The aim of diploma thesis is a comparison of flame and fusion laser cutting of thin metal sheets for ACO Industries k. s. company, where the experimental part was also realized. After consultation with company, the thesis was extended by data samples, which were cut by compressed air for comparison with other two gases. The optimization design of cutting parameters was created by Taguchi method. Afterwards the surface roughness of samples was measured. Based on Ra and Rz5 parameters, the samples were classified to classes based on their accuracy according to ISO 9013 standard. According to results the fusion method of laser cutting is more suitable method, especially for its good quality of cutting edge, which is not affected by the oxidic layer. Fusion method uses cutting speed two times higher than the flame method, which leads to decrease of time and financial consumption of the process despite of its higher hourly rate. In case of laser cutting of material by compressed air the quality of cut is insufficient in comparison with fusion or flame cutting method.

<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>

This study explores the relationship between endmill tool dynamics and cutting parameters, emphasizing the impact of these factors on machining dynamics, surface finish, and dimensional control. It introduces a novel approach to analyze and optimize the overall performance of a solid carbide endmill, with a specific focus on machining Aluminum 6066-T6. By using stability lobes diagrams (SLD), stable conditions for cutting were chosen, and then surface roughness and tool and workpiece vibration analyses were performed to assess machining performance. This work aims to understand the effects of operating below the peaks and valleys, inherent in the shape of the SLD, using different RPMs. The study's methodology involves tap tests using CutPro - Tap Test Module and milling tests on a horizontal machining center. The surface roughness measurement was performed using an Alicona Infinite Focus confocal microscope and accelerometers were positioned on the spindle bearing housing and workpiece. The findings suggest that within the stable range below the stability lobe diagram's boundary, there is a significant difference in vibration resulting in variation in surface roughness corresponding to the peaks and valleys of the SLD. The variation of acceleration, and consequently vibration, was considerably higher when operating below valleys which negatively affected the surface roughness of the workpiece. The surface roughness plays a pivotal role in tool performance and subsequently influences metal removal rate and tool and spindle life. For conditions closer to instability, this is even more important. In conclusion, this research lays the foundation for a holistic approach to solid carbide endmill design and cutting parameter selection, showing that the machining process can be optimized in terms of the SLDs, even in regions far below the stability limit / Thesis / Master of Applied Science (MASc)

<p>Proces glodanja tvrdih (kaljenih) čelika, vretenastim loptastim glodalima,<br />najčešće se primenjuje u operacijama završne obrade kompleksnih<br />površina. Modelovanje ovog procesa i optimizacija njegovih parametara su<br />veoma važni, kao pomoć za razumevanje samog procesa tako i za rešavanje<br />praktičnih problema. Za modelovanje izlaznih performansi procesa obrade<br />i nalaženje optimalnih vrednosti ulaznih parametara, korišteno je<br />nekoliko klasičnih i prirodom-inspirisanih metoda. Od klasičnih metoda<br />modelovanja i optimizacije, u radu su primenjene: metodologija odzivne<br />površine-RSM, Taguči metoda i Taguči metoda sa sivom relacionom<br />analizom. Korištene prirodom-inspirisane metode modelovanja i<br />optimizacije su: genetski algoritam&ndash;GA, sivi vuk optimizer&ndash;GWO i<br />nedominantno sortirajući genetski algoritam II&ndash;NSGA II. Dobijeni pouzdani<br />matematički modeli izlaznih performansi procesa obrade i optimalni<br />ulazni parametri obrade, potvrđuju opravdanost primene svih navedenih<br />metoda u procesu glodanja vretenastim loptastim glodalima tvrdih<br />(kaljenih) čelika. Posebno treba izdvojiti rezultate dobijene pomoću metode<br />sivi vuk optimizer&ndash;GWO. Ova prirodom-inspirisana metoda je potpuno nova<br />metoda i do sada nije bilo literaturnih informacija o mogućnostima njene<br />primene u procesima obrade rezanjem.</p> / <p>The ball end milling process of hard (hardened) steel, is usually applied in the<br />finishing operations of machining comlex surfaces. Modeling of this process and<br />optimization of its parameters are very important as an aid to understanding the<br />processes and to solve practical problems. Several classic and nature-inspired<br />methods were used for modeling of the output process performances and finding<br />the optimal values of input parameters. From traditional methods of modeling and<br />optimization Response Surface Methodology-RSM, Taguchi method and Taguchi<br />method with Gray Relational Analysis, and nature-inspired methods of modeling<br />and optimization Genetic Algorithm-GA, Gray Wolf Optimizer-GWO and Nondominant<br />Sorting Genetic Algorithm II- NSGA-II, were applied in the paper. Reliable<br />mathematical models of the output process performances and the optimal input<br />parameters, confirm the validity of the application of these methods in the process<br />of ball end milling hard (hardened) steel. The results obtained by the method of the<br />Gray Wolf Optimizer-GWO should be particulary noted. This nature-inspired<br />method is quite a new method, and so far there was no literature information on<br />the possibilities of its application in the cutting processes.</p>

Stabilitet och vibrationer inom invändiga svarvningsprocesser är ett område som kräver mer forskning. Tidigare studier visar att problem med stabilitet och utböjning är vanligt vid dessa processer och att de orsakar oönskade vibrationer i processen. Vibrationerna har en negativ effekt på bland annat ytjämnheten, som har visat sig vara en viktig parameter vid invändig svarvning. Syftet med den här studien var därför bland annat varit att undersöka utifrån vilka olika skärparametrar en konstruktions stabilitet kan säkerställas för att uppnå kravspecificerad ytjämnhet. Utöver det skapades en rörkonstruktion med 3D-programmet Autodesk Inventor 2017.Studien påbörjades genom att undersöka problematiken inom området, innan beräkningar på skärparametrar påbörjades parallellt med konceptframtagning.Beräkningarna i resultatet visar att utböjningen som uppstår i processen, är högre med den framtagna rörkonstruktionen än utan den. Dessutom krävs optimering av vissa skärdata för att kunna uppnå kravspecificerat värde på ytjämnhet.Beräkningarna fick baseras på en del approximationer vilket innebär att resultatet inte är tillförlitligt och att syftet inte uppnåtts helt.Den framtagna rörkonstruktionen är inte optimalt monterad på svarvmaskinen vilket betyder att monteringssätt måste optimeras. Utöver det är beräkningarna baserade på teori och approximationer och är därför inte lika tillförlitliga som exempelvis fysiska tester hade varit. / Stability and vibrations in internal turning processes is a field that requires more research. Current studies show that stability and deflection is a common problem with these processeses and that they cause unwanted vibrations in the process. The vibrations have a negative impact on the surface roughness, which has shown to be a crucial parameter in internal turning.The purpose of this thesis has therefore been to investigate by which cutting parameters a constructions stability can be ensured to achieve a required surface roughness. Furthermore a construction was designed with the 3D-program Autodesk Inventor 2017.The study started with an information investigation about the problems within the area of internal turning, before calculations and investigations of cutting parameters began. Parallel to the calculations of cutting parameters, a development of a construction began.The calculations in the result show that the deflection that occurs in the process is greater with the developed construction than without it. Besides this, an optimization of some cutting parameters are needed to obtain the required surface roughness.The calculation are had to be based on some approximations which means that the result is not reliable and therefore the purpose is not completely achieved.The designed construction is not optimally placed on the turning machine which indicates that the placement of the construction needs optimization. In addition to this, the calculations are based on theory and approximations and is therefore not as reliable as physical tests would have been.

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: In a move towards cleaner and more sustainable energy systems, hydrogen as an energy carrier and hydrogen fuel cells as energy converters are receiving increasing global attention. Considering the vital role that platinum plays in the operation of hydrogen fuels cells, South Africa stands to gain enormously as the world’s leading platinum group metals supplier. Therefore, in order to benefit across the whole value chain, it is imperative to develop the capability to manufacture hydrogen fuel cell stacks locally. This project addresses this imperative, in part, by building a framework to evaluate the manufacturing performance of one of the more costly components of the hydrogen fuel cell stack. More specifically, this project builds a cost evaluation model (or cost model) for the manufacture of bipolar plates using micro milling. In essence, the model characterises manufacturing cost (and time) as a function of relevant inputs. The model endeavours to be flexible in accommodating relevant contributing cost drivers such as tool life and manufacturing time. Moreover, the model lays the groundwork, from a micro milling perspective, for a comparison of different manufacturing methods for bipolar plates. The approach taken in building the cost model is a fundamental one, owing to the lack of historical cost data for this particular process. As such, manufacturing knowledge and experimentation are used to build the cost model in a structured way. The process followed in building the cost model begins with the formulation of the cost components by reviewing relevant examples from literature. Thereafter, two main cost drivers are comprehensively addressed. Tool life is characterised experimentally as a function of cutting parameters and manufacturing time is characterised as a function of relevant inputs. The work is then synthesized into a coherent cost model. Following the completion of the cost model, analysis is done to find the near-optimal combination of machine cutting parameters. Further, analysis is done to quantify the sensitivity of manufacturing cost to design changes and production volumes. This attempts to demonstrate how typical managerial issues can be addressed using the cost model format. The value of this work must be seen in terms of its practical contribution. That is, its contribution to the development of the capability to manufacture hydrogen fuel cells locally. By understanding the effect of relevant input factors on manufacturing cost, ‘upstream’ design and development activities can be integrated with ‘downstream’ manufacturing activities. Therefore, this project supports the development of manufacturing capability by providing a mechanism to control cost throughout the process. / AFRIKAANSE OPSOMMING: In die soeke na skoner, meer volhoubare energie bronne word die fokus op waterstof, as energie draer, en waterstof brandstofselle, as energie omskakelaars, al meer verskerp. Deur die sleutelrol van platinum in die werking van waterstof brandstofselle in ag te neem, word Suid-Afrika, as die wêreld se grootste platinum verskaffer, in `n uitstekende posisie geplaas om voordeel te trek uit hierdie geleentheid. Om dus as land voordeel te trek uit die proses in geheel, is dit van kardinale belang om die vermoë te ontwikkel om waterstof brandstofsel stapels op eie bodem te vervaardig. Hierdie projek adresseer gedeeltelik hierdie noodsaaklikheid, deur `n raamwerk te bou wat die vervaardigingsoptrede van een van die meer duursame komponente van die waterstof brandstofsel stapel evalueer. Meer spesifiek, bou hierdie projek `n koste evaluerings model (of koste model) vir die vervaardiging van bipolêre plate deur die gebruik van mikro-masjienering. In wese kenmerk hierdie model vervaardigings kostes (en tyd) as `n funksie van relevante insette. Hierdie model poog om buigsaam te wees met die in ag neming van relevante bydraende kostedrywers soos buitelleeftyd en vervaardigingstyd. Daarbenewens lê hierdie model die grondwerk, vanuit `n mikro masjienerings oogpunt, vir die vergelyking van verskillende vervaardingings metodes vir bipolêre plate. Die benadering wat gevolg word in die bou van die koste model is fundamenteel as gevolg van die gebrek van historiese data vir hierdie spesifieke proses. As sodanig word vervaardigings kennis en eksperimentering gebruik om die koste model in `n gestruktueerde wyse te bou. Die proses gevolg in die bou van die koste model begin met die formulering van die koste komponente deur die hersiening van relevante voorbeelde vanuit die literatuur. Daarna word twee hoof koste drywers deeglik geadresseer. Buitelleeftyd word ekperimenteel gekenmerk as funksie van masjieneringsparameters en vervaardigingstyd word gekenmerk as `n funksie van relevante insette. Die werk word dan gesintetiseer in `n samehangende koste model. Wat volg op die voltooiing van die koste model is `n analise om die optimale kombinasie masjieneringsparameters te vind. Daaropvolgens word analises gedoen om die sensitiwiteit van vervaardigingskoste onderworpe aan ontwerpsveranderings en produksie volumes te kwantisfiseer. Dit poog om te demostreer hoe tipiese bestuursproblem geadresseer kan word deur die koste model formaat te gebruik. Die waarde van hierdie werk moet in die lig van die praktiese bydrae daarvan gesien word, menende, die bydrae tot die ontwikkeling van die vermoë om waterstof brandstofselle in Suid-Afrika te vervaardig. Deur die effek van relevante inset faktore op vervaardigingskoste te verstaan, kan ‘stroom-op’ ontwerp en ontwikkelings aktiwiteite geïntegreer word met ‘stroom-af’ vervaardigings aktiwiteite. Dus, hierdie projek ondersteun die ontwikkeling van vervaardigingsvermoëns deur `n meganisme te voorsien om kostes oor die omvang van die proses te beheer.

Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The aerospace- and automotive industries have an urgency to save space and reduce weight, as well as a need to increase fuel efficiency and reduce emissions. This has led to the use of lightweight structural materials, such as Ti6A14V alloy, which is the most widely used titanium alloy in the aerospace industry. This alloy has an exceptional strength-to-density ratio. The work also covers studies on tool steel 40CrMnMo7 that is used in applications in the tooling-, aerospace and automotive industry. In the quest for improved performance new alternative methods of efficiently machining these materials are investigated. One of the important criteria during machining of these materials is their machinability. This study discusses current research in high performance machining strategies and techniques for advanced materials such as Ti6Al4V and 40CrMnMo7. The properties that make these materials advantageous for the use in the aerospace- and automotive industry also make them difficult to cut. The widespread application of Ti6Al4V in the aerospace industry has encouraged investigations into cooling strategies or -techniques to maintain and improve tool life. Ti6Al4V has a low thermal conductivity causing the heat generated during machining to accumulate on the cutting edge of the tool. During various experiments the application of external compressed air blow cooling (dry cutting), flood cooling, high pressure through spindle cooling (HPTSC) and modifications thereof were investigated. The research project also evaluated the performance of a coating (TiAlN) and various coating treatments. The objectives of the HPTSC modifications were to improve the coolant stream impingement on the tool surface, effectively compressing the thermal barrier, and to reduce the chip-tool contact area. This would lead to a decrease in tool heating and wear. The modified techniques failed to increase tool life but showed signs of increased heat removal capability under the given conditions. It was observed that air blow cooling (dry cutting) delivered the best results when considering cutting materials, coating, coating treatment and cooling strategies or –techniques throughout the experiments conducted. / AFRIKAANSE OPSOMMING: Die Ruimte-en motor-industrie het 'n dringendheid om ruimte te bespaar en gewig te verminder, sowel as 'n behoefte om brandstofdoeltreffendheid te verbeter en emissies te verminder. Dit het gelei tot die gebruik van liggewig strukturele materiale, soos Ti6A14V Allooi , wat die mees gebruikte titanium allooi in die Ruimte is. Hierdie allooi het 'n uitsonderlike krag-tot-digtheid-verhouding. Die studie dek ook gereedskapstaal 40CrMnMo7 wat in die gereedskap, Ruimte-en motor-industrie aangewend word. In die soeke na verbeterde prestasie word nuwe alternatiewe metodes om effektief bewerking van hierdie materiaal ondersoek. Een van die belangrikste kriteria tydens bewerking van hierdie materiaal is die bewerkbaar daarvan. Hierdie studie bespreek die huidige navorsing in hoë prestasie bewerking strategieë en tegnieke vir gevorderde materiale, soos Ti6Al4V en 40CrMnMo7. Die eienskappe wat hierdie materiaal voordelig maak vir die gebruik in die lug-en Ruimte-en motor-industrie, maak dit terselfdetyd moeilik om te sny. Die wydverspreide toepassing van Ti6Al4V in die lug-en Ruimte industrie moedig ondersoeke aan na koelstrategieë of -tegnieke om die instrumentlewe te handhaaf en te verbeter. Ti6Al4V het lae termiese geleidingsvermoë wat veroorsaak dat die hitte, wat gegenereer word tydens bewerking, versamel op die voorpunt van die instrument. Tydens verskillende eksperimente was die toepassing van eksterne saamgeperste lugblaas-verkoeling (droë sny), vloed verkoeling, hoë-druk-deur-die-spil-afkoeling (HPTSC) en aanpassings daarvan geondersoek. Die navorsingsprojek het ook die prestasie van 'n bedekkingslaag (TiAlN) en verskeie bedekkingslaagbehandelings geëvalueer. Die doelwit van die HPTSC aanpassing was om die koelmiddelstroom beklemming op die instrument oppervlak te verbeter, en effektiewelik die termiese versperring saam te pers, asook die skerf-teenoorinstrument kontak te verminder. Dit sou lei tot 'n afname in die instrumentverwarming en -slytasie. Die gewysigde tegnieke het daarin misluk om die instrumentlewe te verhoog, maar het tekens getoon van 'n toename in hitte verwydering vermoë onder die gegewe omstandighede. Dit is dus waargeneem dat lugblaasverkoeling (droë sny) die beste resultate gelewer het in die oorweging van sny materiale, bedekkingslaag, bedekkingslaagbehandelings en verkoeling strategieë of -tegnieke wat regdeur die eksperimente uitgevoer was.

Visto o alto custo gasto nas linhas de usinagem com processos de rebarbação e a crescente demanda na utilização do ferro fundido vermicular, principalmente em motores diesel, este trabalho visou investigar as rebarbas formadas no fresamento de faceamento em uma face similar à face de fogo de um bloco de motor de ferro fundido vermicular FV450. Foram utilizados insertos de metal duro em fresas de facear com 100 mm de diâmetro. Os ensaios foram divididos em duas etapas. Na primeira etapa foi estudada a influência da geometria da ferramenta e a formação da rebarba remanescente. Na segunda etapa foram aplicados os melhores resultados obtidos durante os ensaios da primeira etapa. Um planejamento fatorial completo foi utilizado para a determinação da quantidade de ensaios desta etapa, variando-se a velocidade de corte, o avanço, a profundidade de corte e o desgaste de flanco. A medição da rebarba foi realizada em duas posições diferentes na borda da peça em questão, gerando assim dois ângulos diferentes de saída da ferramenta da peça. Verificou-se que a altura da rebarba foi menor quando se utilizou insertos de geometria mais positiva. O desgaste e o ângulo de saída da peça interferiram de forma significativa no tamanho da rebarba. Também verificou-se a redução da rebarba com o aumento do avanço e da velocidade de corte e com a diminuição da profundidade de corte. Através do software STATISTICA 8.0 foram obtidos os valores dos efeitos principais e das interações, juntamente com o intervalo de confiança e erro padrão. Por fim o planejamento adotado permitiu a elaboração de um modelo empírico capaz de predizer a altura da rebarba. / Since the high cost spent on machining lines with deburring processes and the growing demand in the use of Compacted Graphite Iron (CGI), especially in diesel engines, this work aims to investigate the burr formation mechanisms during face milling of CGI FV450, in a face similar to the combustion face of an engine cylinder block. Carbide inserts were used in a 100 mm of diameter milling cutter. The tests were divided into two stages. In the first stage the following variables were studied: tool geometry and milling with remaining burrs from previous milling. In the second stage, were applied the best results obtained during the tests of the first stage. A Complete Factorial Planning was used to specify the amount of experiments, varying cutting speed, feed rate, cutting depth and the flank wear. The burrs measurement was performed in two different positions of the workpiece exit border, generating two different exit angle from the workpiece. It was found that the burr height was lower with more positive geometry. The wear of the tool and exit angle from the workpiece interfered significantly the burr height. It was observed the decrease of the burr height with the increase of the feed rate and cutting speed and with the decrease of the cutting depth. Through the software STATISTICA 8.0 values were obtained for main effects and interactions, along with confidence intervals and standard error. Finally, the plan adopted allowed the development of an empirical model capable of predicting the burr height.

Visto o alto custo gasto nas linhas de usinagem com processos de rebarbação e a crescente demanda na utilização do ferro fundido vermicular, principalmente em motores diesel, este trabalho visou investigar as rebarbas formadas no fresamento de faceamento em uma face similar à face de fogo de um bloco de motor de ferro fundido vermicular FV450. Foram utilizados insertos de metal duro em fresas de facear com 100 mm de diâmetro. Os ensaios foram divididos em duas etapas. Na primeira etapa foi estudada a influência da geometria da ferramenta e a formação da rebarba remanescente. Na segunda etapa foram aplicados os melhores resultados obtidos durante os ensaios da primeira etapa. Um planejamento fatorial completo foi utilizado para a determinação da quantidade de ensaios desta etapa, variando-se a velocidade de corte, o avanço, a profundidade de corte e o desgaste de flanco. A medição da rebarba foi realizada em duas posições diferentes na borda da peça em questão, gerando assim dois ângulos diferentes de saída da ferramenta da peça. Verificou-se que a altura da rebarba foi menor quando se utilizou insertos de geometria mais positiva. O desgaste e o ângulo de saída da peça interferiram de forma significativa no tamanho da rebarba. Também verificou-se a redução da rebarba com o aumento do avanço e da velocidade de corte e com a diminuição da profundidade de corte. Através do software STATISTICA 8.0 foram obtidos os valores dos efeitos principais e das interações, juntamente com o intervalo de confiança e erro padrão. Por fim o planejamento adotado permitiu a elaboração de um modelo empírico capaz de predizer a altura da rebarba. / Since the high cost spent on machining lines with deburring processes and the growing demand in the use of Compacted Graphite Iron (CGI), especially in diesel engines, this work aims to investigate the burr formation mechanisms during face milling of CGI FV450, in a face similar to the combustion face of an engine cylinder block. Carbide inserts were used in a 100 mm of diameter milling cutter. The tests were divided into two stages. In the first stage the following variables were studied: tool geometry and milling with remaining burrs from previous milling. In the second stage, were applied the best results obtained during the tests of the first stage. A Complete Factorial Planning was used to specify the amount of experiments, varying cutting speed, feed rate, cutting depth and the flank wear. The burrs measurement was performed in two different positions of the workpiece exit border, generating two different exit angle from the workpiece. It was found that the burr height was lower with more positive geometry. The wear of the tool and exit angle from the workpiece interfered significantly the burr height. It was observed the decrease of the burr height with the increase of the feed rate and cutting speed and with the decrease of the cutting depth. Through the software STATISTICA 8.0 values were obtained for main effects and interactions, along with confidence intervals and standard error. Finally, the plan adopted allowed the development of an empirical model capable of predicting the burr height.

This thesis deals with laser cutting of metal sheets from selected steel producers. The basics of laser technologies, especially in industrial use, are described in the introductory part. There the material requirements are described from the point of view of laser cutting. The comparison of materials from different steel producers is made from different angles in the practical part. The conclusion is dedicated to the evaluation of achieved results.