Cutting Carbon Footprint With Smart Tool Management And Cemented Carbide (WC-Co) Upcycling

During the production of a small to medium-sized aircraft, approximately 250,000 rivet holes are required. These must be manufactured according to strict aviation specific technical, quality, and safety standards. High-quality cemented carbide (WC-Co) drilling tools are used to ensure the necessary precision and durability. However, the high energy requirement for production, especially for sintering the WC-Co blanks, and grinding the final tool geometry negatively impacts the carbon footprint of aircraft production. This study aims to analyse the environmental impact of each step in the WC-Co tool production chain and proposes innovative methods to upcycle worn tools without the need of conventional recycling processes. To reduce the climate impact, a novel smart digital tool management system is introduced containing digital twins of the individual tools. This system is complemented with three new methods of upcycling WC-Co drilling tools: regrinding worn tools to smaller diameters, applying a PVD-coating to compensate for diameter deviations, and de- and recoating diamond coatings on WC-Co tools. Preliminary results in modelling the climate impact show that these strategies can reduce the carbon footprint by up to 53 %

Вдосконалення ріжучого інструменту для оптимізації процесу виготовлення авіаційних компонентів

Робота публікується згідно наказу Ректора НАУ від 27.05.2021 р. №311/од "Про розміщення кваліфікаційних робіт здобувачів вищої освіти в репозиторії університету". Керівник роботи: доцент, к.т.н. Закієв Вадим ІсламовичThis master degree thesis is dedicated to improvement of mechanical properties of cutting insert to increase cutting performance. In the work were considered hardening methods that ensure optimal improvement of the cutting inserts, experimental studies are based on the determination of mechanical characteristics by methods of cantilever bending and when a concentrated load is applied to a sample resting on two supports. It has been confirmed that the processing technology using a pulsed magnetic field has high efficiency and is convenient to use. The proposed strengthening method will increase tool life and cutting performance, which will significantly reduce cost and efficiency manufacturers can use high hardness and high strength advanced materials with confidence to achieve a comprehensive improvement in the performance of aviation aircraft.Магістерська робота присвячена покращенню механічних властивостей ріжучих пластин для підвищення продуктивності різання. В роботі розглянуті методи загартування, які забезпечують оптимальне вдосконалення ріжучих пластин. Експериментальні дослідження базуються на визначення механічних характеристик методами консольного згинання та при дії зосередженого навантаження на зразок, що лежить на двох опорах. Підтверджено, що технологія обробки з використанням імпульсного магнітного поля має високу ефективністю, є зручною у використанні. Запропонований метод зміцнення підвищить терміну служби інструменту та продуктивність різання, що значно знизити вартість та ефективність

Investigation into deep hole drilling of austenitic steel with advanced tool solutions

Deep hole drilling processes for high-alloyed materials are characterised by worn guide pads and chatter vibrations. In order to increase feed rates, process stability and bore quality in STS deep hole drilling, various investigations were carried out with adjustments to the tool. First, a new process chain for the production of tribologically optimised guide pads and their effects on the guide pad shape is described in detail. The results of these studies show that the shape change in the area of the axial run-in chamfer through a micro finishing process leads to a better bore hole quality. Furthermore, the influence of guide pad coating and cooling lubricant on the deep hole drilling process was investigated. In addition, the machining of the austenitic steel AISI 304 is analysed by using a conventional steel boring bar and an innovative carbon fibre reinforced plastic (CFRP)-boring bar. While the conventional drill tube oscillates with different eigenfrequencies, the CFRP-boring bar damps chatter vibrations of the drill head and stabilises the process. Even at higher feed rates up to f = 0.3 mm, it is possible to machine austenitic, difficult-to-cut-materials with significantly reduced vibrations

Focused ion beam machining of hard materials for micro engineering applications

The Focused Ion Beam (FIB) milling of single crystal diamond was investigated and the beam drift and mill yield were quantified. The effect of water assistance on the milling of diamond was found to double the yield. The surface morphology that spontaneously forms during milling was measured and the mechanisms behind its formation investigated. The effect of gallium implantation on the diamond crystal structure was measured by x-ray diffraction. Chemical vapour deposited polycrystalline diamond (PCD) has been machined into micro scale turning tools using a combination of laser processing and FIB machining. Laser processing was used to machine PCD into rounded tool blanks and then the FIB was used to produce sharp cutting edges. This combines the volume removal ability of the laser with the small volume but high precision ability of the FIB. Turning tools with cutting edges of 39µm and 13µm were produced and tested by machining micro channels into oxygen free high conductivity copper (OFHCC). The best surface quality achieved was 28nm Sq. This is compared to a Sq of 69nm for a commercial PCD tool tested under the same circumstances. The 28nm roughness compares well to other published work that has reported a Ra of 20nm when machining OFHCC with single crystal diamond tools produced by FIB machining. The time taken to FIB machine a turning tool from a lasered blank was approximately 6.5 hours. Improvements to the machining process and set up have been suggested that should reduce this to ~1 hour, making this a more cost effective process. PCD tools with sinusoidal cutting prongs were produced using FIB. The dimensions of the prongs were less than 10µm. The tools were tested in OFHCC and the prongs survived intact. Changes to the machining conditions are suggested for improved replication of the prongs into metal. Sapphire was FIB machined to produce nano and micro patterns on a curved surface. The sapphire is part of a micro injection mould for replication of polymer parts. The comparative economics of hot embossing and injection moulding have been studied. Injection moulding was found to be the more cost effective process for making polymer parts at commercial production levels.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Surface finish in micromilling

Mestrado em Engenharia MecânicaA presente investigação contempla a realização de um estudo experimental usando um centro de maquinagem CNC convencional. Foi simulada e concebida a microfresagem de diversos provetes recorrendo a software CAD/CAM, usando diversas estratégias. Foi analisado o acabamento de superfície obtido bem como o tipo de rebarba produzido. Finalmente, foi efectuada uma optimização do processo de microfresagem. ABSTRACT: The present investigation contemplates the realization of an experimental study using a convencional machining CNC centre. The micromilling of samples was done and simulated using CAD/CAM software, using several strategies. The obtained surface finish was analyzed, as was the produced burr. Finally, an optimization of the micromilling process was optimized

Tribossistemas de revestimentos multicamada de diamante CVD micro/nanocristalino

Doutoramento em Ciência e Engenharia de MateriaisA combinação das características do diamante microcristalino (MCD) e nanocristalino (NCD), tais como elevada adesão do MCD e a baixa rugosidade superficial e baixo coeficiente de atrito do NCD, é ideal para aplicações tribológicas exigentes. Deste modo, o presente trabalho centrou–se no desenvolvimento de revestimentos em multicamada MCD/NCD. Filmes com dez camadas foram depositados em amostras de cerâmicos de Si3N4 pela técnica de deposição química em fase vapor assistida por filamento quente (HFCVD). A microestrutura, qualidade do diamante e adesão foram investigadas usando técnicas como SEM, AFM, espectroscopia Raman, DRX, indentação Brale e perfilometria ótica 3D. Diversas geometrias para aplicações distintas foram revestidas: discos e esferas para testes tribológicos à escala laboratorial, e para testes em serviço, anéis de empanques mecânicos e pastilhas de corte para torneamento. Nos ensaios tribológicos esfera–sobre–plano em movimento recíproco, sob 10–90% de humidade relativa (RH), os valores médios dos coeficientes de atrito máximo e em estado estacionário são de 0,32 e 0,09, respetivamente. Em relação aos coeficientes de desgaste, observou–se um valor mínimo de cerca de 5,2×10–8 mm3N–1m–1 para valores intermédios de 20–25% de RH. A humidade relativa tem um forte efeito sobre o valor da carga crítica que triplica a partir de 40 N a 10% RH para 120 N a 90% de RH. No intervalo de temperaturas 50–100 ° C, as cargas críticas são semelhantes às obtidas em condições de baixa RH (~10–25%). A vida útil das ferramentas com revestimento de dez camadas alternadas MCD/NCD e 24 μm de espessura total no torneamento de um compósito de matriz metálica Al– 15 vol% Al2O3 (Al–MMC) é melhor do que a maioria das ferramentas de diamante CVD encontradas na literatura, e semelhante à maioria das ferramentas de diamante policristalino (PCD). A formação de cratera ocorre por desgaste sucessivo das várias camadas, atrasando a delaminação total do revestimento de diamante do substrato, ao contrário do que acontece com os revestimentos monocamada. Os anéis de empanque testados com biodiesel apresentaram coeficientes de desgaste (4,1x10–10 mm3N–1m–1) duas ordens de grandeza menores do que em ensaios esfera–sobre–plano em movimento recíproco (k = 5,0x10–8 mm3N–1m–1), mas não foi possível obter vedação completa devido a sobreaquecimento do fluido. Esta condição foi obtida com água sob pressão, para condições P.V na gama 0,72–5,3 MPa.ms–1. Um coeficiente de atrito em estado estacionário de ~ 0,04 e um valor de coeficiente de desgaste de 6,0x10–10 mm3N–1m–1, característico de um regime desgaste ultra–suave, revelam o alto desempenho deste tribossistema.The combination of the characteristics of microcrystalline diamond (MCD) and nanocrystalline diamond (NCD) varieties, such as high adhesion of MCD and low surface roughness and low friction coefficient of NCD, is ideal for highly–demanding tribological applications. The main objective of this study was thus the development of multilayered MCD/NCD coatings for such purpose. Single layer and tenfold multilayer coatings were grown onto Si3N4 ceramic samples by the hot–filament CVD (HFCVD) process and their microstructure, diamond quality and adhesion were investigated using SEM, AFM, Raman spectroscopy, XRD, Brale indentation and 3D optical profilometry. Several geometries for distinct applications were then coated: discs and balls for lab–scale tribological testing, mechanical seal rings and cutting inserts for in–service testing. For the ball–on–flat reciprocating tests in the 10–90% relative humidity (RH) range the average values of the maximum and steady–state friction coefficients are 0.32 and 0.09, respectively. Regarding the wear coefficient of the discs, a valley–shaped evolution is observed within the same RH range, with a minimum of about 5.2×10–8 mm3N–1m–1. Humidity has a strong effect on the value of the critical load that triples from 40 N at 10% RH to 120 N at 90% RH. In the 50–100 °C range the critical loads are similar to those attained under dry conditions ( 25% RH). The tool life of a 24 μm thick tenfold multilayered MCD/NCD coated insert in the turning of an Al–15 vol.% Al2O3 metal matrix composite (Al–MMC) is better than most reported CVD diamond systems, behaving as well as most PCD tools. Crater wear occurs by successive wear of the layers, delaying total delamination of the diamond coating from the substrate, unlike what would happen with monolayer coatings. Under biodiesel lubrication seal rings present wear coefficients (4.1x10–10 mm3N–1m–1) two orders of magnitude lower than the reciprocating sliding ball–on–flat experiments (k = 5.0x10–8 mm3N–1m–1), but no full sealing was possible due to overheating of the fluid. This condition was only attained with pressurized water, for P.V conditions in the range 0.72–5.3 MPa.ms–1. A steady state friction coefficient value of ~0.04 and a wear coefficient value of 6.0x10–10 mm3N–1m–1, characteristic of an ultra–mild wear regime, reveal the high performance of this tribosystem