Thermal Investigation on Coated and Uncoated HSS Twist Drill using ANSYS Software

In drilling, a cylindrical hole is produced in workpiece, removing the material inside the workpiece. The cutting tool used in drilling operation is called ‘Twist Drill’; it rotates and allows the material to be removed from the workpiece in the form of chips and thus drill the hole. Cutting fluids or coolants are used to perform this operation smoothly. The coating on the drill bits helps to reduce friction in the cut and the heat buildup in the drill bit. Coating also helps in protecting against corrosion. The present work focuses on the features of uncoated High Speed Steel (HSS) Twist Drill bit and Titanium Nitride (TiN) and Titanium Aluminium Nitride (TiAlN) coated on HSS Drills. The workpiece material was Mild Steel and the drilling operation was done using normal machining condition i.e. in presence of coolant. The cutting parameters used are cutting speed (35.5 m / min), spindle speed (1500 rpm), feed rate (0.2 mm / rev.), depth of cut (10 mm). These parameters were kept constant. Temperatures were measured with the help of thermal imaging camera and with the help of ANSYS software thermal analysis were done. Experimental results showed that the average rise in temperature of uncoated HSS tool was higher as compared to TiN coated and TiAlN coated HSS tools. TiAlN coated drills showed the least average rise in temperature. Keywords: High Speed Steel (HSS) Drill, TiN and TiAlN Coated HSS Twist Drill, Mild Steel (MS), Thermal Analysis, ANSYS Software.

P.206 Tissue Plasminogen Activator in Addition to Twist Drill Drainage as a Treatment for Chronic Subdural Hematomas – A Descriptive Analysis

Background: Current literature provides little consensus on universal guidelines for first-line treatment of chronic subdural hematomas (cSDH). However, administration of local tissue plasminogen activator (tPA) may enhance the traditional method of twist drill drainage (TDD). The study aims to explore the efficacy of TDD with and without tPA, at achieving clinically relevant drainage (200mL) and reducing recurrence of cSDH. Methods: A retrospective review of patients (N=34) with cSDH is presented. Patients who received TDD with tPA (n=17) were identified and matched, based primarily on age and hematoma volume, to a control group (n=17), TDD without tPA. Variables of interest include initial hematoma volume, volume drained, length of stay, and recurrence rates. Descriptive analysis was run. Results: Average age for patients was 74.6 with 76% male. Mean drainage volumes for the tPA cohort was 381.6mL and TDD without tPA cohort was 151.3mL. The addition of tPA resulted in drainage volumes nearly double (1.9x) the clinically relevant amount and had low recurrence rates (12.5%). TDD without tPA failed to result in clinically relevant drainage and had a recurrence rate of 52.9%. Average length of stay differed by two days (9.71 tPA; 7.71 control). Conclusions: TDD with tPA was effective at treating cSDH in our population.

Management of chronic subdural hematoma: our experience of last seven years

Background: Chronic SDH is collection of altered blood under dura mater which is variably more than 4-6 weeks old. It usually occurs in presence of atrophic brain which usually occurs in chronic alcoholics and in old age. Pathogenetic factors are mild trauma with or without some form of coagulopathy. There are various management options like twist drill and drainage, burr hole with evacuation with or without placement of drain and mini craniotomy. There are specific indications for each procedure with individual variations. We operated 74 patients of chronic SDH in last 7 years and are presenting analysis of our series.Methods: The study is retrospective. We studied records of 74 consecutive patients operated in single unit at our institute from February 2014 to December 2020. Patients with very poor GCS (less than 5) and children are not included in this study.Results: There was no benefit of drainage tube seen in our series of patients in decreasing incidence of residual collection.Conclusions: Timely intervention in case of chronic SDH is very gratifying in view of improvement of GCS and motor deficit without much effect of the type of procedure performed. Burr hole evacuation is the procedure of choice. Placement of drainage tube in subdural space is not effective in decreasing the incidence of residual collection. But it is very helpful in management of residual/recurrent collections.

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.

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.

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.

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 drill with special structure had certain advantage compared with common twist drill in the drilling process. In this paper, 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 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 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 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.

Desain Mekanisme Ballscrew untuk Retrofit Drilling axis Mesin Ficep H-Beam Drilling LFB-200-49

Proses retrofit adalah proses penggantian atau penambahan suatu komponen ke mesin dengan tujuan untuk memberikan nilai tambah pada performa mesin tersebut. Pada penelitian ini, proses retrofit diaplikasikan pada penggantian penggerak drilling axis mesin Ficep H-beam Drilling LFB-200-49. Proses retrofit ini membutuhkan komponen motor servo sebagai energi penggerak dan ballscrew sebagai pengubah rotasi motor menjadi gerakan linear twist drill saat melakukan proses pengeboran untuk menggantikan sistem hidrolik yang digunakan sebelumnya. Pada perancangan retrofit yang dilakukan terhadap mesin Ficep H-beam Drilling ini, gaya dorong yang dihasilkan sistem hidrolik digunakan sebagai acuan untuk mengetahui kebutuhan dynamic load yang harus ditransmisikan oleh ballscrew sedangkan thrust axial force dari mata bor digunakan sebagai acuan dalam menentukan daya motor servo. Dalam merancang penggantian sistem hidrolik ke sistem motor servo ini, komponen yang disarankan adalah ballscrew dengan pitch 10 mm dan diameter poros ballscrew 38 mm yang memenuhi syarat transmisi dynamic load 50.210,56 N dan motor servo dengan daya 8,12 kW dengan penambahan gear ratio 3 : 1. The retrofit process is the process of replacing or adding a component to a machine with the aim of adding value to the machine's performance. In this study, the retrofit process was applied to the replacement of the Ficep H-beam Drilling LFB-200-49 drilling machine axis. This retrofitting process requires a servo motor component as driving energy and a ballscrew to convert the motor rotation into a linear twist drill motion during the drilling process to replace the hydraulic system used previously. In the retrofit design carried out on the Ficep H-beam Drilling machine, the thrust generated by the hydraulic system is used as a reference to determine the dynamic load requirements that must be transmitted by the ballscrew while the thrust axial force from the drill bit is used as a reference in determining the power of the servo motor. In designing the replacement of the hydraulic system to this servo motor system, the recommended components are a ballscrew with a pitch of 10 mm and a ballscrew shaft diameter of 38 mm which meets the requirements for dynamic load transmission of 50,210.56 N and a servo motor with a power of 8.12 kW with the addition of a gear ratio of 3. : 1.