Drill Wear Research Articles

Advanced Feature Extraction Methods from Images of Drillings in Melamine Faced Chipboard for Automatic Diagnosis of Drill Wear.

In this paper, a novel approach to evaluation of feature extraction methodologies is presented. In the case of machine learning algorithms, extracting and using the most efficient features is one of the key problems that can significantly influence overall performance. It is especially the case with parameter-heavy problems, such as tool condition monitoring. In the presented case, images of drilled holes are considered, where state of the edge and the overall size of imperfections have high influence on product quality. Finding and using a set of features that accurately describes the differences between the edge that is acceptable or too damaged is not always straightforward. The presented approach focuses on detailed evaluation of various feature extraction approaches. Each chosen method produced a set of features, which was then used to train a selected set of classifiers. Five initial feature sets were obtained, and additional ones were derived from them. Different voting methods were used for ensemble approaches. In total, 38 versions of the classifiers were created and evaluated. Best accuracy was obtained by the ensemble approach based on Weighted Voting methodology. A significant difference was shown between different feature extraction methods, with a total difference of 11.14% between the worst and best feature set, as well as a further 0.2% improvement achieved by using the best voting approach.

A novel domain adversarial time-varying conditions intervened neural network for drill bit wear monitoring of the jumbo drill under variable working conditions

The challenges in monitoring the drill bit wear of the jumbo drill lie in the difficulty of measuring the drill bit wear directly, and the coexistence of time-invariant conditions and time-varying conditions with complex and everchanging changes. The existing tool wear monitoring methods are limited to the time-invariant conditions with minor change, without resolving the situation of major change. And they do not consider the influence of the time-varying conditions on the wear. An accurate drill bit wear monitoring modelling method based on Domain Adversarial Time-varying Conditions Intervened Neural Network (DATCINN) is proposed in this paper. A novel measuring method based on ORB (Oriented FAST and Rotated BRIEF) is developed to accurately measure the drill bit wear using images, as the data sources. Domain adversarial mechanism helps extract features desensitized to time-invariant conditions to improve the model accuracy under variable working conditions. Time-varying conditions intervention mechanism uses the network correction term to deal with the influence of time-varying driving parameters on the drill bit wear to improve the model accuracy in different construction modes. The experimental results in 2 cases show that the accuracy and stability of the proposed model are better than the existing statistical and machine learning models. The performance is prominent in the task of monitoring drill bit wear under complex working conditions using model trained under single working condition. And DATCINN can be widely applied to wear monitoring of other non-precision cutters.

Improved Drill State Recognition during Milling Process Using Artificial Intelligence

In this article, an automated method for tool condition monitoring is presented. When producing items in large quantities, pointing out the exact time when the element needs to be exchanged is crucial. If performed too early, the operator gets rid of a good drill, also resulting in production downtime increase if this operation is repeated too often. On the other hand, continuing production with a worn tool might result in a poor-quality product and financial loss for the manufacturer. In the presented approach, drill wear is classified using three states representing decreasing quality: green, yellow and red. A series of signals were collected as training data for the classification algorithms. Measurements were saved in separate data sets with corresponding time windows. A total of ten methods were evaluated in terms of overall accuracy and the number of misclassification errors. Three solutions obtained an acceptable accuracy rate above 85%. Algorithms were able to assign states without the most undesirable red-green and green-red errors. The best results were achieved by the Extreme Gradient Boosting algorithm. This approach achieved an overall accuracy of 93.33%, and the only misclassification was the yellow sample assigned as green. The presented solution achieves good results and can be applied in industry applications related to tool condition monitoring.

Experimental Study on Titanium Coating Carbide Drill Cutting Nickel-Base Superalloy

A nickel-base superalloy drilling comparison test was carried out with a carbide drill of the Chinese brand YG10, which was selected and coated with TiN coating, AlTiN coating and TiAlSiN coating. Analysis of drill life, drilling force, drilling temperature, drill wear and machined surface quality were carried out. It can be seen that both TiN coating and AlTiN coating can prolong the tool life of the carbide drill YG10 when drilling nickel-base superalloy GH4169. In contrast, the TiAlSiN-coated drill has poor hardness and is easy worn, which is not suitable for processing nickel-base superalloy which has high hardness and strength. Adhesive wear is the main form of coated drill wear. As the coated drill number of drilling holes increases, the adhesion increases. Coated drills can reduce the machined surface roughness of a workpiece and improve the machined quality.

Heat Generation During Initial Osteotomy for Implant Site Preparation: An In Vitro Measurement Study

IntroductionControlling temperature generation during implant site preparation is important to prevent implant early failure.AimThe present in vitro study aimed at measuring temperature variation generated during the initial osteotomy using both rotatory and piezo-surgical inserts.MethodsNine groups were defined according to drill and insert type, cooling volume (mL/min) and cooling temperature. A total of 315 implant site preparations were performed in an artificial bone sample and the temperature was measured using an infrared camera. Drills’ wear was assessed using scanning electron microscopy at baseline and after 10 and 35 utilizations.ResultsPiezo-surgical insert groups determined a temperature increase that was significantly higher than the one generated by rotatory drills groups (p < 0.001). When considering rotatory drills groups a temperature ≥ 40 °C was never recorded.ConclusionLower saline temperature implied a significant temperature decrease (p < 0.001), while the increase in cooling volume did not imply a temperature decrease. The scanning electron microscopy analysis of the drills demonstrated that little drill wear occurred up to 35 utilization times.

Study on the working performance of CrAlCN coated and uncoated carbide twist drill

A drilling test was carried out for a 6 mm diameter carbide twist drill with CrAlCN coating and an uncoated carbide twist drill to grasp the effect of CrAlCN coating on the tool performance. Drilling and machining tests on ASTM1045 steel workpieces using CrAlCN coated and uncoated tools. Observe the pattern of variation of surface morphology and roughness of holes with the number of drilled holes using SEM and optical microscope. The effect of CrAlCN coating on carbide twist drill on drilling quality was analyzed by comparing the wear, surface roughness and chip shape of twist drill at different periods and parameters of drilling. The study concluded that using CrAlCN coated tools improved the wear resistance of the drill and significantly reduced BUE. Compared to the uncoated bit, the diameter of the drill decreased to 5.91 mm for the coated tool and 5.79 mm for the uncoated tool after 80 holes. The roughness of the coated bit was 3.324 µm at a feed rate of 0.12 mm/r and several holes of 40, which was significantly lower than that of the uncoated bit. Chip analysis showed that the coated tool maintained well-broken and tightly spiraled chips. In contrast, the uncoated tool produces tightly spiraled chips and short ribbon chips at a feed rate of 0.18 mm/rev, and the edges of the chips can appear significantly serrated. The research results improve the understanding of the drilling wear mechanism, provide new technical means to improve the analysis of working tool performance and provide a reference basis for the design of new coating tools.

Elucidation of Drilling Behavior on Workpiece Superimposed with Ultrasonic Vibration

This study quantitatively and theoretically clarifies the machining characteristics of the chisel engagement and the cutting-edge wear behavior in drilling in a workpiece superimposed with ultrasonic vibration. The machining phenomenon of drilling by this method considers being the same as drilling by ultrasonic vibration spindle from the viewpoint of the relative motion of the cutting edge and workpiece. However, the details have not been clarified yet. The chisel engagement behavior experiment at the initial stage of the drilling and cutting-edge wear experiment were carried out in this study. The chisel engagement behavior experiment revealed lower axial relative velocity results in a minor effect. In the cutting-edge life experiment, when the cutting fluid and the supply method were changed, the minimal oil with mist supply showed the same result as water-soluble with jet supply without breaking the drill. However, considerable wear was generated at the cutting edge in the initial drilling stage. When suitable ultrasonic vibration-assisted drilling was applied, initial wear decreased by 40% but could not be suppressed entirely. As a result of theoretical elucidation on this initial wear, it was proven that the flank face of the cutting edge contacted the workpiece when critical amplitude was exceeded. In the experiment to prove the validity of this theory, the initial wear occurred when the critical amplitude was exceeded. The cutting-edge wears increased in proportion to the working relief angle.

Effect of Drill Attrition on Machinability in Drilling Woven GFR Epoxy Composites

Drilling processes in fiber-reinforced polymer composites Composite structures are essential for assembly and fabrication of parts. The economic impact of rejecting the drilled area, when reaching the assembly stage It is important to consider the associated loss. Therefore, the motivations in drilling E-Class Fiber Reinforced Epoxy (GFRE) composites, this explains cutting conditions on torque and wear Feed, speed and pre-drill wear values. Four feeds (0.056, 0.112, 0.22, 0.315, 0.45 mm/rev) and three speeds (6.41, 12.71, 20.25, 32.03, and 50.63 m/min) and five pre-drill wear values and Four artificially introduced wears) were used. Values; W = 7, 19, 26, 34 All samples are 8 mm diameter holes Drilled using a cemented carbide drill bit. Current In work, Multi-linear Regression models were used were used, Parameters of mechanical properties are related to: Thrust, torsion, peel-up, delamination, push-out delamination, Drill wear and machining parameters such as surface roughness before: feed and speed. Perforated model has high resolution; Scanning is done using flatbed color scanner, then to estimate the delamination factor, Image analysis was performed using Corel DRAW software. Multi-variable regression analysis significant coefficients of each variable, contribution is made to promotion and elimination. Laminate thickness on torque and displacement factor the results illustrate that there are significant effects. Cronbach's alpha value for the model is 0.924.

Effects of Coating Parameters of Hot Filament Chemical Vapour Deposition on Tool Wear in Micro-Drilling of High-Frequency Printed Circuit Board

High-frequency and high-speed printed circuit boards (PCBs) are made of ceramic particles and anisotropic fibres, which are difficult to machine. In most cases, severe tool wear occurs when drilling high-frequency PCBs. To protect the substrate of the drills, diamond films are typically fabricated on the drills using hot filament chemical vapour deposition (HFCVD). This study investigates the coating characteristics of drills with respect to different HFCVD processing parameters and the coating characteristics following wear from machining high-frequency PCBs. The results show that the methane concentration, processing time and temperature all have a significant effect on the grain size and coating thickness of the diamond film. The grain size of the film obviously decreases as does the methane concentration, while the coating thickness increases. By drilling high-frequency PCBs with drills with nanocrystalline and microcrystalline grain sizes, it is discovered that drills with nanocrystalline films have a longer tool life than drills with microcrystalline films. The maximum length of the flank wear of the nanocrystalline diamond-coated drill is nearly 90% less than microcrystalline diamond-coated tools. Moreover, drills with thinner films wear at a faster rate than drills with thicker films. The findings highlight the effects of HFCVD parameters for coated drills that process high-frequency PCBs, thereby contributing to the production of high quality PCBs for industry and academia.

Prediction of TiAlN- and TiN-coated carbide tool wear in drilling of bidirectional CFRP laminates using wavelet packets of thrust–torque signatures

Prediction of TiAlN- and TiN-coated carbide tool wear in drilling of bidirectional CFRP laminates using wavelet packets of thrust–torque signatures

Numerical Simulation on Erosion Wear Law of Pressure-Controlled Injection Tool in Solid Fluidization Exploitation of the Deep-Water Natural Gas Hydrate

The pressure-controlled injection tool (PCIT) is the key equipment in the process of high-pressure water jet fragmentation in the solid fluidization exploitation of deep-sea natural gas hydrate (NGH). The internal flow field erosion wear numerical simulation model of PCIT is established through computational fluid dynamics software to study the influence law and main factors of the drilling fluid erosion wear of PCIT. The influence laws of different drilling fluid physical parameters and different structural parameters on PCIT erosion wear were analyzed based on the Euler–Lagrangian algorithm bidirectional coupled discrete phase model (DPM) and the solid–liquid two-phase flow model. The results show that the easily eroded areas are the cone of the sliding core, the plug transition section, the plug surface, and the axial flow passage. The sliding core inlet angle and solid particle size are the main factors affecting the PCIT erosion rate. When the inlet angle of the sliding core is 30°, the diameter of solid-phase particles in drilling fluid is less than 0.3 mm, and the erosion degree of the PCIT could be effectively reduced. The research results can provide guidance for the design and application of the PCIT and advance the early realization of the commercial exploitation of hydrate.

Comparison of TiAlN DLC and PCD Tool Wear in CFRP Drilling

Comparison of TiAlN DLC and PCD Tool Wear in CFRP Drilling

Development and deployment of a digital twin for monitoring of an adaptive clamping mechanism, used for high performance composite machining

In this work, we present a cloud-based digital twin for monitoring of a clamping technology for machining of composite parts. Supporting large and/or freeform composite parts is crucial to avoid bending during drilling. Bending of the part will lead to delamination and frayed edges of the drilled holes. The new active clamping technology allows to realise a stabilised fixture, localised in the area where the drilling occurs, to avoid bending. This significantly improves the quality of the drilled holes. The clamping device is equipped with an IoT edge device, with a bidirectional communication to the cloud. The cloud-based digital twin analyses the quality of the drilled holes based on computer vision, monitors the drill wear and detects incorrect operation of the active clamping device. All data is stored in the cloud. By means of a knowledge graph, which acquires and integrates information into an ontology and provides a central information access, it will be easier for a data scientist to query this data and to gain new insights in the operation of the drill with active clamping device. The full deployment occurs on the Microsoft Azure cloud platform. This transforms the standard machine into an Industry 4.0 compliant machine.

Effect of Nitrogen Ion Implantation on the Tool Life Used in Particleboard CNC Drilling.

The paper presents the effect of nitrogen ion implantation on the tool life of the tools commonly used in the furniture industry for drilling particleboards. Nitrogen ions with different accelerating voltages of 25, 40, 55, and 70 kV and a fluence of 5 × 1017 cm−2 were implanted into the surface of commercially available high-speed steel (HSS) drills, using the implanters without mass-separated ion beams. The tests were carried out in a computerized numerical control (CNC) machining center used in the furniture industry. Based on the measurements of the direct tool wear indicator (W), the drill wear curves were determined and the relative tool life index, standard deviation, coefficient of variation, and the implantation quality index of tool life were calculated. The studies have shown that the modification of the drill surface layer by the nitrogen ion implantation process increases the tool life. The obtained results allow the research to be the continued in a wider scope.

Forming the geometric accuracy and roughness of holes when drilling aircraft structures made from polymeric composite materials

The subject of this study is indicators of the quality, geometric accuracy, and roughness of holes in aviation structures (AS) made from polymeric composite materials (PCM) produced by drilling. The indicators of quality, geometric accuracy, and roughness of PCM holes were investigated by using kinematic hole drilling schemes and the creation of PCM chips. A kinematic scheme has been built of the cutting forces operating in PCM when drilling with the distribution of zones from 0° to 360°. Experimental studies on the establishment of characteristic shrinkage zones in the drilling of PCM, as well as their values, have been implemented. The methods used are the analysis of the quality indicators of PCM holes, and the method of expert assessments. The following results were obtained. Based on the analysis and synthesis, it was found that with incorrectly selected geometric parameters for drills involving the work accompanied by the wear of drills on the back surface, stratification, cracks, or chips of PCM may appear. It is shown that the decisive factor is a comprehensive assessment, which is determined not only by the quality, accuracy, and roughness but also by the condition of the holes at the input and output of the drill. Features and characteristic contact zones for PCM drilling were identified. It has been established that within the drill operating areas from 0° to 90° and from 180° to 270° the cutting forces are reduced while the indicators of surface quality, roughness, and geometric accuracy of a PCM hole are improved. In zones from 90° to 180° and from 270° to 360° – on the contrary, low quality of the machined surface is assumed. The calculation of the required cutting forces and calculation of the height of roughness of drilling holes in PCM have been proposed, taking into consideration the bearing of chips under the action of the wedge. The results of experimental studies on the establishment of characteristic shrinkage zones when drilling PCM confirmed the adequacy of the results of theoretical studies on the kinematic schemes of drill operation in PCM

DRILLING MECHANISM BASED ON THE APPLICATION OF DIAMOND DRILLING BITS

In order to express how much the drill selection depends on the rock properties and its effect on the percentage of core and drilling speed, diamond drill selection and drilling mechanisms are taken. In diamond drills, enough pressure should be applied to ensure that each active diamond grain sinks into the rock for the best drilling speed. This stress should be above the surface strength of the rock to be drilled and below the diamond grain strength. The main goal to be achieved in engineering and research and development studies is to ensure that both the designed system and the product to be developed have maximum performance. In order to reveal the conditions in which the best results will be obtained, first the feature that determines the performance is determined and the factors affecting this feature are examined. Then, experiments are carried out to determine the effects of these factors on the feature that determines the performance and to find the most suitable combination (by taking into account the uncontrollable factors). Optimum conditions are determined by evaluating the performance indicator obtained as a result of the experiments. The experiments carried out within the framework of this approach can be perceived as the question asked to the system, and the results of the experiments as the answer given by the system. The critical point is that it is necessary to ask the right question in order to get the right answer. Drilling is a complex event influenced by many factors. Drill type and diameter, rotational speed, pressing force, torque and circulating fluid are controllable parameters. On the other hand, physic mechanical properties of the rock and geological conditions (uncontrollable factors such as discontinuities, bedding conditions, grain size, matrix structure, porosity, cementation degree and abrasive mineral ratio) affect rock drill ability. The drill ability of rocks can be defined by various concepts such as feed rate, drill wear amount, drill life and tooth penetration. Drilling method classification can be made according to several criteria. The most logical classification can be made according to the type of energy required for rock fragmentation. Drilling is done in rocks for many purposes and many methods developed for this purpose have successfully drilled into rocks. Many new methods in rock drilling have been acquired through experience. The most successful practical application is the mechanical shredding process. Although it is mostly applied for cutting soft rocks, this method is done by spraying high pressure water. Keywords: drilling, drilling process, drilling operations, tools, drilling mechanism, drilling diamond.

Initial Study of the Effect of Some PVD Coatings (“TiN/AlTiN” and “TiAlN/a-C:N”) on the Wear Resistance of Wood Drilling Tools

The wear of drills when processing wood-based boards is an important problem in industrial practice. The main objective of the study was to experimentally check whether two types of PVD coatings (multilayer nanocomposite “TiN/AlTiN” and double-layer coatings “TiAlN/a-C:N”) increase the wear resistance of the drill bits significantly (in terms of statistics). The typical two-blade drill bits intended for drilling in wood-based panels were used. During the experiments, the holes were drilled in samples made of commercial raw three-layer particleboard with the spindle speed of 4500 rpm, and the feed per revolution was 0.15 mm. The tool wear was monitored using a microscope. The advantage (greater resistance to wear) of both of the tested coatings (“TiN/AlTiN” and “TiAlN/a-C:N”) over raw cemented carbide was statistically significant in the initial period of machining (before 800 holes were drilled). Unfortunately, in the final period (when the number of holes drilled was over 800), only one coating (“TiN/AlTiN”) retained its advantage over raw cemented carbide. The effect of the second coating (“TiAlN/a-C:N”) turned out to be statistically insignificant.

The Electrode Wear and Effective Energy Detection in Micro-EDM Drilling of Micro-hole Array

With the micro-hole array structure more and more used in industrial areas, such as oil nozzle, spinneret and so on, its machining accuracy significantly affects the performance of the product. In the machining of micro-hole array by micro-EDM drilling, unavoidable tool electrode wear is one key factor affecting machining geometric and dimensional accuracy, and the effective energy of the discharge gap directly determines the amount of electrode wear. In present study, the characteristics of electrode wear and gap effective discharge energy were explored to meet the requirements of machining accuracy of micro-hole array machining. The effect of pulse generator parameters and electrode eccentric radius on electrode wear were concerned, and the electrode wear was reduced by optimizing pulse generator parameters and electrode eccentric radius. The geometry evolution rule of electrode was investigated, and the electrode wear model was established based on the electrode wear characteristic. The experimental result show that the electrode tip morphology tended to be stable and the axial wear of the tool electrode could be compensated evenly. In order to realize the accurate calculation of the gap effective discharge energy, a gap effective discharge energy detection system was built based on Lab VIEW. And the variation rule of gap effective discharge energy was obtained by micro-hole array machining experiment. In addition, the relationship between electrode wear and gap effective discharge energy was also studied in this paper. It was found that there was a parabolic relationship between electrode wear and effective energy before electrode wear was stable, and there was a linear relationship between them after electrode wear was stable.

A cloud-based digital twin for monitoring of an adaptive clamping mechanism used for high performance composite machining

In this work, we present a cloud-based digital twin for monitoring of a clamping technology for machining of composite parts. Supporting large and/or freeform composite parts is crucial to avoid bending during drilling. Bending of the part will lead to delamination and frayed edges of the drilled holes. The new active clamping technology allows to realize a stabilized fixture, localized in the area where the drilling occurs, to avoid bending. This significantly improves quality of the drilled holes. The clamping device is equipped with an IoT edge device, with a bidirectional communication to the cloud. The cloud-based digital twin analyses the quality of the drilled holes based on computer vision, monitors the drill wear and detects incorrect operation of the active clamping device. All data is stored in the cloud to gain new insights in the operation of the drill with active clamping device. The full deployment occurs on the Microsoft Azure cloud platform. This transforms the standard machine into an Industry 4.0 compliant machine.

Effect of cutting edge geometry change due to tool wear on hole quality in drilling of carbon fiber reinforced plastics using advanced ceramic coated tools

This paper aims to study the evolution of cutting edge geometry due to tool wear and discuss its impact on the hole quality of a carbon fiber reinforced plastic (CFRP) laminate. A drilling experiment was conducted using three types of twist drills: uncoated, BAM (AlMgB14) coated, and (AlCrSi/Ti)N nanocomposite coated tungsten carbide tools. After generating 120 holes, the uncoated drill had the largest cutting edge radius (∼36 µm), while the BAM coated drill had the most extensive flank wear (∼287 µm) among the three drills. This relatively rapid tool wear results in a reduction of average hole size and a considerable variation on the hole profiles. The worn drills with the cutting edge radius greater than 19.3 µm form the fiber pull-outs in not only the 135° plies but also the adjacent 45° and 90° plies from the cutting direction, creating deep void networks. This type of networked fiber pull-out damage was observed with the holes machined by the uncoated and BAM coated drills. The (AlCrSi/Ti)N coated drill, which experienced the least amount of flank wear and the least increase of cutting edge radius, generated consistently sized holes up to 120 holes. However, the relatively sharp (AlCrSi/Ti)N coated tool results in the higher arithmetic roughness average (Ra) and the maximum roughness height (Rz) values than the other tools due to the localized fiber pull-outs and the absence of severe matrix smearing.