Drill Material Research Articles

The effect of ceramic and conventional implant drill materials on heat generation in osteotomy sites

The effect of ceramic and conventional implant drill materials on heat generation in osteotomy sites

An experimental investigation of thrust force, delamination and surface roughness in drilling of jute/carbon hybrid composites

Purpose This paper aims to deal with the influence of cutting parameters on drill thrust force, delamination and surface roughness in the drilling of laminated jute/carbon hybrid composites. Design/methodology/approach The hybrid composites were fabricated with four layers of fabrics, which are arranged in different sequences using the hand-layup technique. Drilling experiments involved drilling of 6 mm diameter holes on the prepared composite plates using high-speed steel and solid carbide drill materials. Analysis of variance was used to find the influence, percentage contribution and significance of drilling parameters on drilling-induced damages. Scanning electron microscopy analysis was also conducted to understand the fracture behavior and surface morphology of the drilled holes. Findings The experimental study reveals that the most significant effect was the feed rate influenced the drill thrust force and the drill speed influenced both delamination factor and surface roughness of hybrid fiber-reinforced composites. From observations, the suggested combination for drilling jute/carbon hybrid composites is carbide drill, spindle speed of 1,750 rpm and feed of 0.03 mm/rev. Originality/value The new lightweight and low-cost hybrid composites were developed by hybridizing jute with carbon fabrics in the epoxy matrix with interplay arrangements. The influence of cutting speed and feed rate on delamination damage and surface roughness in the drilling of hybrid composites have been experimentally evaluated.

Analytical and experimental investigation of the parameters in drilling flax/poly(lactic acid) bio-composite laminates

Understanding the influences of drilling parameters on machinability characteristics of NFRCs is of value to both academia and manufacturing industries. The present work investigates drilling-induced delamination and hole quality of fully biodegradable flax/poly(lactic acid) composites in response to cutting speed, feed rate, drill diameter, and drill material. Among various types of drilling-induced damages, exit-ply delamination is found to be the most destructive damage and cutting thrust force is identified as the main reason. The experimental results revealed that thrust force is highly dependent on drilling parameters where feed rate and drill material were found to be the most influential parameter on it. The choice of drill bit in terms of diameter and material has a considerable effect on the machinability. Drilling with HSS drills resulted in nearly 60% lower thrust force and better hole quality compared to that with carbide drills. While the size of delamination damage in the samples drilled at the lowest feed (0.02 mm/rev) sounds to be unrelated to cutting forces, the overall trend confirms that decreasing the value of thrust force leads to lowering delamination damages. Hence, an effective strategy in avoiding such undesirable defects is calculating the critical thrust force below which delamination is negligible. An analytical model is developed based on the theory of virtual work to determine the critical thrust force at delamination onset. Through validating with experimental data, the proposed model agrees better with a more accurate prediction than existing models.

Analysis of Surface Roughness and Burr Height in Drilling of Aluminium Matrix Composites using Taguchi Technique

The present research involves the opportunity of utilising the signal to noise (S/N) ratio analysis to set machining factors in the drilling of aluminium alloy LM6-Fly ash composites (AMCs). The purpose of this research is to understand, during drilling of AMCs, the consequences of variables, feed rate, spindle speed, drill material and amount of reinforcing material on surface roughness and burr height. AMCs are formed with LM6 (Al alloy) as continuous component via the stir casting process and fly ash as reinforced content. The Taguchi design strategy is a widely accepted method which is used to produce quality products that require minimum commitment. Likewise, the L27 orthogonal array is used for conducting experiments. The response table, response graphs and analysis of variance (ANOVA) illustrate the prospective atmosphere and the impacts of input process variables. Taguchi technique considerably enhances the drilling operation.

Multi-objective drilling parameter optimization of hybrid metal matrix composites using grey relational analysis

The aim of this research work is to investigate the effect of the process parameters on the thrust force and burr height during the drilling of hybrid metal matrix composites. Stir casting was used to manufacture hybrid MMCs. Fly ash and boron carbide were the reinforcements used in the manufacture. Tests were carried out in a computer-controlled vertical machining center together with a cutting tool dynamometer to measure the thrust power. The experiments were conducted based on a L 27 orthogonal array. Multi-response optimization was performed using grey relational analysis for obtaining minimum thrust force and minimum burr height. The optimum level of input factors namely feed, spindle speed, drill material and reinforcement percentage was defined for low thrust force and low burr height. Confirmation experiments showed that the drilling parameters in the drilling of hybrid metal matrix composites are precisely optimized.

In Vitro Study on Bone Heating during Drilling of the Implant Site: Material, Design and Wear of the Surgical Drill.

Objective: An in vitro study was made to compare mean thermal variation according to the material, design and wear of the surgical drills used during dental implant site preparation. Material and methods: Three study groups (stainless steel drills with straight blades; diamond-like carbon-coated drills with straight blades; and diamond-like carbon-coated drills with twisted blades) were tested to compare material, design and wear of the surgical drill in terms of overall mean values (complete sequence of drills) and specific mean values (each drill separately). The groups comprised four drills: initial, pilot, progressive and final drill. Implant site configuration was performed through an intermittent and gradual drilling technique without irrigation at 800 rpm in standardized synthetic blocks. Maximum axial loading of two kilograms was controlled by an automatic press. Each surgical drill was submitted to 50 drillings and was sterilized every five uses. A thermographic camera analyzed the mean thermal changes. The software-controlled automatic press kept systematic drilling, axial loading and operational speed constant without any human intervention. Student’s t-test, ANOVA and multiple linear regression models were performed. The level of significance was 5% (p = 0.05). Results: The overall mean comparison between the stainless steel and diamond-like carbon-coated materials showed no statistically significant differences (p > 0.05), though specific mean comparison showed statistically significant differences between the drills of the different groups (p < 0.05). The twisted blades exhibited less overall and specific mean thermal variation than straight blades for the progressive and final drills (p < 0.01). In addition, the initial and pilot drills showed a greater mean thermal change than the progressive and final drills. The mean thermal variation was seen to increase during the 50 drillings. Conclusions: Within the limitations of this study, it can be concluded that the drill material did not significantly influence the overall mean thermal variation except for the pilot drill. The drill design affected overall and specific mean thermal variation since the twisted blades heated less than the straight blades. The initial and pilot drills increased the specific mean thermal variation with respect to the progressive and final drills. In addition, all drills in each group produced a gradual increase in mean temperature during the 50 drillings.

Drilling of Hybrid Aluminum Matrix Composites using Grey-Taguchi Method

Drilling is a very important hole making process. It is very much useful for assembly of parts. Incorporation of hard ceramic particles into the matrix of metallic composites made them difficult to machine. So, it becomes inevitable to optimize the drilling parameters. The foremost objective of this research work is to fabricate Hybrid Aluminium Matrix Composites(AMCs) of LM6/B4C/Fly Ash with 3%, 6% &amp; 9% by weight percentages of both reinforcements, equally using stir casting technique. The next objective is drilling of composites with feed, speed, drill and percentage of reinforcement as input process parameters at three levels each by Taguchi’s Design of Experiments approach. The final objective is to optimize the drilling process parameters for achieving low thrust force, low surface roughness and minimum burr height using the multi-objective Grey Relational Analysis. Results reveal that drill material plays a major role, being closely followed by feed and speed.

Infrared Thermographic Evaluation of Temperature Modifications Induced during Implant Site Preparation with Steel vs. Zirconia Implant Drill.

Background: The heat produced during implant site osteotomy can potentially interfere with and influence the osseointegration process of a dental implant. The objective of this in vitro investigation was to measure the temperature changes during simulated osteotomies in bovine rib bone. The measurements were made at the apical area of the osteotomies with steel implant drills compared to zirconia implant drills. Methods: Steel cylindrical drills (2 mm) and zirconia cylindrical drills (2 mm) were evaluated in vitro using bovine rib bone for a total of five groups based on the number of osteotomies performed with each drill: 10, 20, 40, 90, or 120 osteotomies. Bone and apical drill temperatures were measured by means of infrared thermography. The drilling time for each osteotomy was measured for each preparation. Results: Statistically significant differences were found in the temperature measurements in the bone and apical portion of the drills between the study groups (p < 0.05). A statistically significant difference was observed for drilling time preparation between steel cylindrical drill (2 mm) and zirconia cylindrical drills (2 mm) (p < 0.01). Conclusions: The drill material has an impact on the temperature changes that occur at its apical portion during bone preparation for implant placement.

Evaluation of surface roughness in drilling particle-reinforced composites

Aluminum matrix composite materials being used in different sectors including automobile, aerospace, defense, and medical and are currently displacing unreinforced materials with their superior mechanical properties. The metal removal process of drilling is widely used in many structural applications. This study experimentally investigates the drilling characteristics of silicon carbide (SiCp)-reinforced Al 7075 composites produced by stir casting method. Also, two different drill materials with high-speed steel (HSS) and titanium nitride (TiN)-coated HSS carry out in drilling operation. The effect of operational parameters such as cutting speed and feed rate and materials parameters such as weight fraction of reinforcement and cutting tools on the surface roughness of drilled holes were evaluated in the drilling operations. The results of the drilling test indicate that the feed rate and cutting speed have a very strong effect on the surface roughness of matrix alloy and composite materials. The surface roughness ( Ra) values increased with increasing the feed rate and decreased with increasing the cutting speed. Under 0.10 mm/rev and 20 m/min drilling conditions and using HSS drill, surface roughness values for matrix, 5% SiC-, 10% SiC-, and 15% SiC-reinforced composites, were obtained 2.57, 2.59, 2.61, and 2.64 µm, respectively; besides, using TiN-coated HSS drill, surface roughness values were obtained 1.60, 1.63, 1.64, and 1.66 µm, respectively. An increase in the weight fraction of the abrasive SiC particle resulted in a very crucial deterioration quality of the drilled hole. TiN-coated HSS drills better performance exhibits than uncoated HSS drills for all the drilling operations about surface roughness properties. Short chip formations observed both the matrix alloy and the composite materials for two different drills in the drilling operations.

Drilling parameter optimization of metal matrix composites (LM5/ZrO2) using Taguchi Technique

Metal matrix composites (MMCs) contain hard ceramic particles are difficult to machine due to their abrasive nature. It is necessary to develop a suitable technology for the efficient machining of MMCs because of their potential widespread usage. An attempt is made to find out the best machining parameters in the drilling of (LM5/ZrO2) using Taguchi Technique. A novel composite made of LM5 aluminum alloy reinforced with Zirconia with three different weight percentages (3, 6 & 9%) was fabricated by stir casting process. In the fabricated composite material the influence of input parameters like feed rate, spindle speed, drill material and percentage of reinforcement on the thrust force is determined by performing drilling operation in CNC machine using L27 Orthogonal array. The analysis was done using Taguchi’s Signal-to-Noise ratio analysis. Response graphs are used to analyze the response characteristics of the parametric results. Analysis of Variance (ANOVA) was performed to classify the relevant variables and measure their effect on response characteristics. Spindle Speed and Feed rate are the most important input parameters for obtaining minimum thrust force.

Effect of Drilling Process Parameters on Surface Roughness of LM6/B4C Composites

Metal matrix composites are a new course of materials with superior properties to those of the components. Such materials ' machining is distinct from that of traditional materials. So the optimization of machining process parameters becomes inevitable. By applying Taguchi's Signal-to-Noise ratio method, this paper examines the effects of drilling process parameter such as feed, spindle speed, drill material and percentage reinforcement on the drilled hole’s surface roughness. Variance analysis was used to evaluate each system parameter's contribution to surface roughness. The composites were manufactured by stir casting technique using aluminium alloy (LM6) as matrix material and boron carbide particulates at 3%, 6% and 9% by weight as material for the reinforcement. There are four factors investigated each at three levels, so 34 which implies 81 experiments has to be conducted, but by using Design of Experiments approach 27 experiments were conducted using L27 orthogonal array The minimum surface roughness measured for the hole was 1.08 μm at combination of 3000 rpm spindle speed, 50 mm/min feed rate, 3% reinforcement and Carbide drill.

Optimization of drilling process parameter during of drilling of AISI 317L stainless steel

Present study focuses on optimization of drilling process parameters during machining of AISI 317 L stainless steel workpiece on Vertical Machining Centre (VMC). To achieve higher dimensional accuracy, maximum circularity and minimum surface roughness, the best optimal level of input process parameters has to be chosen carefully. Hence, in this study cutting speed has been considered at three levels 500, 800 and 1100 rpm and feed rate at 50, 75 and 100 mm min−1 levels. Further, two different drill materials were considered for experimentation namely, HSS and CARBIDE. Experiments were designed using Taguchi mixed orthogonal array L36 as two factors were at three levels and one factor was at two levels. For designing experimental layout and further analysis MINITAB statistical software was used. Based on experimental results and analysis it was observed that cutting speed of 1100 rpm, feed rate of 50 mm min−1 and HSS drill materials resulted in optimal values of dimensional accuracy, circularity and surface roughness. The Monte carlo simulation sensitivity charts illustrated that the drill material is a most effective parameter for the Accuracy 39.9% and for Circularity 49.1% and feed is a most effective parameter for Surface Roughness 54.8%.

Measurement and analysis of thrust force and delamination in drilling glass fiber reinforced polypropylene composites using different drills

Fiber Reinforced Plastic (FRP) composites are widely used in various engineering fields and applications. FRPs were initially fabricated using thermoset polymers owing to ease of manufacturing. Of late, FRP based thermoplastics is gaining importance due to various factors such as impact resistance, recycling, and an absence of any chemical reaction. In the present investigation, Glass Fiber Reinforced Plastic (GFRP) laminates of woven glass fabric reinforcements with Polypropylene (PP) thermoplastic matrix is manufactured using film stacking technique. To analyze the performance in machining, drilling studies are carried out using a 6 mm diameter twist drill of High Speed Steel (HSS) drill, tipped carbide and solid carbide drill. The drilling experiments are conducted on a CNC Vertical Machining Centre (VMC) to measure and assess the drilling induced thrust force and the respective exit delamination. The drill spindle speed and feed rate are considered as process parameters. To correlate the process parameters with responses, the regression models are developed. The results indicate that the most significant control parameter for process responses and also it shows the developed regression models are highly reliable. The influence of drill materials on the performance of the responses is also discussed in detail.

Drilling of In-Line Compression Molded Jute / Polypropylene Composites

ABSTRACT Compression molding can be used to fabricate polymer composites with long-, short- and intermediate-length fibers. In-line compression molding reduces cycle time through a single-step process in which fibers are directly introduced into the molten polymer in the extruder which is directly molded. It eliminates additional stage of heating and processing and hence is preferred in industries. This paper deals with the influence of fiber type and direction, coupling agent, spindle speed, feed rate, drill material and diameter on delamination and thrust force in in-line compression molded jute/polypropylene. Thrust force was greater in the specimens with 30 wt% long fiber, in longitudinal direction processed without coupling agent and drilling with high-speed steel drill. Delamination was severe in chopped fiber composites, in longitudinal direction processed without coupling agent and with cobalt-high-speed steel tool. Effect of speed, feed, drill diameter and tool material was analyzed using ANOVA, signal-to-noise ratio and Grey relational analysis. Residual tensile strength reduced by 24.7% in the composites drilled using the optimized parameters.

Micro-drilling of AISI 1045 steel using a centering micro-drill

Micro-hole drilling is experiencing a very rapid growth in precision production industries. The micro-drills play a critical role in manufacturing industry. There are many factors which influence the micro-drill performance including the drill point geometry, the drill material, and the workpiece material, among which the most fundamental factor is the drill point geometry. In this paper, a new micro-drill point geometry, termed the centering micro-drill point, is developed. A mathematical model for this new micro-drill point has been established. Micro-drilling tests in AISI 1045 steel are performed with different cutting conditions. By contrasting centering micro-drill and planar drill point micro-drill, the cutting performance of the centering micro-drill has been investigated. The results showed that, when the cutting speed is 35 m/min and the feed rate is 44 mm/min, the thrust force of the centering micro-drill reduces by 21.7% than that of planar micro-drill and the drilling hole amounts increase by 13.5%. The roundness of the thirtieth hole drilled by centering micro-drill is 1.02, and it is 1.08 by planar micro-drill; the centering micro-drill has better position accuracy than planar micro-drill, and further gets good size and shape accuracy.

Tribological behaviors of the diamond films sliding against the T800/X850 CFRP laminates

The frictional resistance and hole quality when drilling CFRP laminates are associated with tribological behaviors of drill materials. In the present study, tribological tests are conducted on various diamond coated WC-Co balls sliding against T800/X850 CFRP laminates with [-45/90/45/0]s lay-up, under specific conditions similar to the drilling process. It is firstly found that the coefficient of friction (COF) varies with the sliding direction. The boron-doped micro-crystalline and nano-crystalline composite diamond (BDMC-NCCD) film synthesized by optimized growth durations (9 h for BDMCD and 2.5 h for NCD) presents relatively low COF and wear rate (0.193 and 0.97 × 10−8 mm3/N m, when the sliding velocity and normal load are respectively 1.5 m/s and 5.0 N), as well as high critical load for the film peeling (35 N), owing to the nano-sized diamond grains and low surface roughness (Ra~125.09 nm measured by the confocal microscopy) of the surface NCD layer, and high hardness and favorable adhesion of the underlying BDMCD layer. Besides, influences of the sliding velocity and normal load are clarified, indicating that the COF increases with the load, but decreases with increasing the velocity, while the wear rate increases with either the load or velocity.

Optimization and sensitivity analysis of drilling parameters for sustainable machining of carbon fiber–reinforced polypropylene composites

Machining processes face two major challenges: sustainability and cleaner production. However, the effective utilization of tool and methods of lubrication system in sustainable machining have been dealt in depth in earlier investigations. This work aims to optimize sustainable machining parameters in drilling process for recyclable carbon fiber-reinforced polypropylene (CFR-PP) composites. This work is focused on modeling and optimization of drilling parameters for sustainable machining with respect to thrust force and torque for CFR-PP composites. The response surface method based on D-optimal design of experiments is used for modeling and optimization with variables such as drill spindle speed and drill feed rate as numerical factors, which includes different drill material as the categorical factor. The influences of tool materials on the sustainable machining are also discussed in detail. Further, the sensitivity analysis is applied to compare the relative impact of control parameters (spindle speed, feed rate, and drill materials) on thrust force and torque. The scanning electron microscope images are used for analyzing the morphologies of drilled surfaces.

Evaluation of user impressions, micromorphological bone surface properties and material attrition by three generations of osteotomy methods

Background: Ultrasonic-driven osteotomy is associated with a safe processing method and has broadened the daily used armamentarium of maxillofacial surgeons. As further development, sonic-based osteotomy method was newly introduced. Objectives: To analyse user impressions micromorphological bone changes and material attrition by sound-, ultrasound and conventionally driven osteotomy. Methods: In fresh bovine ribs conventional — (Lindemann-drill H254E, Brasseler GmbH and Co. KG, Lemgo, Germany), sound – (saw SFS 101 Brasseler GmbH and Co. KG, Lemgo, Germany) and ultrasound (saw OT7S-4, Piezosurgery, Mectron Medical Technology, Carasco, Italy) guided osteotomies were performed by novice (N) and expert (E) practitioners with different irrigation volumes. Bone surfaces were analysed by (environmental) scanning electron microscopy. Energy dispersive spectroscopy was carried out to detect possible material attrition. Findings: Sonic system was significantly slowest with worst noise impact subjectively (N: 2.9, E: 3.2) and objectively (92.9 dB; SD 7.1). However, both user groups improved significantly in a second run (N: 7.9, E: 7.6). Bone structure was mostly preserved after sonic and ultrasonic assisted preparation. By contrast, using the conventional technique showed significant changes especially with regard to the cancellous layer of the bone with incorporation of abundant bone debris. None of the tested treatment procedures resulted in relevant attrition of drill materials. Conclusion: The practitioners had a promising experience with ultrasonic and specially the sonic system. In contrast to conventional osteotomy, osseous micromorphology was mostly preserved by sonic and the piezoelectric method. This could have a positive effect on bone healing and osseointegration and should be investigated in future studies.

Thermal Variation During Osteotomy With Different Dental Implant Drills: A Standardized Study in Bovine Ribs.

This study evaluated thermal variation (heat generation) by dental drills of similar geometries, made from different materials, during performance of 450 standardized osteotomies in bovine ribs to simulate implant site preparations. Each of the 3 groups-steel with a diamond-like carbon coating (SG), experimentally surface-treated steel (EG), and aluminum-toughened zirconium ceramic (ZG)-included 3 drills, distributed across 6 subgroups. An implant motor provided torque, rotation, and irrigation for 50% of subgroups. In preparations drilled to 5 mm under irrigation, the number of osteotomies, material, and diameter did not influence thermal variation (ΔT); when drilling to 13 mm, the greatest ΔT occurred in EG (2.8°C). When drilling to 5 mm without irrigation, drill material influenced mean temperature; when drilling to 13 mm without irrigation, the greatest ΔT (5.5°C) occurred in EG. The highest temperature was observed in SG (79.6°C). After 50 uses, the greatest ΔT occurred in EG and the ∅3.0-mm drill exhibited the highest mean and peak temperatures. Temperatures were influenced by irrigation, number of uses, depth, drill diameter, geometry, and material; however, mean values were within physiological limits.

Investigation and optimization of machining parameters in drilling of carbon fiber reinforced polymer (CFRP) composites

PurposeThis paper aims to attempt to use grey relational analysis (GRA) coupled with Taguchi technique for the optimization of machining parameters (cutting speed, feed rate and drill bit type) with multiple performance characteristics of delamination factor, surface roughness and circularity in drilling of carbon fiber-reinforced polymer (CFRP) along the fiber direction.Design/methodology/approachMachining trials involved drilling of 6-mm diameter holes on 8-mm-thick CFRP plates was performed according to L27 (313) Taguchi’s orthogonal array technique using the drill material of high speed steel (HSS), Titanium Nitride (TiN) and Titanium Aluminium Nitride (TiAlN). Analysis of variance has been used find the effect, percentage contribution and significance of the process parameters, namely, cutting speed, feed rate and drill bit type.FindingsThe Taguchi technique is combined with the GRA to find the optimum process parameter which minimizes the delamination factor, surface roughness and circularity within the range of parameters investigated. The effective implementation of the hybrid approach helps to produce quality and defect free holes.Originality/valueExperimental investigation on delamination factor, surface roughness and circularity in drilling of CFRP along the fiber direction using Taguchi-GRA was seldom reported.