Drill Material Research Articles

Grey Relational Analysis Based Optimization Of Multiple Responses in Drilling Of Carbon Fiber-Epoxy Composites

Carbon Fiber Reinforced Polymer (CFRP) composites are popularly used in aerospace industry in lieu of its high strength to weight ratio. This paper that is reported herein is an attempt to use Grey relational analysis (GRA) coupled with Taguchi Technique for the optimization of cutting parameters like cutting speed, feed rate and drill bit type with multiple performance characteristics of delamination factor, surface roughness and circularity. Machining trials involved drilling of 6 mm diameter holes on 8 mm thick CFRP plates was performed according to L27 Taguchi’s orthogonal array technique using the drill material of HSS, TiN and TiAlN. The results of the optimization technique reveals that the delamination factor, surface roughness, circularity can be simultaneous optimized using the GRA coupled with Taguchi Technique.

Effect of Cutting Speed on Thrust Force and Torque in Drilling of Glass Fiber Reinforced Polymer Based on Defects Tolerance

Glass Fiber Reinforced Polymer (GFRP) composites are being used to replace metallic materials in a wide range of industries. In the drilling of GFRP, the quality of hole is strongly dependent on process parameters. The aim of this work is to investigate the effect of cutting speed and drill material on thrust force and torque in drilling of GFRP. Drilling tests were carried out using HSS and tipped carbide twist drills and damage development during drilling was studied. The critical thrust for Iso-phthalic glass composite was found to be 60 N.

A Time Series Study of Lophelia pertusa and Reef Megafauna Responses to Drill Cuttings Exposure on the Norwegian Margin.

As hotspots of local biodiversity in the deep sea, preservation of cold-water coral reef communities is of great importance. In European waters the most extensive reefs are found at depths of 300 – 500 m on the continental margin. In Norwegian waters many of these reefs are located in areas of interest for oil and gas exploration and production. In this study drilling was carried out in the Morvin drill field in proximity to a number of small Lophelia pertusa coral reefs (closest reefs 100 m upstream and 350 m downstream of point of waste drill material release). In a novel monitoring study, ROV video surveys of 9 reefs were conducted prior, during, immediately after and >1 year after drilling operations. Behavior of coral polyps inhabiting reefs exposed to differing concentrations of drill cuttings and drilling fluids (waste drilling material) were compared. Levels of expected exposure to these waste materials were determined for each reef by modelling drill cutting transport following release, using accurate in-situ hydrodynamic data collected during the drilling period and drill cutting discharge data as parameters of a dispersal model. The presence / absence of associate reef species (Acesta excavata, Paragorgia arborea and Primnoa resedaeformis) were also determined from each survey video. There were no significant differences in Lophelia pertusa polyp behavior in corals modelled to have been exposed to pulses of >25 ppm drill cutting material and those modelled to be exposed to negligible concentrations of material. From the video data collected, there were no observed degradations of reef structure over time, nor reductions of associate fauna abundance, regardless of modelled exposure concentration at any of the surveyed reefs. This study focused exclusively on adult fauna, and did not assess the potential hazard posed by waste drilling material to coral or other larvae. Video data was collected by various ROV’s, using different camera and lighting setups throughout the survey campaign, making comparison of observations prior, during and post drilling problematic. A standardization of video monitoring in future monitoring campaigns is recommended.

Non-contact measurement and multi-objective analysis of drilling temperature when drilling B4C reinforced aluminum composites

Non-contact measurements of machining temperatures were performed with optical pyrometer when drilling particle (B4C) reinforced metal matrix composites (MMCs) with different drills. The effect of particle content, cutting speed, feed rate and tool material on the maximum drilling temperature was investigated. The drilling parameters were optimized based on multiple performance characteristics in terms of the maximum cutting temperature and tool wear. According to the results, the most influential control factors on the cutting temperatures are found to be particle fraction, feed rate and interaction between the cutting speed and particle content, respectively. The influences of the cutting speed and drill material on the drilling temperature are found to be relatively lower for the used range of parameters. Minimum cutting temperatures are obtained with lower particle fraction and cutting speed, with relatively higher feed rates and carbide tools. The results reveal that optimal combination of the drilling parameters can be used to obtain both minimum cutting temperature and tool wear.

Comparative Analysis of PCD Drill Designs During Drilling of CFRP Laminates

As a result of increased use of CFRPs in the aerospace industry, the machining of CFRPs has been studied extensively. The majority of these studies consider drilling of CFRPs, since it is the most common process in the machining of structural parts used in aircraft. It has been shown that drilling process parameters and drill geometry significantly influence the quality of holes. In this study, a systematic approach has been used to compare the influence of drill geometry on process outputs such as drilling forces, torques and tool wear. Custom-made double point angle polycrystalline diamond (PCD) drills from the same manufacturer were used in the experiments. The advantage of this approach is that it eliminates the drill material and edge preparation effects on the experimental measurements, thus helps reveal the influence of drill geometry on the process outputs.The pros and cons of different drill designs are discussed and an appropriate design is identified for the drilling of thick CFRP laminate considered in this study.

Optimization of thrust, torque, entry, and exist delamination factor during drilling of CFRP composites

Among variety of fiber-reinforced polymer (FRP) composites, the carbon fiber-reinforced plastics (CFRP) are found to be highly promising materials for widespread applications in aeronautical and aerospace industries. The delamination is a major problem associated with drilling of fiber-reinforced composite materials, which tends to reduce structural integrity of the said material. The problems in drilling, particularly the heterogeneity and anisotropy of composite materials increase delamination. Therefore, drilling of CFRP composites requires adequate attention toward achieving superior hole quality, surface finish, as well as dimensional accuracy by achieving delamination-free machining. However, drilling process is influenced by several machining parameters like drill speed, drill bit diameter, as well as drill material, feed, etc. Direct and interactive effect of aforesaid process variables influences machining performance in terms of quality of the drilled hole. Therefore, an optimal parameter setting is indeed required. To address these issues, present study aims at evaluating an appropriate drilling parameter setting toward optimization of thrust, torque, entry, and exist delamination factor during drilling of CFRP (epoxy) composites. An integrated multiresponse optimization philosophy combining principal component analysis (PCA), fuzzy inference system (FIS), and Taguchi method has been proposed here. The aforesaid optimization module has been found efficient enough to overcome inherent limitations as well as unrealistic assumptions of existing optimization approaches as documented in literature so far.

Influence of Implant Drill Materials on Wear, Deformation, and Roughness After Repeated Drilling and Sterilization

The aim of this study was to evaluate deformation, roughness, and mass loss of stainless steel, diamond-like carbon (DLC)-coated and zirconia drills after multiple osteotomies with sterilization procedures. Drilling procedures were performed using stainless steel (G1), DLC-coated (G2), and zirconia (G3) drills. All groups were divided in subgroups 1, 2, 3, 4, and 5, corresponded to drills used 0, 10, 20, 30, and 40 times, respectively. No significant differences in mass and roughness were detected among all groups and subgroups. In SEM images, all groups revealed signs of wear while coating delamination was detected in G2. Drills from G1 displayed more irregular surface, whereas cutting edges were more regular in G3. Zirconia drills presented more regular surfaces whereas stainless steel drills revealed more severe signs of wear. Further studies must be performed to evaluate the putative influence of these findings in heat generation.

Optimization of the Cutting Parameters for Drilling Magnesium Alloy AZ 91

Abstract In this study, machinability of AZ 91D magnesium alloy, which has been widely used in automotive and aircraft industries, was investigated by using HSS and carbide tools at dry cutting conditions. Taguchi's L18 (2**1 3**2) mixed model was used for the experiments. Drilling parameters such as feed rate, spindle speed and cutting tool were optimized according to the multiple responses (diametral error, circularity and surface roughness) by grey relational analysis. The effects of machining parameters and their interactions on the hole diameter, circularity and surface roughness were determined. The analysis of Taguchi and ANOVA indicated that the influence of drill material on the surface roughness of the drilled hole was high, but on the hole diameter and circularity it was low. Furthermore, the results of grey relational analysis revealed that optimal combination of the drilling parameters (0.3 mm/rev feed rate, carbide tool and 3000 rpm spindle speed) can be used to obtain the minimum diametral error, circularity error and surface roughness.

Effects of Implant Drill Wear, Irrigation, and Drill Materials on Heat Generation in Osteotomy Sites

This study evaluated the effects of drill wear on bone temperature during osteotomy preparation with 3 types of drills and compared heat production between drills. The drills used in this study were titanium nitride-coated metal, tungsten carbide carbon-coated metal, and zirconia ceramic drills. An osteotomy 11 mm in depth was formed in bovine scapular bone following the manufacturer's recommended drill sequences. Drilling was performed without irrigation and repeated 20 times; temperature was measured every 5 times. Next, 200 rounds of drilling during irrigation were performed for each drill, with temperature change monitored until round 200. Analysis of variance statistics were used for analyses of the measured data. Drilling without irrigation showed significant thermal increase at all time points compared to drilling with irrigation (P < .001). No significant difference was found between drill materials. Under irrigation, the frequency of previous drilling had minimal effects on thermal change. The repeated-measures analysis of variance revealed major thermal change at the initial time point (P < .0001), and the multiple comparison tests revealed a significant difference in temperature between the initial drills that had been used 50 or fewer times and those that had been used more than 50 times, irrespective of the drill material. The results of this study indicate that the initial drill should be changed in osteotomy preparation with irrigation after they have been used 50 times. Irrigation may be a more critical factor for the control of temperature elevation than is the drill material.

Analysis of Burr Formation and Surface Roughness in Step Drilling of AA 2024– SiC - Fly Ash Hybrid Composites

Metal Matrix Particulate Composites have become as a potential material particularly for automotive and aerospace applications. In view of the growing engineering applications of composites, the machining parameters must be optimized to achieve the good surface quality, reduced tool wear and cutting forces. In this paper, the effect of the feed, spindle speed and step drill material on the exit burr height and surface roughness have been analyzed. Experimental study was conducted for Al- SiC – fly ash hybrid composites which are fabricated through the stir casting method. Optimum drilling parameters were identified by employing Taguchi method and ANOVA techniques. The results were validated by confirmation test. Results revealed that feed, spindle speed and step drill materials are the most significant factors on the burr height and surface roughness. Dynamometer was used to evaluate the thrust that was being applied to the work piece when it was drilled.

Analysis and optimization of drilling parameters for tool wear and hole dimensional accuracy in B4C reinforced Al-alloy

Cutting parameters were evaluated and optimized based on multiple performance characteristics including tool wear and size error of drilled hole. Taguchi's L27, 3-level, 4-factor orthogonal array was used for the tests. It is shown that generally abrasive wear and built up edge (BUE) formation were seen in the tool wear, and the corner wear was also of major importance. Flank wear of the cutting tool was found to be mostly dependent upon particle mass fraction, followed by feed rate, drill hardness and spindle speed, respectively. Among the tools used, TiAlN coated carbide drills showed the best performance with regard to the tool wear as well as hole size. Grey relational analysis indicated that drill material was the more influential parameter than feed rate and spindle speed. The results revealed that optimal combination of the drilling parameters could be used to obtain both minimum tool wear and diametral error.

Experimental investigation and multi-objective analysis on drilling of boron carbide reinforced metal matrix composites using grey relational analysis

In this study, machining parameters were evaluated and optimized with grey relational analysis in drilling B4C reinforced metal matrix composites (MMCs) produced by powder metallurgy. HSS, TiAlN coated and uncoated cementide carbide drills were used under dry cutting conditions. The drilling parameters such as feed rate, spindle speed, drill material and wt.% of B4C particles were optimized based on multiple performance characteristics including thrust force, torque and surface roughness. The experimental study showed that increasing the weight fraction of the B4C resulted in a considerable increase in the thrust force. Furthermore, average surface roughness of drilled hole decreased with increasing particle content for carbide tools and increased for HSS tools. Among the tools used, TiAlN coated carbide drills showed the best performance with regard to the surface roughness. Moreover, ANOVA analysis indicated that the most effective factor on grey grade was found to be weight fraction and followed by drill material, feed rate and spindle speed, respectively.

Modeling and analysis of performances in drilling hybrid metal matrix composites using D-optimal design

The present paper deals with the modeling and analysis of machining responses such as the thrust force, surface roughness, burr height, and tool wear in the drilling of hybrid metal matrix composites using carbide, coated carbide, and polycrystalline diamond drills. Experiments are conducted on Al 356 aluminum alloy reinforced with silicon carbide of size 25 μm and mica of size 45 μm. Machining parameters such as spindle speed, feed rate, and weight percent of silicon carbide are chosen as the numerical factors; the drill material is considered as the categorical factor. An experimental plan of a four-factor (three numerical plus one categorical) D-optimal design based on the response surface methodology is employed to carry out the experimental study. The results indicated that the predicted values through the developed model are well in agreement with the experimental results. The results also indicated that the method used is effectively applied for the modeling and analysis of drilling parameters in drilling hybrid metal matrix composites.

Influence of the drill material and method of cooling on the development of intrabony temperature during preparation of the site of an implant

Our aim was to evaluate the intrabony friction heat produced by implant drills, using different drill materials and methods of cooling. Four pilot drills and 4 form drills were used. The following combinations of drill material and cooling supply were tested: steel and external cooling; steel and internal cooling; steel coated with zirconium nitride and external cooling; and zirconium oxide and external cooling. The handpiece that supported the drill was fixed in a lifting device. Specimens of bovine ribs were fixed below the handpiece, and the drill speed was set to 1200rpm. The vertical force was adjusted to 1kg for pilot drills and 0.5kg for implant drills. Intrabony temperature during drilling was measured at depths of 4, 8, and 12mm parallel to the drill, and the depth was limited to 13mm. There were no significant differences in heat generation between the drill materials (p>.05), but the differences between groups with internal or external cooling supplies were significant (p≤.05). The method of cooling affected the development of the intrabony temperature during preparation of the site of the implant, but the drill material seemed to play no particular role.

3D Topography for Drilled Surfaces

Nowadays more and more scientific papers deal with drilling. The drilling process has been used for more than 5000 years and the development of conventional drills is more than 200 years old. In recent years there have been limited changes to the drill design but considerable improvements have been made in the selection of drill materials, drill coatings, flute design and cutting fluid guiding methods. The paper briefly describes the development of surface characterisation including its current 3D capability. It shows how selected parameters can assist with drill process analysis and how this can be supported through the introduction of the planned new ISO International Standard for 3D Surface characterisation. The paper is supported by a sample drilling test to demonstrate the power of the proposed analysis.

Experimental investigation on drilling temperature of composites

Drilling is one of the most usual processes for manufacturing carbon fibre reinforced plastic (CFRP) composite components, but this kind of composites are difficult to machine. Cutting temperature is a basal problem of machining mechanism, however, the research literatures on cutting temperature of composites, in particular, under the condition of high speed machining, have been found seldom. This paper introduces an experimental investigation on drilling temperature of drilled hole wall of CFRP composites by means of inserted thermocouples. The investigation results indicate that when drilling CFRP composite with solid carbide drills in low-medium speed region and high speed region, the effects of cutting speed and feed on cutting temperature have different trends; work piece thickness and drill material have notable effects on drilling temperature but the drill diameter does not.

3D topography for environmentally friendly machined surfaces

Nowadays more and more scientific paper deals with drilling. In recent years there have been limited changes to the drill design but considerable improvements have been made in the selection of drill materials, drill coatings, flute design and the cutting fluid guiding methods. All of these improvements have been introduced to improve the surface finish of the drilled hole, reduce the energy during drilling process and to reduce ecological damage to the cutting fluids, which carry away heat and debris from the cutting zone. The paper briefly describes the development of surface characterization to its current 3D capability. It shows how selected parameters can assist with drill process analysis and how this can be supported through the introduction of the planned new ISO International Standard for 3D surface characterization. The paper is supported by a sample-drilling test to demonstrate the power of the proposed analysis.

Tool wear and failure in the drilling of stainless steel

Three studies on the tool behaviour in the cutting of stainless steel, which is a work-piece material with a relatively poor machinability, are presented. In the first study, three cutting fluids are evaluated, in the second two different high-speed steel (HSS) tool materials are compared; one of them as uncoated and as TiN-coated. Finally, the suitability of some on-line measurements for tool-monitoring methods are studied. The differences in the behaviour of three cutting fluid emulsions observed in the drilling of stainless steel with the tools of high speed steel were significant enough to facilitate ranking of the fluids. The test method presented may be adapted as a method for cutting fluid testing in industry. The main result of the tests with different drill materials was that more expensive bright drills with or without TiN-coating had a lower productivity than the less expensive black drills. This is due to the low feed rate values causing a strong decrease in the chip flow rate. The on-line measurement results show that all the quantities measured remain at an almost constant level during the entire tool life-time until the hole in which the drill totally fails. Therefore it is impossible to successfully apply these measurements as tool monitoring methods, stopping the machining after the increase in one or several signals above a certain limit value before an actual tool failure. However, the measurements can be used for tool breakage detection where the machining operation is interrupted after a tool breakage.

Application of Self-Learning for Tool Failure Diagnosis in Robotic Drilling System

The effort in monitoring tool condition for fully automatic drilling processes has resulted in the development of an intelligent drilling machine to work with industrial robots. This computer-controlled drilling machine has five built-in sensors. Based on the pattern recognition of sensor outputs with sets of algorithms, an intelligent diagnostic system has been developed for on-line detection of and pin-pointing of anyone of the nine drill failures: chisel edge wear, margin wear, breakage, flank wear, crater wear, lip height difference, corner wear and chipping at lips. Many inherent factors affecting the criteria for the judgement of drill wear/breakage, such as drill size, drill material, drill geometry, workpiece material, cutting speed, feed rate, material microstructure, hardness distribution, etc. is avoided by implementing, a self-learning system.

Study of a High Performance Drill Geometry

Summary To reduce the high thrust force generated in the cutting action of the “chisel edge” that is the intersection of the two conical flank surfaces of the most commonly used “conical ground” drill point geometry, alternatives have been devised in the past such as the “three rake” and the “spiral point” geometries. A new point geometry called the “circular center edge” has been introduced by one of the authors. T. Hosoi, that has an S-shaped cutting edge generated by the point thinning and no chisel edge. This new point geometry may be used both on the regular drill stem having the traditionally narrow web and on the newly designed wide-webbed drill stem. The latter of the High Speed Steel (HSS) drill material is now commercially available with the TIN surface coating. Investigation reported herewith have been conducted to evaluate experimentally the force, wear, life, and chip control performances of the new circular center edge point geometry provided on HSS drills of the regular and wide-webbed designs, in comparisons with conventional alternatives, and to understand the characteristic mechanisms that bring about the superior cutting performance. Also included as a part of the objectives is to evaluate the effect of TIN surface coating on cutting performances.