Twist Drill Research Articles

Twist drill aspiration of chronic subdural hematoma at the Ignace Deen hospital of Conakry

Bedside percutaneous twist drill aspiration (TDA) is described as a surgical method of management of Chronic subdural hematoma (CSDH) and appear to be a reasonable approach in low medical resources environment. We report the results of TDA of CSDH in a single tertiary centre in Conakry Republic of Guinea in West Africa, for the period March 2015 to October 2017. The charts and medical record of 38 cases of CSDH treated with TDA were collected retrospectively, with a mean follow-up of 84.2 days. The outcome data assessed were neurologic status evaluated by the follow-up Markwalder grading scale (MGS: 0=normal to 4=coma), recurrence, infection and mortality. The Male-Female ratio was 1.3:1. Mean age at diagnosis was 78.2+/-12 years. Traumatic brain injury (TBI) was identified as causal in 28.2% of cases studied. All patients were operated on under local anesthesia and had a postoperative drain left in place for 3 days. The mean postoperative MGS was 1.06, up from a mean preoperative MGS of 3.7. Two cases of recurrence occurred subsequent to TDA causing death and three other patients died from unknown causes during the follow-up period. No cases of post-operative infection were diagnosed during the follow-up. Our study shows that Bedside TDA appears to be a suitable alternative to burr hole craniotomies in urgent cases of CSDH in the low socio-economic setting, where a surgical theatre is not always available.

Drilling of a bidirectional jute fibre and cork-reinforced polymer biosandwich structure: ANN and RSM approaches for modelling and optimization

The present study examined the effects of drilling parameters such as spindle speed (N), feed rate (f), diameter of the tools (d) and drill geometry such as twist drills (HSS-TiN) and brad and spur drills (BSD) used on delamination damage in a biosandwich structure consisting of an epoxy matrix reinforced with bidirectional jute fibres and cork (JFCE). Response surface methodology (RSM) and artificial neural networks (ANNs) were exploited to evaluate the influence and interaction of the cutting parameters on the delamination factor (Fd) at the output during drilling. In addition, several optimization methods, such as desirability-based RSM, the genetic algorithm (GA) and the fmincon function, were applied to validate the optimal combination of cutting parameters (f, N and d) in the structures studied in biosandwiches during this research. According to the experimental results, severe damage was indeed observed with the BSD tool (Fd = 1.684) compared to the HSS-TiN tool (Fd = 1.555) for the same cutting conditions. To obtain the minimum Fd, the optimum conditions obtained by GA were respectively 1397.54 rev/min, 51.162 mm/min and 5.981 mm for HSS-TiN for f, N and d.

Osseodensification Versus Subtractive Drilling Techniques in Bone Healing and Implant Osseointegration: Ex Vivo Histomorphologic/Histomorphometric Analysis in a Low-Density Bone Ovine Model.

The aim of this study was to qualitatively and quantitatively assess the effect of osteotomy preparation by conventional, subtractive, or osseodensification instrumentation on osteotomies, treated with or without endosteal implants, and healing capacity. Seven sheep were used, and 56 osteotomies were made in the left and right ilium of the sheep (n = 8/sheep [4 per side/time point (3 and 6 weeks)]). Two different instrumentation techniques were used: (1) conventional/regular drilling in a three-step series of a 2-mm pilot and 3.2-mm and 3.8-mm twist drills and (2) osseodensification drilling with a Densah Bur 2.0-mm pilot and 2.8-mm and 3.8-mm multi-fluted tapered burs. Drilling was performed at 1,100 rpm with saline irrigation. Qualitative histomorphometric evaluation of the osteotomies after 3 and 6 weeks did not indicate any healing impairment due to the instrumentation. In all samples, histologic examination suggested bone remodeling and growth (empty and treated with an implant), irrespective of preparation technique. Osteotomies prepared using the osseodensification instrumentation showed the existence of bone chips autografted into the trabecular spaces along the length of the osteotomy wall. The osseodensification group yielded higher osseointegration rates, as distinguished through qualitative assessment, bone-to-implant contact, and bone-area-fraction occupancy, indicating an increased osteogenic potential in osteotomies prepared using the osseodensification technique.

Modeling of drilling process of GFRP composite using a hybrid random vector functional link network/parasitism-predation algorithm

Non-laminated glass fiber-reinforced epoxy composites (GFREC) have shown promising applications in various engineering fields. In this study, an experimental investigation followed by artificial intelligent modeling is carried out on the drilling of GFREC under two cooling conditions, namely internal and external. The damage factor of the drilled holes and the temperature of the drill tip were considered as main process responses. The experiments were conducted under different combinations of feed, spindle speed and coolant pressure. All holes were drilled using fresh tungsten carbide twist drills coated by TiN/TiAlN layer. A fine-tuned random vector functional link network (RVFL) model incorporated with a new optimizer called parasitism-predation algorithm (PPA) was developed to model the drilling process. PPA acts as an advanced metaheuristic optimizer to obtain the best model variables of RVFL. The developed model was compared with the stand-alone RVFL as well as the fined-tuned RVFL using particle swarm optimizer (PSO). RVFL-PPA outperformed other models in terms of coefficient of determination, root mean square error and other measures. The coefficient of determination of RVFL-PPA for different responses and cooling conditions ranges between 0.995 and 1.

Research on drilling CFRP laminate with a thin woven glass fiber surface layer using plane rake–faced twist drill

The delamination produced during drilling CFRP will affect its structural strength seriously. Delamination is closely related to the thrust force during drilling, which is closely related to the tool, so it is particularly important to choose the tools with appropriate geometric structure. Many scholars used tools with different geometric structure to drill CFRP, and then conducted the drilling damage analyses and drilling mechanism researches. It finally came to a conclusion that a drill with a special structure had certain advantages compared with a common twist drill in the drilling process. A new type of plane rake–faced twist drill was used to drill the CFRP laminate with a thin-woven glass fiber surface layer. Experimental results showed that the plane rake–faced twist drill along cutting edge had a constant reference rake angle value, which caused the plane rake–faced twist drill generated smaller thrust force and less drilling damage than the common twist drill. As the reference rake angle of the plane rake–faced twist drill increased, the thrust force and drilling damage decreased. It was revealed the inhibition of the thin-woven glass fiber surface layer on the drilling damage at entrance and exit. Finally, it was proposed that when the plane rake–faced twist drill was used to drill CFRP laminate with a thin-woven glass fiber surface, 46° reference rake angle should be selected.

Point angle effect in drilling of syntactic foams

Borosilicate glass microballoons (GMBs) of three different density grades are dispersed in epoxy resin for fabricating syntactic foams. The influence of different twist drill (coated solid tungsten carbide) point angles (85,110, and 135°) in dry drilling is conducted through full factorial design using a vertical machining centre. The influence of various parameters in drilling (point angle, feed, cutting speed) and GMBs density are examined, and their effects are reported. Analysis of variance and response surface methodology is employed to determine the significant parameters influencing the responses. Drill point angle shows a substantial impact on cylindricity (31.81%), circularity error (42.86%) and damage factor at hole exit (34.29%). Feed significantly affects the thrust force (40.76%) and specific cutting coefficient (53.60%), whereas surface roughness is highly influenced by GMBs density (47.05%). Cutting speed governs cylindricity (32.73%) and exit side damage factor (43.38%) of the drilled holes. Multiple response optimization based on grey relational analysis reveals that combining higher feed, lower cutting speed and drill point angle, and intermediate GMBs density is the optimal condition for achieving sound quality hole. Drill point angle has a remarkable impact (88.35%) on hole quality at the optimum condition. Chip morphology of syntactic foams is presented finally. This research may be beneficial for the industrial practitioners in minimizing poor hole quality, thereby saving time and cost in drilling syntactic foams used in weight-sensitive structures.

Comparison of Frame-Based Versus Frameless Image-Guided Intracranial Stereotactic Brain Biopsy: A Retrospective Analysis of Safety and Efficacy

A definitive diagnosis of brain lesions not amenable to surgery is mainly made by stereotactic needle biopsy. The diagnostic yield and safety of the frameless versus frame-based image-guided stereotactic techniques is unclear. Our objective was to evaluate the safety and accuracy of frameless versus frame-based stereotactic brain biopsy techniques. A total of 278 patients (153 men; mean age: 65.5 years) with intra-axial brain lesions underwent frame-based (n= 148) or frameless image-guided stereotactic brain biopsy (n= 130) using a minimally invasive twist drill technique during 2010-2016 at Sheba Medical Center. Demographic, imaging, and clinical data were retrospectively analyzed. The diagnostic yield (>90%) did not differ significantly between groups. Overall morbidity (6.8% vs. 8.5%), incidence of permanent neurologic deficits (2.1% vs. 1.6%), mortality rate (0.7% vs. 0.8%), and postoperative computed tomography-detected asymptomatic (14.2% vs. 16.1%) and symptomatic (2.0% vs. 1.6%) bleeding also did not differ significantly between the frame-based and frameless cohorts, respectively. The diagnostic yield and complication rates related to the biopsy technique were not significantly associated with sex, age, entry angle to the skull and skull thickness, lesion location or depth, or radiologic characteristics. Diagnostic yield was significantly associated with the mean lesion volume. Smaller lesions were less diagnostic than larger lesions in both techniques (P= 0.043 frame-based and P= 0.048 frameless). The frameless biopsy technique is as efficient as the frame-based brain biopsy technique with a low complication rate. Lesion volume was the only predictive factor of diagnostic yield. The minimally invasive twist drill technique is safe and efficient.

Effect of Twist Drill Geometry and Drilling Parameters on Hole Quality in Single-Shot Drilling of CFRP/Al7075-T6 Composite Stack

Drilling two different materials in a layer, or stack-up, is being practiced widely in the aerospace industry to minimize critical dimension mismatch and error in the subsequent assembly process, but the compatibility of the drill to compensate the widely differing properties of composite is still a major challenge to the industry. In this paper, the effect of customized twist drill geometry and drilling parameters are being investigated based on the thrust force signature generated during the drilling of CFRP/Al7075-T6. Based on ANOVA, it is found that the maximum thrust force for both CFRP and Al7075-T6 are highly dependent on the feed rate. Through the analysis of maximum thrust force, supported by hole diameter error, hole surface roughness, and chip formation, it is found that the optimum tool parameters selection includes a helix angle of 30°, primary clearance angle of 6°, point angle of 130°, chisel edge angle of 30°, speed of 2600 rev/min and feed rate of 0.05 mm/rev. The optimum parameters obtained in this study are benchmarked against existing industry practice of the capability to produce higher hole quality and efficiency, which is set at 2600 rev/min for speed and 0.1 mm/rev for feed rate.

Piezoelectric driven mandibular ridge split technique with immediate implant placement: A case report

Narrow dentoalveolar ridges pose a major challenge for the successful placement of endosseous implants. This case report focuses on a Piezoelectric driven mandibular Ridge Split technique without vertical osteotomy for an immediate implant placement in a narrow alveolar ridge measuring 3.0mm.Following anaesthesia, a mucoperiosteal flap was elevated after giving a mid-crestal incision distal to 35 along the entire edentulous ridge. Then, with the help of a micro-saw and horizontal spreaders, an osteotomy site of required diameter was achieved. Finally twist drills were used and implants were placed in the expanded site.Clinically, healing was uneventful with no step defect in the expanded buccal bone and the final occlusion obtained was satisfactory.The Piezo-electric driven Ridge Split technique promises to be a minimally invasive option for horizontal augmentation of narrow alveolar ridges- predictability within a short interval of time and with minimal risk of fracture.

Cutting-fluid flow with chip evacuation during deep-hole drilling with twist drills

In this study the important aspects of cutting fluid distribution and the chip evacuation during micro twist deep-hole drilling are investigated using 3D multi-physics simulation methods. A coupled particle simulation is performed to analyze the chip transport by combining Smoothed Particle Hydrodynamics and the Discrete Element Method. Therefore, the transient transport of the chips is compared to a simulation scenario without chips. The coupled particle approach is capable to deal with free surfaces and fluid–solid interactions, that are subject to major topological changes over time. The chip positions resulting from the coupled particle simulation are used to carry out a Computational Fluid Dynamics simulation which considers the physical boundary conditions of the fluid and the process parameters to perform in-depth flow analyses. The results show good qualitative agreement between both simulation methods. Furthermore, the results show that large dead-zones with no fluid or almost zero fluid velocity exist in the flutes and that the chips there only experience a small evacuation force from the cutting fluid. The presented coupled approach of combining CFD and SPH–DEM simulation provide a significant support for future investigations to research the chip transport and to improve the tools and the process further.

Control of Fine Cutting Chips to Improve the Processing Environment in CFRP Drilling

Carbon fiber reinforced plastic (CFRP) is increasingly used in aerospace, automobile, and other industries. With the improvement of carbon fiber reinforced thermoplastic molding technology using thermoplastic resin, it is expected that the applications of CFRP will be expand further. Because of the following issues, CFRP is known as a difficult-to-cut material. i) Machining CFRP is difficult. ii) Its finished surface deteriorates due to delamination and uncut fiber. iii) It has a shortened tool life due to severe tool wear. In addition to these issues, we has been problem presentation of fine cutting chips generated by machining. Because these fine cutting chips may scatter in the atmosphere and adversely affect the human body and machine tools, we have established a chip disposal technology that suppresses these issues to improve the processing environment. A previous study reported that shape of the tool edge is responsible in suppressing the generation of fine cutting chips. Here, we experimentally investigated the effects of tool edge shapes on the chip collection rate and tool life. An attempt was made to determine whether the same effect can be obtained by using the outside dust-collection method which is known that the dust collection efficiency is low. We revealed that the chip collection rate increases if a tool that suppresses the generation of fine cutting chips is used instead of a conventional tool; furthermore, the tool life is insensitive to coating. In contrast, a comparison of our results with previous findings indicates that the tool with a sharpened cutting edge has a longer tool life than the conventional twist drill with honing. A high cutting chip collection rate was obtained, even with the outside dust-collection method, which led to an improvement in the working environment.

Parameter optimization of 7050 aluminum alloy drilling based on ABAQUS

For the drilling of 7050-T7450 aluminum alloy commonly used in the aerospace field, this article uses ABAQUS finite element software to establish a drilling simulation model of 7050-T7450 aluminum alloy. A simplified cutting model is created based on the actual cutting model, combined with the Johnson-Cook material constitutive equation, and then the actual drilling process is simulated. At the same time, through the use of orthogonal experiment analysis method, the influence of the four factors of tool diameter, drilling speed, feed rate and tool tip angle on the axial force and moment of twist drill is analyzed. The extremely poor method is used to determine the best cutting combination plan. According to the results of the orthogonal experiment, a multiple linear regression was performed using MATLABLE software, and a drilling model was established to obtain an empirical formula. The accuracy of the empirical formula is verified by comparing the calculation of the empirical formula with the simulation result, and it provides a reference for the actual processing.

Experimental and numerical investigation of the thrust force and temperature generation during a drilling process

Abstract Although advances have been made in manufacturing technology, a number of problems still exist in the drilling process due to the chip formation which occurs in a closed area. This situation results in unpredictable force, torque and temperature generation. This study investigated the machining parameters in the drilling process using a finite element method (FEM). In the numerical analysis, thrust force, torque and temperature were calculated by three-dimensional simulation. Drilling processes were carried out with twist drill bits at three different cutting speeds and three different feed rates. The numerical analysis results were verified by experimental studies. The results show that FEM is a good candidate for obtaining cutting forces and temperature generation in drilling process.

Single versus double burr holes evacuation in the treatment of chronic subdural hematoma

Background: Chronic subdural hematoma (CSDH) is a well-known entity and common surgical disorder managed by the neurosurgeon and, if not recognized and treated timely, may prove fatal. It can be non-traumatic or post-traumatic and all of them need urgent attention irrespective of aetiology. It manifests with a progressive neurologic deficit that occurs >3 weeks following head injury. The principal techniques used in the treatment of CSDHs presently are burr hole, twist drill craniostomy, craniectomy and craniotomy. Objective: The aim of this study was to assess clinical outcome in unilateral chronic subdural hematoma patients treated by single or double burr-hole drainage. This prospective study was carried out at the Department of Neurosurgery, IMS, BHU, Varanasi from September 2016 to August 2018. A total of 60 patients with their age ranged from 22to 88 years with GCS 6 to 15 & hematoma thickness 10mmc were included in this study and randomly divided into two groups using random allocation software. In group A, patients with chronic subdural hematoma (CSDH) were managed with single burr-hole drainage. In group B, patients were managed with double burr-hole drainage. Clinical outcome was measured on the1st postoperative day, 3rd postoperative day and 7th postoperative day by GCS and at 1month follow-up by measuring the Glasgow outcome scale (GOS). Result: In this study double burr-hole drainage and single burr-hole drainage surgery shows equal success in the management of CSDHs with single burr hole taking less operative time.

Experimental study on drilling characteristics of the hybrid sisal–jute fibre epoxy composites

Natural fibre composites have received worldwide attention due to their good mechanical properties, lightweight and low density. Due to these advantages, the natural fibre composites have been used in various engineering applications. Drilling is one of the most frequent machining operations performed on hybrid sisal–jute polymer composites, to assemble the numerous structural components by using mechanical joining process. Furthermore, the machining of fibre reinforced composite material has attracted several researchers because of its non-homogeneous and anisotropic structure. The present research work concerns with the experimental studies on the drilling process of hybrid sisal–jute epoxy composite, using three different types of drill geometry (twist drill, step drill and core drill). The significance of the current work aims to reveal the effect of drill geometry configuration and drilling parameters in terms of drilling-induced force and damages (delamination and surface roughness) for the drilling of hybrid natural fibre composites. Drilling forces, drilling-induced damages and hole quality attributes were experimentally investigated for different drill geometries. The delamination and surface roughness type damages are revealed by microscopic analysis with the help of scanning electron microscope (SEM). The results show that twist drill is best suited for the hole- and force-induced damages.

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.

Analytical study and experimental investigation on delamination in drilling of CFRP laminates using twist drills

Delamination in composite laminates is one of the most common and critical defects, it would significantly reduce the stiffness and strength of components. This paper aims at reducing the drilling-induced delamination to improve hole quality. First, drilling tests are carried out to examine the distribution and amplitude of thrust force on drill under different cutting conditions. Empirical thrust force models are developed using experimental data. Then, analytical models of critical thrust force (CTF) are separately established considering two drilling states, considering the actual interactions between the drill and laminate. Anisotropy of composite, tool geometry and load distribution on drill are considered. Comparisons with experimental data and existing models show that the proposed models are capable of predicting CTFs under different loading conditions. In addition, the critical feed rates at different ply locations are determined. This study can provide guidance for the selection of cutting parameters to reduce drilling-induced delamination.

Awake transradial middle meningeal artery embolization and twist drill craniostomy for chronic subdural hematomas in the elderly: case series and technical note.

Due to prohibitive perioperative risk factors, optimal treatment for chronic subdural hematomas (cSDH) in the elderly remains unclear. Minimally invasive techniques are a viable option and include bedside subdural evacuation port system (SEPS), as well as prevention of recurrence with middle meningeal artery (MMA) embolization. We present a case series of elderly patients undergoing combined transradial MMA embolization and bed-side craniostomy as primary treatment for cSDH. Patients 70 years and older from 2019 to 2020 that underwent single setting, awake transradial MMA embolization with concurrent SEPS placement under local anesthesia were included. Those with prior treatments, interventions performed under general anesthesia, or with less than 60-day follow-up were excluded. Descriptive analyses of baseline characteristics, radiologic parameters, comorbidities, and outcome measures were completed. Twenty elderly patients (mean age of 81.0 years) with multiple comorbidities underwent 28 MMA embolization+SEPS procedures as primary treatment for cSDH. Mean cSDH thickness was 1.8cm±0.6 cm with 7.3±3.9 mm midline shift. All patients tolerated the procedure well. 1/20 (5.0%) patients died within 30 days of the procedure. A majority of patients were discharged to home (12/20; 60.0%). There was an average of 3.6-month follow-up and one patient (5.0%) developed recurrence in the follow-up period requiring further intervention. In select elderly patients with high perioperative risk factors, primary treatment of cSDH using awake transradial MMA embolization+SEPS placement is a minimally invasive, feasible, and safe option. Further comparative studies are warranted to evaluate efficacy of the treatment.

Tool wear in ultrasonic vibration–assisted drilling of CFRP: a comparison with conventional drilling

Carbon fiber reinforced polymers (CFRPs) are becoming increasingly prevalent in the industries including automobile, aerospace, and military due to their light quality, high specific strength, high corrosion resistance, excellent thermodynamics performance, etc. However, these excellent properties easily result in intensive tool wear, short tool life, and reduced machining accuracy. Although ultrasonic vibration–assisted drilling (UVAD) was considered an effective drilling method to reduce tool wear, most reported studies focused on machining kinematics or mechanics, and very few studies systematically explored the tool wear behaviors in UVAD of CFRP. To fill this gap, this paper aims to investigate tool wear of high-speed steel (HSS) twist drill in UVAD of CFRP and compares these wear behaviors with those in conventional drilling based on the experimental observation of the worn drill morphologies. The effects of cutting parameters on tool wear were discussed with the special focus on the differences in tool wear between conventional drilling (CD) and UVAD. The observed wear behaviors can include abrasion, adhesion, oxidization, or the combination of them. The introduction of UVAD can effectively reduce the average width of tool flank wear with a maximum reduction of 13.0% when compared with CD. Both increased feed rate and decreased spindle speed can lead to decreased tool wear. The findings in this paper might offer guidance on the selection of cutting parameters for extending tool life in UVAD of CFRP.

Sustainable hole-making in a titanium alloy using throttle and evaporative cryogenic cooling and micro-lubrication

• Effectiveness of using evaporative and throttle cryogenic coolants in titanium drilling is investigated. • Throttle cooling favored tool life, productivity, cleanliness, energy consumption, and process cost. • Evaporative cooling caused thick adhesion on drills and did not support any sustainability measure. • Micro-lubrication also favored most of the sustainability measures but at a low productivity level. • Pecking should not be used in drilling of low to medium depth holes in titanium alloys. Titanium, being a structural material, undergoes drilling process frequently for its engineering applications. The superior mechanical properties of titanium alloys make hole-making a highly unsustainable process. The process is marred by high cutting forces, intense tool damage, high energy consumption, poor hole quality, and high process cost. The work presents an approach for viable and cleaner drilling of the difficult-to-cut material by investigating the effects of micro-lubrication and the following two options of cryogenic cooling: (1) evaporative cooling using liquid nitrogen and (2) throttle cooling using compressed carbon dioxide gas. Additionally, the effects of cutting speed and pecking – a technique actualized by rapidly retracting the twist drill by 2 mm at two levels of depth during thru-cutting of the holes – are also quantified. Pecking is not found to be favorable to any of the evaluated sustainability measures. Of the three cutting fluids testes, throttle cryogenic cooling yielded the most advantageous results. The coolant, because of its effective heat dissipation capability, yielded superior outcomes with respect to all the sustainability measures except surface quality. Micro-lubrication proved to be beneficial, at the low level of cutting speed, to specific cutting energy, surface quality, and process cost. Evaporative cryogenic cooling did not yield promising results. The runs employing evaporative coolant or the high level of cutting speed experienced thicker tool adhesions whereas those utilizing pecking showed signs of intense progressive wear. Moreover, the thrust force data indicated occurrence of thermal softening of the work material as the drills progressed through the hole-cutting process. From the holistic perspective of sustainability, it is recommended to adopt throttle cryogenic cooling, a medium-to-high level of cutting speed, and no-pecking for hole-making in the titanium alloy.