Tool Face Research Articles

Wear behavior of SiAlON ceramic tool and its effects during high-speed cutting

Nickel-based superalloys are widely employed in aerospace and other fields on account of excellent performance. However, the tool is easily worn out in cutting of superalloys, which will deteriorate the surface quality and lower the service life of the components. In this paper, the effect of ceramic tool wear on surface integrity during high-speed turning of superalloy GH4169 was studied. The results demonstrate that tool wear raises cutting temperature and cutting force. The wear mechanisms of the rake face of the ceramic tool are adhesive wear and oxidation wear, and the wear mechanisms of the flank face are adhesive wear, oxidation wear and abrasive wear. The enhancement effect of tool wear on thermal effect is greater than that on mechanical effect, which forms a larger tensile residual stress on the machined surface. In addition, tool wear increases the thickness of the plastic deformation layer, raising the KAM value from 0.43° to 0.63° at a cutting speed of 200 m/min.

Investigating the effect of novel self-lubricant TiSiVN films on topography, diffusion and oxidation phenomenon at the chip-tool interface during dry machining of Ti-6Al-4V alloy

Machining of titanium alloys such as Ti-6Al-4 V can be very intimidating due to their low thermal conductivity leading to elevated cutting temperatures at the chip-tool interface (ICT). In this regard, the self-lubrication effect of coatings like TiSiVN represented by topography, oxidation, and diffusion at the chip-tool interface are crucial. Thus, the present work investigates the latter three mechanisms during dry machining of Ti-6Al-4 V titanium alloy with uncoated and TiSiVN coated Al2O3/SiC whiskers-reinforced ceramic cutting tools. The results reveal that the adhesion height (AH) and O% increases with cutting temperature, showing the dominant influence of cutting temperature on material adhesion and oxidation levels at the ICT. AH increases with increased cutting speed for both coated tools, indicating that the crater depth increment was not so severe for the coated tools. However, a drastic upward surge of crater depth for uncoated and TiSiN coated tools at 125 m/min cutting speed makes the crater edge near the ICT act as a chip breaker and facilitates the chip's bending away from the tool face causing reduction in chip bend angles (BA). Additionally, the TiSiVN coating accounts to a reduction of approximately 23% in AH and 18% in Ti%, and 37% lower oxygen levels at the highest cutting speed when compared to the uncoated tool primarily due to lower cutting temperatures and self-lubricating behavior.

Tool surface modification methodology to improve the machinability of Ti6Al4V through combination of micro-EDM texturing and AlSi-10Mg soft coating techniques in dry turning

Machinability of Ti-6Al-4V, despite its numerous applications, is challenging owing to its poor thermal conductivity, severe chemical affinity and strain hardening characteristics. Although various coating techniques and expensive lubrication strategies have been tried, a significant improvement in tool life characteristics are yet to be achieved. Hence this work aims at suggesting a novel cost-effective and ecofriendly tool treatment technique by exploring the impact of a dual combination of an AlSi-10Mg coating developed by an emerging pre-conditioning technique with the incorporation of micro-textures on tool face to observe significant improvements in tool life and machinability characteristics of the alloy. It was analyzed from the results that while the micro-textures played a vital role in reducing the severe contact stress and machining temperature due to its improved heat transfer by convection, AlSi-10Mg film effectively shielded the cutting edges of the tool by providing a dampening effect along the edges, thereby ensuring improved tool life and enhanced machinability characteristics at the same time. The proposed tool combination was observed to be successful in significantly reducing the flank wear by 35%, 43% and 30% where 75, 253, and 371 µm were observed at 80, 100, and 120 m/min as compared to 117, 449, and 531 µm in the case of uncoated non-textured tool at the same operating conditions. Surface roughness of Ti-6Al-4V also reduced by 25%, 34%, and 37% where 1394, 1168, and 872 nm as compared to plain tool where 1840, 1770, and 1370 nm were recorded. Moreover, average chip curl diameter was observed to be 2.62, 3.36, and 6.49 mm as compared to chips generated by uncoated tools which recorded values of 4.33, 11.9, and 18.87 mm at 80, 100, and 120 m/min respectively.

Development of a Wound Assessment Tool for Use in Adults at End of Life: A Modified Delphi Study

Some patients at end of life (EOL) develop wounds known as Kennedy terminal ulcers, terminal ulcers, and Skin Changes At Life's End. However, there is ambiguity around the defining wound characteristics of these conditions and a lack of validated clinical assessment tools available to identify them. To gain consensus on the definition and characteristics of EOL wounds and establish the face and content validity of a wound assessment tool for use in adults at EOL. Using a reactive online Delphi technique, international wound experts reviewed the 20 items in the tool. Over two iterative rounds, experts assessed item clarity, relevance, and importance using a four-point content validity index. The content validity index scores were calculated for each item, with a level of 0.78 or higher signifying panel consensus. Round 1 included 16 panelists (100.0%). The agreement for item relevance and importance ranged from 0.54% to 0.94%, and item clarity scored between 0.25% and 0.94%. Following round 1, four items were removed, and seven others reworded. Other suggestions included changing the tool name and including Kennedy terminal ulcer, terminal ulcer, and Skin Changes At Life's End in the EOL wound definition. In round 2, the now 13 panel members agreed with the final 16 items included and suggested minor wording changes. This tool could provide clinicians with an initially validated tool to accurately assess EOL wounds and gather much needed empirical prevalence data. Further research is needed to underpin accurate assessment and the development of evidence-based management strategies.

Cutting performance and antifriction mechanism of Al2O3/TiC/TiB2/h-BN@Al2O3 self-lubricating ceramic tool

The machinability and wear reduction mechanism of self-repairing and self-lubricating ceramic tools sintered by vacuum hot-pressing method in the dry turning of 40Cr hardened steel was studied. By comparing the cutting performance and wear morphology of AT (Al2O3/TiC) ceramic tools under different cutting parameters, it was found that AT10B@5 (Al2O3/TiC/10 vol% TiB2/5 vol% h-BN@Al2O3) tool has a longer service life and better machining quality. Owing to the precipitation of solid lubricant during the cutting of AT10B@5 ceramic tool, the friction force during the cutting is reduced, thus decreasing the cutting force and cutting temperature of AT10B@5 ceramic tool during the cutting. The main cutting force decreased by 20.8%; the cutting temperature decreased by 22.2%; and the friction coefficient of front tool face decreased by 11.6% compared with AT tool. This effectively improved the surface quality of working parts, reduced the tool wear, increased the processing quality of work piece, and prolonged the tool life.

A comparative study of hybrid bit over roller cone and PDC bits

Early hybrid drilling concepts date back to the 1930s, but the development of a viable drilling tool has only become feasible with recent advances in Polycrystalline Diamond Compact (PDC) cutter technology. This paper describes a new generation of hybrid bits based on proven PDC bit designs with roll cutters on the bit periphery. Laboratory and field results will be presented, comparing the performance of hybrid bits with that of conventional PDC and roller bits. A hybrid bit can drill shale and other plastically behaving formations two to four times faster than a roller cone because it is more aggressive and efficient. The penetration rate of a hybrid bit responds linearly to Revolutions Per Minute (RPM), unlike roller taper bits that exhibit an exponential response with an exponent less than one. In other words, a hybrid drill will drill significantly faster than a comparable roller drill in motor applications. Another advantage is the influence of rolling mills on bit dynamics. Compared to conventional PDC bits, torsional oscillations are up to 50% lower, and low-speed slip/slip and high-speed swirl are reduced. This gives the hybrid drill a wider operating window and greatly improves tool face control in directional drilling. The Hybrid Drill is a highly specific drill aimed at traditional cylindrical taper applications limited by the Rate of Penetration (ROP), large-diameter PDC-bit and roller-cone-bit applications limited by torque or Weight on Bit (WOB). Highly interconnected formations with high torque fluctuations can cause premature C3 failure and limit mean operating value torque, and motor and/or P applications where higher ROP and better build speed and tool face control are desired.

Статистические зависимости влияния времени воздействия ультразвука на прочность и другие параметры сварного соединения полипропилена

Polypropylene is one of the most popular thermoplastic materials used in industry. To produce goods from this material, the ultrasonic welding method is often used. However, despite a large number of scientific papers, the influence of some parameters of the ultrasonic welding mode on the strength characteristics of polypropylene joints remains unstudied. The paper presents the results of experimental studies of contact spot ultrasonic welding of plates 3 mm thick made of 01003-26 grade polypropylene. The authors considered the process of gradual penetration of the ultrasonic tool working face into polypropylene to a depth equal to the total thickness of the welded plates. Statistical dependences of the depth of the tool face penetration into the material and the force of material separation on the ultrasound exposure time are obtained. The influence of the depth of the ultrasonic tool working face penetration on the tearing force of welded specimens is determined. A significant increase in the tearing force from 150 to 400 N was found at the tool penetration depth of more than 3.5 mm due to an increase in the nominal area of mutual mixing of the material between the welded plates caused by the flow of molten material into the gap. The authors proposed a hypothesis about the flow of the molten material in the direction opposite to the direction of penetration of the working tool by forming traveling Rayleigh waves. However, its confirmation requires additional studies of the influence of the ultrasonic welding mode parameters and the size of the gap between the parts to be joined on the rate of the molten material flow into the gap.

Taguchi Analysis of the Deformation Characteristics of Single-Point Cutting Tool with Micro-Tool Coatings During Orthogonal Machining

Machining, the art of processing materials, has progressed significantly over the past century. Advances in tool materials look at blended advantages of conventional and modern tool materials through coatings at micro-scales. Tool coatings improve the hot hardness and wear resistance of tool tip and faces. The current study utilizes the Taguchi technique to analyze the deformation response of HSS tools with three different tool coatings—titanium carbide, titanium nitride and titanium aluminum nitride. The coating thicknesses of 10, 50 and 100 μ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\upmu$$\\end{document}m were employed on the rake face and the flank faces of the single-point cutting tool. The response of the tools while machining medium carbon steel 42CrMo4 has been studied using the finite element approach—transient structural analysis module on ANSYS®. The tool deformation was taken up as the key metric.

Multi-objective parametric optimization on the EDM machining of hybrid SiCp/Grp/aluminum nanocomposites using Non-dominating Sorting Genetic Algorithm (NSGA-II): Fabrication and microstructural characterizations

AbstractIn this study, different input parameters for electric discharge machining (EDM) are examined in order to revise the distinctiveness of EDM for machining aluminum-based hybrid metal matrix composites (MMCs). The versatility of hybrid aluminum MMCs makes them very popular and sought after in the automotive, aerospace, marine, and space industries. In this article, an optimized process parameter setting for hybrid MCCs machining with an EDM machine is determined that have silicon carbide (SiCp) and graphite (Grp) particles added as reinforcement materials in varying amounts (Al–0.7Fe–0.6Si–0.375Cr–0.25Zn/10 wt%SiC/3 wt%Gr–MMC, Al–0.7Fe–0.6Si–0.375Cr–0.25Zn/15 wt%SiC/5 wt%Gr–MMC, and Al–0.7Fe–0.6Si–0.373Cr–0.25Zn/20 wt%SiC/8 wt%Gr–MMC). The stir casting method was used to prepare these hybrid aluminum MMCs (3 samples). A study of surface roughness (SR) and material removal rate (MRR) was conducted to examine the effects of dominant parameters. An experiment is planned using a central composite rotatable design (CCRD) of response surface methodology (RSM). It is possible to predict MRR and SR with 95% degree of accuracy by utilizing the quadratic model. Non-dominating Sorting Genetic Algorithm-II was employed to solve “mathematical models” for multi-objective optimization of output response characteristics. The scanning electron microscope (SEM) images of the tool and workpiece materials show that the recast layer has been formed on the tool face and the surface of the machined work-piece. Based on the results, it was determined that an optimal value of MRR (2.97 g·min−1) was obtained at 90 µs, 30 µs, 7.0 V, and 14 A asPon,Poff, gap voltage, and peak current, respectively. As a result of the findings, the SR is reciprocally proportional toPon, and the SR is commensurate withPoff. It was determined that the optimal value of SR (2.41 µm) could be attained at 30 µs, 52 µs, 6.0 V, and 12 A as thePon,Poff, gap voltage, and peak current, respectively. For an optimal set of response variables,Poncan be specified as 30 µs,Poffas 30 µs, gap voltage as 6 V, and peak current as 14 A as process parameters for MRR and SR. The SEM images of the tool material and the workpiece material clearly demonstrate a recast layer formed on the tool face and the machined surface of the workpiece. The optical microscopy analysis reveals a uniform distribution of SiCpand Grpparticles in the Al–0.7Fe–0.6Si–0.375Cr–0.25Zn matrix. In addition to recast layers and machined surfaces, EDS analysis reveals the deposition of tool material on the surface of the workpiece. The composites fabricated may replace materials in many of these applications where “friction” is a significant factor.

Factors influencing implementation of food and food-related waste audits in hospital foodservices.

Designing a food waste audit tool for novel hospital foodservice practice does not guarantee uptake. Intended users must be consulted to understand the tool's feasibility and face validity. This study aimed to identify the perspectives of staff involved in the operation of hospital foodservices on (1) how an evidenced based consensus pathway food waste audit tool is perceived to translate into practice, and (2) to determine the factors that influence the completion of food and food-related waste audits within this setting. Purposeful sampling was used to recruit staff with knowledge on the operation/governance of foodservices within hospitals in Victoria, Australia. Semi-structured interviews (n = 20) were conducted via Zoom to explore barriers and enablers to completing food and food-related waste audits and a previously published food waste audit tool. NVivo was used for inductive thematic analysis. Three factors determined the completion of food and food-related waste audits in hospital foodservices, and each factor could be a barrier or an enabler; (1) capacity: the availability of time, labour and materials to complete an audit (2) change: staff resistance to audit procedures and how to gain their buy-in (3) processes, governance, and leadership: the opportunity for high level support, policy and structure to encourage waste audits if present. The consensus tool appeared to have face validity. Planning audit operations, conducting stakeholder meetings, providing education/training to foodservice team members, and facilitating communication between managers and staff were described to support consensus tool use and audit completion. The consensus tool can be used to support hospital foodservices to complete food and food-related waste audits, although it may need to be customised to be fit for purpose. Optimising the capacity, change management and processes, governance and leadership of the foodservice department may improve the experience and success of a food and food-related waste audit.

Environmental, economical, and machinability based sustainability assessment in hybrid machining process employing tool textures and solid lubricant

Different techniques can be employed to improve the sustainability and machinability characteristics of a machining process. The sustainability assessment analyzes different aspects and indicators of an operation, including environment (energy consumption and carbon emission), economy (cost and production rate), and social (operator health and safety). The comparison of machining techniques based on sustainability assessment requires quantitative evaluation of indicators and sustainability index (SI) based on machining characteristics.Current research employs two main techniques of tool textures (on dual tool faces) and solid lubricant during the external grooving operation to make a sustainable hybrid process. Tool textures include pit-shape and linear patterns fabricated on rake and clearance faces.Results showed that in the case of energy consumption, the linear textured tool with solid lubricant consumed the minimum value by about 10.7 kJ. In the case of carbon emission, linear textured tool in dry machining conditions emitted about 0.008 kg-CO2 which was the minimum value. In the case of cost, a linear textured tool in dry machining conditions required 0.118 $ which was the cheapest process. In the case of production rate, the linear textured tool with solid lubricant presented the highest production rate by about 1773 parts/shift. On average, textures achieved about 23 higher SI values whereas solid lubricant reduced SI by about 13. Finally, linear texture in the dry condition achieved the most considerable value of the SI (52.5) and was selected as the best sustainable machining operation.

Design and validation of a preparedness evaluation tool of pre-hospital emergency medical services for terrorist attacks: a mixed method study

IntroductionTerrorist attacks are one of the human problems that affect many countries, leaving behind a huge toll of disabilities and deaths. The aim of this study was to use a mixed-method analysis to design and validate an evaluation tool for pre-hospital emergency medical services for terrorist attacks.MethodsThe present study is a mixed-method (qualitative and quantitative) study that was conducted in two phases. In the qualitative phase (item generation), semi-structured interviews were conducted with 34 Iranian emergency medical technicians who were selected through a purposive sampling method and a scoping literature review was conducted to generate an item pool for the preparedness evaluation of Emergency Medical Services (EMS) in terrorist attacks. In the quantitative phase (item reduction), for validity of tool face, content and construct validity, were performed; for tool reliability, the test and retest and intra-class correlation coefficient were evaluated.ResultsAt the first stage, 7 main categories and 16 subcategories were extracted from the data, the main categories including “Policy and Planning”, “Education and Exercise “,“ Surge Capacity”, “Safety and Security”, “Command, Control and Coordination”, “Information and Communication Management “and “Response Operations Management”. The initial item pool included 160 items that were reduced to 110 after assessment of validity (face, content and construct). intra-class correlation coefficient (ICC = 0.71) examination and Pearson correlation test (r = 0.81) indicated that the tool was also reliable.ConclusionThe research findings provide a new perspective to understand the preparedness of pre-hospital emergency medical services for terrorist attacks. The existing 110-item tool can evaluate preparedness of pre-hospital emergency medical services for terrorist attacks through collecting data with appropriate validity and reliability.

Generation mechanism of surface micro-texture in axial ultrasonic vibration-assisted milling (AUVAM)

Although axial ultrasonic vibration-assisted milling (AUVAM) is promising for rapid and economical fabrication of 3D micro-texture on various surfaces, it has been a challenge to obtain micro-texture with small feature size and large height simultaneously. The mechanism and major influence factors for the formation of micro-texture by this method were explored in this study. It was found that the generation of micro-texture was mainly caused by cutting and extrusion from the flank face of the milling tool under ultrasonic vibration. Therefore, a novel 3D tool model that considered the relief angle, end cutting edge angle and the blade profile was established in simulation analysis. The good agreement between simulation and experimental results demonstrated that the influence of the flank face on the micro-texture was mainly attributed to the relief angle of the milling tool. It was the first time to report that both the height and the profile shape of the micro-texture unit were affected by the overlap and extrusion between the flank surface and the micro-texture. But this influence diminished with the increase of spindle speed. 3D sinusoid-shaped micro-texture with minimum width of 20 μm and height of 2 μm (fully reproduced the ultrasonic amplitude) was realized with the relief angle of 40° and spindle speed of 4000 rpm. Other typical textures of weave, shell, scale and corrugation were also presented to show the effective regulation of texture patterns in AUVAM. This work provides both theoretical and practical basis for such a low-cost, efficient and controllable 3D micro-texture preparation method.

THE REGIME CHOICE WITH EFFECTIVE GRINDING BY THE WAY CONTROL INTER-AXIS DISTANCE MACHINE TOOLS

The problem of effective grinding of rotating surfaces is to improve the quality and increase productivity, while reducing costs. The problem can be solved by controlling the distance H between of the rotation tool axes with the part on CNC machines and rational choosing of a shape tool. The purpose of the article is to increase the grinding efficiency of the rotation surfaces with the end face of the conical abrasive tool by rational choice of mode parameters when controlling the inter-axis distance machine tools. To achieve this goal, the following research objectives should be solved. Determine the modes of grinding by limiting the kinematic factors. To find the influence of the dependence of the angular spatial orientation of the contact line of the tool and the part on the angle of small taper of its formed fragment by choosing the dimensions of the machine adjustment. To analyze the influence of the relative position and size of the contact area depending on the kinematics and technical requirements for processing. For the first time, the kinematic constraints of the limit value of the projection of the speed of relative motion in the normal direction, which is used as the grinding intensity, taking into account the rotational and translational motions of the feed. The spatial angular position of the contact line of the tool with the part is determined taking into account the dimensions of the machine adjustment, namely, the wheelbase and the angle of the circle profile. The algorithm of definition of modes of deep grinding is established. The graphical dependences of the angles of orientation of the contact line on the angle of editing of the circle and the wheelbase of the machine are obtained. The dependences of the reduction of the radial dimensions of the conical surface of the part during grinding in the direction opposite to the axial feed of the wheel are described. The dimensions of the contact area determine the quality: the length along the axis of the part, the number of passes, and the width - the conditions of heat release and cooling

Electrochemical Milling of Deep-Narrow Grooves on GH4169 Alloy Using Tube Electrode with Wedged End Face.

Deep-narrow grooves (DNGs) of nickel-based alloy GH4169 are extensively used in aerospace industry. Electrochemical milling (EC-milling) can manufacture special structures including DNGs by controlling the moving path of simple tool, showing a flexible process with the advantages of high machining efficiency, regardless of material hardness, no residual stresses, burrs, and tool wear. However, due to the inefficient removal of electrolytic by-products in the inter-electrode gap (IEG), the machining accuracy and surface quality are always unsatisfactory. In this paper, a novel tube tool with wedged end face is designed to generate pulsating flow field in IEG, which can enhance the removal of electrolytic by-products as well as improve the machining quality of DNG. The flow field simulation results show that the electrolyte velocity in the IEG is changed periodically along with the rotation of the tube tool. The pulsating amplitude of electrolyte is changed by adjusting the wedged angle in the end face of the tube tool, which could affect the EC-milling process. Experimental results suggest that the machining quality of DNG, including the average width, taper of sidewall, and surface roughness, is significantly improved by using the tube tool with wedged end face. Compared with other wedged angles, the end face with the wedged angle of 40° is more suitable for the EC-milling process. DNG with the width of 1.49 mm ± 0.04 mm, taper of 1.53° ± 0.46°, and surface roughness (Ra) of 1.04 μm is well manufactured with the milling rate of 0.42 mm/min. Moreover, increasing the spindle speed and feed rate can further improve the machining quality of DNG. Finally, a complex DNG structure with the depth of 5 mm is well manufactured with the spindle speed of 4000 rpm and feed rate of 0.48 mm/min.

Assessing the Utility of a Quality-of-Care Assessment Tool Used in Assessing Comprehensive Care Services Provided by Community Health Workers in South Africa.

BackgroundFew studies exist on the tools for assessing quality-of-care of community health worker (CHW) who provide comprehensive care, and for available tools, evidence on the utility is scanty. We aimed to assess the utility components of a previously-reported quality-of-care assessment tool developed for summative assessment in South Africa.MethodsIn two provinces, we used ratings by 21 CHWs and three team leaders in two primary health care facilities per province regarding whether the tool covered everything that happens during their household visits and whether they were happy to be assessed using the tool (acceptability and face validity), to derive agreement index (≥85%, otherwise the tool had to be revised). A panel of six experts quantitatively validated 11 items of the tool (content validity). Content validity index (CVI), of individual items (I-CVI) or entire scale (S-CVI), should be >80% (excellent). For the inter-rater reliability (IRR), we determined agreement between paired observers' assigned quality-of-care messages and communication scores during 18 CHW household visits (nine households per site). Bland and Altman plots and multilevel model analysis, for clustered data, were used to assess IRR.ResultsIn all four CHW and team leader sites, agreement index was ≥85%, except for whether they were happy to be assessed using the tool, where it was <85% in one facility. The I-CVI of the 11 items in the tool ranged between 0.83 and 1.00. For the S-CVI, all six experts agreed on relevancy (universal agreement) in eight of 11 items (0.72) whereas the average of I-CVIs, was 0.95. The Bland-Altman plot limit of agreements between paired observes were −0.18 to 0.44 and −0.30 to 0.44 (messages score); and −0.22 to 0.45 and −0.28 to 0.40 (communication score). Multilevel modeling revealed an estimated reliability of 0.77 (messages score) and 0.14 (communication score).ConclusionThe quality-of-care assessment tool has a high face and content validity. IRR was substantial for quality-of-care messages but not for communication score. This suggests that the tool may only be useful in the formative assessment of CHWs. Such assessment can provide the basis for reflection and discussion on CHW performance and lead to change.

Designing and validating an evaluation tool for nurse educators regarding core competencies

Using standardized evaluation tool for core competencies of nurse educator is essential to prepare faculty member. This study was aimed to design and validate an evaluation tool for nurse educators core competencies based on literature review. Also, Assessing the validity of the proposed tool by panel of experts and assessing the reliability of the proposed tool. Methodological design was used to carry out this study on two group "Jury group" was recruited for testing the face and content validity of the preliminary tool, this group consists of (35) members selected from different fields in nursing and "nurse educators" group working at two selected technical institutes of nursing Which affiliated to Ain-Shams Specialized Hospital and Ain-Shams University Hospitals. Data collection tool included Opinionnaire sheet for validity of the proposed tool, questionnaire sheet for eliciting the importance of preliminary tool from the viewpoint of nurse educator and developed evaluation tool. The results revealed that a majority agreement of jury group regarding face and content validity. Also a majority agreement of nurse educator regarding importance of proposed tool items of. Construct validity is measured by exploratory factor analysis (EFA) and Eigen value. It proved to be high reliability through intra-rater and inter-rater testing.

Drilling study on CFRP/Ti-6Al-4V stacks using chip breaker grooved drill

ABSTRACT Carbon fiber reinforced plastic/Ti-6Al-4V stacks are most commonly utilized in aircraft structures as they have a higher strength-to-weight ratio. Usually, these materials are stacked together and riveted by drilling holes. The holes produced during the operation require more precision and high quality. In general, the chips produced during the drilling of Ti-6Al-4V alloy stacked underneath the surface of CFRP material increase the damage and thrust force during drilling CFRP/Ti stacks. In this experimental investigation, a chip breaker in the form of a groove was machined on the rack face of the drill tool. Sixteen drilling experimental runs were conducted on CFRP/Ti-6Al-4V stacks along with standard and grooved tungsten carbide drills. Two input parameters such as cutting speed and feed with four levels were considered during drilling under a dry machining environment. The response attributes measured were thrust force, chip formation and delamination. Based on the study, a decrease in cutting force with an increase in the chip breakability was found at maximum speeds. Furthermore, a significant decrement was noticed in the delamination and formation of burrs with the grooved drill tool compared to the standard tool.

Fabrication of a microlens array featuring a high aspect ratio with a swinging diamond tool

Microlens arrays are gaining wider applications due to their unique optical geometry and excellent optical properties. Ultra-precision diamond turning is preferable for fabricating microlens arrays with high form accuracy. However, the interference between the flank face of the diamond tool and the finished surface restricts its application in machining microlens arrays with a high aspect ratio. In this paper, a novel method based on the slow tool servo turning technique is proposed to fabricate these microlens arrays by introducing a rotational motion (A-axis) to swing the diamond cutting tool and adjust the actual tool clearance angle in real time, which can prevent tool interference effectively. The machining system and method principle are introduced first. Then, the toolpath is generated, and the influence of the tool nose radius is compensated for. Finally, machining experiments of cutting spherical lens arrays with high aspect ratios are conducted on a Nanotech 650UPL ultraprecision lathe, and the machined lenses are inspected with an optical microscope, a stylus profilometer and a white light interferometer. The measurement results of the spherical lens arrays machined by the proposed method and the conventional slow tool servo turning method are compared, which demonstrates the superiority of the proposed method in fabricating high-quality lens arrays featuring a high aspect ratio.

When Slick Is Not Smooth: Bottomhole Assembly Selection and Its Impact on Wellbore Quality

Summary Appropriate selection of a bottomhole assembly (BHA) is critical to the success of a drilling operation. In US land drilling, these assemblies are often selected using local heuristics rather than rigorous analysis. These heuristics are frequently derived from the incentives of the directional contractor as opposed to incentives for the operator. Large motor bends enable more rotation through the curve and reduce the possibility of tripping for build rates. Unstabilized motors are believed to aid sliding and tool face control. Both of these practices lead to drilling a more tortuous wellbore and may cause problems later in the well’s life. This study quantifies the impact of these practices and proposes alternatives that can balance the needs of directional companies with the desire of operators for high-quality wellbores. More than 60 conventional motor assemblies used to drill curves in the Eagle Ford and Permian basins were analyzed for directional performance using commercial drillstring analysis software. The sliding and rotary tendencies were modeled through the curve across a range of potential drilling conditions. Expected build-rate models were validated by comparison to the maximum achieved doglegs in the directional surveys. When available, additional validation was performed using motor yields calculated from slide sheets. The validated models were compared to the dogleg severity (DLS) requirements for each assembly’s respective well plan. Comparisons of slide ratios and slide/rotate tendencies of the BHAs were used to estimate the impact on wellbore quality using the tortuosity metric proposed by Jamieson (2019). Typical well plans for both basins had curves of 10° per 100 ft with no well plan greater than 12° per 100 ft. Typical BHAs were capable of &amp;gt;15° per 100 ft under normal sliding conditions, with some assemblies capable of &amp;gt;20° per 100 ft of build. Predicted build rates were validated by slide sheets and observed DLSs. Common characteristics among assemblies with excess capacity were high-bend angles (≥2°) and minimal stabilization. These understabilized assemblies exhibited unstable rotary tendencies across a range of drilling parameters. The combination of high-build rates with rotary drop masks the true level of tortuosity in a wellbore, leading to an underestimation of unwanted curvature. A minority of the assemblies used a lower motor bend angle (&amp;lt;2°) combined with multiple stabilizers. These assemblies had a more consistent directional capability throughout the curve and exhibited stable behavior in rotation. The success of these assemblies confirms that there is potential for tailoring BHA designs to improve wellbore quality without compromising the technical objectives of the well. As increasing attention is afforded to the topic of wellbore quality, it is important to have methods available to technically achieve high-quality wellbores. In addition to the management of drilling practices, it is also important to have an appropriate BHA design that can enable those practices