Drill Diameter Research Articles

Fabrication and Performance Analysis of an Arduino-based Mini CNC Machine with Drilling and Engraving Tool

Abstract: The present work focuses on fabrication of a low cost numerically controlled machine with easily available materials and devices. The machine has been primarily fabricated to carry out a few low duty mechanical applications in a short period of time as well as at a minimal cost. Engraving tool of diameter mm and drill bit of diameter mm are used in our operations. Foam, Plywood, Aluminium sheet and Wood have been used as work-piece material. Study has been carried out to observe performance analysis on the above work-piece materials. Mathematical analysis has been done for different operating parameters like cutting speed, feed, depth of cut, machining time and MRR (Material removal rate) . It has been observed that for low duty applications, small size numerically controlled machines are more effective as well as advantageous compared to conventional large size cutting machines.

Effect of Guided Implant Drilling on Bone Temperature Changes During Implant Osteotomy: A Comprehensive Systematic Review.

The preparation of the implant site and the quality of the bone are crucial factors for preliminary healing following implant surgery. Therefore, any thermal or mechanical damage to the bone must be minimized during osteotomy preparation. The use of guided implant drilling is now widely employed for the precise placement of implants. Although guided implants are accurate, they are said to generate more heat compared to non-guided osteotomy. This systematic review was conducted to evaluate the heat generation that occurs during osteotomy with both guided and non-guided drilling. A comprehensive search of dental literature in PubMed, EBSCOhost, and Google Scholar was performed for articles published from 2010 to 2024. The search strategy incorporated MeSH terms and Boolean operators. The initial search across all three databases yielded a total of 548 articles. Of these, 477 were discarded after reviewing the titles and abstracts, 26 were removed as duplicates, 15 studies were excluded due to unavailable full texts, and 19 were excluded for not meeting the study design criteria set for the systematic review. Eleven articles were ultimately selected for review and data extraction. After analyzing and collating the results from all the studies, it can be concluded that using surgical guides does cause significant heat generation in the bone at the osteotomy site. However, this rise in temperature generally remains below the threshold that could cause bone necrosis. Additionally, other factors, such as irrigation temperature, drill length, drill diameter, and drilling speed, also influence heat generation during osteotomy in guided drilling.

WEAR MECHANISM FOR DEEP-WELLS DRILLING TOOLS

When drilling deep wells with a large diameter drill bit, it is important to ensure optimum progress with the cutting tool, effectively cutting or crushing the rock through which we are penetrating for as long as possible. When drilling a well, we encounter complex conditions at depth resulting from variables such as the strength of the rock, the load on the bit, the number of revolutions of the tool, significant temperature and pressure fluctuations and the material properties of the tools used in the drilling. The article shows how mechanisms develop due to the drilling parameters used and the complex drilling conditions, which lead to wear of the cutting unit and a decrease in efficiency. The influence of the aforementioned drilling conditions on the steel materials of the roller-cone drill bit, which is the tool we use to penetrate deeper, is reflected in the change in the material properties of the steels. These changes, which are explained in the article, lead to gradual fatigue and degradation of the materials. The wear mechanism of the cutting tool is composed of the different material properties of the steel from which the roller-cone drill bit is formed, the influence of sudden temperature changes on the steel materials and erosion processes on free, newly formed surfaces, which are the result of the erosion effect.

Determinants of Temperature Development during Dental Implant Surgery

Mechanical and thermal trauma during implant surgery may be reasons for initial peri-implant bone loss. Temperature development during drilling and implant insertion were quantified in this series of in vitro and animal experiments. Polyurethane foam material mimicking different classes of alveolar bone was used as a model material for simulating implant surgery. Using thermocouples, temperature development was determined in the model material at depths of 3 mm and 10 mm during site preparation and implant insertion. Additionally, an infrared camera allowed for measuring drill temperatures both in vitro and as part of an animal trial using an intraoral minipig model. Drill diameter and repeated usage of drills did not have a major effect on temperature generation. The addition of a diamond-like carbon coating, bone density, predrilling, and irrigation heavily affected intraosseous temperatures. In vivo, applying regular drill protocols, an intraosseous temperature rise of approximately 3 °K was determined. Implant geometry as well as the amount of undersizing of an osteotomy governed heat generation during implant insertion. Drill protocols and the amount of undersizing of an implant osteotomy constitute parameters by which clinicians can limit trauma during implant surgery.

Assessment of Thermal Osteonecrosis during Bone Drilling Using a Three-Dimensional Finite Element Model.

Bone drilling is a common procedure used to create pilot holes for inserting screws to secure implants for fracture fixation. However, this process can increase bone temperature and the excessive heat can lead to cell death and thermal osteonecrosis, potentially causing early fixation failure or complications. We applied a three-dimensional dynamic elastoplastic finite element model to evaluate the propagation and distribution of heat during bone drilling and assess the thermally affected zone (TAZ) that may lead to thermal necrosis. This model investigates the parameters influencing bone temperature during bone drilling, including drill diameter, rotational speed, feed force, and predrilled hole. The results indicate that our FE model is sufficiently accurate in predicting the temperature rise effect during bone drilling. The maximum temperature decreases exponentially with radial distance. When the feed forces are 40 and 60 N, the maximum temperature does not exceed 45 °C. However, with feed forces of 10 and 20 N, both the maximum temperatures exceed 45 °C within a radial distance of 0.2 mm, indicating a high-risk zone for potential thermal osteonecrosis. With the two-stage drilling procedure, where a 2.5 mm pilot hole is predrilled, the maximum temperature can be reduced by 14 °C. This suggests that higher feed force and rotational speed and/or using a two-stage drilling process could mitigate bone temperature elevation and reduce the risk of thermal osteonecrosis during bone drilling.

Experimental Analysis of Effect of Machined Material on Cutting Forces during Drilling.

Current research studies devoted to cutting forces in drilling are oriented toward predictive model development, however, in the case of mechanistic models, the material effect on the drilling process itself is mostly not considered. This research study aims to experimentally analyze how the machined material affects the feed force (Ff) during drilling, alongside developing predictive mathematical-statistical models to understand the main effects and interactions of the considered technological and tool factors on Ff. By conducting experiments involving six factors (feed, cutting speed, drill diameter, point angle, lip relief angle, and helix angle) at five levels, the drilling process of stainless steel AISI1045 and case-hardened steel 16MnCr5 is executed to validate the numerical accuracy of the established prediction models (AdjR = 99.600% for C45 and AdjR = 97.912% for 16MnCr5). The statistical evaluation (ANOVA, RSM, and Lack of Fit) of the data proves that the drilled material affects the Ff value at the level of 17.600% (p < 0.000). The effect of feed represents 44.867% in C45 and 34.087% in 16MnCr5; the cutting speed is significant when machining C45 steel only (9.109%). When machining 16MnCr5 compared to C45 steel, the influence of the point angle (lip relief angle) is lower by 49.198% (by 22.509%). The effect of the helix angle is 163.060% higher when machining 16MnCr5.

Biomechanical Parameters of Implants Placed with Osseodensification Versus Implants Placed with Under-drilling Osteotomy Techniques in Posterior Maxilla: A Comparative Clinical Study

BACKGROUND: To facilitate better implant survival rates in areas with clinically low bone density, osteotomy techniques that provide higher implant stability and improve bone quality are often recommended. The most widely used are under-drilling (UD) and osseodensification (OD). In the UD technique, the diameter of the final osteotomy drill is narrower that the diameter of the placed implant, whereas in the OD technique, special drills that rotate counter-clockwise to condense and densify the bone are used. AIM: The aim of this study was to evaluate the effect of two different implant osteotomy methods – UD versus osseodensification (OD) in terms of implant stability during the period of osseointegration in the posterior maxillary region. MATERIAL AND METHODS: This prospective randomized clinical study included 22 patients who received a total of 37 implants in the posterior maxillary region. They were divided into two groups: In 11 patients, 18 implants were placed using the under-drilling method (UD), while the other 11 patients received 19 implants using the osseodensification method (OD). Within the OD group, 10 implants were placed in areas with the initial height that was insufficient to accommodate implants with a minimal length of 8 mm. In these areas, crestal sinus elevation without bone graft use was performed simultaneously with implant placement, according to the osseodensification protocol proposed by the manufacturer. All implants were placed in a dual-stage manner – completely covered with soft tissue and uncovered 4 months later, at the time of second-stage surgery. The implant stability was determined by measurement of implant stability quotient (ISQ) with instrument that utilizes the method of resonance frequency analysis (RFA) to discover implant stability. The ISQ represents a value on a scale between 0 and 100, with values above 65 indicating high implant stability. ISQ values were measured at two timepoints: At the time of implant placement and at the time of their uncovery. Statistical analysis was performed with Prism 9 statistical program for Mac. The data were analyzed using one-sample t-test, Wilcoxon, and paired two-way ANOVA test. The significance level was set at p ≤ 0.05. RESULTS: The differences between the primary implant stability ISQ values in the UD and osseodensification (OD) groups were not statistically significant. The secondary implant stability was statistically significantly higher in the osseodensification group (p &lt; 0.001) There were no statistically significant differences between secondary implant stability values in implants placed with and without crestal sinus floor lift within the osseodensification group. CONCLUSION: Within the limitations of the study, the conclusion is that osseodensification method of implant osteotomy (OD) results in higher secondary implant stability values that the under-drilling method (UD), which has clinical relevance regarding long-term implant survival. It should be a preferred method of choice for osteotomy in areas with clinically low density of bone due to its predictability and effectiveness.

Parametric optimization in drilling of sisal–glass reinforced epoxy composites using Taguchi grey relational analysis method

This research work intends to study the effect of hybridization of glass and sisal fiber, stacking sequence and tensile properties of the composite. The sisal-glass fiber hybrid composites laminates are prepared using reinforced plain woven sisal fabric (unidirectional) and plainwoven glass fabric. In this research study, 27 experiments are conducted as per L27 orthogonal array. Five process parameters are selected and three responses are considered in this work. The drilling of the composite specimen is considered and the drilling process parameters such as speed, feed rate, drill diameter, material thickness, and drill point angle are selected. The responses considered in this work are delamination factor, thrust force, and torque. Taguchi analysis is performed and the response table for means for the responses is determined, and the most influencing parameter in the drilling of the composite specimen is analyzed. The grey relational coefficients are computed and followed with the computation of the grey relational grade. The grey relational grades are calculated for determining the highest contributing parameter in the drilling of the sisal fiber and glass fiber reinforced hybrid composite specimen. The optimum drilling process parameters are ranked and the ranks presented represent the sequence of run resulting in optimum solutions.

Autologous bone harvested during implant bed preparation: A randomized clinical trial comparing high-speed drilling with irrigation versus low-speed drilling without irrigation.

To compare collected bone weight and the frequency of autologous bone harvesting from the flutes of surgical drills used for implant bed preparation using two different drilling techniques. A comparative evaluation of radiographic bone density and bone quality was also made. A randomized clinical trial was made of 66 dental implants in patients with a single posterior edentulous site. The compared drilling techniques were high-speed drilling with irrigation (control group) and low-speed drilling without irrigation (test group). The bone collected in both groups was dried and weighed with a precise electronic balance. The frequency of harvesting was calculated. The median radiographic bone density of each implant site was measured using cone-beam computed tomography (CBCT) pixel values. Patient sex, age, implant position and dimensions, as well as the last drill diameter were analyzed as independent variables. The level of significance was 5%. The harvesting of bone chips from drill flutes proved possible in 51.5% of the procedures in the control group and in 100% in the test group (p < 0.001). There were also statistically significant differences in bone weight between the control group (6.7 ± 10.6 mg) and the test group (41.9 ± 30.3 mg) (p < 0.001). The CBCT pixel values were directly correlated with the collected bone weight in both groups. The median radiographic bone density, arch and last drill diameter were significantly associated with harvesting bone frequency and collected bone weight (p < 0.05). Our findings suggest that the frequency and weight of autologous bone harvested from drills are greater with low-speed drilling without irrigation than with high-speed drilling with irrigation. Radiographic bone density, arch and last drill diameter also significantly influenced the harvesting outcomes.

Research and Application of High Efficiency Pressure Relief Technology for Ultra-high Pressure Hydraulic Slotted Coal Seam

In order to solve the technical problem of efficient pressure relief of the impact coal seam, the principle of ultra-high pressure hydraulic slit relief and anti-impact technology is expounded, and the ultra-high pressure hydraulic slit device with working pressure up to 100MPa is selected as the pressure relief equipment of coal seam. The field test of high-efficiency pressure relief by ultra-high pressure hydraulic slotting in impact coal seam was carried out. The test showed that the slotting radius of No.3 coal in Tangkou Mine could reach 1.5m under the condition of 100MPa slotting pressure. The stress variation in seam area and large diameter drilling area is compared and analyzed. The stress in seam area decreases significantly by 40%. The stress of bolt (cable) and the deformation of surrounding rock in the slit area are investigated. Compared with the large-diameter pressure relief area, the increase value of bolt is lower and the increase value of cable is significant in the hydraulic slit test area. The technical benefits of hydraulic slotting and large-diameter drilling are summarized and compared. The engineering quantity of drilling with ultra-high pressure hydraulic slotting is reduced by 60%, and the coal output is 2.5 times of that of large-diameter drilling. The large-diameter drilling provides limited pressure relief space for coal seam, but the ultra-high pressure hydraulic slotting technology can effectively increase the deformation space in the coal body and reduce the elastic energy stored in the coal pillar, so as to achieve a good pressure relief effect. The field test shows that compared with large diameter drilling, ultra-high pressure hydraulic slotting technology has remarkable effects of pressure relief, shock absorption and shock prevention.

On the importance of precision in cortical bone drilling: Integrating experimental validation and computational modeling

BackgroundCortical bone drilling is integral to orthopedic and dental surgeries, yet challenges such as thermal necrosis persist. Previous finite element (FE) models may overlook critical parameters, impacting accuracy. This study aims to integrate experimental and computational approaches to predict essential parameters—initial temperature, point angle, and spindle speed—enhancing precision in cortical bone drilling. MethodsBovine cortical samples were utilized to systematically investigate the impact of four independent parameters on maximum temperature (MT) and maximum thrust force (MTF). Parameters included drill bit initial temperature (IT), diameter, point angle, and spindle speed (225–2700 rpm, feed rate 0.5–3 mm/s). Experimental procedures involved an orthopedic handpiece with titanium drill bits. DEFORM-3D V6.02 facilitated FE simulation, with the validated model developed for the second stage of the drilling process. ResultsThe validated model highlighted the significant impact of drill bit IT on MT, predicting a 26.14 % decrease in final bone temperature as IT decreased from 25 to 5 °C. Increasing the point angle from 70 to 120° resulted in a 13.1 % MT increase and a 26.9 % decrease in MTF. Spindle speed variations exhibited a 48.3 % temperature increase and an 82.8 % MTF decrease. ConclusionsIntegrating experimental validation and computational modeling offers a comprehensive approach to predict drilling parameters. Precision in cortical bone drilling can be optimized by selecting specific parameters, including lower drill bit IT, smaller point angles, and controlled spindle speeds. This optimization reduces the risk of bone necrosis and thermal damage, thereby enhancing surgical outcomes.

Hydrogeological characterization of low permeability medium for conceptualization of a mine site in Eastern Turkey

The mining site in Eastern Anatolia of Turkey were encounter a significant risk of slope instability within the operational area. One of the processes that govern slope stability is the pore water pressure distribution. The conceptualization and characterization of porous media serve as fundamental prerequisites for the implementation of numerical methods aimed at predicting pore water distribution. This study aims to characterize the hydrogeological properties of water bearing rocks in the active mining site in Eastern Anatolia of Turkey. A total of 21 wells and drill holes were drilled in the study area to conduct in-situ tests, monitoring, and sampling. The large diameter wells drilled in surrounding the carbonate rocks were to determine the groundwater flow and boundary conditions and also wells tapped metasediments and diorite unit for hydraulic testing. The lugeon tests and installation of vibrating wire piezometers were carried out at small diameter drill holes to obtain localized hydraulic conductivity of metasediments and diorite at different depths and monitoring pore water pressure distribution along some critical cross-sections. The results obtained from these tests are used for developing hydrogeological conceptual model for groundwater flow. The results of in-situ tests show that the metasediment and diorite units act as a single hydrostratigraphic unit. The metasediments and diorite have high total porosity and low specific yield indicating that the pore water is retained by electrostatic forces in the medium and it resists flow due to low hydraulic conductivity. The vertical variation in hydraulic conductivity values indicates that the medium is highly heterogeneous.

Imaging anatomy study related to unilateral biportal endoscopic lumbar spine surgery.

To provide lumbar spine anatomical parameters relevant to the UBE technique and explore their intraoperative application. CT imaging data processed by Mimics for parametric measurements, including laminar abduction angle (LAA), laminar slope angle (LSA), minimum laminar height (MLH), distance between the inferior margin of the lamina and attachment of the ligamentum flavum onto the cephalad lamina (DLL), distance between the initial point and the middle of the articular process (DIA), and distance from the inferior margin of the lamina to the inferior border of the vertebral body (DLV), and were manually measured. LAA and DIA gradually increase from L1 to L5. At L1, the DIA is approximately the length of 2 drill bits with a diameter of 3mm (male: 7.77 ± 1.39mm, female: 7.22 ± 1.09mm), while at L5, it can reach the length of 4-5 drill bits (male: 14.96 ± 2.24mm, female: 13.67 ± 2.33mm). MLH, DLL, and DLV reach their maximum values at the L3 and decrease toward the cranial and caudal ends. The DLL is smallest at L5 (male: 9.58 ± 1.90mm, female: 9.38 ± 2.14mm), equivalent to the length of 3 drill bits, while the DLL at L3 is the length of 4-5 drill bits (male: 14.17 ± 2.13mm, female: 14.01 ± 2.07mm). Referring to the drill diameter during surgery can mark the extent of laminotomy. The characteristics of vertebral plate angles at different lumbar levels can provide references for preoperative incision design.

Enhancing rock fragmentation assessment in mine blasting through machine learning algorithms: a practical approach

The optimization of blasting operations greatly benefits from the prediction of rock fragmentation. The main factors that affect fragmentation are rock mass characteristics, blast geometry, and explosive properties. This paper is a step towards the implementation of machine learning and deep learning algorithms for predicting the extent of fragmentation (in percentage) in open pit mining. While various parameters can affect rock fragmentation, this study considers ten among them (i.e., spacing, drill hole diameter, burden, average bench height, powder factor, number of holes, charge per delay, uniaxial compressive strength, specific drilling, and stemming) to train and test the models. However, due to a weak correlation with rock fragmentation, drill diameter, average bench height, compressive strength, stemming, and charge per delay are eliminated to reduce model complexity. A total of 219 data sets having five input features including the number of holes, spacing, burden, specific drilling, and powder factor are used to develop the models. Machine learning models (random forest regression, support vector regression, and XG boost), as well as a deep learning model (neural network regression), are applied to develop a practical way that can optimize the prediction of fragmentation. This study employs performance measures such as R-squared, RMSE, MSE, MAPE, and MAE. The optimization of the model revealed promising results, indicating that the architecture 5-64-32-16-1 exhibits strong performance. Specifically, the model achieved mean squared error (MSE) values of 41.32 and 28.59 on the training and test datasets, respectively. The R2 value for both training and test is 0.83. RFR is also performing well compared to SVR and XG boost with MSE values of 12.37 and 9.89 on training and testing data, respectively.in both sets, the R2 value is 94%. Based on permutation importance and shapely plot values, it is observed that the powder factor has the highest impact, while the burden has the lowest impact on fragmentation.

Multivariate modelling of AA6082-T6 drilling performance using RSM, ANN and response optimization

The AA6082-T6 was experimentally studied in the present research with respect to the drilling performance. Drill diameter, cutting speed and feed rate were examined, using a full factorial design. Mathematical modelling of the process was carried out using the Response Surface Methodology (RSM) as well as the Artificial Neural Network (ANN) techniques. The output results in terms of cutting force, torque and surface roughness, revealed high levels of correlation between the experimental and the predicted data. Specifically, the Mean Absolute Percentage Error (MAPE) values using RSM compared to the ones of the experiments, were equal to 2.14%, 3.49% and 6.16% for Fz, Mz and Ra respectively. The equivalent MAPE between the ANN and the experiments were found to be 2.19%, 1.82% and 2.85% accordingly. Moreover, the most significant terms were revealed, being the interaction D × f for the thrust force and the torque with contribution percentages equal to approximately 44% and 42% respectively, and the term D2 for the surface roughness with 51%. The evaluation of the machining parameters, identified their significance, enabling the selection of the optimal cutting parameters, which were obtained by the desirability function, taking into account the importance of the generated surface quality and the reduction of cost. The solutions given by this approach, pointed out the Ø9 tool, coupled with Vc = 50 m/min and f = 0.15mm/rev as a well-balanced combination, whereas the Ø9.9 tool used under the same conditions, yielded the best possible surface quality (appr. 0.2 μm).

Estimation of heat flux entering the bone during the drilling process using the inverse heat transfer method

Drilling is one of the most important surgical steps and bone fracture repair. In this step, the temperature may exceed 47 °C and thermal necrosis may occur, which has irreversible consequences. Knowing the amount of heat transferred to the bone and its changes can be effective in recognizing this heat damage and minimizing it. In this research, it was tried to estimate the amount of heat flux entering the bone during the drilling process using the inverse heat transfer method. Drilling tests were performed on cow bone samples and the temperature changes at the hole location were measured using the inverse heat conduction transfer method. The amount of heat input was estimated. The K-type thermocouple is used to measure temperature. The diaphysis fragment of the cow's thigh (middle part), which has a length of about 90 mm and the thickness of the cortical bone in this range is about 8–10 mm, was used. Also, to ease the tests, the beginning and end parts of the fresh femur were cut with a saw. The results show that the maximum heat flux occurs earlier than the maximum temperature. It was observed that the maximum heat flux and the maximum temperature rise with the increase of the rotational speed and the diameter of the tool. As the feed speed rises, first the maximum temperature and maximum heat flux decrease and then increase. By tripling the feed speed, the maximum heat flux decreases by about 20%. The highest percentage rise in temperature and heat flux occurs with a rise in rotational speed, which is around 130–140%. After the rotational speed, increasing the drill diameter increases the temperature up to about 66.7%. The results can be used to prevent thermal necrosis because the maximum heat flux is visible before the occurrence of the maximum temperature.

Study of the distribution of residual stresses across the surface layer depth following machining through probing hole drilling and digital image correlation

The article aims to study the distribution of residual stresses across the surface layer depth following the machining of test specimens (free orthogonal cutting and burnishing). The machining by cutting and burnishing of 45 steel specimens was carried out using a milling machine with numerical control under varying machining factors. For a comparative analysis, the processes were also modeled via the finite element method using identical experimental values of geometric parameters and machining modes. In order to obtain residual stress distributions across the surface layer depth, probe holes having depths of 0.5; 0.75; 1; 1.5; and 2 mm were drilled. By differentiating the displacement of specimen surface particles, measured using digital image correlation, radial strains around the probe holes were determined. Then, these values were used to determine the residual stress components for each probe hole, and the averaged values of each residual stress component were calculated using the calculation algorithm presented in this article. After burnishing the specimen with a force of 3400 N, the test value of the σx component within the depth range (from the surface) of 0.5–0.75 mm amounted to -250 MPa. Model and experimental distributions of residual stress tensor components across the surface layer depth were obtained following machining via two methods. The experimental values of residual stresses were found to have good convergence with each other and with model distributions at depths up to 1 mm from the machined surface at a drill diameter of 1.7 mm. The proposed approach provides a means to obtain the residual stress distribution across the surface layer depth by drilling probe holes of different depths and estimating radial strains on the specimen surface using the digital image correlation method.

A Comprehensive Study on the Optimization of Drilling Performance in Hybrid Nano-Composites and Neat CFRP Composites Using Statistical and Machine Learning Approaches

Carbon fiber-reinforced polymer (CFRP) composites have gradually replaced metals due to their exceptional strength-to-weight ratio compared to metallic materials. However, the drilling process often reveals various defects, such as surface roughness, influenced by different drilling parameters. This study explores the drilling quality of uni-directional CFRP composites, as well as hybrid Al2O3 alumina and hybrid SiC silicon carbide nano-composites, through experimental exploration using step, core, and twist drills. Response surface methodology (RSM) and statistical tools, including main effect plots, ANOVA, contour plots, and optimization techniques, were used to analyze the surface roughness of the hole. Optimization plots were drawn for optimal conditions, suggesting a spindle speed of 1500 rpm, feed of 0.01 mm/rev, and a 4 mm drill diameter for achieving minimum surface roughness. Furthermore, two machine learning models, artificial neural network (ANN) and random forest (RF), were used for predictive analysis. The findings revealed the robust predictive capabilities of both models, with RF demonstrating superior performance over ANN and RSM. Through visual comparisons and error analyses, more insights were gained into model accuracy and potential avenues for improvement.

Impact of process parameters in drilling of glass epoxy composite with clam shell and cenosphere filler: A comparative analysis

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.

Optimization of drilling parameters on delamination and burr formation in drilling of neat CFRP and hybrid CFRP nano-composites

Carbon fibre-reinforced polymer (CFRP) composites have exceptional mechanical advantages such as high specific strength and stiffness, lightweight, and high damping capacity, making them very attractive for aircraft, aerospace, automotive, marine, and sporting applications. However, various defects such as delamination, burr formation, and surface roughness are observed during the drilling of CFRP composites, which are influenced by various drilling process parameters. In this work, the drilling quality of uni-directional CFRP composites. and the hybrid Al2O3 and hybrid SiC nano-composites are investigated experimentally using different types of drills such as step drill, core drill, and twist drill, as there is a limited study done on the comparative analysis of the impact of the above drills on the delamination factor and burr area on the above CFRP and hybrid nano-composites. The design of the experiment table was developed using response surface methodology (RSM) for input process parameters of spindle speed, feed, drill diameter, and drill type. The output surface characteristics (delamination factor and burr area) of the hole were measured quantitatively using the stereo zoom optical microscope. The main effect plots, contour plots, and analysis of variance (ANOVA) were used to examine the effect of spindle speed, feed, drill diameter, and drill type on exit delamination and burr formation. The analysis of main effect plots, contour plots, and analysis of variance showcased the optimum process parameters, such as a high spindle speed of 5500 rpm, low feed of 0.01 mm/rev, and drill diameter of 4 mm. The step drill demonstrated the least damage mechanism among drill geometries, followed by the twist and core drills. The minimum drilling damage was observed for the Al2O3 hybrid nano-composite compared to the neat CFRP composites.