The laboratory cutting specific energy is widely used to estimate the cuttability of rocks by a roadheader fitted with sharp picks. Sharp picks on the other hand become blunt due to wear in time and require replacement. Although it is known that the pick blunting affects adversely the rock cuttability, no study exists to show the relationships between the degree of pick wear and the cutting specific energy obtained by standard cutting tests. In this study, standard cutting tests were carried out on different rock types, with picks having varying degrees of blunting. The relationships between wear flats and the cutting forces, specific energies and size distribution for various rock properties such as uniaxial compressive strength, tensile strength, cone indenter number, shore hardness, schmidth hammer hardness, density and grain size were established. The mean cutting force and the cutting specific energy have been found to increase 2-3 times and 4-5 times respectively with 4 mm wear flat as compared to sharp picks as the strength and density of rocks increase. No relation exists between mineral grain size and the cutting performance. A definite relation could not be established between the wear land and the size distribution of the product. Charts have been produced to predict critical wear flats for different rock property values considering 25 MJ/m&sup3 / as the limiting specific energy above which poor cutting performance occurs. Nine prediction models have been developed by statistical analysis to estimate the laboratory cutting specific energy from various rock properties and wear rates.

Performance of indexable insert cutting tools is not only about the performance of cutting inserts. It is also about the cutting tool body, which has to provide a secure and accurate insert positioning as well as its quick and easy handling under severe working conditions. The common damage mechanisms of cutting tool bodies are fatigue and plastic deformation. Cutting tools undergo high dynamic stresses going in and out cutting engagement; as a result, an adequate level of fatigue strength is the essential steel property. Working temperatures of tool bodies in the insert pocket can reach up to 600°C, why the tool steel requires high softening resistance to avoid plastic deformation. Machinability is also essential, as machining of the steel represents a large fraction of the production cost of a cutting tool. The overall aim of the study is to improve the tool body performance by use of an advanced steel grade with an optimized combination of all the demanding properties. Due to the high-temperature conditions, the thesis concerns mostly hot-work tool steels increasing also the general knowledge of their microstructure, mechanical properties and machinability. Knowing the positive effect of sulphur on machinability of steels, the first step was to indentify a certain limit of the sulphur addition, which would not reduce the fatigue strength of the tool body below an acceptable level. In tool bodies, where the demand on surface roughness was low and a geometrical stress concentrator was present, the addition of sulphur could be up to 0.09 wt%. Fatigue performance of the cutting tools to a large extent depended on the steel resistance to stress relaxation under high dynamic loading and elevated temperatures. The stress relaxation behaviour, material substructure and dislocation characteristics in low-alloyed and hot-work tool steels were studied using X-ray diffraction under thermal and mechanical loading.  Different tool steels exhibited different stress relaxation resistance depending on their microstructure, temper resistance and working temperature. Hot-work tool steels showed to be more preferable to low-alloyed tool steels because of their ability to inhibit the rearrangement and annihilation of induced dislocations. High-temperature softening resistance of the hot-work tool steels was investigated during high-temperature hold-times and isothermal fatigue and discussed with respect to their microstructure. Carbide morphology and precipitation were determined using scanning and transmission electron microscopy. Machinability of a prehardened hot-work tool steel of varying nickel content from 1 to 5 wt% was investigated in end milling and drilling operations. Machining the higher nickel containing steels resulted in longer tool life and generated lower cutting forces and tool/workpiece interface temperature. The difference in machinability of the steels was discussed in terms of their microstructure and mechanical properties.

This thesis compares the force load of two kinds of cutting tool inserts while milling. The thesis is devided into two main parts – research and experiment. The research part is focused on the theory of the force load measuring, cutting tools and cutting tool inserts and their coating. 14 grooves were made with each cutting insert while the force load was measured. Constant cutting conditions were applied. The experiment was repeated four times for each kind of cutting insert. The aim of the thesis is to determine if both kinds of inserts mill with the same force load. The results reveal that one kind of cutting tool inserts mill with the force load higher up to 85 %.

This thesis compares the properties of four types of replaceable cutting tool inserts from different suppliers during milling. The comparative factors are cutting force, material loss of the insert and the roughness of the resulting surface. The thesis is divided into two parts - a comprehensive overview of the current state of knowledge and an experiment. The first part analyzes the load, the possibility of its measurement, surface treatment of tools, milling cutters and replaceable inserts. The experiment took the form of measuring the load during face milling, measuring the surface roughness of the machined material and measuring the material loss of the inserts on an optical strain gauge. The replaceable cutting tool inserts were compared based on the performed measurements.

This thesis is focused on cutting tools made of cemented carbides. It contains analysis of cemented carbides for uncoated and coated cutting tools. It contains examples of modern tools for turning, milling and drilling. Practical part of this thesis evaluates and compares cutting properties of two types of spiral drills.

The master’s thesis elaborates an optimum proposal of the production technology of a cutting – a part made of steel plate 11 320.3. The theoretical part represents the problematic issue of cutting technology and on the basis of this part was designed a production of components in processual tool. The processual tool is composed of normalized components and is resolved by using a easel, which is attached into the eccentric press LEXN 100 C (producer Toma Industries) with the nominal drawing force of 1000 kN. The press was chosen on the basis of technological calculations. The work contains necessary calculations, economical evaluation and design documentation of the cutting tool for the components production. The last part contains the technical and economic evaluation of the recently designed technology.

Aim master´s thesis is analyzed technological and economical parameters of cutting tool. Firstly there are the parameters cutting tool, cutting wear, economical parameters and costs on running tools specified. In the conclusion there are reach technological and economical parameters of cutting tools analyzed and tested on practical sample. The sample is part of attachments in form programme on calculation in Excel, together with evaluation by means of graphs.

This thesis deals with modern cutting cemented carbide tools. In the first section are stated several basic innovations already used tools for basic machining operations, which is turning, milling and drilling. It continues with analysis of single materials for production of cemented carbides, non coated as well as coated and with comparing of their properties. There are listed the basic cutting properties of the cutting tools after that. The penultimate point of the work is optimization of the basic machining operations, namely roughing and finishing, for a given application, which is in this case turning on the lamp stand. Finally, everything is summed up and evaluated in the conclusion.

The aim of the thesis is to design a manufacturing technology of a part of the universal opener with an innovated design. The component is made of stainless steel 17 240 (X5CrNi18-10). The blank is 2 mm thick sheet metal. Within the literary study the comparison of the possible technologies of manufacturing has been carried out. With respect to the batch size (200 000 pieces) and to the required quality of the component the fineblanking technology has been selected. For the manufacturing of the component a triple action hydraulic press HFA 3200plus has been chosen. This press will be coupled in production line with a feeding line FBA 8/300. The main point of the thesis is to design a cutting tool and to create a drawing documentation. Another part of the project is the technical and economical evaluation of the designed manufacturing process.

O objetivo principal desse trabalho é investigar a aplicação de cerâmica á base de Zirconia em ferramentas de corte na usinagem de aço temperado (VND) utilizando um torno de ultraprecisão. Foram analisados dois tipos de composições de cerâmicas com estrutura cristalina diferentes, sendo elas: monoclínica e tetragonal. A diferença destas estruturas é devido à adição de Ytria. A fase monoclínica não contém Ytria em sua composição, enquanto, a fase tetragonal é obtida com Ytria (\'Y IND.3\') (chamada zirconia parcialmente estabilizada com Ytria). A fase tetragonal apresenta uma resistência elevada ao impacto junto com alta dureza (1800 kgf/\'MM POT.2\') quando comparada com a fase monoclínica que apresenta alta dureza mas menor tenacidade. Devido a este fato, esses materiais têm chamado à atenção dos pesquisadores para a usinagem de aços endurecidos. A geração de superfície é influenciada por diversos fatores, sendo eles: material peça, condições de corte, erros macro geométrico, erros de micro geometricos e do estado da aresta da ferramenta. Na usinagem de ultraprecisão a alta rigidez e vibração/trepidação máquina ferramenta é usada para evitar erros de micro geometria e macro geometria que conseqüentemente são transferidos para superfície da peça. Neste trabalho, devido ao fato de se usar um torno de ultraprecisão é possível afirmar que o perfil da rugosidade é gerado pela replicação do perfil da aresta da ferramenta de corte para a superfície da peça. A rugosidade da superfície foi medida com um perfilometro óptico com resolução de 0,1 nm. Os resultados mostraram que a rugosidade da superfície obtida após os testes de usinagem com as ferramantas de cerâmicas chegou á valores em torno de 0,140 microns, o que equivale ao acabamento com processo de retificação. Outro aspecto importante refere-se ao desgaste das ferramentas que, conseqüentemente, tem uma grande influência nos resultados obtidos. As ferramentas de corte foram analisadas antes e depois da usinagem por microscópio eletrônico de varredura. Verificou-se que as ferramentas de corte na fase tetragonal apresentaram desgaste do tipo cratera na aresta da ferramenta enquanto a aresta da ferramenta monoclínica apresentou desgaste do tipo lascamento. / The main objective of this work is to investigate the application of a ceramic composite of Alumina-Zirconia cutting tools inserts in the machining of hardened steel (VND) in an ultraprecision lathe. Two different ceramic compositions with different crystalline structure were tested, to know: monoclinic and tetragonal. The difference in these structures is due the addition of Yttrium. The monoclinic phase has no Yttrium in its composition while the tetragonal phase is obtained with Ytrium (\'Y IND.3\') (named partially stabilized zirconium). The tetragonal phase presents a high impact toughness along with high hardness (1800 kgf/\'MM POT.2\') when compared to the monoclinic phase which presents high hardness but lower toughness. Due to this fact, these materials have draw attention of researchers in the field of machining of hardened steels. The surface generation is influenced by several factors, to know: workpiece material, cutting conditions, macro geometry errors, micro geometry errors and the sharpness of the cutting edge. In ultraprecision machining, a high stiffness and chatter/vibration free machine tool is used in order to avoid common macro and micro geometry errors replicated into the workpiece surface. In this case, it is possible to assert that the roughness profile is generated by the replication of the cutting tool edge profile to the workpiece surface. The surface roughness was measured by an optical profiler with resolution of 0,1 nm. The results showed that the surface roughness obtained after machining tests with these ceramic inserts were in the range of 0,140 micrometers, which is in the same range of roughness obtained by the grinding process. Another important aspect refers to the wear of the ceramic inserts which has direct influence in the performance as a cutting tool material. The cutting inserts were evaluated before and after machining by scanning electron microscope. It was found that the tetragonal phase cutting tools presented crater wear on the rake face while the monoclinic phase presented cutting edge chipping as the main main type of wear.