The diploma thesis deals with the analysis of the wear of tools fitted with cermet cutting edge. The first part is focused on the theoretical aspects of the problem, which are applied in the practical part. The aim was to perform cutting tests in which carbon steel was turned under selected cutting conditions. Tool wear during turning and the quality of the machined surface were monitored. Machining continued until the selected wear criterion reached the limit value. Two different cermets were tested and the measured data were the basis for the analysis of the wear of the tool edges and the determination of the tool life.

This master‘s thesis deals with optimization of cutting conditions when machining of precise parts in mass production. In experimental part of this thesis is a comparison of the roughing tool with indexable cutting inserts with the new implemented milling cutter. Tool wear of both roughing tools has been analysed. The surface roughness analysis after machining with the face milling cutter was performed. The output of this work is to obtain optimal cutting conditions to gain a minimum surface roughness.

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.

The master`s thesis deal with analysis of machining technology of the bolt from the superalloy Ni80TiAl for the company Sanborn a.s. The aim of the thesis is the project of new technology by usage of new tool, indexable inserts and cutting conditions. The results are speedup of the roughing operation, reduction of the manufacturing cost and the product price.

This diploma thesis deals with the durability of PVD coating in front groove milling. In the theoretical part there is the analysis of high-speed steels, a survey of milling and an overview of coating methods. The experimental part is focused on the power ratios during milling with a router cutter and its wear. From the experiment it is possible to conclude that nanocomposite coatings reduce cutting forces, but do not produce the most durable tool under the cutting conditions.

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The material removal process uses cutting tools in order to produce the desired shape of the workpiece. Tool wear has been a problem for cutting tools, since cutting tools wear and break. Research has been accomplished in the tool wear field for tool life and more recently tool wear. The computer generation has created a method to simulate the material removal process. These computer simulations model the cutting tool reaction with the workpiece. Many of the simulation models use finite element analysis to calculate the reaction of the cutting tool. Different finite element models are being used throughout the world for research. This thesis used an updated Lagrangian model in conjunction with Archard's law to predict the wear of the cutting tool. This research used experimental data to correlate with simulation data to see whether or not Archard's law was a good approximation for tool wear. The research used different side rake angles and cutting surface speed to test the simulation. Shear angle, contact length, cutting ratio, and force are used to provide output values to compare the experimental and computer simulation data. The comparative results showed good trends between the experimental and computer simulation data in every comparison. The results also showed a good approximation for the force and contact length values. Archard's law can be used to model wear on cutting tools with further research.

Milling tests were performed in stainless steel to investigate the formation of built-up edge (BUE). Three variants of tests were conducted which were divided as high-, medium, and low temperature milling tests. These tests were run in the austenitic stainless steel SS2343. The medium temperature milling tests were run in duplex SS2343 and precipitation hardened CORRAX. BUE was found for all tests. With the exception of the high temperature milling tests, BUE was formed locally on the main cutting edge. When milling at higher temperature the BUE covered the entire edge. All inserts used, each with different technologies had the same amount of BUE formation. The tool wear was similar for the CVD-coated inserts used, while the PVD-coated insert suffered less coating detachment along the edge.   Cross sections showed that in addition to BUE, smearing had occurred on the rake face of the inserts, showing that multiple layers of material adhered to the tool surface. Cross sections also showed that the tool wear was similar for the different milling methods, even though it was known that tool failure eventually would be caused by different wear types.   Microhardness tests of the BUE gave results where the austenitic- and duplex stainless steel had in average almost doubled their hardness. Work hardening for CORRAX was lower with an average hardness increase below 9 percent. As CORRAX gave the same amount of BUE formation as the other steels it could be concluded that work hardening did not affect the amount of BUE formation.   For one sample milled at high temperature a new phase had formed on the insert surface. Analysis in EPMA and EDS indicated that it contained chromium, manganese and oxygen. This indicated that the stainless steel had oxidized when milled at higher temperature. When comparing the composition, it was similar for both BUE and the workpiece material SS2343. The only exception was that titanium could be found in the bulk of the BUE, having higher amount when milled at higher temperature. This indicated that the BUE had interacted with the coating, as this was the only source of titanium. / Fräsningstest utfördes I rostfritt stål för att undersöka bildande av lösegg. Tre testvarianter gjordes, uppdelade i hög-, medium-, och låg frästemperatur. Dessa prov kördes i austenitiskt rosfritt stål, SS2343. Fräsning vid mediumtemperatur gjordes även i duplexa SS2377 och utskiljningshärdade CORRAX. Lösegg bildades vid alla tester. Med undantag för högtemperaturstesterna bildades lösegg lokalt på huvudskäreggen. Vid hög temperastur täckte i stället löseggen hela eggen. Alla skär, med olika skärteknologier hade samma mängd bildad lösegg. Den initiala verktygsförlitningen var samma för alla skär, med undantag av det PVD-beläggda skäret, som hade mindre lossnande av beläggning på skäreggen. Tvärsnitt visade att förutom lösegg hade även smearing inträffat på skärens arbetssida, vilket visade att vidhäftande inträffade i flera lager på skäret.Tvärsnitten visade även att skären hade slitits likartat för de olika fräsmtoderna, trots att det var känt att verktygsfel skulle orsakas av olika förslitningstyper. Mikrohårdhetstester av löseggarna gav resultat där det austenitiska-, och duplexa rostfria stålet hade fördubblat sin hårdhet i jämförelse med arbetsmaterialet. Deformationshärdning av CORRAX var lägre i genomsnitt, där dess hårdhet hade ökat med midre än 9 procent. Då CORRAX gav samma mängd löseggsbildning som de andra stålen kunde slutsatsen dras att arbetshärdning inte påverkade BUE-bildningen. För ett prov fräsat vid hög temperatur hade en ny fas bildats på skärytan. Analys i EPMA och EDS indikerade att den innehöll krom, mangan och syre. Detta indikerade att det rostfria stålet oxiderades vid fräsning vid högre temperatur. Jämförelse av kompositionen, visade att den var likartad för lösegg och arbetsmaterialet SS2343. Det enda undantaget var att titan kunde hittas i löseggens bulk, vid högre temperatur. Detta indikerade att löseggen hade interagerat med beläggningen, då det var den enda titankällan

This thesis covers some aspects of hard part turning of carburised steels using a poly‑crystalline cubic boron nitride (PCBN) cutting tool during fine machining. The emphasis is on the influence of the steel cleanliness and the characteristics of non‑metallic inclusions in the workpiece on the active wear mechanisms of the cutting tool. Four carburising steel grades suitable for automotive applications were included, including one that was Ca‑treated. A superior tool life was obtained when turning the Ca-treated steel. The superior machinability is associated with the deposition of lubricating (Mn,Ca)S and (CaO)x-Al2O3-S slag layers, which are formed on the rake face of the cutting tool during machining. Moreover, the transfer of work material to the rake face crater is characteristic in hard part turning of clean steels. It can be because of the lack of sulfides that protect the cutting edge when turning machinability treated steels. This corresponds to the more pronounced crater wear caused by the low‑sulfur steels than that of the steels with higher sulfur contents. It was also concluded that the composition of the non‑metallic inclusions in the Ca‑treated steel is a more important factor than the inclusion number and size, in hard part turning using a PCBN cutting tool. Also, a 3D analysis after electrolytic extraction was found to give a more precise characterisation of non‑metallic inclusions than the conventional 2D analysis by SEM‑EDS. In turn, better correlations to machinability and mechanical properties can be obtained. Hence, the use of this technique is beneficial for future material development. Finally, the challenge for future metallurgy is to manufacture high‑performance steels with improved combined properties of mechanical strength and machinability. / <p>QC 20150422</p>

H13 tool steel is widely used in the mold and die industry. Due to tighter geometric tolerances and higher quality expectations, the use of hard machining has increased over the years. Hard machining refers to the machining of materials in their hardened state. The challenges with hard machining are rapid tool wear and maintaining a high surface integrity of the machined surface. Surface integrity is measured in terms of surface roughness, residual stresses, presence of surface and subsurface cracks, and the quality of the developed microstructure. In order to minimize wear and improve product quality, researchers are working on the development of different tool coatings. Some of the recent tool coatings function by adapting to their environment using heat to form thin layers of oxides, referred to as ―tribo-films‖, on the surface of the tool. If engineered properly, these tribofilms can prolong tool life and improve the surface integrity of a hard machined surface. A titanium based nano multi-layered coating (TiAlCrSiYN/TiAlCrN) has been developed by researchers at the MMRI. The tribological performance of two different coatings TiAlCrSiYN/TiAlCrN and TiAlCrN were tested in a hard machining metal cutting process. The impact of these coatings on tool wear, Cutting process (Chips) and Surface Integrity (Quality of machined surface) was assessed. This research involves characterizing the coating to understand how the formation of different oxide films (tribofilms) effect tool wear and surface integrity. The generation of these tribofilms is sensitive to coating composition and cutting condition (temperature/pressure). Next, an in-depth characterization of the chips produced during machining was carried out as part of studying the effect of different tribological conditions between the tool and workpiece. The chip's hardness, oxidation, chip formation mechanism and topography as the chip slid against the cutting tool surface was studied. Also, the Surface integrity of the machined part was investigated, considering its microstructure, residual stresses and surface roughness. Lastly, tests were performed in an attempt to accelerate the generation of beneficial tribofilms. Results indicate significant improvement in wear life and surface integrity of the machined surface due to the generation of tribo-films in this machining application. / Thesis / Master of Applied Science (MASc)