Concebido há milhares de anos, o forjamento passa por melhorias contínuas, mantendo-se como um processo de fabricação moderno, capaz de agregar características importantes a produtos forjados que são utilizados em inúmeras aplicações. Na indústria automobilística, responsável pelo consumo de cerca de 60% de todos os produtos forjados, o forjamento mostrou-se como um processo de conformação plástica eficaz no atendimento das especificações de resistência mecânica e nos quesitos de produtividade. Esta demanda por produtos forjados estimulou a busca por processos mais robustos, nos quais as ferramentas de forjamento possuem papel fundamental para possibilitar a produção de lotes maiores sem paradas de máquina devido a falhas. Cerca de 70% das falhas estão relacionadas ao desgaste das ferramentas. Este trabalho buscou identificar no ambiente industrial, os modos de desgaste responsáveis pela degradação da superfície de contato de um punção, fabricado em aço H-10. Um conjunto de punções foi utilizado no forjamento a quente em prensa mecânica excêntrica horizontal e automática de múltiplos estágios, que utiliza água na refrigeração das ferramentas, durante a fabricação de porcas de roda, em aço SAE 1045. Os resultados obtidos basearam-se: (i) nas análises da superfície e da seção transversal de seis punções em microscópio eletrônico de varredura, (ii) na análise da nanodureza e (iii) na variação dimensional e da massa dos punções. Os resultados apontaram para o desgaste da superfície dos punções logo nas primeiras peças forjadas devido à transferência de óxidos do blank para a superfície da ferramenta. Nesta camada transferida para a superfície dos punções, foram encontrados danos causados pelo desgaste abrasivo e pela fadiga térmica. / Since the initial development, thousands of years ago, forging has faced continuous improvements, remaining as a modern manufacturing process, capable of adding important characteristics to forged products that are used in numerous applications. In the automotive industry, responsible for the consumption of approximately 60% of all forged products, the forging has proved to be an effective metal forming process in terms of mechanical strength specifications and productivity requirements. This demand for forged parts has stimulated the search for more robust processes in which the forging tool has a fundamental role to enable the production of larger batches without downtime due to failures. Approximately 70% of these failures are related to tool wear. This work aimed identifying, in an industrial environmental, the wear modes responsible for the degradation of the contact surface of a punch, made of H-10 steel. A series of punches was used for hot forging in a horizontal and automatic multi-stage eccentric mechanical press which uses water for tool cooling, during the manufacture of wheel nuts, made of SAE 1045 steel. Results were based: (i) on the analysis of the surface and cross section of six punches in a scanning electronic microscope, (ii) on nanohardness analyses and (iii) as well as on mass and dimensional variations. Results pointed to the punch wear in the first forged pieces, due to oxides transferring from blank to the punch surface. On this transferred layer to punch surface, have also found damage caused by abrasive wear and thermal fatigue.

Concebido há milhares de anos, o forjamento passa por melhorias contínuas, mantendo-se como um processo de fabricação moderno, capaz de agregar características importantes a produtos forjados que são utilizados em inúmeras aplicações. Na indústria automobilística, responsável pelo consumo de cerca de 60% de todos os produtos forjados, o forjamento mostrou-se como um processo de conformação plástica eficaz no atendimento das especificações de resistência mecânica e nos quesitos de produtividade. Esta demanda por produtos forjados estimulou a busca por processos mais robustos, nos quais as ferramentas de forjamento possuem papel fundamental para possibilitar a produção de lotes maiores sem paradas de máquina devido a falhas. Cerca de 70% das falhas estão relacionadas ao desgaste das ferramentas. Este trabalho buscou identificar no ambiente industrial, os modos de desgaste responsáveis pela degradação da superfície de contato de um punção, fabricado em aço H-10. Um conjunto de punções foi utilizado no forjamento a quente em prensa mecânica excêntrica horizontal e automática de múltiplos estágios, que utiliza água na refrigeração das ferramentas, durante a fabricação de porcas de roda, em aço SAE 1045. Os resultados obtidos basearam-se: (i) nas análises da superfície e da seção transversal de seis punções em microscópio eletrônico de varredura, (ii) na análise da nanodureza e (iii) na variação dimensional e da massa dos punções. Os resultados apontaram para o desgaste da superfície dos punções logo nas primeiras peças forjadas devido à transferência de óxidos do blank para a superfície da ferramenta. Nesta camada transferida para a superfície dos punções, foram encontrados danos causados pelo desgaste abrasivo e pela fadiga térmica. / Since the initial development, thousands of years ago, forging has faced continuous improvements, remaining as a modern manufacturing process, capable of adding important characteristics to forged products that are used in numerous applications. In the automotive industry, responsible for the consumption of approximately 60% of all forged products, the forging has proved to be an effective metal forming process in terms of mechanical strength specifications and productivity requirements. This demand for forged parts has stimulated the search for more robust processes in which the forging tool has a fundamental role to enable the production of larger batches without downtime due to failures. Approximately 70% of these failures are related to tool wear. This work aimed identifying, in an industrial environmental, the wear modes responsible for the degradation of the contact surface of a punch, made of H-10 steel. A series of punches was used for hot forging in a horizontal and automatic multi-stage eccentric mechanical press which uses water for tool cooling, during the manufacture of wheel nuts, made of SAE 1045 steel. Results were based: (i) on the analysis of the surface and cross section of six punches in a scanning electronic microscope, (ii) on nanohardness analyses and (iii) as well as on mass and dimensional variations. Results pointed to the punch wear in the first forged pieces, due to oxides transferring from blank to the punch surface. On this transferred layer to punch surface, have also found damage caused by abrasive wear and thermal fatigue.

In this diploma thesis, literary research about drilling and coating technology focused on PVD coatings was performed. Furthermore, there is an overview of cutting materials. In the experimental part of the work, the attention is dedicated to tests of twist drills from cemented carbide and high-speed steel materials. For these drills, the feed force Ff and the cutting moment Mc were measured when drilling into austenitic stainless steel. At the end of this work, the technical and economic evaluation of the practical part is presented.

Thesis (PhD (Industrial Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Information on the milling of Ti6Al4V is limited; with most studies concluding that it is not possible to obtain a significant increase in the material removal rate (Qw). Tool wear maps can be a diagnostic instrument for failure analysis. Cutting speed (vc), maximum un-deformed chip thickness (heMax) and the radial immersion percentage (ae/Ø %) are the key variables in understanding the milling of titanium alloys. The objective of this research study was to construct tool wear maps for the milling of Ti6Al4V. This will form the foundation of understanding the cutting demands on the tool, in order to analyse the main wear mechanisms. Remedial actions, which are developed by tool suppliers, can be considered and integrated via this understanding of the failure modes and related mechanisms. Firstly, experimental data from background studies, literature and industry on wear rates and wear mechanisms pertaining to the milling conditions was gathered to construct the tool wear map. Mathematical models describing the wear behaviour for these conditions were also investigated. Secondly, work piece failure maps have been superimposed onto the tool wear maps constructed to understand the global failure boundaries. Experimentation was carried out to validate the constructed maps. The tool wear map could then be used to discuss the observed effects and consider remedial actions. Cutting speed corresponds to the magnitude of the thermal load and heMax represents the mechanical load. The ae/Ø % defines the duration of the exposure to the thermal load at the edge of the cutting tool. This investigation has shown the following issues to be of importance when considering tool performance via the tool wear map approach: 1. The key to designing tool wear maps is to identify the most economic Scheduled Replacement Time (SRT) for the specific components. Knowing the correct SRT makes it possible to optimize the milling conditions so that the cutting tool wears gradually under the cutting conditions, and lasts longer than the economic SRT. 2. Increased vc will decrease tool life (TL). However, in low transverse rupture strength tools there may be a minimum vc below which mechanical overload may occur. Similarly, a local maximum TL (a sweet spot) may exist if there is a phase change in the work piece material. 3. Increased heMax will decrease TL. However, heMax must be kept below a maximum critical value to avoid mechanical overload, but above a minimum critical value to avoid work hardening. 4. Increased ae/Ø % will decrease TL. The best balance of high Qw and economic TL is found with ae/Ø between 30-40% for rough milling. In finish milling the radial cut is limited to 1 mm finishing stock of the work piece. This study revealed the following important factors when considering work piece failure in the milling of Ti6Al4V: 1. Increased vc will reduce the cutting resistance of the work piece and increase Qw. However, vc must be kept below a maximum critical value to avoid work piece material burn, but above a minimum critical value to avoid burring and poor surface finish, due to tool build-up and chip jamming. 2. Increased heMax will increase the cutting resistance of the work piece and increase Qw. The heMax must be kept below a maximum critical value to avoid poor surface finish, poor flatness and parallelism (due to work piece bending). Likewise, heMax must be kept above a minimum critical value to avoid work hardening and burring. The constructed tool wear maps are validated with experimental work. This research work identified safe zones to productively mill Ti6Al4V, while producing components with a sufficient surface integrity. / AFRIKAANSE OPSOMMING: Inligting rondom freeswerk van Ti6Al4V is beperk en volgens meeste studies is dit nie moontlik om ‗n wesenlike toename in die materiaal verwyderingstempo (Qw) te behaal nie. Snybeitel verwerings kaarte kan ‗n diagnostiese hulpmiddel wees tydens analisering van snybeitels. Snyspoed (vc), maksimum onvervormende spaanderdikte (heMax) en radiale snitdiepte persentasie (ae/Ø %) is die sleutel veranderlikes om die freeswerk van Ti6Al4V beter te kan verstaan. Die doel van die navorsingstudie was om snybeitel verweringskaarte vir die freeswerk van Ti6Al4V te bou. Die werk vorm ‗n fondasie om die eise van freeswerk op die snybeitel beter te verstaan. Sodoende kan die hoof verweringsmeganismes analiseer word. Regstellende aksies wat deur snybeitel vervaardigers ontwikkel is, was ondersoek en integreer met die huidige kennis rondom die falingstipe en verwerings meganismes. Aanvanklik was eksperimentele data van agtergrond studies, literatuur en industrie oor die verweringstempos en -meganismes rondom die freeswerk van Ti6Al4V versamel. Hiermee is verweringskaarte gebou. Wiskundige modelle wat die verwering kan beskryf was ook ondersoek. Daarna was werkstuk falingskaarte integreer met die ontwikkeling van die snybeitel verweringskaarte om sodoende die grense in geheel te verstaan. Eksperimentele werk was gedoen om die snybeitel verweringskaarte se uitleg te toets. Sodoende kon die snybeitel verweringskaarte gebruik word om die gedrag van die snybeitel te bespreek en regstellende aksies te ondersoek. Snyspoed (vc) stem ooreen met die grootte van die termiese lading en heMax verteenwoordig die grootte meganiese lading. Die ae/Ø % omskryf die tydperk van blootstelling aan die termiese lading op die snyrand. Die ondersoek het bewys dat die volgende faktore belangrik is wanneer snybeitel prestasie met die snybeitel verweringskaart evalueer word: 1. Die sleutel tot die ontwerp van snybeitel verweringskaarte is om die mees ekonomies beplande vervangingstyd (SRT) vir spesifieke komponente te identifiseer. Sodoende is dit moontlik om die frees toestande te optimaliseer, waaronder die snybeitels geleidelik sal verweer onder die eise en vir ‗n langer tydperk as die ekonomiese SRT sal kan sny. 2. Toename in vc sal snybeitelleeftyd (TL) laat afneem. Snybeitels met ‗n lae dwarsbreuksterkte, kan ‗n minimum vc hê waaronder meganiese oorlading plaasvind. Terselfdertyd, kan ‗n maksimum TL (‗n ―sweet spot‖) bestaan as daar ‗n fase verandering in die werkstuk materiaal plaasvind. 3. Toename in heMax sal TL laat afneem, maar moet laer as ‗n maksimum- en hoer as ‗n minimum kritiese waarde wees, om sodoende meganiese oorlading en werksverharding onderskeidelik te vermy. 4. Toename in ae/Ø % sal TL laat afneem. Die beste balans tussen TL en ae/Ø % is gevind met ae/Ø % tussen 30-40% vir growwe freeswerk. In afrondingsfreeswerk is die radiale snit beperk tot 1 mm van die oorblywende werkstuk. Die ondersoek het bewys dat die volgende faktore belangrik is wanneer werkstukfaling in ag geneem word met snybeitel verweringskaarte: 1. Toename in vc sal die werkstukweerstand geleidelik verminder en Qw laat toeneem. Ongelukkig is vc beperk tot ‗n maksimum kritiese waarde om werkstukfaling te voorkom weens ‗material burn‘. Die snyspoed moet ook hoër as ‗n kritiese waarde wees om werkstukklitsing en swak afronding weens spaander probleme te vermy. 2. Toename in heMax sal die werkstuk weerstand geleidelik vermeerder en Qw laat toeneem. Die heMax is beperk tot ‗n maksimum kritiese waarde om swak werkstuk afronding, weens die buiging van die werkstuk, te vermy. Terselfdertyd moet heMax hoër as ‗n kritiese waarde wees om werkstukverharding en -klitsing te voorkom. Die saamgestelde snybeitel verweringskaarte was bekragtig met eksperimentele werk. Die navorsingswerk het veiligheidsareas identifiseer om Ti6Al4V produktief te frees, sonder om die werkstukoppervlak krities te beïnvloed.

The thesis focuses on the morphology of defects and cause of wear in coat cutting tools, the description of the chip formation and its effects on the machined area. The experiment drala with the description of the chip form in connection with the cutting properties, type of tools, wear in removable parting cutting tips and the comparison of cutting tips from two leading manufacturers.

The topic of this thesis is divided in two main parts. The first is about the “tool/workpiece pair” method and the second is related to wear monitoring. The entire project will be about drilling and tapping operations done in SNECMA Vernon. In fact, the part is very expensive so they have to be closely controlled to avoid a maximum scrap pieces. Two software will be used to control it. Firstly, the “tool/workpiece pair” will be done through AMC3 (software developed at the ENSAM). And secondly the wear monitoring will be ensured by the software CTM Visu (developed by ARTIS). My task will be to learn how to use those software and then to implement them in the company.