Spelling suggestions: "subject:"engtool"" "subject:"a2tool""
361 |
OPTIMIZATION OF CUTTING CONDITIONS FOR SUSTAINABLE MACHINING OF SINTERED POWDER METAL STEELS USING PCBN AND CARBIDE TOOLSJoshi, Kunal J. 01 January 2006 (has links)
Powder metals are becoming a popular choice in the automotive and other manufacturing industries because of their ability to meet wide ranging product functional requirements without compromising the performance of the product. They offer various advantages, including weight reduction, near net-shape processing capability, and their ability to be sintered to achieve desired properties in the end-product. However, in order to satisfy the product design requirements during manufacturing, they need to be machined to the required tolerances. Machining of powder metals is quite different to machining of traditional metals because of their specific properties, including porosity. This thesis work deals with the finish machining of powder metal steels in automotive applications, for increased tool-life/reduced tool-wear. Tool-life is affected by a variety of factors such as tool grade selection, tool coating, cutting conditions and tool geometry including cutting edge geometry. This work involves optimization of cutting conditions for plunge cutting and boring operations of automotive powder metal components using PCBN and carbide tools. The cycle time of the process introduces an additional constraint for the optimization model along with the tool-wear criterion. Optimized cutting conditions are achieved for maximum tool-life.
|
362 |
Wear of coated and uncoated PCBN cutting tool used in turning and millingSveen, Susanne January 2014 (has links)
This licentiate thesis has the main focus on evaluation of the wear of coated and uncoated polycrystalline cubic boron nitride cutting tool used in cutting operations against hardened steel. And to exam the surface finish and integrity of the work material used. Harder work material, higher cutting speed and cost reductions result in the development of harder and more wear resistance cutting tools. Although PCBN cutting tools have been used in over 30 years, little work have been done on PVD coated PCBN cutting tools. Therefore hard turning and hard milling experiments with PVD coated and uncoated cutting tools have been performed and evaluated. The coatings used in the present study are TiSiN and TiAlN. The wear scar and surface integrity have been examined with help of several different characterization techniques, for example scanning electron microscopy and Auger electron spectroscopy. The results showed that the PCBN cutting tools used displayed crater wear, flank wear and edge micro chipping. While the influence of the coating on the crater and flank wear was very small and the coating showed a high tendency to spalling. Scratch testing of coated PCBN showed that, the TiAlN coating resulted in major adhesive fractures. This displays the importance of understanding the effect of different types of lapping/grinding processes in the pre-treatment of hard and super hard substrate materials and the amount and type of damage that they can create. For the cutting tools used in turning, patches of a adhered layer, mainly consisting of FexOy were shown at both the crater and flank. And for the cutting tools used in milling a tribofilm consisting of SixOy covered the crater. A combination of tribochemical reactions, adhesive wear and mild abrasive wear is believed to control the flank and crater wear of the PCBN cutting tools. On a microscopic scale the difference phases of the PCBN cutting tool used in turning showed different wear characteristics. The machined surface of the work material showed a smooth surface with a Ra-value in the range of 100-200 nm for the turned surface and 100-150 nm for the milled surface. With increasing crater and flank wear in combination with edge chipping the machined surface becomes rougher and showed a higher Ra-value. For the cutting tools used in milling the tendency to micro edge chipping was significant higher when milling the tools steels showing a higher hard phase content and a lower heat conductivity resulting in higher mechanical and thermal stresses at the cutting edge.
|
363 |
Förutsättningar för ett bra hälsosamtal utifrån ungdomars perspektiv / Prerequisites for a good health dialogue from adolescents' perspectiveVinterljung, Sandra, Eek, Sandra January 2015 (has links)
Hälsosamtal med elever i skolan är ett arbetssätt för att främja barns hälsa. Studiens syfte är att beskriva förutsättningar för ett bra hälsosamtal utifrån ungdomars perspektiv. 16 individuella intervjuer med ungdomar på högstadiet och gymnasiet genomförda inom ramen för ett större forskningsprojekt har analyserats med kvalitativ innehållsanalys. Resultatet visar hur ett elevcentrerat, tryggt och strukturerat hälsosamtal skapar förutsättningar för lärande, reflektion, motivation, relation och delaktighet. Ungdomarna uttrycker önskemål om ett elevcentrerat hälsosamtal, anpassat efter deras individuella behov och önskemål. Hälsosamtalet stärkte ungdomen och relationen till skolsköterskan som genom sin personlighet och sina strategier bidrog till känslan av trygghet. Ungdomarna upplevde att de fick ökad kunskap genom struktur, delaktighet och respekt. De beskrev vikten av delaktighet i samtalet för att kunna förmedla sina tankar och åsikter till skolsköterskan. Hälsoverktyget upplevdes skapa struktur i samtalet, förberedelse, en större förståelse, ett helhetsperspektiv över hälsan samt motivation till ändrade levnadsvanor. Resultatet talar för vikten av ett elevcentrerat hälsosamtal där ungdomen görs delaktig för att skapa möjligheter att främja hälsan. Resultatet har i enlighet med tidigare forskning pekat på fördelen med användandet av ett strukturerat hälsoverktyg och hälsosamtalets betydelse för ungdomars tankar om sin hälsa. / Health dialogue with pupils, a way to promote children’s health. The Purpose of the study is to describe prerequisites for a good health dialogue from adolescents´ perspective. 16 individual interviews with adolescents in upper level lower secondary school and high school completed within a major research project were analysed with qualitative content analysis. The result show that Pupil centred, secure and structured health dialogues creates conditions for learning, reflection, motivation, relation and participation. Adolescents express wishes of pupil centred health dialogues, adjusted to individual needs and requests. Helath dialouge strengthened adolescent and relation to school nurse, whom through strategies and personality contributes to the sense of security. Importance of freedom of choice and voluntariness was emphasized by adolescents. Adolescents experienced increased knowledge through structure, participation and respect. The health and lifestyle tool perceived to create structure, preparedness, a greater understanding, holistic perspectives over one’s health and motivation for lifestyle changes. Results indicates importance of pupil centred health dialogues where adolescents is made participant to create possibilities to promote health. In concurrence with previous research results points to advantage of using structured health and lifestyle tools and health dialogue’s importance for adolescents thoughts about health.
|
364 |
Financial reporting as a tool for promoting accountability at Metsimaholo Local Municipality / Palesa Yvonne NotsiJanuary 2012 (has links)
Sound financial management is a growing concept in the public sector, especially in local government. The South African government has put in place policies and mechanisms to create a conducive environment for municipalities to manage finances in an effective manner. The management of municipal finance is supported by a set of policies and regulations to strengthen the use of public money. Among the respective policy frameworks, the Constitution of the Republic of South Africa expects the government entities to be transparent and accountable. Here in, these financial measures are also guided by the Municipal Finance Management Act 56 of 2003 and the Public Finance Management Act 1 of 1999 (as amended 29 of 1999). Measured transparency is critically important for management public funds. Accountability is an essential element in achieving institutional goals, especially where public funds are used. Accountability allows public institutions to provide assurance to the tax payers and to their principals. The Auditor General expects municipalities to be accountable for their financial activities through regular reporting. The Annual Report will therefore be compiled for reporting and it must include all required information. Audit Committee becomes very critical, as a structure established to guide the municipality on finances and ensure that the report is credible in every respect. Metsimaholo municipality has however been facing challenges as per the opinions of the Auditor General based on financial reporting, amongst other things. This study involves the extent to which financial reporting serves as a tool for promoting accountability. In order to test the hypothesis, literature was reviewed to analyse and evaluate financial reporting and accountability. Empirical research was conducted to test and analyse the existence of practices, procedures and policies that promote sound financial management and their effectiveness. Data was collected through questionnaires and face to face structured and unstructured interviews, with respondents from employees of Metsimaholo Local Municipality and community structures. This study found among others that: *Policies for financial reporting exist but are not fully complied with *There is a lack of follow up with and implementation of Auditor General’s recommendations *Audit Committee recommendations are not fully implemented *There are no clear lines of responsibilities between councillors and officials with regard to financial management The study concludes with recommendations to assist the municipality in committing themselves to adopt strategies towards financial reporting for improved accountability. / Thesis (M. Development and Management (Public Management and Government))--North-West University, Vaal Triangle Campus, 2013
|
365 |
Fiscal decentralization as efficiency tool for supply chain management at Emfuleni Local Municipality / M.A. MahlokoMahloko, Maainini Annette January 2011 (has links)
Decentralization is a buzzword in current discussions on Public Management and its debate has always been a contentious one. The concept involves the restructuring or reorganization of authority so that there is a system of co-responsibility between institutions of governance at the central, provincial, regional and local levels according to the principle of subsidiary, thus increasing the overall quality and effectiveness of the system of governance, while increasing the authority and capacities of sub-national levels. The dispersal of financial responsibility is a core component of decentralization. Similarly, fiscal aspect is one of the decentralization programs. Moreover, fiscal as a tool is to change from inefficient to efficient public sector functioning and to improve relations between local governments for more efficient in public service. Importantly, decentralization of fiscal responsibilities is envisaged to increase efficiency in service delivery and reduce information and transaction costs associated with the provision of public services. By implication, efficiency in this context means how a country’s public finances are structured and how nation-state that is fragmented holds its finances together in the first place. The concept of “Supply Chain Management” (SCM) is the network of organizations that are involved, through upstream and downstream linkages, in the different processes and activities that produce value in the form of products and services delivered to the ultimate customer. Public sector SCM is seen as an acquisition of goods and service which has broader social, economic and political implications. Effective public sector SCM has potential benefits such as inventory reduction, improved service delivery and cost reduction across supply chain. Despite these benefits, South African (SA) public sector encounters challenges of SCM. In Emfuleni Local Municipality (ELM), these challenges range from a paucity of human resources due to lack of skills and capacity in the implementation and execution of SCM functions, poor implementation of SCM practices, quality of service in the SCM and to poor collaborative planning. Other barriers are lack of fiscal accountability, tight budget constraints and conflict of interest in the awarding of tenders which leads to political elite and bureaucratic corruption which cascades into unethical and unfair procurement dealings. These costly burdens result in ELM’s failure to meet community needs. Due to these challenges, the Fiscal Decentralization of SCM functions currently occupies a centre stage in the financial management reform process at ELM. Evaluating the efficiency of fiscal decentralization within the Supply Chain Management Department of Emfuleni Local Municipality requires an in-depth understanding of criteria. The concepts and principles from an examination of documentary data and analysed by the researcher were applied. In addition, semi-structured interviews, focus group discussion and observation methods were conducted to solicit comments from senior managers, employees and service providers This study reports the results of a full survey among a sample of the municipality-wide customers in the study area. It was found amongst other that: • Fiscal Decentralization as SCM efficiency tool has had only marginal positive effect at ELM • Effective implementation of fiscal decentralization is a function of well trained, qualified personnel crop, an attribute which is only beginning to get at ELM • Fiscal decentralization is best promoted wish performance management, a strategy which is well performed at ELM The study ends with recommendations for management action in committing themselves to take strategic fiscal decisions and actions that hold the key to the success of decentralized decision making. / MA, Public Management and Administration, North-West University, Vaal Triangle Campus, 2011
|
366 |
Culture and variation in wild chimpanzee behaviour : a study of three communities in West AfricaHumle, Tatyana January 2003 (has links)
The concept of culture has recently been used to explain behavioural variation and trans-generational continuity of behaviour in non-human animals and in chimpanzees in particular. However, few studies in the wild have systematically investigated how the environment and behavioural adaptation might influence behavioural diversity. In this context, one habituated community of wild chimpanzees (Pan troglodytes verus) at Bossou, Guinea, and two neighbouring non-habituated communities in the Nimba Mountains region of Guinea and Cote d'Ivoire were the subject of a detailed study of behavioural variation at the intra- and inter-community level. An ecologically-based approach was adopted to investigate variation in nest building, in the use of the oil-palm tree (Elaeis guineensis), in ant-dipping and in tool-choice and -manufacturing. A significant influence of environmental variables on nesting parameters emerged explaining much of the variation observed between the three sites. However, some differences that arose are more likely to reflect differences in social structure and organisation. The comparative study of the utilisation of the oil-palm tree failed to reveal proximate environmental parameters that might explain significant observed variations in use. These findings raise interesting and important questions pertaining to diffusion of behaviour between neighbouring chimpanzee communities. Dipping for driver ants, Dorylus spp., is often cited as one of the best examples of culture in chimpanzees. A detailed analysis of this behaviour at Bossou suggests that risk exposure affects frequency of performance in the developing chimpanzee and reveals a strong influence of prey characteristics, including aggressiveness and/or gregariousness , on tool length and technique employed. Variations in tool-choice and tool-manufacturing within and between three tool-use behaviours at Bossoui nvolving the use of a stick or a stalk were found to be significantly associated with the nature of the task and its predictability, emphasising the importance of environmental affordance and constraints on these processes. In addition, efficiency in behaviour across another set of three tool-use behaviours was explored focusing chiefly on age-class differences. An analysis of individual and community-level patterns of laterality in hand-use between these three tool-use behaviours is also provided. The data supply some evidence to support the selective advantages of lateralization in hand-use with respect to behavioural efficiency. The findings also suggest that haptic tasks have played an important evolutionary role in driving population-level handedness, and reveal that although complex tool-uses exhibited high levels of lateralization, these failed to show task specialisation across individuals. Finally, this thesis presents a comprehensive review analysis of individual and community-wide variation across a range of behaviours observed in chimpanzees and identifies paths and hypotheses that warrant further exploration and testing with the aim to gain further insight into cultural processes in nonhuman animals.
|
367 |
Very high cycle fatigue of tool steelsKazymyrovych, Vitaliy January 2010 (has links)
An increasing number of engineering components are expected to have fatigue life in the range of 107 - 1010 load cycles. Some examples of such components are found in airplanes, automobiles and high speed trains. For many materials fatigue failures have lately been reported to occur well after 107 load cycles, namely in the Very High Cycle Fatigue (VHCF) range. This finding contradicts the established concept of a fatigue limit, which postulates that having sustained around 107 load cycles the material is capable of enduring an infinite number of cycles provided that the service conditions are unchanged. With the development of modern ultrasonic fatigue testing equipment it became possible to experimentally establish VHCF behaviour of various materials. For many of them the existence of the fatigue limit at 107 load cycles has been proved wrong and their fatigue strength continues to decrease with increasing number of load cycles. High performance steels is an important group of materials used for the components subjected to VHCF. This study explores the VHCF phenomenon using experimental data generated by ultrasonic fatigue testing of selected tool steels. The overall aim is to gain knowledge of VHCF behaviour of some common tool steel grades, while establishing a fundamental understanding of mechanisms for crack development in the very long life regime. The study demonstrates that VHCF cracks in tested steels initiate from microstructural defects like slag inclusions, large carbides or voids. It is established that VHCF life is almost exclusively spent during crack formation at below threshold stress intensity values which results in a unique for VHCF morphology on the fracture surface. Significant attention is devoted in the thesis to the ultrasonic fatigue testing technique, i.e. the validity and applicability of its results. FEM is employed to give an additional perspective to the study. It was used to calculate local stresses at fatigue initiating defects; examine the effect of material damping on ultrasonic stresses; and to evaluate various specimen geometries with respect to resulting stress gradient and maximum stressed material volume.
|
368 |
Splinebasierte hochdynamische Drehbearbeitung mit dezentralen PC-Steuerungen /Wetter, Oliver. January 2006 (has links)
Zugl.: Aachen, Techn. Hochsch., Diss., 2006.
|
369 |
Mechanical properties and microstructure study for direct metal deposition of titanium alloy and tool steelBao, Yaxin, January 2007 (has links) (PDF)
Thesis (M.S.)--University of Missouri--Rolla, 2007. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed November 29, 2007) Includes bibliographical references.
|
370 |
Skládání papíru jako pomůcka ve výuce matematiky / Paper folding as a tool in teaching mathematicsSCHINKOVÁ, Nikol January 2018 (has links)
In my thesis I am dealing with the usage of origami at teaching mathematics. In the first chapters I mention a brief history and kinds of creases such as Huzita axioms etc. In the second part I introduce three chapters concerning folding of structures supported by work-sheets at different difficulty levels. The content of these chapters comprises of conic sections and diameters of trapezoids. The last chapters of the thesis are focused on three kinds of folding: Yoshimura, Miura and modular, which are also used in architecture, house design and astronautics.
|
Page generated in 0.0467 seconds