Surgical Drilling: Design and Performance of an Improved Drill

1982 ◽  
Vol 104 (3) ◽  
pp. 245-252 ◽  
Author(s):  
S. Saha ◽  
S. Pal ◽  
J. A. Albright
Keyword(s):  
Compact Bone ◽  
Helix Angle ◽  
Rake Angle ◽  
Peak Temperature ◽  
Published Data ◽  
Drill Bit ◽  
Effective Removal ◽  
Split Point ◽  
And Performance ◽  
Twist Drills

The majority of twist drills used in orthopaedics are very similar to chisel pointed metal drilling bits. Modifications usually observed are reduction of the point angle to 90 deg and sometimes grinding of the entire cutting lip at 0 deg rake angle, which appeared to have been made arbitrarily without any advantage. We have attempted to design a surgical drill bit with the objective of minimization of the drilling thrust and temperature and effective removal of bone chips. Our results showed that the presence of the chisel edge was mainly responsible for increasing the thrust force and the temperature developed. The effects of a constant feed rate and thrust on the peak temperature were also examined. The combined effect of the helix and the point angles on the rake angle which in turn determines the cutting efficiency was analyzed for various types of surgical bits. Based on our results and previously published data from the literature an optimized drill bit was designed with a split point, a point angle of 118 deg, a parabolic flute, and a helix angle of 36 deg and its performance was compared with other existing surgical drill bits. For drilling in compact bone, the new design decreased the thrust load by 45 percent and the peak temperature rise by 41 percent. Simlar improvements were also recorded for drilling bone cement. The time of drilling a bone cortex was also significantly reduced and “walking” on the curved bone surface was eliminated and dimensional tolerance on hole sizes was improved. The new design is likely to reduce the time of surgery and also minimize the tissue damage.

Experimental Analysis of the Effect of Cutting Conditions on the Initial Penetration in Drilling: A Comparative Study Between Conventional and Split Chisel Drills

2009 ◽  
Author(s):  
Sungwoo Park ◽  
Issam Abu-Mahfouz ◽  
Amit Banerjee
Keyword(s):  
Time Domain ◽  
Drilling Process ◽  
Drill Bit ◽  
Penetration Process ◽  
Initial Penetration ◽  
Split Point ◽  
The Time Domain ◽  
Twist Drills ◽  
Skewness And Kurtosis ◽  
Peak Value

To improve the performance and the capability of the drilling process, it is necessary to understand the mechanics of drilling. In particular, drill bit vibrations lead to undesirable effects such as chatter, hole location and roundness errors. In this study, the wandering motion during initial penetration in drilling is experimentally investigated. Four quantities, namely, mean, peak-to-peak value, skewness, and kurtosis are calculated for the time-domain orbital signals. The orbital signals were obtained using proximity probes. The drilling was performed in plates of aluminum, brass, steel, and stainless steel using conventional point and split-chisel symmetrical twist drills. The conventional and split-point drills show different wandering paths during the penetration process. In general, split-point drills produced larger size orbits with more chatter during initial penetration, but showed better centering. On the other hand, conventional drills were found to produce holes that were more offset with smaller size and smoother wandering motion around the actual centers.

Drilling of bone: Effect of drill bit geometries on thermal osteonecrosis risk regions

2018 ◽  
Vol 233 (2) ◽  
pp. 207-218 ◽  
Author(s):  
Mohd Faizal Ali Akhbar ◽  
Ahmad Razlan Yusoff
Keyword(s):  
Ex Vivo ◽  
Helix Angle ◽  
Simulation Software ◽  
Drilling Process ◽  
Drill Bit ◽  
Temperature Elevation ◽  
Bone Drilling ◽  
Drilling Simulation ◽  
Deform 3D ◽  
Bone Effect

Bone-drilling operation necessitates an accurate and efficient surgical drill bit to minimize thermal damage to the bone. This article provides a methodology for predicting the bone temperature elevation during surgical bone drilling and to gain a better understanding on the influences of the point angle, helix angle and web thickness of the drill bit. The proposed approach utilized the normalized Cockroft–Latham damage criterion to predict material cracking in the drilling process. Drilling simulation software DEFORM-3D is used to approximate the bone temperature elevation corresponding to different drill bit geometries. To validate the simulation results, bone temperature elevations were evaluated by comparison with ex vivo bone-drilling process using bovine femurs. The computational results fit well with the ex vivo experiments with respect to different drill geometries. All the investigated drill bit geometries significantly affect bone temperature rise. It is discovered that the thermal osteonecrosis risk regions could be reduced with a point angle of 110° to 140°, a helix angle of 5° to 30° and a web thickness of 5% to 40%. The drilling simulation could accurately estimate the maximum bone temperature elevation for various surgical drill bit point angles, web thickness and helix angles. Looking into the future, this work will lead to the research and redesign of the optimum surgical drill bit to minimize thermal insult during bone-drilling surgeries.

Influence of Cutting Parameters and Tool Geometric Angles on TC4 Titanium Alloy Chip Shape

2012 ◽  
Vol 490-495 ◽  
pp. 3912-3915 ◽  
Author(s):  
Wei Hua Wu ◽  
Wen Min Chen ◽  
Xue Hui Wang ◽  
Can Zhao
Keyword(s):  
Titanium Alloy ◽  
Tool Life ◽  
Cutting Parameters ◽  
Helix Angle ◽  
Rake Angle ◽  
Serrated Chip ◽  
Tc4 Titanium Alloy ◽  
Chip Shape ◽  
Radial Depth ◽  
Geometric Angles

To select reasonable cutting parameters, improve the processing surface quality, and extend the tool life, this paper uses four solid carbide end milling tools to process TC4 titanium alloy, and analyses the influence of the difference cutting parameters and the geometric angles to chip shape. The experiment results indicate that the degree of serrated chip shape is increased by increasing the feed rate under the condition of certain spindle speed. But the degree of serrated chip shape may be decreased by the adoption of small axial and radial depth, or bigger rake angle and smaller helix angle. Select larger rake angle, cutting edge is sharp, the metal deformation of cutting layer is small, which can reduce the friction force when chip flowing through the tool rake face, so that the cutting force and cutting temperature decreases accordingly.The greater the helix angle is, the worse the chip removal conditions is, and the degree of serrated chip becomes larger, the blade is more sharp, easily crack, and the tool life decreases. So relatively small helix angle is better. The choice of angles is interrelated with each other, the selection of some angle separately cannot get the desired reasonable value.

Handball concussion case series in a Brazilian Team

Neurology ◽  
2020 ◽  
Vol 95 (20 Supplement 1) ◽  
pp. S13.1-S13
Author(s):  
Carlos Pinheiro ◽  
Mariana Maciel Fejio
Keyword(s):  
Motor Coordination ◽  
Case Series ◽  
Head Impact ◽  
Published Data ◽  
Symptom Scale ◽  
Cervical Injury ◽  
Brain Concussion ◽  
Single Task ◽  
Falling Asleep ◽  
And Performance

ObjectiveTo analyze the history of self-reported head impacts, prevalence of post-concussion symptoms and performance in motor coordination tests in amateur handball athletes.BackgroundHandball is a contact sport where athletes can suffer collisions through different mechanisms and there are few published data about brain concussion in handball, mainly in Brazilian athletes.Design/MethodsAmateur male athletes aged between 18 and 35 years, with 4–6 hours of training per week and an average of 12.5 games in the last 6 months were evaluated regarding to the head impact history during handball games and practices. The athletes were also evaluated regarding of the most common kind of impact mechanism, loss of consciousness (LOC), reported cervical injury (pain and decreased range of motion), symptoms prevalence and their severity using the Post Concussion Symptom Scale (PCSS), time to execution of single-task tandem gait (TG) and performance in the Finger-to-Nose test (>4 seconds to perform five successive finger to nose repetitions was considered abnormal).ResultsSix athletes reported direct impacts on the head while playing handball. Falls, elbow to the head, trunk to the head and hit by the ball were the most reported mechanisms of head impact in handball athletes. Two athletes reported LOC and all of them denied cervical injury after trauma. Regarding the PCSS score, three athletes had a score between 6-21 and five athletes had a 22–84 score. The most reported symptoms were sleeping more than usual, drowsiness, fatigue, changes in behavior (nervousness, feeling more emotional and irritability), trouble falling asleep and dizziness. However, athletes shown a normal performance in the single task TG (14.6–17.2 seconds) compared to normative data and three athletes shown altered performance on the Finger-to-Nose test.ConclusionsAmateur handball athletes had significant scores of PCSS mainly related to sleep, emotional and possibly to the vestibular function.

Relationship Between Alloy Composition and Tool-Life of High-Speed Steel Twist Drills

1992 ◽  
Vol 114 (4) ◽  
pp. 459-464 ◽  
Author(s):  
W. E. Henderer
Keyword(s):  
Tool Life ◽  
High Speed ◽  
Alloy Composition ◽  
High Speed Steel ◽  
Vanadium Content ◽  
The Matrix ◽  
Life Tests ◽  
And Performance ◽  
Twist Drills ◽  
The Relationship

Tool-life tests are reported which show the relationship between the alloy composition of high-speed steel twist drills and performance. Tool-life is shown to depend primarily on the composition of the matrix consisting of tempered martensite and precipitated secondary carbides. The longest tool-life was obtained from alloys with high vanadium content and low tungsten or molybdenum content. This observation is consistent with the dispersion characteristics of vanadium carbide which precipitate during tempering.

scholarly journals Analysis on the Effects of Tool Rake Angle and Helix Angle of a Flat End-mill in the Milling of Ti-alloy

2015 ◽  
Vol 24 (5) ◽  
pp. 508-513 ◽  
Author(s):  
Dong-Hee Ye ◽  
Joon-Young Koo ◽  
Young-Koon Park ◽  
Jeong-Suk Kim
Keyword(s):  
Helix Angle ◽  
Rake Angle ◽  
Ti Alloy ◽  
End Mill

scholarly journals EMPLOYEE PERCEPTION AND PERFORMANCE APPRAISAL: AN EVALUATION OF SELECTED DEPOSIT MONEY BANKS IN PORT HARCOURT

2020 ◽  
pp. 80-95
Author(s):  
Bienwi-Patrick, Ledum ◽  
B. Chima Onuoha ◽  
Best C. Eke
Keyword(s):  
Procedural Justice ◽  
Performance Appraisal ◽  
Pay For Performance ◽  
High Rate ◽  
Published Data ◽  
Employee Perception ◽  
Appraisal System ◽  
Port Harcourt ◽  
Performance Appraisal System ◽  
And Performance

Performance Appraisal system represents a major tool for most of the organizations to evaluate various aspects of their employees. Despite the prominence of the organizational phenomenon, very limited research is done in Nigerian organization in this area .To analyses the perception of employees regarding the performance appraisal system implementation, the Deposit Money Banks in Port Harcourt, Rivers state are selected due to the reported high rate of staff turnover. In order to analyze the perception of employees regarding the new system and its implementation, 33 item questionnaires consist of 4 independent and one dependent variables was distributed among 150 employees who were acquainted with the Performance appraisal procedure. The study employed four measures of performance appraisal which are Procedural justice, Goal setting, feedback and Pay for performance and one criterion variable, the employee perception towards these performance appraisal process. The instrument used was a 5 point Likert scale questionnaire. Factor analysis and regression analysis was done through the Statistical Package for Social Sciences version 25.The result shows the process was implemented as per organization guidelines to the overall satisfaction of employees. There are however some areas of improvement which have been noted in the conclusion. The results and outcome are in line with international published data. KEYWORDS: Employee Perception, Performance Appraisal, Procedural Justice.

Detrimental or beneficial? Untangling the literature on developmental stress studies in birds

2021 ◽  
Vol 224 (19) ◽  
Author(s):  
Haruka Wada ◽  
Victoria Coutts
Keyword(s):  
Developmental Plasticity ◽  
Published Data ◽  
Developmental Stress ◽  
Physiological Functions ◽  
Thrifty Phenotype ◽  
Physiological Variables ◽  
Stress Studies ◽  
Organ Systems ◽  
And Performance ◽  
The Individual

ABSTRACT Developing animals display a tremendous ability to change the course of their developmental path in response to the environment they experience, a concept referred to as developmental plasticity. This change in behavior, physiology or cellular processes is primarily thought to allow animals to better accommodate themselves to the surrounding environment. However, existing data on developmental stress and whether it brings about beneficial or detrimental outcomes show conflicting results. There are several well-referred hypotheses related to developmental stress in the current literature, such as the environmental matching, silver spoon and thrifty phenotype hypotheses. These hypotheses speculate that the early-life environment defines the capacity of the physiological functions and behavioral tendencies and that this change is permanent and impacts the fitness of the individual. These hypotheses also postulate there is a trade-off among organ systems and physiological functions when resources are insufficient. Published data on avian taxa show that some effects of developmental nutritional and thermal stressors are long lasting, such as the effects on body mass and birdsong. Although hypotheses on developmental stress are based on fitness components, data on reproduction and survival are scarce, making it difficult to determine which hypothesis these data support. Furthermore, most physiological and performance measures are collected only once; thus, the physiological mechanisms remain undertested. Here, we offer potential avenues of research to identify reasons behind the contrasting results in developmental stress research and possible ways to determine whether developmental programming due to stressors is beneficial or detrimental, including quantifying reproduction and survival in multiple environments, measuring temporal changes in physiological variables and testing for stress resistance later in life.

scholarly journals Outdoor testing of photovoltaic modules during summer in Taxila, Pakistan

2016 ◽  
Vol 20 (1) ◽  
pp. 165-173 ◽  
Author(s):  
Hafiz Ali ◽  
Mubashar Mahmood ◽  
Muhammad Bashir ◽  
Muzaffar Ali ◽  
Aysha Siddiqui
Keyword(s):  
Amorphous Silicon ◽  
Operating Conditions ◽  
Performance Ratio ◽  
Published Data ◽  
Photovoltaic Modules ◽  
Efficiency Performance ◽  
Higher Temperature ◽  
Low Efficiency ◽  
And Performance ◽  
Module Efficiency

An experimental study has been carried out to measure the performance of commercially available photovoltaic modules during summer months in the climate of Taxila, near the capital of Pakistan. The modules used in the study are monocrystalline silicon (c-Si), polycrystalline silicon (p-Si) and single junction amorphous silicon (a-Si). The analysis has been focused on the measurement of module efficiency, performance ratio and temperature of each module at actual operating conditions using outdoor monitoring facility. The measured results are compared with the already published data of peak winter month at the same site. Overall, the monocrystalline module showed high average module efficiency while amorphous silicon module was better in term of average performance ratio. Furthermore, the module efficiency and performance ratio has shown decreasing trend with increase of module temperature. It was found that modules have much higher temperature in summer months (about 20?C higher) and showed low efficiency and performance ratio than peak winter month. The average ambient temperature varied from 18.1?C to 38.6?C from winter to summer.

Long-Term Outcomes of ADHD: Academic Achievement and Performance

2015 ◽  
Vol 24 (1) ◽  
pp. 73-85 ◽  
Author(s):  
L. Eugene Arnold ◽  
Paul Hodgkins ◽  
Jennifer Kahle ◽  
Manisha Madhoo ◽  
Geoff Kewley
Keyword(s):  
Academic Performance ◽  
Academic Outcomes ◽  
School Environment ◽  
Performance Outcomes ◽  
Achievement Test ◽  
Published Data ◽  
Long Term Effects ◽  
And Performance ◽  
Test Outcomes

Objective: The aim of this study was to synthesize published data regarding long-term effects of ADHD on information learned (measured via achievement tests) and success within the school environment (academic performance). Method: A systematic search identified 176 studies (1980-2012) of long-term (≥2 years) academic outcomes with ADHD. Results: Achievement test outcomes (79%) and academic performance outcomes (75%) were worse in individuals with untreated ADHD compared with non-ADHD controls, also when IQ difference was controlled (72% and 81%, respectively). Improvement in both outcome groups was associated with treatment, more often for achievement test scores (79%) than academic performance (42%), also when IQ was controlled (100% and 57%, respectively). More achievement test and academic performance outcomes improved with multimodal (100% and 67%, respectively) than pharmacological (75% and 33%) or non-pharmacological (75% and 50%) treatment alone. Conclusion: ADHD adversely affects long-term academic outcomes. A greater proportion of achievement test outcomes improved with treatment compared with academic performance. Both improved most consistently with multimodal treatment.

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