2% SiC and 2.5% (fly ash + bagasse ash) as the reinforcements. Based on Taguchi's orthogonal array, 27 experiments are conducted, and the main effects and interaction effects of spindle speed, feed rate and drill diameter on material removal rate (MRR), delamination factor and conicity of the machined holes are studied. It is noticed that higher values of all the three drilling parameters would result in higher MRR. On the other hand, lower delamination damage can be achieved at lower values of spindle speed and feed rate, and moderate drill diameter. Lower spindle speed and drill diameter, and moderate feed rate are responsible for minimum conicity. This paper proposes application of two recently developed multi-criteria decision making (MCDM) tools, i.e. ranking alternatives by median similarity (RAMS) and ranking alternatives by trace to median index (RATMI) to solve the corresponding multi-objective parametric optimization problem of the said drilling operation. It can be interestingly noted that both these approaches identify the optimal parametric combination as spindle speed = 170 rpm, feed rate = 41 mm/min and drill diameter = 10 mm yielding maximum MRR of 7.473 g/min, and minimum delamination and conicity of 1.0416 and 0.00002 respectively. The metallurgical characterization of the developed hybrid Al-MMCs is also performed with the help of scanning electron microscopic images which show good bonding between the matrix and the reinforcement particles. It is noticed that the average hardness of Al-MMCs increases with addition of SiC + flyash + bagasse ash as the reinforcement particles. A comparative analysis of the derived results against other popular MCDM tools proves the efficacy of RAMS and RATMI methods in optimizing the considered drilling operation on the hybrid Al-MMCs. [ABSTRACT FROM AUTHOR]

Composite materials are utilized in various industries due to their advantageous properties. Drilling is a crucial process for joining these materials to construct the structures. During the drilling of composite materials, several types of defect can occur, with delamination being the most prevalent. Delamination adversely effects the properties of the drilled hole and diminishes the quality of the final structure. Thrust force is a key parameter used to monitor the drilling process; a higher thrust force increases the likelihood of defects, particularly delamination, in the drilled area. In this article, a central composite design is applied to the drilling process of carbon fiber-reinforced polymer (CFRP) composites, focusing on parameters such as rotational speed, feed rate, and the angle between the composite layer sequences. The objective is to minimize delamination factors and thrust force. The effect of drilling parameters on the responses is analyzed independently. The results indicate that the derived models can predict the thrust force and delamination factors in the drilling of CFRP composites. [ABSTRACT FROM AUTHOR]

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Drilling is one of the secondary machining techniques most frequently utilised when Glass Fibre Reinforced Polymer (GFRP) materials are assembled into a structure. The present work examines the drilling GFRPs and analyses hole quality based on the different traditional parameters: feed rate, spindle speed, and drill tool diameter. However, the hybridization of glass fiber- reinforced polymers (GRPs) by incorporating fillers as secondary reinforcement in the present piece of research has introduced new challenges for hole drilling and achieving the desired surface finishes. The delamination at the hole entrance and exit, considering the drill diameter of the HSS twist drill (6, 8, 10 mm), feed rate (0.04, 0.08, 0.12 mm/rev), cutting speed (1000, 1200, 1400 rpm), and filler content (0, 10, 20 wt.%) in GFRP, are the major factors are considered. The fillers used are clamshell powder and cenosphere, which are marine waste and thermal power plant waste, respectively. The present paper aims to study the effect of these fillers on the drilling-induced damages to the holes in terms of delamination factor, surface roughness, and dimensional accuracy of the hole (taper error, circularity error) of GFRPs. The most widely preferred Taguchi experimental design has been used for optimising the process parameters to obtain minimum delamination, surface roughness, and hole error. The study also aims to develop a correlation between feed rate, cutting velocity, drill diameter, and filler content with the delamination factor, surface roughness, taper error, and circularity error in a GFRP material. The observed results show that clamshells filled GFRP shows lower delamination, surface roughness, circularity error, and taper error compared to cenosphere filled GFRP composites under the same process parameters. It indicates the positive impact of the fillers in the drilling of GFRP, where the main objective is to reduce drilling-induced defects. [ABSTRACT FROM AUTHOR]

The mining industry is a driving force of economic development, but this branch of industry is known as one of those with the most unfavorable working conditions, a large number of occupational injuries at work and the possible occurrence of collective accidents. This paper presents a risk assessment model with an occupational health and safety aspect in the process of extracting minerals by drilling. A key element of improving safety and working areas is the control and control of risks. Special attention must be paid to the risk assessment itself, which includes the identification of hazards, the probability of the occurrence of a dangerous situation, the analysis of the volume and level of unwanted events, the way possible situations unfold, and at the same time determining the sequence and order of procedures and measures that should be applied in order to eliminate or reduce the risk to a satisfactory level, i.e. to a level at which it can be controlled. The risk assessment model for the driller workplace is in accordance with the Occupational Safety and Health Act and the KINNEY Method. The model has been applied, checked and proven at the approved investigative sites during execution and inspection supervision in the territory of the Republic of North Macedonia. [ABSTRACT FROM AUTHOR]

Objective: This study analyzed Ohio workers' compensation data to identify potential prevention strategies for common oil and gas extraction industry claims. Methods: Claim rates for 2001-2018 were calculated per full-time equivalent employee. Descriptive analyses on free-text descriptions of lost-time (LT) claims (>7 days away from work) identified common characteristics among claims and injured workers. Results: Among 3134 claims, 860 (27%) were LT. The industry group, drilling contractors, experienced the highest LT claims rate, whereas the cost from servicing contractors was the highest. Contact with objects and equipment caused the highest LT claims rate. The most frequent LT occupation was roustabout, and the most frequent LT work activity was material handling. Transportation incidents caused most fatalities and hospitalizations. Over half of LT claims were from short-tenured workers. Conclusions: Both proven and innovative approaches are needed to reduce severe workers' compensation claims in this industry. [ABSTRACT FROM AUTHOR]

To investigate the performance characteristics of polymers with different functional groups in drilling fluid matrix (clay suspension), two anionic acrylamide-based polymers with molecular weights of approximately 1 million and the same monomer ratio, namelypoly(acrylamidoacrylate) (P(AM-AA)) and poly(acrylamidoallyl sulfonate) (P(AM-SAS)), were synthesized using a water-dispersion polymerization method. Using polyacrylamide (PAM) with the same molecular weight as a reference, thermogravimetric analysis, scanning electron microscopy, zeta potential analysis, particle size distribution test, and drilling fluid performance test were conducted to assess the thermal stability of the polymers as well as the microstructures and properties of the corresponding drilling fluids. The results demonstrated that both P(AM-AA) and P(AM-SAS) exhibited significant intercalation effects on clay in drilling fluids, leading to an increase in the zeta potential of clay particles and the formation of a bimodal particle size distribution. These polymers also effectively reduced filtration loss and altered the rheological properties of the drilling fluids. However, the influence of polymers on temperature and salt resistance did not conform to the traditional understanding that sulfonic acid groups offer better hydration and salt resistance compared to carboxyl groups. The performance characteristics of the polymers were influenced not only by their own structure, but also by the clay content, salt content, temperature in the drilling fluids. Specifically, in freshwater drilling fluids, P(AM-AA) exhibited a slightly lower but comparable reduction in filter loss compared to P(AM-SAS). Furthermore, P(AM-AA) was less affected by clay content than P(AM-SAS) and showed stronger filter loss reduction in brine drilling fluids with NaCl content ≤3 wt%, while exhibiting less sensitivity to variations in NaCl content. Conversely, P(AM-SAS) demonstrated stronger filter loss reduction and lower sensitivity to NaCl content in brine drilling fluids with NaCl content >3 wt%. The influence of high-temperature aging (120–180 °C) on filter loss reduction function was similar for both P(AM-AA) and P(AM-SAS). The rheology of the formulated drilling fluid was less sensitive to clay content when utilizing P(AM-AA) compared to P(AM-SAS). Moreover, the apparent viscosity of the drilling fluid with P(AM-AA) was more impacted by NaCl when the NaCl content was below 5 wt%, showing greater sensitivity than P(AM-SAS). However, there was no significant difference in rheological stability between P(AM-AA) and P(AM-SAS) under high-temperature aging conditions. [ABSTRACT FROM AUTHOR]

By benchmarking with the iteration of drilling technology, fracturing technology and well placement mode for shale oil and gas development in the United States and considering the geological characteristics and development difficulties of shale oil in the Jiyang continental rift lake basin, East China, the development technology system suitable for the geological characteristics of shale oil in continental rift lake basins has been primarily formed through innovation and iteration of the development, drilling and fracturing technologies. The technology system supports the rapid growth of shale oil production and reduces the development investment cost. By comparing it with the shale oil development technology in the United States, the prospect of the shale oil development technology iteration in continental rift lake basins is proposed. It is suggested to continuously strengthen the overall three-dimensional development, improve the precision level of engineering technology, upgrade the engineering technical indicator system, accelerate the intelligent optimization of engineering equipment, explore the application of complex structure wells, form a whole-process integrated quality management system from design to implementation, and constantly innovate the concept and technology of shale oil development, so as to promote the realization of extensive, beneficial and high-quality development of shale oil in continental rift lake basins. [ABSTRACT FROM AUTHOR]

Glass fiber-reinforced polymer (GFRP) composites are extensively used in many sectors because of their high strength, low weight, and resistance to corrosion properties. Drilling operations are needed to make holes for the joining of the components. Various defects were reported during the drilling, and the authors in this study tried to provide an approach to minimize the drilling defects. Selection of the optimum level of the input parameters can reduce defects generated during drilling. This study used grey relational analysis to optimize input parameters during glass fiber-reinforced composite drilling. Three tools (T1, T2, T3) with point angles (118°, 135°, 140°), feed rate in mm/min (10, 20, 30), and spindle speed in rpm (1000, 2000, 3000) were taken as input parameters. Taguchi L27 orthogonal arrays were selected for the three factors at three levels. Machining force (Fm), surface roughness (Ra), peel-up delamination factor (DF1), push-out delamination factor (DF2), hole size error, and circularity error were taken as output responses. Drilling GFRP composite by considering these input parameters combined with all these output responses using grey relational analysis was not explored before. The effect of input parameters on individual output response was analyzed using Taguchi and analysis of variance. Feed rate influenced machining force the most (65.34%), tool geometry influenced surface roughness the most (38.32%), and spindle speed influenced the push-out delamination factor the most (18.11%). SEM analysis was done to explain the aftereffects of drilling. [ABSTRACT FROM AUTHOR]

Drilling muds play the essential role the drilling process as they perform many functions, such as the removing of drill cuttings and controlling well pressure. Water-based drilling muds, through the use of more environmentally friendly additives, can meet increased environmental requirements. Many researchers have studied the effects of different natural materials on drilling mud to find environmentally friendly and effective drilling mud materials. The popularity of using waste materials is mainly due to their cost and favourable environmental impact. Performed literature review showed that the rheological and filtration characteristics of water-based drilling muds are enhanced with the addition of leaves of various plants and trees. This article presents investigations of clay-free drilling mud with the addition of birch and aspen leaf powder. This is relevant in the autumn period, since fallen leaves are solid municipal waste and should be disposed of by removal to landfills. The obtained data indicate the possibility of using leaf powder in the drilling mud composition. Addition of leaf powder to the base mud increases the gel strength and plastic viscosity of the mud. In an extent reduces the yield point and filtration index. Rheological parameters increase by 10-30% and filtration index decreases up to 15-17%. [ABSTRACT FROM AUTHOR]

Composite materials, such as aluminum alloy FGMs, provide advantageous weight reduction properties compared to homogenous pure structures while still preserving sufficient stiffness for diverse applications. Despite various research on drilling simulation concepts and ideas for these materials, there still needs to be an agreement on the process modeling. Researchers have looked into a lot of different numerical methods, including Lagrangian, Eulerian, arbitrary Lagrangian–Eulerian (ALE), and coupled Eulerian–Lagrangian (CEL), to find solutions to problems like divergence issues and too much mesh distribution, which become more of a problem at higher speeds. This research provides a global analysis of bottom-up meshing for eleven 1 mm layers using ABAQUS® software. It combines the internal surface contact approach with the Lagrangian domain's kinematic framework. The model uses the Johnson–Cook constitutive equation to precisely predict cutting forces, stress, and strain distributions, optimizing cutting parameters to improve drilling performance. According to Taguchi analysis, the most favorable parameters for reducing cutting force and improving performance are a rotational speed of 700 rpm, a feed rate of 1 mm/s, and a depth of cut of 3 mm. The findings suggest that increasing the feed rate and depth of cut substantially affects the cutting force, while the rotational speed has a comparatively little effect. These ideal settings serve as a foundation for improving FGM drilling efficiency. [ABSTRACT FROM AUTHOR]

Weighting materials such as barite and ilmenite are crucial for controlling fluid density during deep or ultra-deep drilling operations. However, sagging poses significant challenges, especially in highly deviated high-pressure and high-temperature (HP/HT) wells. This leads to inadequate well control, wellbore instability, and variations in hydrostatic pressure in extended-reach wells. Given the challenges of experimental research, reliable prediction models are imperative for evaluating the interaction between the ratio of anti-sagging additives, temperature, and wellbore inclination on sag factor (SF). This research presents statistical-based empirical models for predicting the SF at various wellbore inclinations (0°, 30°, 45°, 60°, 70°, 80°, and 90°) and assessing the influence of fly ash on the SF. The regression equations, developed using the Response Surface Methodology in Minitab 18 software, show high reliability, with R2 values approaching unity. Contour and surface response plots provide a clear understanding of the variable interactions. The analysis reveals that sagging is most severe at 60° to 65° inclination. At 400 °F and 60° inclination, adding 4 lb/bbl of fly ash reduces sagging in barite and ilmenite-densified fluid by 63.9% and 63.1%, respectively. Model validation shows high accuracy, with percentage errors below 3%. This study offers valuable insights for optimizing drilling fluid formulations in HP/HT well environments. [ABSTRACT FROM AUTHOR]

Electric discharge drilling (EDD) is a competent method for drilling hard-to-cut materials despite its drawbacks, including minimum material removal rate (MRR), excess tool wear rate (TWR), high surface roughness (Ra), and power consumption (PC). To address these issues, EDD's performance was explored by varying factors like tool electrode geometry (TEG), current (I), pulse-on-time (TON), and tool electrode speed (TES) to investigate the effect on MRR, TWR, Ra, and PC. Cu-6 produced the highest MRR of 36.26 mm³/min, surpassing Cu-7, Cu-8, and Cu-solid by 28.309%, 44.866%, and 51.843% respectively. Cu-solid revealed the lowest TWR of 4.397%, significantly lower than Cu-6, Cu-7, and Cu-8. Ra followed the trend: Cu-solid < Cu-8 < Cu-7 < Cu-6. Cu-solid consumed more power than hollow electrodes. Microscopic analysis attributed rough surfaces to high currents. Energy dispersive X-ray (EDX) analysis exhibits material migration from a workpiece and tool electrode on the machined surface.. [ABSTRACT FROM AUTHOR]

A planetary penetrator is a kind of machine that can use its special structure to independently penetrate an exoplanet and sample it for storage. It is a hot research topic in the world and has important development potential in the field of deep space exploration. Based on the analysis of relevant literature, this paper classifies and compares various representative planetary penetrator projectiles around the current research status. The development progress and key technologies of the planetary penetrator are analyzed, the current technical challenges are summarized, and the development trend of the planetary penetrator has prospected. The planetary probe has a broad application prospect, and its development will provide technical support for humans to establish extraterrestrial habitat, and play an important role in the field of deep space exploration. Currently, planetary penetrator research is still in its infancy, and the field is full of possibilities that need to be explored and improved. [ABSTRACT FROM AUTHOR]

Abstract Coal is currently the most important energy source in most countries. With the advent of information intelligence, more and more intelligent technologies are being applied in coal mine detection. A new model for coal mine drilling detection, which combines improved YOLOv5 and Gaussian filtering, is proposed to address the low efficiency and poor accuracy in manual detection of coal mine drilling. This new model incorporates attention mechanism and multi-object detection model on the basis of traditional YOLOv5. Due to factors such as equipment vibration and electrical interference in drilling detection, random noise is often mixed into the image signal data obtained. In order to effectively reduce the impact of noise on data and improve signal-to-noise ratio, Gaussian filtering method is studied for data denoising. This new model’s border regression loss value was 0.004 lower than the YOLOv5 loss value. This new optimization method’s accuracy was improved from 0.966 to 0.982. This new model improved the detection accuracy of small cracks by about 0.05. The detection depth of the coal seam in this new model was 9.54 m, which was closer to the true value than other methods. Therefore, using the new model to detect coal mine boreholes can effectively improve the accuracy of borehole detection images, which has a good effect on the analysis of coal mine rock layers. This new model has a good guiding role in the detection images and rock analysis research of future coal mine boreholes. The research has good research value in oil drilling inspection, natural gas pipeline monitoring, and quality inspection of industrial automation systems. This provides important technical support for future coal mine drilling image detection and rock analysis research.

Optimal and cost-effective drilling operations in extended-reach horizontal wells depend on efficient solid cuttings removal from the borehole. Several solids-suspended multiphase processes such as crude petroleum transportation, separation, and processing of oil and gas streams also require the efficient removal of these solids. The terminal settling velocity (Vts) of the solid particle is a vital parameter that controls the removal efficiency of these solids. In a drilling scenario when there is a hold on fluid circulation such as connection time, the accurate estimation of Vs provides the driller with time available to prevent solid deposition. In severe conditions, this can result in a stuck pipe, especially for extended-reach horizontal wells. In this work, both spherical and non-spherical particle deposition were experimentally investigated in several fluid rheology and salinity. Two concentrations (0.1vol% and 0.05vol%.) of partially-hydrolyzed polyacrylamide (PHPA) were used as a drag-reducing additive for water-based drilling mud. The PHPA drag-reducing fluid (reduced pressure loss) acts as a turbulence inhibitor. The PHPA polymer chain suppresses any turbulence in the flow, reducing the turbulent eddy viscosity. The effects of salinity (3wt.%NaCl and 3wt.%CaCl2 contamination) on solid particle settling velocity (Vs) in drag-reducing fluids were also investigated. Terminal velocity was achieved for all experiments and seemed to increase with increased diameter/sphericity. However, cases when this trend was not consistent were observed and therefore a new parameter of Φ (sphericity index × diameter) was proposed. Vs increases with Φ value for all cases. During drilling, PHPA also aids in sealing the fracture in the formation. With and without salt in the fluid, how lowering drag affected the settling velocity of solid particles (drill cuttings) could be observed. The settling velocity tests will be improved in drag-reducing PHPA solutions with the knowledge from this study.

This article used Guiyang Metro Line 3 under construction as an example to study the application of cross hole seismic computed tomography (CT) technology in the exploration process of Karst complex areas, thereby revealing the characteristics of Karst development in the study area. Through comparative analysis of various algorithms, it was determined that compared to the conjugate gradient least squares (CGLS) algorithm, the sparse linear equations and least square problems (LSQR) algorithm is more sensitive and accurate in identifying low-speed anomalies, and has better convergence and reliability. Drilling verification shows that using the LSQR algorithm and bending ray tracing method for seismic tomography inversion can achieve meter level accuracy in cross hole seismic CT detection, obtain high-quality velocity images, and identify the depth, scale, and extension of Karst between boreholes, neutralizing the limitations of drilling. This indicates that seismic CT technology based on the LSQR algorithm is practical and feasible for detecting Karst.

By benchmarking with the iteration of drilling technology, fracturing technology and well placement mode for shale oil and gas development in the United States and considering the geological characteristics and development difficulties of shale oil in the Jiyang continental rift lake basin, East China, the development technology system suitable for the geological characteristics of shale oil in continental rift lake basins has been primarily formed through innovation and iteration of the development, drilling and fracturing technologies. The technology system supports the rapid growth of shale oil production and reduces the development investment cost. By comparing it with the shale oil development technology in the United States, the prospect of the shale oil development technology iteration in continental rift lake basins is proposed. It is suggested to continuously strengthen the overall three-dimensional development, improve the precision level of engineering technology, upgrade the engineering technical indicator system, accelerate the intelligent optimization of engineering equipment, explore the application of complex structure wells, form a whole-process integrated quality management system from design to implementation, and constantly innovate the concept and technology of shale oil development, so as to promote the realization of extensive, beneficial and high-quality development of shale oil in continental rift lake basins.

Environmental awareness has driven a crucial search for biodegradable materials. Over the past few decades, the machining of these materials, particularly through drilling, has garnered significant research interest. This study presents an evaluation of the drilling performance of a hybrid composite (jute/glass), considering factors such as the concentration of chemical treatment with sodium bicarbonate, the type of glass fiber (random or woven), the degree of hybridization between the jute and glass fibers, and cutting parameters like rotation speed, feed rate, and drill diameter. Drilling operations were conducted to determine the maximum temperature in the cutting zone, the surface roughness of the drilled holes, and the maximum delamination factor. A Sobol sensitivity analysis was performed to identify the input parameters influencing these responses studied. Predictive modeling of the results based on the input factors was then conducted using the deep neural network (DNN) and Adaptive Neuro-Fuzzy Inference System (ANFIS) approaches. The results show that the type of glass fiber significantly affects surface roughness, while rotation speed primarily influences cutting temperature. Similarly, the drill diameter directly impacts the maximum delamination factor. Finally, the predictive modeling demonstrates that the ANN-IGWO models provide the best predictions of drilling parameters compared to the ANN-GA and ANFIS models, with mean absolute errors ranging from 1.22 to 12%. [ABSTRACT FROM AUTHOR]

To improve the abrasive waterjet drilling procedure for yttrium-stabilized zirconia-coated Inconel 718 superalloy, this study suggests an integrated approach using machine learning and an evolutionary algorithm. The objective is to simultaneously minimize the erosion diameter and taper angle of the drilled holes by identifying the best combination of drilling parameters such as stand-off distance, abrasive flow rate, waterjet pressure, and angle of impact. The machine learning models are developed using the random forest algorithm after tuning its hyperparameters to predict the erosion diameter and taper angle. The multi-verse optimization (MVO) algorithm is used to identify the best combination of drilling parameters. The comparison of results proved the efficacy of MVO over other algorithms. Confirmation experiment results are also in line with the results of MVO, since the percentage of deviation is meager. This integrative approach has the capability of significantly improving aerospace and industrial abrasive waterjet drilling operations. [ABSTRACT FROM AUTHOR]

Rate of drilling bit penetration into the subsurface formations, referred to as rate of penetration (ROP), is considered as the main optimization parameter in the drilling operation. ROP optimization results in a faster and cheaper operation. The rate of bit penetration depends on several factors, including but not limited to rock properties, fluid characteristics and drilling operational parameters. Due to the diversity of affecting parameters, prediction of rate of penetration is a challenging task. There are various mathematical relations in the literature to estimate ROP. However, these relations are developed based on specific conditions, where data from a field or experimental tests are used to develop the relations. In this work, drilling data of three wells from one onshore oil fields are gathered and then the performances of some common ROP models are investigated. Results show that the simplified Bourgoyne and Young model can accurately predict the ROP in the mentioned field, which makes the model applicable for planning of the new offset wells in the future. It should be noted that the model requires fewer input data, which makes it more applicable. The results show the average R2 coefficient for the model is 0.91, which is higher than other models. The results confirmed the applicability of the model. [ABSTRACT FROM AUTHOR]

Abstract To enhance the drilling efficiency and extend the service life of PDC (Polycrystalline Diamond Composite) bits in shale formations, this study delves into the rock-breaking mechanisms of special-shaped cutters through a comprehensive experimental approach. This involves optimizing the cutter designs, conducting laboratory experiment and field testing. Among the various cutter geometries considered, concave, axe, planar, and triangular cutters are chosen as the focal points for unit rock-breaking experiments. These tests aim to assess their cutting loads and cutting specific energy to gain a deeper understanding of their performance characteristics. Based on experimental, the debris characteristics are analyzed. Based on the understanding of the shale-breaking characteristics of special-shaped cutters, field testing is performed using a novel PDC bit with a special-shaped cutter. Compared with planar cutters, the concave cutter and the triangular cutter generate lower cutting loads and cutting specific energy. Under identical conditions, the average cutting force and cutting specific energy of concave cutter at different cutting depths are reduced by 16.1% and 19.6% Specifically, the concave cutter generates the largest debris when operated under similar conditions, which is beneficial for increasing rock-breaking efficiency. Laboratory experiment indicate that compared to conventional drill bits, the novel drill bit experiences an increase in torque of approximately 9.8% with increasing WOB (weight on bit). Under high WOB, the ROP (rate of penetration) increases by about 75.4%, while the mechanical specific energy decreases by nearly 40%. Additionally, the novel bit vibration characteristics remain superior to conventional drill bits. Field testing shows that the average ROP of the novel bit and total footage drilled increase by up to 13.3% and 27.2%, respectively, in comparison with those for the conventional bit. The research results are helpful to speed up the efficiency of shale gas drilling.

The current work investigates the effects of drilling parameters on hole quality, including delamination and circularity, produced in hybrid composite materials consisting of neat glass fibre (NG) and hybrid glass fibre/Al-wire mesh in two distinct sequences, the first one being with Al-mesh in the outermost layers (AG) and the other with Al-mesh in the central layer (GA). The operation's process parameters are feed rate (F = 20, 40, and 60 mm/min), spindle speed (N = 1000, 2000, and 3000 rpm), and drill point angle (Ɵ = 90°, 120°, and 135°). Taguchi's L9 orthogonal array is used for the study. The optimal levels and effects of the process parameters were determined. Gray relational analysis (GRA) was employed to examine the complicated interactions influencing the results and ANOVA was used to evaluate the influence of process parameters. The results indicated that for all specimens, push-out delamination was more severe than peel-up. Circularity is minimized by using N = 3000 rpm, F = 20 mm/min, and Ɵ = 90°. At speed (N) of 3000 rpm circularity reduces by 83.5% and 76.5% compared to 1000 or 2000 rpm, respectively. Compared to other specimens, AG-specimen produced minimal delamination and circularity by an average of 6% and17.38%. The results of the confirmation test and regression model provide good agreement between the experimental and predicted results.

The hole-exit defect of C/SiC composites formed during drilling process seriously affects the working performance and reliability of manufactured components. At present, the serious problem of hole-exit defect during ultrasonic vibration drilling C/SiC composites still exists. In this study, the formation mechanism of hole-exit defect during drilling C/SiC composites is analyzed. The results indicate that the hole-exit defect is related to fiber-matrix debonding caused by the outermost cutting edge. Moreover, a factor λ is proposed to characterize the hole-exit defect formation quantitatively based on image processing technology. The hole-exit defect suppression effect of ultrasonic vibration under different cutting parameters is evaluated through the contrast experiments with or without ultrasonic vibration. Compared with traditional drilling, the reduction rates of hole-exit defect factor during ultrasonic vibration-assisted drilling exceed 15.9% under all investigated processing parameters. The maximum can reach 34.3% at amplitude of 6 μm, feed per tooth of 0.005 mm/z and spindle rotation speed of 2000 r/min. Finally, a fiber deformation model is proposed to simulate the deformation-fracture process of carbon fiber. The suppression mechanism of hole-exit defect in ultrasonic vibration-assisted drilling can be revealed based on this model. [ABSTRACT FROM AUTHOR]

The selection of appropriate cutting tool (CT) is a critical part of machining. Selecting the right tool for the right job will enable customers to achieve economic machining, saving time and cost while delivering high-quality products. Nowadays, the complexity of CT and workpiece is increasing; this changes the input and output requirements for cutting tool selection paving way to automation. There are two types of CT selection methods, manual and automated CT selection. This article focuses on automated CT selection, which has different inputs and outputs based on the algorithm/AI technique used. The potential and promising aspects of CT selection could enhance the machining in terms of productivity, time, cost, and quality aspects. A comprehensive review of automated CT selection methods has been presented in this paper. The review surveys different automated CT selection methods in terms of inputs, outputs, and artificial intelligence (AI) techniques/different algorithms since most of the researchers have not focused on this perspective. It outlines the current status of research and application, which has the potential to improve the automated CT selection methods for the benefit of the manufacturing industry. [ABSTRACT FROM AUTHOR]

In the current study, micro-electric discharge drilling (µEDD) is conducted on a titanium grade 2 alloy using a tungsten carbide (WC) tool electrode of 496 µm diameter. Capacitance, voltage, and feed rate are selected as machining variables to conduct the experiments based on the full factorial experimental design method. Overcut, material removal rate (MRR), circularity, and hole taper are considered as performance measures. Furthermore, overall evaluation criteria (OEC) is utilized for multiple-objective optimization by allotting varying and equal weight percentages to each response measure. The results of OECs are compared with a revolutionary heuristic multi-objective genetic algorithm (MOGA), resulting in a similar optimal parametric combination and close response measures are obtained. Micrographic investigation demonstrates that at lower capacitance and voltage levels, there is less burr formation, recast layer, and circularity error. Moreover, FESEM and EDS analyses are employed to investigate the machined surface topology and elemental composition respectively. [ABSTRACT FROM AUTHOR]

The metallic bone fracture fixation plates are progressively being replaced by epoxy-reinforced glass fiber laminates (ERGFL) due to a higher strength-to-weight ratio and near neat shape manufacturing. Bone fracture fixation laminates are required to sustain the cyclic load due to the physical movement of the body. Therefore, the characterizations of glass fiber/epoxy laminates with drilled holes are important to study. Despite extensive research on the mechanical characterization of composite laminates, several unique circumstances remain unexplored, such as the characterization of glass fiber/epoxy laminates with drilled holes. The drilling laminates weakened the laminates' mechanical strength and damaged the area around the drilled hole. With Jo drill point designs, the greatest thrust forces (0.56 kN) were observed at 2800 rpm of cutting speed and 0.19 mm/rev of feed rate. Among the various drill points used, the drilled ERGFL laminates with Jo drill had the maximum fatigue life cycle of 87×10³. [ABSTRACT FROM AUTHOR]

Deep water areas with soft subsea soils, conventional surface conductor into the mud depth is too deep, long waiting time for resting, prone to surface conductor sinking and submerged wellhead instability. In this paper, based on the basic principles of mechanics and the understanding of the structure of the surface conductor, a mechanical model of the bearing capacity of the surface conductor is established. Three types of expandable surface conductors were designed by changing the distribution of the expansion material, in contrast to conventional surface conductors. The bearing characteristics of different structural surface conductors are also investigated by changing the soil parameters from the strength of the submarine soil. The study has obtained: the load-bearing capacity comparison graph between conventional surface conductor and expandable surface conductor; the load-bearing capacity change of expandable surface conductor under the change of soil parameters and the change of expansion material section; and the load-bearing capacity improvement effect of the three expandable surface conductors designed in the paper compared with conventional surface conductors, using stress as the evaluation criterion. This paper provides technical support for the design of expandable surface conductors and provides a basis for numerical simulation of surface well construction. [ABSTRACT FROM AUTHOR]

The abrasive waterjet machining process was introduced in the 1980s as a new cutting tool; the process has the ability to cut almost any material. Currently, the AWJ process is used in many world-class factories, producing parts for use in daily life. A description of this process and its influencing parameters are first presented in this paper, along with process models for the AWJ tool itself and also for the jet–material interaction. The AWJ material removal process occurs through the high-velocity impact of abrasive particles, whose tips micromachine the material at the microscopic scale, with no thermal or mechanical adverse effects. The macro-characteristics of the cut surface, such as its taper, trailback, and waviness, are discussed, along with methods of improving the geometrical accuracy of the cut parts using these attributes. For example, dynamic angular compensation is used to correct for the taper and undercut in shape cutting. The surface finish is controlled by the cutting speed, hydraulic, and abrasive parameters using software and process models built into the controllers of CNC machines. In addition to shape cutting, edge trimming is presented, with a focus on the carbon fiber composites used in aircraft and automotive structures, where special AWJ tools and manipulators are used. Examples of the precision cutting of microelectronic and solar cell parts are discussed to describe the special techniques that are used, such as machine vision and vacuum-assist, which have been found to be essential to the integrity and accuracy of cut parts. The use of the AWJ machining process was extended to other applications, such as drilling, boring, milling, turning, and surface modification, which are presented in this paper as actual industrial applications. To demonstrate the versatility of the AWJ machining process, the data in this paper were selected to cover a wide range of materials, such as metal, glass, composites, and ceramics, and also a wide range of thicknesses, from 1 mm to 600 mm. The trends of Industry 4.0 and 5.0, AI, and IoT are also presented. [ABSTRACT FROM AUTHOR]

Efficiency in machining time during drilling is affected by various factors, with one key element being the machining path. Solving the machining path closely resembles the Travelling Salesman Problem (TSP). In this article, drilling on a sample model is simulated using a hybrid algorithm that is developed based on TSP. This hybrid algorithm (GACO) is created by combining the strengths of the Genetic Algorithm (GA) and Ant Colony Optimisation (ACO). Codes written to verify the stability of the algorithms were executed 10 times, and results were recorded indicating the shortest path and machining sequence. Accordingly, the performance of the hybrid GACO algorithm was observed to be 3.16% better than the ACO algorithm in terms of both total path length and total machining time. In terms of computation time, the ACO algorithm lagged behind the GACO algorithm by 6.46%. Furthermore, the hybrid GACO algorithm demonstrated enhanced performance in both total path length and total machining time when compared with the literature. This study aims to contribute to the industry, professionals, and practitioners in this field by providing cost and time savings. [ABSTRACT FROM AUTHOR]

Six-axis robots are increasingly employed in manufacturing due to their excellent volume on cost ratio and extensive reach, facilitating the machining of large components, including those made of composites. However, this enhanced volume on cost ratio often compromises rigidity. This study investigates the effect of cutting conditions on surface integrity and robotic drilling forces when machining Aluminum 6082-GFRP stacks using 6 mm solid carbide drills and a 6-axis Sta¨ubli TX200 robot. Two distinct drill geometries are assessed in various drilling sequences. Feed rate emerges as a pivotal parameter affecting drilling forces and hole quality. Comprehensive testing encompasses a range of feed rates and drilling strategies in both individual materials and stack sequences. The analysis includes cutting forces and hole quality, considering surface integrity and standard quality indicators such as delamination, arithmetic roughness, and burr height. The research seeks to propose optimal cutting conditions, specifically feed rate and cutting speed, essential for advanced industrial applications. These conditions ensure hole quality and surface integrity, which is particularly important for riveting processes and ensuring effective sealing. [ABSTRACT FROM AUTHOR]

Powder metallurgy (PM) processed nickel-based superalloys are increasingly employed in the hot section of gas turbine engines for parts such as high-pressure (HP) compressors and turbine rotor discs over more traditional cast and wrought options such as Inconel 718 due to its improved high-temperature properties. In this paper, the surface integrity and geometrical/dimensional accuracy of holes initially rough drilled using worn tools and subsequently finish plunge end milled in a proprietary PM-processed Ni-based superalloy, were assessed and compared. The influence of tool wear on hole quality after finish plunge end milling was also investigated. Significant improvement in hole quality was evident following finishing with reductions in surface roughness (up to ~86%), subsurface microhardness (up to ~125 HK 0.05) and workpiece microstructure deformation/damage (up to ~80% in terms of average depth) compared to corresponding rough drilled holes. Evidence of chatter marks on holes machined with worn plunge end mills was observed, despite exhibiting reduced surface roughness levels (~45-73%). Generally, somewhat improved hole surface integrity (reduced subsurface deformation by ~47-64%) and geometrical accuracy (circularity decreased by ~10-25%) were produced when employing new tools. [ABSTRACT FROM AUTHOR]