The aim of this thesis is to create the proposal and expansion of knowledge in the field of experimental measurement of force load when milling thin-walled parts made of aluminum alloy monolithic cylindrical shank cutter of cemented carbide (hereinafter referred to as CC). It also discusses the theoretical analysis of the forces generated during milling, and practical approaches to their measurement experiments. This work also deals with the analysis of aluminum and its alloys. The next chapter describes the appropriate strategy for the machining of thin-walled components including defining the problems, that can complicate machining thin walls. The practical part deals with prediction and a following suggestion of the experiment measuring the power load. The last section is devoted to the practical implementation of the measurement of forces during the milling of thin-walled parts with subsequent evaluation and comparison of strength for the record selected from CC carbide tools, including evaluation of roughness parameters.

Call number: LD2668 .T4 1985 S364 / Master of Science

The Bushveld Igneous Complex (BIC) in South Africa holds approximately three quarters of the world’s viable chromite ore deposits. Most chromite is used for the production of ferrochromium (FeCr), which is a relatively crude alloy. Several chromite seams exist in the BIC. The most economically viable seams are the lower group 6 (LG6), the middle group 1 and 2 (MG1 and 2) and the upper group 2 (UG2) seams. The LG and MG seams are exploited specifically for their chromium content, whereas the UG2 seam is mainly exploited for platinum group minerals (PGM). However, the upgraded UG2 chromite in the PGM tailing is increasingly being used as a feedstock for FeCr production. Many different process variations exist for FeCr production. However, the process option applied in most green and brown field FeCr expansion projects during the last two decades in South Africa has been the oxidative sintered process (also referred to as the Outotec or Outokumpu process). Notwithstanding the common application of the oxidative sintered pelletised feed technology in the South African FeCr industry, and the increased utilisation of beneficiated UG2 ore, a direct comparison of the physical properties of oxidative sintered pellets produced from UG2 with the physical properties of that produced with conventional metallurgical grade chromite ore is currently lacking in the peer-reviewed scientific literature. Therefore, the physical properties of oxidative sintered pellets produced from a typical beneficiated South African UG2 ore were compared with the physical properties of that produced with conventional South African metallurgical grade chromite ore in this study. The results indicated that the case study metallurgical grade chromite ore required 13 kWh/t more energy to mill than the case study UG2 ore prior to pelletisation, which can lead to substantial cost savings. The compressive strength of the oxidative sintered pellets of both case study ores statistically showed that oxidative sintered pellets made from UG2 ore Abstract were the same or better than those prepared from metallurgical grade chromite ore. A comparison of the abrasion strengths of the oxidative sintered pellets of both case study ores indicated that the pellets prepared from UG2 ore were superior compared to the metallurgical grade pellets. The reasons for the superior UG2 pellet strength were investigated with backscatter-, secondary electron- and elemental X-ray mapping scanning electron microscopy (SEM), which indicated that differences in crystalline structures at least partially contributed to the differences observed. Results presented here can be utilised by FeCr producers to better quantify the advantages and disadvantages associated with the use of UG2 ore for FeCr production. / MSc (Chemistry), North-West University, Potchefstroom Campus, 2014

The Bushveld Igneous Complex (BIC) in South Africa holds approximately three quarters of the world’s viable chromite ore deposits. Most chromite is used for the production of ferrochromium (FeCr), which is a relatively crude alloy. Several chromite seams exist in the BIC. The most economically viable seams are the lower group 6 (LG6), the middle group 1 and 2 (MG1 and 2) and the upper group 2 (UG2) seams. The LG and MG seams are exploited specifically for their chromium content, whereas the UG2 seam is mainly exploited for platinum group minerals (PGM). However, the upgraded UG2 chromite in the PGM tailing is increasingly being used as a feedstock for FeCr production. Many different process variations exist for FeCr production. However, the process option applied in most green and brown field FeCr expansion projects during the last two decades in South Africa has been the oxidative sintered process (also referred to as the Outotec or Outokumpu process). Notwithstanding the common application of the oxidative sintered pelletised feed technology in the South African FeCr industry, and the increased utilisation of beneficiated UG2 ore, a direct comparison of the physical properties of oxidative sintered pellets produced from UG2 with the physical properties of that produced with conventional metallurgical grade chromite ore is currently lacking in the peer-reviewed scientific literature. Therefore, the physical properties of oxidative sintered pellets produced from a typical beneficiated South African UG2 ore were compared with the physical properties of that produced with conventional South African metallurgical grade chromite ore in this study. The results indicated that the case study metallurgical grade chromite ore required 13 kWh/t more energy to mill than the case study UG2 ore prior to pelletisation, which can lead to substantial cost savings. The compressive strength of the oxidative sintered pellets of both case study ores statistically showed that oxidative sintered pellets made from UG2 ore Abstract were the same or better than those prepared from metallurgical grade chromite ore. A comparison of the abrasion strengths of the oxidative sintered pellets of both case study ores indicated that the pellets prepared from UG2 ore were superior compared to the metallurgical grade pellets. The reasons for the superior UG2 pellet strength were investigated with backscatter-, secondary electron- and elemental X-ray mapping scanning electron microscopy (SEM), which indicated that differences in crystalline structures at least partially contributed to the differences observed. Results presented here can be utilised by FeCr producers to better quantify the advantages and disadvantages associated with the use of UG2 ore for FeCr production. / MSc (Chemistry), North-West University, Potchefstroom Campus, 2014

ENGLISH ABSTRACT: The sugar industry over the years has been producing sugarcane bagasse as part of the sugar milling process. Currently this sugar mill biomass is incinerated inefficiently as a means of their disposal to produce steam and electricity, which in most cases are only just enough to supply the energy required to run the mills, thereby leaving very little or no extra energy for sale to bring in extra income in addition to sales revenue from sugar. However, the recent instability and uncertainties in the price of sugar and the global call for a green and sustainable environment have necessitated the search for ways of making effective use of this biomass to supply sugar mill energy demands, while producing extra energy in the form of electricity and other energy products for sale and at the same time contributing towards environmental sustainability. The main objective of this work was to develop process models for the processing of sugar mill biomass into energy and energy products. Based on this, biomass to energy conversion process (BMECP) models have been developed for various process configurations of two thermochemical processes; Combustion and Fast Pyrolysis using the Aspen Plus® simulation software. The aim of process modelling was to utilizing sugar cane bagasse as an input energy source to supply the energy requirements of two sugar mill configurations (efficient and less efficient mills), while generating extra electricity and high valued energy products for sale. Four BMECP configurations; 30bar BPST, 40bar CEST, 63bar CEST and 82bar CEST systems were modelled for the combustion thermochemical process. For the fast pyrolysis thermochemical process, two process configurations: Pure Fast Pyrolysis BMECP and Partial Fast Pyrolysis BMECP were modelled. The former BMECP utilizes all available bagasse through fast pyrolysis to produce bio-oil and biochar alongside generating electricity as well as energy to run the sugar mill operations. In the latter BMECP model, only surplus bagasse after separation of the quantity needed to supply the sugar mill energy requirement and electricity production is used to produce bio-oil and biochar. The technical performance of the BMECP models have been analysed and compared based on steam and electricity production rates, process efficiencies and environmental impacts (based on CO2 savings). The effects of boiler operating pressure and bagasse moisture content on the performance of the combustion based BMECP models have also been investigated. Finally, detailed economic models have been developed using the Aspen Process Economic Analyzer (Icarus®) to assess the economic viability of the BMECP models and sensitivity analysis performed to study the response of the BMECP models to variations in economic parameters. Technical performance analysis shows the combustion based BMECP models perform better than the Pure Fast Pyrolysis and Partial Fast Pyrolysis BMECP models with regards to steam and electricity production, thereby giving them higher electrical efficiencies. The electricity generation rate has been shown to increase with increasing boiler operating pressure and decreasing bagasse moisture content while steam production rate has been shown to increase with decreasing bagasse moisture content and decreasing boiler operating pressure. Despite the lower electrical efficiencies of the fast pyrolysis based BMECP models, the analysis shows that their overall process efficiencies compare very well with those of the combustion based BMECP models due to the production of high energy value pyrolysis products. Based on common operating pressure and 50% bagasse moisture content, the Pure Fast Pyrolysis and the Partial Fast Pyrolysis models have proved to be more environmental friendly with hourly CO2 savings of 40.44 and 41.30 tons for the Partial Fast Pyrolysis BMECP and the Pure Fast Pyrolysis BMECP respectively based on a 300 ton of sugarcane/h (81 ton bagasse/h) plant size. From an economic point of view, biomass combustion based on the 63bar CEST BMECP model has proved to be the most economically viable option under current economic conditions. First order total capital investment estimate for this BMECP is about $116 million, producing NPV of $390 million at the end of a 20 year plant life and IRR of 34.51%. The Pure Fast Pyrolysis BMECP model is the least economic viable option. Sensitivity analysis shows this BMECP model is the most sensitive to changes in bagasse and electricity prices; recording -191.61/+446.86% change in NPV for a ±30% change in bagasse price and -91.5/+338.60% for a ±30% change in electricity price. / AFRIKAANSE OPSOMMING: Die afgelope jare het suikerriet-afval (bagasse) by suikermeule ‘n belangrik byproduk van die suiker-industie geraak. Tans word hierdie afval of biomasse verbrand in die suikermeule se poging om stoom en elektrisiteit op te wek; maar die die proses is oneffektief. Die hoeveelheid energie wat opgewek word, is skaars genoeg om die suikermeule self aan die gang te hou; daar is feilik geen sprake ‘n surplus energie waaruit ekstra inkomste verkry kan word toevoegend tot inkomste uit die suiker verkope self. Die huidige onstabiele suikerprys en gepaardgaande onsekerhede sowel as die werêldwye oproep vir ‘n groen- en volhoubare omgewing, noodsaak ‘n nuwe soeke na effektiewe manier om die afvalmateriaal sinvol te verwerk. Die tipe effektiwiteit van verwerking waarna gesoek word moet die volgende uitkomste hê: verskaffing van genoeg energie tydens produksie aan die suikermeuele self; vervaardiging van ekstra energie in die vorm van eletrisieteit en ander energie produkte. Terselfder moet die ook bydra tot die volhoubaarheid van die omgewing. Die grootste gedeelte van hierdie navorsing is gewy aan die ontwikkeling van “proses modelle” om suikemeule afval (bagasse) te omskep in energie en energie-produkte. Om hierdie doel te bereik, is biomassa-tot-energie omskeppingsproses- modelle (BMECP) ontwikkel om verskeie proses konfigurasies van twee termo-chemiese prosesse, naamlik Verbranding (Combustion), en Vinnige Pirolise (Fast Pyrolysis) deur die gebruik van die ‘Aspen Plus®’- simulasie sagteware. Die doel van die proses modelering was om suikerriet biomassa as ‘n bron van energie te gebruik om weer die energie benodighehede van twee denkbeeldige suikermeule vas te stel; een meul is voorgestel as effektief, die ander as minder effektief. Terselfdertyd is gekyk na die hoeveelheid ekstra energie wat elkeen sou opwek en ander hoogs waardevolle energie produkte om te verkoop (bv. ‘bio-olies en bio-char’). Vier “BMECP” konfigurasies (voorstellings) 30bar BPST, 40bar CEST, 63bar CEST en 82bar CEST sisteme is gemodelleer vir die Verbranding termo-chemiese proses. In die geval van die Pirolise (Pyrolysis) termo-chemiese proses, is twee proses konfigurasies gemodelleer: 1. Suiwer Vinnige Pyrolyise BMECP en 2. Gedeeltelik Vinnige Pirolise BMECP. In die geval van eersgenoemde, word alle beskikbare ‘bagasse’ deur vinnige pirolise omskep om ‘bio-olie’ en ‘bio-char’ te vervaardig.Verder wek dit ook elektrisiteit op so wel as die nodige energie om die suikermeule te laat opereer. In die geval van die Gedeeltlike Vinnige Pirolise BMECP , moet daar eers genoegsame ‘bagasse’ opsy gesit word om die suikermeule van genoegsame energie te voorsien vir die volle funskionering daarvan en elektrisiteit-opwekking. Van die surplus of oorblywende ‘bagasse’ kan dan gebruik word om ‘bio-olie’ en ‘biochar’ te produseer. Die tegniese prestasie van al die BMECP modelle is geanaliseer en vergelyk ten opsigte van stoom en elektrisiteits-opwekking; proses effektiewiteit asook die impak op die omgewing ( gebaseer op CO2 –besparings). Die effek van stoomkettel-druk tydens operering asook die bagasse se vog-inhoud. Op die prestasie van die verbrandingsgebaseerde modelle is ook ondersoek. Laastens, uitgebreide ekonomeidese modelle is ook ontwikkel deur die gebruik van die ‘Aspen Process Economic Analyser (Icarus®)’. Sodoende is die ekonomiese vatbaarheid van die BMECP modelle ondersoek. Hierdie sagteware help ook met. Sensitiwiteits-analise in die bestudering van die terugvoer van die BMECP modelle tot veranderlikes in ekonomiese parameters. Rakende effektiwiteit, toon die uitslae dat die verbrandings-gebaseerde BMECP modelle beter vaar as die met betrekking tot stoom- en elektrisiteits-opwekking. Verbrandings-gebaseerde-modelle toon hoër elektriese effektiwiteit. Indien die vog-inhoud van die bagasse laag was en die tempo van stoomketel operasie druk verhoog is, het die tempo van elektriesiteits-opwekking ook gestyg. Ten opsigte van stoom daarenteen, het die stoom-opwekking tempo verhoog in die die vogl inhou van diebagasse laag was asook verminderde stoomketel operering druk. Ten spyte van die laer elektriese effektiewiteit van die Suiwer Vinnig- en Gedeeltelik Vinnig BMECP modelle, dui die analise aan dat hul proses effektiewiteit in die geheel Goed vergelyk met die van die verbrandings-gebaseerde BMECP modelle. Dit is toe te skryf aan die produksie van die hoë-energie draende pirolise produkte. Gebaseer op algemene operering druk van 50% ‘bagasse’ vog-inhoud, het die bogenoemde twee modelle bewys om meer omgewings-vriendelik te wees met uurlikse CO2-besparings. In die geval van Gedeeltelike Vinnige Pirolise BMECP, 40.44 en vir die Suiwer Vinnige Pirolise BMECP 41.30 gebaseer op ‘n 300 ton suikerriet/h (81 ton bagasse/h) plantasie-grote. Ten slotte, vanuit ‘n ekonomiese oogpunt, blyk ‘n biomassa verbranding gebaseer op die 63 bar CEST BMECP model die mees ekonomies-vatbare opsie onder huidige ekonomiese omstandighede. Eerste orde totale kapitale belegging beraming vir hierdie BMECP is ongeveer $116 miljoen, produksie NPV is $390 miljoen aan die einde van ‘n 20 jaar tydperk vir ‘n suikerriet-aanleg. IRP is 34.51%. Die Suiwer Vinnige Pirolise BMECP is die mins-ekonomiese vatbare model. Sensitiewiteits-analises het getoon dat hierdie BMECP model baie sensitief is ten opsigte van verandering in die pryse van bagasse en elektrisieteit; in die geval van NPV is veranderinge van -191.61/+446.86% aangedui op ‘n ±30% verandering in bagasse pryse. In die geval van elektrisieteitspryse, is ‘n sensitiewiteit van van -91.5/+338.60% op ‘n ±30% prysverandering getoon.

Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: The difficulties of chemical process control using plain Proportional-Integral- Derivative (PID) methods include interaction of process manipulated- and control variables as well as difficulty in tuning. One way of eliminating these problems is to use a centralized non-linear control solution such as a feed-forward neural network. While many ways exist to train such neurocontrollers, one of the promising active research areas is reinforcement learning. The biggest drawing card of the neurocontrol using reinforcement learning paradigm is that no expert knowledge of the system is neccesary - all control knowledge is gained by interaction with the plant model. This work uses episodic reinforcement learning to train controllers using two types of process model - non-linear dynamic models and non-linear autoregressive models. The first was termed model-based training and the second data-based learning. By testing the controllers obtained during data-based learning on the original model, the effect of plant model mismatch and therefore real-world applicability could be seen. In addition, two reinforcement learning algorithms, Policy Gradients with Parameter-based Exploration (PGPE) and the Covariance Matrix Adaptation Evolution Strategy (CMA-ES) were compared to one-another. Set point tracking was facilitated by the use of integral error feedback. Two control case studies were conducted to test the effectiveness of each type of controller and algorithm, and allowed comparison to multi-loop feedback control. The first is a ball mill grinding circuit pilot plant model with 5 degrees of freedom, and the second a 41-stage binary distillation column with 7 degrees of freedom. The ball mill case study showed that centralized non-linear feedback control using neural networks can improve on even highly optimized PI control methods, with the proposed integral error-feedback neural network architecture working very well at tracking the set point. CMA-ES produced better results than PGPE, being able to find up to 20% better solutions. When compared to PI control, the ball mill neurocontrol solution had a 6% higher productivity and showed more than 10% improvement of the product size set point tracking. In the case of some plant-model mismatch (88% fit), the data-based ball mill neurocontroller still achieved better set point tracking and disturbance handling than PI control, but productivity did not improve. The distillation case study showed less positive results. While reinforcement learning was able to learn successful controllers in the case of no plant-model mismatch and outperform LV - and (L/D)(V/B)-based PI control, the best-performing neurocontroller still performed up to 20% worse than DB-based PI control. Once again, CMA-ES showed better performance than PGPE, with latter even failing to find feasible control solutions. While on-line learning in the ball mill study was made impossible due to stability issues, on-line adaptation in the distillation case study succeeded with the use of a partial neurocontroller. The learner was able to achieve, with a success rate of just over 50%, greater than 95% purity in both distillate and bottoms within 2,000 minutes of interacting with the plant. Overall, reinforcement learning showed that, when there is sufficient room for improvement over existing control implementations, it can make for a very good replacement control solution even when no model is available. Future work should focus on evaluating these techniques in lab-scale control studies. / AFRIKAANSE OPSOMMING: Die probleme van prosesbeheer met behulp van gewone Proporsioneel-Integraal- Afgeleide (PID) metodes sluit interaksie van proses gemanipuleerde- en beheerveranderlikes, sowel as probleme met in-stemming in. Een manier om hierdie probleme te elimineer, is deur ’n gesentraliseerde nie-lineêre oplossing te gebruik, soos ’n vorentoe-gevoerde neurale netwerk. Daar is baie maniere is om sulke neurobeheerders op te lei, waarvan die meer innoverende maniere versterkingsleer is. Die grootste trekpleister van versterkingsleer is dat geen deskundige kennis van die stelsel nodig is nie - alle beheerkennis word opgedoen deur interaksie met die aanleg model. Hierdie werk gebruik episodiese versterkingsleer om beheerders met behulp van twee tipes van prosesmodel op te lei - nie-lineêre dinamiese modelle en nie-lineêre outoregressiewe modelle. Die eerste was model-gebaseerde opleiding en die tweede data-gebaseerde opleiding genoem. Deur die beheerders wat verkry is tydens datagebaseerde opleiding op die oorspronklike model te toets, kon die effek van die verskil tussen aanleg en model gesien word, en ’n aanduiding van werklike wêreld toepaslikheid gee. Twee versterkingsleer algoritmes was met mekaar vergelyk - Policy Gradients with Parameter-based Exploration (PGPE), en die Covariance Matrix Adaptation Evolution Strategy. Stelpunt volging was deur integraalfout-terugvoer gefasiliteer. Twee gevallestudies is uitgevoer om die doeltreffendheid van elke tipe beheerder en algoritme te toets, deur vergelyking met PI terugvoerbeheer. Die eerste is ’n balmeul toetsaanleg met ’n vryheidsgraad van 5 en die tweede ’n binêre distillasie kolom met ’n vryheidsgraad van 7. Die balmeul gevallestudie het getoon dat gesentraliseerde nie-lineêre terugvoerbeheer met behulp van neurale netwerke selfs op hoogs-geoptimeerde PI beheer metodes kan verbeter. In vergelyking met PI beheer, kon die balmeul neurobeheer oplossing ’n 6% hoër produktiwiteit handhaaf en het meer as 10% verbetering in die handhawing van die produkgrootte stel punt getoon. In die geval van ’n 12% aanleg-model verskil, het die data-gebaseerde balmeul neurobeheerder steeds beter stel punt handhawing en versteuring hantering as PI beheer gewys, alhoewel produktiwiteit nie verbeter het nie. In beide gevalle het die integraalfout oplossing sukses getoon, en CMA-ES het tot 20% beter as PGPE gevaar. Die distillasie gevallestudie het getoon dat die sukses van die balmeul gevallestudie nie noodwendig na ander aanlegte uitbrei nie. Alhoewel versterkingsleer in staat was om suksesvolle beheerders in die geval van geen aanleg-model verskil te leer, het die beste presterende neurobeheerder steeds tot 20% swakker as DB-gebaseerde PI beheer gevaar. Weereens het CMA-ES beter as PGPE gevaar, met die laasgenoemde wat selfs nie daarin kon slaag om werkende oplossings te vind nie. Alhoewel onstabiliteit aan-lyn aanpassing in die balmeul gevallestudie onmoontlik gemaak het, is an-lyn aanpassing in die distillasie gevallestudie moontlik gemaak deur die gebruik van ’n gedeeltelike neurobeheerder. Die leerder was in staat om, met ’n slaagsyfer van net meer as 50 %, meer as 95 % suiwerheid in beide uitlaatstrome te bereik in 2,000 minute van die interaksie met die aanleg. Op die ou end het versterkingsleer getoon dat, wanneer daar voldoende ruimte is vir verbetering oor bestaande beheer implementasies, kan dit ’n baie goeie vervanging wees selfs wanneer daar geen model beskikbaar is nie. Toekomstige werk moet fokus op laboratoriumskaal toepassings van hierdie tegnieke.

This work examined the effects of thermal and chemical treatments on zeolite reactivity and determined the zeolite properties governing the development of compressive strengths and pozzolanic reactivity. Zeolites are naturally occurring aluminosilicate minerals found abundantly around the world. Incorporation of zeolites in cement mixtures has been shown by past research to increase concrete’s compressive strength and durability. In addition, use of zeolites as SCMs can decrease the environmental impact and energy demands associated with cement production for reinforced concrete structures. Further, in contrast to man-made SCMs such as fly ash, zeolite minerals provide a reliable and readily available SCM source, not affected by the production limits and regulations of unrelated industries such as the coal power industry. In this work, six sources of naturally occurring clinoptilolite zeolite were examined. The zeolites were first characterized using x-ray fluorescence, quantitative xray diffraction, thermal analysis, particle size analysis, pore size distribution and surface area analysis, and scanning electron microscopy. Cation exchange capacity was also tested for one of the zeolites. Following comprehensive material characterization, the six pozzolanic reactivity of the natural zeolites was determined by measuring the quantity of calcium hydroxide in paste after 28 or 90 days, by measuring calcium hydroxide consumption of the zeolite in solution and by tracking the development of strengths of zeolite-cement mortars. Pretreatments that attempted to increase the reactivity of the zeolites, including calcination, acid treatment, milling and cation exchange, were then tested and evaluated using the same methods of material characterization and testing mentioned previously. Last, the results of the reactivity testing were reanalyzed to determine which properties of natural zeolites, including particle size, nitrogen-available surface area, and composition, govern the development of compressive strengths, pozzolanic reactivity and improved cement hydration parameters of pastes and mortars using natural zeolites as SCMs. Pretreatment testing showed that milling and acid treatment successfully increased the reactivity of zeolites used as SCMs. Additionally, particle size was shown to be the dominant property in determining the development of compressive strengths while particle size and surface area of the zeolites contributed to zeolite pozzolanic reactivity. / text

<p>Condition monitoring of critical machine tool components and machining processes is a key factor to increase the availability of the machine tool and achieving a more robust machining process. Failures in the machining process and machine tool components may also have negative effects on the final produced part. Instabilities in machining processes also shortens the life time of the cutting edges and machine tool.</p><p>The condition monitoring system may utilise information from several sources to facilitate the detection of instabilities in the machining process. To avoid additional complexity to the machining system the use of internal sensors is considered. The focus in this thesis has been to investigate if information related to the machining process can be extracted directly from the internal sensors of the machine tool.</p><p>The main contibutions of this work is a further understanding of the direct response from both linear and angular position encoders due the variations in the machining process. The analysis of the response from unbalance testing of turn tables and two types of milling processes, i.e. disc-milling and slot-milling, is presented. It is shown that operational frequencies, such as cutter frequency and tooth-passing frequency, can be extracted from both active and inactive machine axes, but the response from an active machine axis involves a more complex analysis. Various methods for the analysis of the responses in time domain, frequency domain and phase space are presented.</p> / QC 20100518

Micro-milling represents a versatile and fast manufacturing process suitable for production of fully 3D micro-components. Such components are demanded for a vast number of industrial applications including safety systems, environmental sensors, personalized medical devices or micro-lenses and mirrors. The ability of micro-milling to process a wide range of materials makes it one of the best candidates to take a leading position in micromanufacturing. However, so far it does not seem to happen. By discussion with various industrialists, low predictability of micro-milling process was identified as the major limiting factor. This is mainly because of strong effects of the tool tolerances and process uncertainties on machining performance. Although, these issues are well known, they are not reflected by the current modelling methods used in micro-milling. Therefore, the research presented in this thesis mainly concentrates on development of a method allowing a prediction of the tool life in manner of tool breakage probability. Another important criterion which must be fulfilled is the method applicability to industrial applications. This means that the method must give sufficiently accurate prediction in reasonable time with minimum effort and interactions with day-to-day manufacturing process. The criteria listed above led to development of a new method based on analytically/numerical modelling techniques combined with an analysis of real tool variations and process uncertainty. Although, the method is presented in a relatively basic form, without considering some of the important factors, it shows high potential for industrial applications. Possibility of further implementation of additional factors is also discussed in this thesis. Additionally, some of the modelling techniques presented in this thesis are assumed to be suitable for application during designing of micro end-mills. Therefore, in the last part of this thesis is presented a systematic methodology for designing of micro end-mills. This method is based on knowledge and experience gained during this research.

<p>U radu je izvršeno modeliranje i simulacija procesa obrade glodanjem sa predviđanjem temperature u zoni rezanja pomoću metode konačnih elemenata. Kao ulazni parametri obrade za model uzeti su brzina rezanja, korak i dubina rezanja a kao izlazna performansa temperatura u zoni rezanja. Kreirani model za simulaciju obrade glodanjem proveren je eksperimentalnim testiranjem sa istim parametrima obrade. Izvršena je analiza eksperimentalnih rezultata sa predloženim modelom. Rezultati ovog istraživanja su pokazali da se modeliranjem i simulacijom procesa obrade glodanjem može adekvatno predvideti temperatura u zoni rezanja.</p> / <p>The work explains process of modeling and simulation of milling predictive<br />temperature in the cutting zone by using the finite element method.The input<br />parameters for the processing model are cutting speed, feed and depth of a<br />cut. The temperature in the cutting zone was used as an output performance.<br />Designed model that simulates milling is checked by experimental testing<br />with the same machining parameters. The analysis of the experimental<br />results with the proposed model was carried out. Results of this study show<br />that the modeling and simulation of milling process can adequately predict<br />the temperature in the cutting zone.</p>