Drill Material Research Articles

Investigating the impact of drill material on hole quality in jute/palm fiber reinforced hybrid composite drilling with uncertainty analysis

This study presents a method for modelling, predicting, and evaluating the impact of drill materials on the drilling process of hybrid palm/jute polyester composites, with the aim of enhancing hole quality regarding delamination, circularity, and cylindricity. Three drill materials, including High-Speed Steel (HSS), 5 % Cobalt-coated High-Speed Steel (HSS-Co5), and Solid Carbide drills were tested, and their impacts on drilling performance were assessed. Through thorough experimentation and statistical analysis, significant differences in results were observed between HSS drills and both HSS-Co5 and Solid Carbide drills. However, the variation in results between HSS-Co5 and Solid Carbide drill results was minimal. Additionally, the findings highlight notable disparities among drill types concerning uncertainty. The results also indicate that feed rate, drill material, and their interaction play crucial roles in determining drilling efficiency. Specifically, HSS drills consistently outperformed HSS-Co5 and Solid carbide drills, demonstrating superior performance in minimizing delamination, improving circularity, and enhancing cylindricity along with lower uncertainty.

Wear characteristics and micro-cutting damage model of cemented carbide by deep cryogenic treatment

Wear failure of oil drill bits leads to cost increase, and how to improve the abrasion resistance of cemented carbide (WC–Co) drill bits is an urgent problem, and deep cryogenic treatment (DCT) is a feasible method. The effect of DCT time (i.e., 0, 3, 6, 9, 12, 24, and 48 h) on the Vickers hardness, flexural strength, and wear rate of WC-Co with different Co contents (i.e., 5 wt%, 8 wt%, 10 wt%, and 12 wt%) was investigated. The results showed that the best DCT time for hardness, flexure strength, and abrasion resistance of WC-Co was 12 h. Compared with untreated (e.g., 0 h), the wear rates of WC-Co with different Co contents were reduced by 36%, 34%, 30%, and 19%, respectively at DCT-12. Compared with WC-12Co, the wear rate of WC-5Co with different DCT times was reduced by 75%, 77%, 78%, 78%, 80%, 79%, and 78%, respectively. The precipitation of η phase (Co6W6C), martensite phase transformation (α-Co to ε-Co), and the increase of residual compressive stress (RCS) of WC after DCT improved the hardness, flexural strength and reduced the wear rate of WC-Co. Based on the principle of frictional wear, a micro-cutting wear model considering Co content and DCT time is proposed, which can predict the evolution of the wear rate of WC-Co. The results of the study guide improving the wear resistance of drill materials.

Multi objective optimization of process variables using grey relational analysis for drilling of hybrid composites (LM6/B4C/fly ash)

Aluminium alloys continue to be an effective material for the aviation and automotive sectors in spite of the development of composites and other lightweight materials because of their sophisticated manufacturing techniques, strong durability against fatigue fracture propagation, and excellent impact endurance. As numerous holes are needed for creating rivets, drilling is the most difficult of all the machining operations. The primary problems with drilling these aluminium alloys are represented by a low hole quality, which increases the risk of airframe construction defects and lowers reliability. As a result, parts get discarded throughout the process of assembling, which affects the overall cost of production. To satisfy the needs of machined parts, the selection of Feed rate (F), Spindle Speed (S), Drill Material (D) and percentage of reinforcements (R) as well as drilling equipment, is necessary. The objective of this research work is to study the impact of cutting parameters on surface roughness (SR) and thrust force (TF) during drilling Hybrid MMCs, which were prepared by stir casting. The reinforcements used for fabrication were fly ash and boron carbide. A computer numerical control VMC with a cutting tool dynamometer for measuring TF was used for the experiments. The investigations used the L18 orthogonal array as their base of operation. The multi response optimization considering TF and SR was carried out using grey relational analysis (GRA) and the optimal level of cutting parameters like ‘F’, ‘S’, ‘D’ and ‘R’ were identified to obtain low TF and SR. The optimal machining parameters which give low TF and low SR are at 6 % reinforcement, coated carbide drill, S 3000 rpm and F 50 mm/min. Feed Rate (67.20 %) has the most significance on GRG trailed by S (15.88 %), Drill Material (6.39 %) and reinforcement percentage (3.65 %). Confirmation experiments demonstrated that grey relational analysis precisely optimized the process variables in drilling of hybrid MMCs.

Sustainable Optimization of Drilling Parameters for AA2017/AlN Composite Materials: A Grey Relational Analysis Approach

Modern engineering materials have seen remarkable development. Because conventional materials can no longer meet the needs of modern applications, numerous composites are being employed as viable alternatives. Drilling is the most important production step for most uses, and the resulting holes are high-stress zones that must be handled carefully. Scientists and engineers have long been interested in the challenge of finding the best combination of drilling settings for cutting-edge composite materials. As part of this research, AA2017/AlN composites with matrices made of AA2017 aluminium alloy and reinforcements made of 5, 10, and 15 wt % AlN were produced using stir casting. By experimenting with different input parameters, we were able to utilise the L9 OA to determine the best machining arrangement for drilling materials. The investigation focused on critical drilling characteristics, including burr height (H), thrust force (T), and surface roughness (SR), with a keen emphasis on sustainability.By considering the burr height (H), thrust force (T) and surface roughness (SR) and this work used grey relational analysis (GRA) to establish the optimum cutting parameters for drilling holes in the cutting-edge composite AA2017/AlN. The significance of different machining settings and their effect on the typical characteristics of the drilling were analysed using GRA. However, a confirmation experiment was conducted to ensure the highest quality outcomes. Test results and GRA indicate that the best grey relational grade is achieved with the following parameters: spindle speed (S) of 3500 rpm, feed rate (F) of 60 m/s, drill material (D) of Tungsten Carbide, and reinforcement (R) of 10%.. Analysis of variance (ANOVA) revealed statistically significant impacts on GRG from the drill material (29.08%), the feed rate (24.24%), and the spindle speed (19.52%). The error term was a function of the reinforcement percent and its interactions with all other parameters; however, the influence of the interaction between feed rate and drill material on GRG was small. The GRG is 0.856, which is higher than the prediction of 0.824. The calculated and measured values agree quite well and 3.7% is a negligible margin of error. The mathematical models for all reactions depending on the drill bits employed was also constructed.

3D Finite Element investigation in high speed drilling of unidirectional Glass Fiber Reinforced Polymer composite

The unidirectional Glass Fiber Reinforced Polymers (UD-GFRP) composites have wide spread usage in the current modern industries, because of their significant mechanical behavior over conventional materials and metals. Drilling operation is a vital machining process of making holes with high precision during the pre-assembly process of the laminates. Hole with higher precision is needed to guarantee the strength of the joint made during the assembly process. However, the effect of key drilling parameter settings like cutting speed, tool diameter, tool geometry, drill material and feed rate is more significant in achieving acceptable dimensional tolerance and quality holes. The effect of the thrust forces in the quality of the hole and chip morphology is very high especially during the high speed drilling process. Hence, the prediction and investigation of the critical thrust force is very much needed to reduce the machining induced defects and thereby improving the effectiveness of the drilling process. In this research work, the prevalidated 3D Finite Element Model (3D FEM) developed in ABAQUS/Explicit software is utilized to analyze and explore the complex cutting mechanics behind high speed drilling of GFRP composite. The effect of machining parameters settings on thrust forces are predicted and reported using 3D FE analysis.

The Effect of Dental Implant Drills Materials on Heat Generation in Osteotomy Sites: A Systematic Review.

The aim of this review was to examine the impact of dental implant drill materials and wear profiles on heat generation in the osteotomy sites as reported in experimental studies and to critically appraise these studies. The research question was formulated based on predefined patient, intervention, comparison, and outcome (PICO) elements. A comprehensive electronic search was undertaken in Medline/PubMed Central, Science Direct, and Google Scholar, using predetermined keywords, followed by a manual search of the bibliography of the selected articles. The selection of the studies for the critical appraisal part of our study was based on the criteria used to assess the study designs such as study aims, outcome measure, clarity of method, sample selection, randomization, allocation concealment, sample attrition, bias, method of data analysis, and external validity. Increased heat generation was observed with both ceramic and metal drills; the heat generation was proportional to drills' wear. The literature was inconclusive regarding the association between drill material and heat generation. However, drill materials had a significant influence on the overall temperature increase during osteotomy. The noncoated drills showed a higher wear resistance, and it has been observed that using worn drills leads to more friction contact, reduced drill cutting efficiency, and increased heat generation. Eleven in vitro studies met the inclusion criteria, and showed a considerable methodological heterogeneity and confounding factors, including drill geometry, speed and load, depth and diameter, number of uses, irrigation protocol, study specimens, and the heat measuring device. Besides, most of the studies have a potential operator and assessor bias, and some have sponsorship bias. It is possible to conclude that the literature is not conclusive on the effect of drill materials on heat generation during osteotomy. Lack of standardization and uniformity in the study design, along with potential bias in the study methodology can be the reason for the heterogeneity of the results.

Finite element analysis of process parameters influences on deformation and von mises stress in drilling

Drilling is a very important machining process which accounts for more than 20% of the machining processes. Failure of drill bit is crucial when drilling difficult to machine materials such as composites and high temperature alloys. Selection of drill bit tool geometry, drill material and process parameters are vital for success of drilling difficult to machine materials. Finite element analysis and Taguchi Techniques are coupled to find out the optimum drilling parameters. Three process parameters such as material used for the drilling bit, cutting speed and drill point angle are used for analysis. Deformation and von mises stress are considered as response variables. The Taguchi method is employed to figure out the optimal process parameters for drilling operations. Based on SN ratio analysis and ANOVO, optimum drilling parameters for deformation were found to be CBN with 2000 rpm cutting speed and 114 as the drill point angle. From ANOVO analysis, it was found that drilling RPM is the most significant process parameter.

Wearing Effect of Implant Steel Drills and Tappers for the Preparation of the Bone Osteotomies: An Infrared Thermal Analysis and Energy Dispersive Spectroscopy-Scanning Electron Microscopy (EDS-SEM) Study

Background: The thermal effect correlated with implant osteotomy could produce significant effects on the healing process and fixture osseointegration. The aim of the present investigation was to assess the heat generation and surface wearing of dental implant drills and manual tappers during simulated osteotomies on animal ribs. Methods: Steel drills (20 units per type) and tappers (20 units per type) were evaluated for a total of 30 osteotomies. The infrared thermal analysis was performed at the first and thirtieth osteotomy. The surface alteration and wearing was assessed by energy dispersive spectroscopy–scanning electron microscopy (EDS-SEM) prior to and after use. Conclusions: The drill material produced a non-significant temperature change during bone osteotomy. Lower heating was reported for manual tappers in favor of a manual osteotomy instead rotary instruments.

Drilling- and withdrawing-related thermal effects of implant site preparation for ceramic and stainless steel twist drills in standardized bovine bone.

Excessive surgical trauma is believed to be among the most important causes for early implant losses. As thermal injury to the bone is not only dependent on the amount of generated heat but also on the tissue exposure time, and the greatest temperature increase was found within the withdrawing period, the entire osteotomy procedure with the parameters contributing to thermal damage is of particular clinical relevance. The aim of this study was to investigate the thermal performance of metal-based and ceramic implant drills regarding the temperature exposure time during the whole osteotomy process. This investigation consisted of 240 individual preparations in total, comprising two different drilling depths (10 and 16 mm), two irrigation methods (external and without irrigation), two implant drill materials (stainless steel and zirconia), and three consecutive drill diameters per material (2.0/2.2, 2.8, and 3.5 mm) with 10 identical repetitions. Real-time multichannel temperature measurement was conducted during automated drilling procedures in standardized bovine bone specimens. The maximum temperature changes were highly associated with the time period of passive drill withdrawing (p≤ 0.05), irrespective of drill material, drilling depth, or drill diameter. Statistically significant differences in temperature generation between stainless steel and ceramic drills were observed in irrigated testing sites at both drilling depths with smaller drill diameters (2.0/2.2 and 2.8 mm, p≤ 0.05). Results of this in vitro study could demonstrate a strong association between the highest temperature increase and the passive withdrawing time period in both investigated drill materials. Considering these findings and the resulting thermal bone damage due to the whole surgical procedure, high overall temperatures in combination with a prolonged heat exposure time may impact the future osseointegration process.

Heat generation during implant site preparation and its effects on osseointegration: A review

Dental implants act as a bridge between the oral environment and deep core structures of the jaw. The temperature rise leading to heat generation in the course of operation of the dental implants results in thermal injury of the adjoining bone tissue to the implant site resulting into implant failure. Present review is focused on existing research done in the heat generation and its distribution during dental implant drilling. Various factors such as drill speed, drill design, mode of irrigation, depth of drill, drill diameter, drill material that affect osseointegration due to heat generated while drilling, are compared. The motive of this review is to assess the various factors that are responsible for heat generation and their effects on osseointegration during osteotomy. A systematic study reveals that the rise in the temperature at the implant site mainly depends upon the drill speed, drill diameter, depth of drill as well as irrigation used. The purpose of this review is taking these factors into consideration to find out the best possible parameters during implantation to avoid bone necrosis. The temperature during dental implantation ranges from 35 ℃ to 43 ℃ while in some in-vitro studies the temperature increases up to 50 ℃ was observed which is not admissible due to the thermally induced necrosis.

Optimization of Process Variables in the Drilling of LM6/B4C Composites through Grey Relational Analysis

The objective of this investigational analysis was to study the influence of process variables on the response during the drilling of composite materials. Stir casting was employed to produce the composites. A Vertical Machining Center (VMC) with a dynamometer was used to drill the holes and to record the thrust force. An L27 orthogonal array was used to carry out the experimental work. A grey relational analysis (GRA) was employed to perform optimization in order to attain the lowest Thrust Force (TF), Surface Roughness (SR) and Burr Height (BH). For minimal responses, the optimum levels of the process variables viz. the feed rate (F), spindle speed (S), drill material (D) and reinforcing percentage (R) were determined. The process variables in the drilling of the composites were indeed optimized, according to confirmational investigations. The predicted Grey Relational Grade was 0.846, whereas the experimental GRG was 0.865, with a 2.2% error—indicating that the optimization process was valid.

Effect of Intermetallics and Drill Materials on the Machinability of Al-Si Cast Alloys.

The present study was conducted on the machinability of 396 alloy (containing approximately 11% Si) and B319.2 alloy mainly to emphasize the effects of Fe-intermetallics, i.e., α-Fe, β-Fe, and sludge. The results demonstrate that the presence of sludge in the form of hard spots has a significant effect on cutting forces and tool life, in that it decreases drill life by 50% compared to the base alloy. The formation of the α-Fe phase in the M1 base alloy has a beneficial effect on tool life in that this alloy produces the highest number of holes drilled compared to alloys containing sludge or β-Fe; this result may be explained by the fact that the formation of the α-Fe intermetallic, with its rounded Chinese script morphology and its presence within α-Al dendrites, is expected to improve matrix homogeneity via hardening of the soft α-Al dendrites. Increasing the Fe-content from 0.5% to 1% in the 396-T6 alloy containing 0.5% Mn produces a distinct improvement in alloy machinability in terms of cutting force and tool life. The addition of Fe and/or Mn appears to have no discernible effect on the build-up edge area (BUE) and chip shape.

Optimization of process variables in drilling of LM6/fly ash composites using Grey-Taguchi method

Drilling is a critical step in the hole-making operation. It is quite beneficial for part assembly. Hard particulatesintroduced into the continuous phaseof thecomposite materials, makes them hard to process. As a result, optimizing the drilling variables is inevitable . The primary goal of this study is to manufacture LM6/Fly Ash with weight percentages of fly ash 3, 6 and 9 adopting the stir casting technique. The second objective is to use Taguchi's Design of Experiments (L27 OA) to drill composite materials using feed rate (F), spindle speed (S), drill material (D), and % of reinforcement (R) as drillingprocess variables at 3 levels. The ultimate goal is to optimize the drilling process variables for obtaining minimumthrust force (TF), surface roughness (SR)and burr height (BH) using multi-objective Grey Relational Analysis. The optimum process variable achieved is F1S3D3R3, i.e., 50 mm/min, 3000 rpm, TiN-coated drill bit and 9 wt% of fly ash.

Optimization of drilling process variables using taguchi technique for LM6 aluminium alloy

The abrasive characteristics of LM6 alloys are difficult to machine, so designing a technology that allows for effective machining is essential. This paper aims to evaluate the effect of process variables, namely feed rate, spindle speed and drill material, towards the responses like Thrust force, Surface roughness and burr height when drilling of LM6 alloy. LM6 aluminium alloy was fabricated by the stir casting process. Experiments were conducted using L9 orthogonal array in a Vertical Machining Centre coupled with a dynamometer for measuring thrust force. Surface roughness was found by Surface roughness tester and burr height was measured using Vision Measuring System. The findings show that the created model can accurately estimate the thrust force (TF), surface roughness (SR) and burr height (BH) in LM6 alloy drilling within the parameters examined.

Optimization of machining parameters in drilling of LM6/B4C/Fly ash hybrid composites

Metal matrix composites (MMCs), innovative replacements for traditional materials, are currently achieving a growing trend in engineering and research for operations like aviation, nuclear power, and automotive. Machining of MMCs makes it challenging to get good dimensional accuracy, surface finish and lower tool wear. Drilling is a necessary and immensely useful tool for component assembly in the manufacturing sector. As a result, optimization of drilling process variables is unavoidable. The fundamental purpose of this study is to use the stir casting technique to manufacture LM6/B4C/Fly ash composites with 3, 6 and 9 wt.% of second phase materials. Taguchi's design of experiments strategy was used to drill with three levels of feed rate (F), spindle speed (S), drill material (D) and percentage of reinforcement (R) as input process parameters. Optimization of drilling variables for attaining lower surface roughness (SR) and burr height (BH) using single objective approach. The optimum process variable achieved for surface roughness is F1S3D3R2, i.e., 50 mm/min, 3000 rpm, TiN-coated drill bit and 6 wt.% of reinforcements (B4C and Fly-ash) and for burr height is F1S3D3R3, i.e., 50 mm/min, 3000 rpm, TiN-coated drill bit and 9 wt.% of reinforcements.

Investigation of thrust force in drilling polyphthalamide (PPA) composites

In this study, the drilling process is explored on 30% glass fiber reinforced PPA composite to investigate the influence of drilling parameters on thrust force. HSS, TiN coated HSS and carbide twist drills with 5 mm diameter and 118° point angle are used to perform the drilling tests. The drilling tests were carried out in dry conditions on the 3-axis CNC milling machine. Three different cutting speeds such as 15, 20, and 25 m/min and feed rate such as 0.05, 1.0, and 1.5 mm/rev were selected as drilling conditions. Experimental results indicated that the thrust force increases with increasing the feed rate and in contrast the force decreases with increasing the cutting speed. Statistical Analysis of Variance (ANOVA) method was used to determine the effects of drilling parameters and interactions on the thrust force. According to the analysis, drill materials play the most important role on the thrust force. In addition, mathematical models were developed using the multi-linear regression method. The optical microscope and Scanning Electron Microscopic (SEM) images were used to examine the drilled hole surface of the PPA composite material. According the images of the drilled hole surfaces indicated the existence of matrix crack, fiber pull-out, and shearing of fibers. In order to obtain the best surface quality (in terms of delamination factor and surface roughness) and minimum thrust, it is recommended to use carbide drill bits at the lowest feed rate and highest cutting velocity cutting conditions.

Analysis of cognitive level biology exercise questions in science text books based on TIMSS frame work

In the book, exercise questions are given to discuss the content taught by focusing on these exercise questions. One of the best feature of the book is that it includes many drill materials and assignments. Books are one of the reasons for the variation in the results of Indonesian student achievement. So it is essential to conduct an analytical study of existing textbooks, especially in terms of the implementation of the cognitive level contained in the exercises.This study aimed to describe the cognitive level of biology exercise questions in science textbooks based on TIMSS 2015 frameworks. The method of this research was a descriptive research method with a qualitative approach. This study used two science textbooks with a different publisher, namely book A and book B, which the most used in South Jakarta Junior High School. The instrument used was sheets document analysis. To analyze the questions used indicators in the TIMSS framework as a guide. The result showed that biology exercise questions in book A were contained 54,45% knowing domain, 29,25% applying domain, and 16,3% reasoning domain, while in book B was contained 80,2% knowing domain, 13,43% applying domain, and 6,33% reasoning domain.

Influence of cutting conditions in drilling of CFRP/Al stacked composites

Composite laminates are gorgeous for several applications such as aerospace and aircraft structural components due to their excellent properties. Typically, mechanical drilling has been important machining operation for components made of composite laminates. Nevertheless, laminated composites are considered as hard-to-machine material which results in low drilling efficiency and drilling-induced delamination which is undesirable. This paper reviews the experiments during drilling of CFRP/Al stacked and sandwich composites. The machinability facets of these material stacks has been generally used in aerospace applications, it has been studied based on impact of drill material, drill geometries, and drilling process parameters such as speed and feed. Composite material requires high spindle speed and low feed rate, whereas drilling aluminum requires stability between speedsto feed rate. The review reports essential results and gap in the collected literature for CFRP/Al stacked and sandwich composites. A compromise between several parameters is required during drilling of multi-material stacks. The problems and solutions allied to drilling of multi-material stacks are deliberated and the directions in which the research on drilling of multi-materials may be carried out are suggested in this paper. It is intended to assist readers to acquire a thorough view on mechanical drilling of laminated composite.

Thermal effects of various drill materials during implant site preparation-Ceramic vs. stainless steel drills: A comparative in vitro study in a standardised bovine bone model.

ObjectivesThe aim of this study was to evaluate thermal effects of ceramic and metal implant drills during implant site preparation using a standardised bovine model.Material and MethodsA total of 320 automated intermittent osteotomies of 10‐ and 16‐mm drilling depths were performed using zirconium dioxide‐based and stainless steel drills. Various drill diameters (2.0/ 2.2, 2.8, 3.5, 4.2 mm ∅) and different cooling methods (without/ with external saline irrigation) were investigated at room temperature (21 ± 1°C). Temperature changes were recorded in real time using two custom‐built multichannel thermoprobes in 1‐ and 2‐mm distance to the osteotomy site. For comparisons, a linear mixed model was estimated.ResultsComparing thermal effects, significantly lower temperatures could be detected with steel‐based drills in various drill diameters, regardless of drilling depth or irrigation method. Recorded temperatures for metal drills of all diameters and drilling depths using external irrigation were below the defined critical temperature threshold of 47°C, whereas ceramic drills of smaller diameters reached or exceeded the harmful temperature threshold at 16‐mm drilling depths, regardless of whether irrigation was applied or not. The results of this study suggest that the highest temperature changes were not found at the deepest point of the osteotomy site but were observed at subcortical and deeper layers of bone, depending on drill material, drill diameter, drilling depth and irrigation method.ConclusionsThis standardised investigation revealed drill material and geometry to have a substantial impact on heat generation, as well as external irrigation, drilling depth and drill diameter.

Feasibility of tool configuration and the effect of tool material, and tool geometry in multi-hole simultaneous drilling of Al2024

The use of the multi-spindle head in drilling technology can reduce the drilling cycle time by simultaneously producing multiple holes in one go. However, selecting the appropriate drill material and geometry is critical to overcoming the challenges of multi-hole drilling to ensure high-quality holes. This study investigates the use of the multi-spindle head with different tool configuration, tool materials and tool geometry during multi-hole simultaneous drilling of Al2024. A comparison is made among the high-speed steel drills (diameter: 6 mm; point angle: 118°) and two different carbide drills (diameter: 6 mm and 10 mm; point angle: 140°) as well as the maximum and minimum possible centre to centre tool distances of the multi-spindle head. The experiments are based on measuring the thrust force, evaluating the hole quality in terms of surface roughness and burrs, the formation of chips and post-drilling tool conditions. The results showed that carbide drills with high point angle and smaller diameter generated less thrust force, produced higher quality holes, and formed less built-up edge due to short chips. Besides, tools of the multi-spindle head can be adjusted in any position without affecting the hole quality which is useful for increasing productivity at a higher rate in manufacturing industries.