Valorization and analysis of machining technology for the production of aluminium part and consecutively project optimization part production. New advanced cutting tools selection and application of new technologies. The adjustment and simplification of the existing NC program for given CNC machining centre and its final debugging. In the final part, there is an economical and technical evaluation of firm benefits and recommendations into production.

Published Article / In this paper the time and cost parameters of tooling manufacturing by metal casting in rapid prototyping sand moulds are assessed and comparison is made with alternative tool making processes such as computer numerical control machining and investment casting (Paris Process). To that end two case studies obtained from local companies were carried out. The tool manufacturing was conducted according to a five steps process chain referred to as Rapid Casting for Tooling (RCT). These steps include CAD modelling, casting simulation, rapid prototyping, metal casting and finishing operations. In particular the Rapid Prototyping (RP) step for producing the sand moulds was achieved with the aid of an EOSINT S 550 Laser Sintering machine and a Spectrum 510 Three Dimensional Printer. The results indicate that RP is the rate determining step and cost driver of the proposed tooling manufacturing technique. In addition it was found that this tool making process is faster but more expensive than machining and investment casting.

No estado do Rio Grande do Sul, os garimpos de pedras preciosas estão distribuídos em duas regiões principais: no Distrito Mineiro de Ametista do Sul (maior produtor de ametista) e no Distrito Mineiro de Salto do Jacuí (maior produtor de ágata). Nestes dois distritos mineiros são explorados geodos, parcial ou totalmente preenchidos por camadas intercaladas de ágata, quartzo incolor, ametista, calcita e opala. O processo de extração desses geodos gera grande quantidade de rejeito, composto tanto pela rocha portadora do minério como também por minério de baixa qualidade. No município de Soledade se concentram as principais empresas de beneficiamento e também o comércio dos materiais gemológicos explorados no Rio Grande do Sul. No entanto, a maioria dos objetos produzidos que visam à exportação se repete nas diversas indústrias beneficiadoras sem diferencial aparente. A opala encontrada nos garimpos de Salto do Jacuí ocorre em muitas cores. A opala branca é a mais comum e não é valorizada, gerando, assim, significativa quantidade de rejeito. Através deste estudo, objetiva-se estabelecer uma metodologia de beneficiamento por usinagem CNC do rejeito de opala branca e ágata oriundo do Distrito Mineiro de Salto do Jacuí, que agregue valor pelo design e tecnologia. Considerando que os processos mais utilizados nas indústrias atualmente para a ágata, o tingimento e o corte em chapas, não se aplicam à opala, pode-se afirmar que a introdução da tecnologia de usinagem CNC neste setor pode auxiliar no aproveitamento desse material, ao modificá-los e valorizá-los como objetos de adorno sob a forma de camafeus. A metodologia empregada para a presente pesquisa consistiu de etapas de identificação dos locais de extração de ágata e de opala branca do Estado; avaliação dos procedimentos mais utilizados para beneficiamento destes materiais; estudo e análise do material por técnicas específicas; ensaios de usinagem CNC, análise das fresas utilizadas e dos materiais envolvidos após os processos de usinagem e desenvolvimento de produto. Foram realizados nove ensaios de usinagem e as análises posteriores, identificando nos resultados obtidos que, com as fresas adequadas destinadas ao desgaste (maior diâmetro) ou acabamento (menor diâmetro de ponta), quando utilizados em conjunto com parâmetros e estratégias de usinagem bem definidos, são suficientes para que se alcance o objetivo definido nesta pesquisa. / In the state of Rio Grande do Sul, the precious stones mines are distributed in two main regions: in the Mining District of South Amethyst (largest producer of amethyst) and the Mining District of the Salto Jacuí (largest producer of agate). In these two districts Geodis miners are exploited, partially or completely filled by intercalated layers of agate, clear quartz, amethyst, opal and calcite. The extraction process of Geodis generates large amounts of waste, comprising both the rock of the ore carrier as well as of low quality ore. In the municipality of Soledade focus the main company to benefit from trade and gemological materials used in Rio Grande do Sul. However, most of the objects produced aimed at the export is repeated in various industries benefit without apparent difference. The opal found in the mines of the Salto Jacuí appears in many colors. The white opal is the most common and is not valued, thus generating significant amount of waste. Through this study, that aims to establish a methodology for processing by the CNC machining waste of opal and white agate from the Mining District of the Salto Jacuí, a great value was added for design and technology. Whereas the most currently used in industries for agate, dyeing and cut into plates, are not applied to the opal, one can say that the introduction of CNC machining in this sector can assist in the exploitation of such material, to modify and value them as objects of adornment in the form of camafeus. The methodology used for this research consisted of steps of identifying locations for extraction of opal and white agate the state, evaluate the procedures used for further processing of these materials, study and analysis of the material by specific techniques, testing of CNC machining, analysis of cutters and materials used after the processes involved in machining and product development. Were conducted nine tests of machining and the subsequent analysis, identifying the results that, with the cutters suitable for the wear (larger diameter) or finishing (minor diameter of tip), when used together with parameters and machining strategies for well-defined, are sufficient to achieve the goal defined in this study.

To further the research done in machining complex surfaces, Jensen [1993] developed an algorithm that matches the normal curvature at a point along the surface with the resultant radius formed by tilting a standard flat end mill. The algorithm called Curvature Matched Machining (CM2) is faster and more efficient than conventional three-axis machining [Jensen 1993, Simpson 1995 & Kitchen 1996]. Despite the successes of CM2 there are still many areas available for research. Consider the machining of a mold or die. The complex nature of a mold requires at least 20-30 weeks of lead time. Of those 20-30 weeks 50% is spent in machining. Of that time 50-65% is spent in rough machining. For a mold or die that amounts to 7 to 8 weeks of rough machining. If one could achieve as much as a 10-15% reduction in machining time that would amount to almost one week worth of time savings. As can be seen, small improvements in time and efficiency for rough machining can yield significant results [Fallbohmer 1996]. This research developed an algorithm that focused on reducing the overall machining time for parts and surfaces. Particularly, the focus of this research was within rough machining. The algorithm incorporated principles of three-axis rough cutting with five-axis CM2, hence Rough Curvature Matched Machining (RCM2). In doing so, the algorithm ‘morphed‘ planar machining slices to the semi-roughed surface allowing the finish pass to be complete in one pass. This roughing algorithm has significant time-savings over current roughing techniques.

The purpose of the present study is to develop techniques for manufacturing anatomically-shaped substrates of implants made from calcium polyphosphate (CPP) ceramic. These substrates have tissue-engineered cartilage growing on their top surfaces and can be used as implants for osteochondral focal defect repair. While many research groups have been fabricating such substrates using standard material shapes, e.g., rectangles and circular discs, it is considered beneficial to develop methods that can be integrated in the substrate fabrication process to produce an implant that is specific to a patient’s own anatomy (as obtained from computer tomography data) to avoid uneven and/or elevated stress distribution that can affect the survival of cartilage. The custom-made, porous CPP substrates were fabricated with three-dimensional printing (3DP) and computer numerically controlled (CNC) machining for the first time to the best of the author’s knowledge. The 3DP technique was employed in two routines: indirect- and direct-3DP. In the former, 3DP was used to fabricate molds for pre-shaping of the CPP substrates from two different powder size ranges (<75 μm and 106-150 μm). In the latter, CPP substrates were produced directly from the retrofitted 3DP apparatus in a layer-by-layer fashion from 45-75 μm CPP powder with a polymeric binder. The prototyped samples were then sintered to obtain the required porosity and mechanical properties. These substrates were characterized in terms of their dimensional shrinkage and density. Also, SEM images were used to assess the particle distribution and neck and bond formations. The substrates produced using the indirect-3DP method yielded densities (<75 μm: 66.28 ± 11.62% and 106-150 μm: 65.87 ± 6.12%), which were comparable to the substrates used currently and with some success in animal studies. Geometric adjustment factors were devised to compensate for the slight expansion inherent in the 3DP mold fabricating process. These equations were used to bring the plaster molds into true dimension. The direct-3DP method has proven to be the ultimate choice due to its ability to produce complex anatomically-shaped substrates without the use of a chemical solvent. In addition, it allows for precise control of both pore size and internal architectures of the substrates. Thus, the direct-3DP was considered to be superior than the indirect-3DP as a fabrication method. In the alternative CNC machining approach to fabrication, the ability to machine the CPP ceramic was feasible and by careful selection of the machining conditions, anatomically-shaped CPP substrates were produced. To develop strategies for optimizing the machining process, a mechanistic model was developed based on curve fitting the average cutting forces to determine the cutting coefficients for CPP. These cutting coefficients were functions of workpiece material, axial depth of cut, chip width, and cutter geometry. To explore the utility of this modelling approach, cutting forces were predicted for a helical ball-end mill and compared with experimental results. The cutting force simulation exhibits good agreement in predicting the fundamental force magnitude and general shape of the actual forces. However, there were some discrepancies between the predicted and measured forces. These differences were attributed to internal microstructure defects, density gradients, and the use of a shear plane model in force prediction that was not entirely appropriate for brittle materials such as CPP. The present study successfully developed 3DP and CNC fabrication methods for manufacturing anatomically-shaped CPP substrates. Future studies were recommended to explore further optimization of these fabrication methods and to demonstrate the utility of accurate substrates shapes to the clinical application of focal defect repair implants.

The purpose of the present study is to develop techniques for manufacturing anatomically-shaped substrates of implants made from calcium polyphosphate (CPP) ceramic. These substrates have tissue-engineered cartilage growing on their top surfaces and can be used as implants for osteochondral focal defect repair. While many research groups have been fabricating such substrates using standard material shapes, e.g., rectangles and circular discs, it is considered beneficial to develop methods that can be integrated in the substrate fabrication process to produce an implant that is specific to a patient’s own anatomy (as obtained from computer tomography data) to avoid uneven and/or elevated stress distribution that can affect the survival of cartilage. The custom-made, porous CPP substrates were fabricated with three-dimensional printing (3DP) and computer numerically controlled (CNC) machining for the first time to the best of the author’s knowledge. The 3DP technique was employed in two routines: indirect- and direct-3DP. In the former, 3DP was used to fabricate molds for pre-shaping of the CPP substrates from two different powder size ranges (<75 μm and 106-150 μm). In the latter, CPP substrates were produced directly from the retrofitted 3DP apparatus in a layer-by-layer fashion from 45-75 μm CPP powder with a polymeric binder. The prototyped samples were then sintered to obtain the required porosity and mechanical properties. These substrates were characterized in terms of their dimensional shrinkage and density. Also, SEM images were used to assess the particle distribution and neck and bond formations. The substrates produced using the indirect-3DP method yielded densities (<75 μm: 66.28 ± 11.62% and 106-150 μm: 65.87 ± 6.12%), which were comparable to the substrates used currently and with some success in animal studies. Geometric adjustment factors were devised to compensate for the slight expansion inherent in the 3DP mold fabricating process. These equations were used to bring the plaster molds into true dimension. The direct-3DP method has proven to be the ultimate choice due to its ability to produce complex anatomically-shaped substrates without the use of a chemical solvent. In addition, it allows for precise control of both pore size and internal architectures of the substrates. Thus, the direct-3DP was considered to be superior than the indirect-3DP as a fabrication method. In the alternative CNC machining approach to fabrication, the ability to machine the CPP ceramic was feasible and by careful selection of the machining conditions, anatomically-shaped CPP substrates were produced. To develop strategies for optimizing the machining process, a mechanistic model was developed based on curve fitting the average cutting forces to determine the cutting coefficients for CPP. These cutting coefficients were functions of workpiece material, axial depth of cut, chip width, and cutter geometry. To explore the utility of this modelling approach, cutting forces were predicted for a helical ball-end mill and compared with experimental results. The cutting force simulation exhibits good agreement in predicting the fundamental force magnitude and general shape of the actual forces. However, there were some discrepancies between the predicted and measured forces. These differences were attributed to internal microstructure defects, density gradients, and the use of a shear plane model in force prediction that was not entirely appropriate for brittle materials such as CPP. The present study successfully developed 3DP and CNC fabrication methods for manufacturing anatomically-shaped CPP substrates. Future studies were recommended to explore further optimization of these fabrication methods and to demonstrate the utility of accurate substrates shapes to the clinical application of focal defect repair implants.

A tool path generation method for sculptured surfaces defined by triangular meshes is presented in this thesis along with an algorithm that helps determine the best type of cutter geometry to machine a specific surface. Existing tool path planning methods for sculptured surfaces defined by triangular meshes require extensive computer processing power and result in long processing times mainly since surface topology for triangular meshes is not provided. The method presented in this thesis avoids this problem by offsetting each triangular facet individually. The combination of all the individual offsets make up a cutter location surface. A single triangle offsetting results in many more triangles; many of these are redundant, increasing the time required for data handling in subsequent steps. To avoid the large number of triangles, the proposed method creates a bounding space to which the offset surface is limited. The original surface mesh describes the bounding surface of a solid, thus it is continuous with no gaps. Therefore, the resulting bounding spaces are also continuous and without gaps. Applying the boundary space limits the size of the offset surface resulting in a reduction in the number of triangular surfaces generated. The offset surface generation may result in unwanted intersecting triangles. The tool path planning strategy addresses this issue by applying hidden-surface removal algorithms. The cutter locations from the offset surface are obtained using the depth buffer. The simulation and machining results show that the tool paths generated by this process are correct. Furthermore, the time required to generate tool paths is less than the time required by other methods. The second part of this thesis presents a method for selecting an optimal cutter type. Extensive research has been carried out to determine the best cutter size for a given machining operation. However, cutter type selection has not been studied in-depth. This work presents a method for selecting the best cutter type based on the amount of material removed. By comparing the amount of material removed by two cutters at a given cutter location the best cutter can be selected. The results show that the optimal cutter is highly dependent on the surface geometry. For most complex surfaces it was found that a combination of cutters provides the best results.

A tool path generation method for sculptured surfaces defined by triangular meshes is presented in this thesis along with an algorithm that helps determine the best type of cutter geometry to machine a specific surface. Existing tool path planning methods for sculptured surfaces defined by triangular meshes require extensive computer processing power and result in long processing times mainly since surface topology for triangular meshes is not provided. The method presented in this thesis avoids this problem by offsetting each triangular facet individually. The combination of all the individual offsets make up a cutter location surface. A single triangle offsetting results in many more triangles; many of these are redundant, increasing the time required for data handling in subsequent steps. To avoid the large number of triangles, the proposed method creates a bounding space to which the offset surface is limited. The original surface mesh describes the bounding surface of a solid, thus it is continuous with no gaps. Therefore, the resulting bounding spaces are also continuous and without gaps. Applying the boundary space limits the size of the offset surface resulting in a reduction in the number of triangular surfaces generated. The offset surface generation may result in unwanted intersecting triangles. The tool path planning strategy addresses this issue by applying hidden-surface removal algorithms. The cutter locations from the offset surface are obtained using the depth buffer. The simulation and machining results show that the tool paths generated by this process are correct. Furthermore, the time required to generate tool paths is less than the time required by other methods. The second part of this thesis presents a method for selecting an optimal cutter type. Extensive research has been carried out to determine the best cutter size for a given machining operation. However, cutter type selection has not been studied in-depth. This work presents a method for selecting the best cutter type based on the amount of material removed. By comparing the amount of material removed by two cutters at a given cutter location the best cutter can be selected. The results show that the optimal cutter is highly dependent on the surface geometry. For most complex surfaces it was found that a combination of cutters provides the best results.

No estado do Rio Grande do Sul, os garimpos de pedras preciosas estão distribuídos em duas regiões principais: no Distrito Mineiro de Ametista do Sul (maior produtor de ametista) e no Distrito Mineiro de Salto do Jacuí (maior produtor de ágata). Nestes dois distritos mineiros são explorados geodos, parcial ou totalmente preenchidos por camadas intercaladas de ágata, quartzo incolor, ametista, calcita e opala. O processo de extração desses geodos gera grande quantidade de rejeito, composto tanto pela rocha portadora do minério como também por minério de baixa qualidade. No município de Soledade se concentram as principais empresas de beneficiamento e também o comércio dos materiais gemológicos explorados no Rio Grande do Sul. No entanto, a maioria dos objetos produzidos que visam à exportação se repete nas diversas indústrias beneficiadoras sem diferencial aparente. A opala encontrada nos garimpos de Salto do Jacuí ocorre em muitas cores. A opala branca é a mais comum e não é valorizada, gerando, assim, significativa quantidade de rejeito. Através deste estudo, objetiva-se estabelecer uma metodologia de beneficiamento por usinagem CNC do rejeito de opala branca e ágata oriundo do Distrito Mineiro de Salto do Jacuí, que agregue valor pelo design e tecnologia. Considerando que os processos mais utilizados nas indústrias atualmente para a ágata, o tingimento e o corte em chapas, não se aplicam à opala, pode-se afirmar que a introdução da tecnologia de usinagem CNC neste setor pode auxiliar no aproveitamento desse material, ao modificá-los e valorizá-los como objetos de adorno sob a forma de camafeus. A metodologia empregada para a presente pesquisa consistiu de etapas de identificação dos locais de extração de ágata e de opala branca do Estado; avaliação dos procedimentos mais utilizados para beneficiamento destes materiais; estudo e análise do material por técnicas específicas; ensaios de usinagem CNC, análise das fresas utilizadas e dos materiais envolvidos após os processos de usinagem e desenvolvimento de produto. Foram realizados nove ensaios de usinagem e as análises posteriores, identificando nos resultados obtidos que, com as fresas adequadas destinadas ao desgaste (maior diâmetro) ou acabamento (menor diâmetro de ponta), quando utilizados em conjunto com parâmetros e estratégias de usinagem bem definidos, são suficientes para que se alcance o objetivo definido nesta pesquisa. / In the state of Rio Grande do Sul, the precious stones mines are distributed in two main regions: in the Mining District of South Amethyst (largest producer of amethyst) and the Mining District of the Salto Jacuí (largest producer of agate). In these two districts Geodis miners are exploited, partially or completely filled by intercalated layers of agate, clear quartz, amethyst, opal and calcite. The extraction process of Geodis generates large amounts of waste, comprising both the rock of the ore carrier as well as of low quality ore. In the municipality of Soledade focus the main company to benefit from trade and gemological materials used in Rio Grande do Sul. However, most of the objects produced aimed at the export is repeated in various industries benefit without apparent difference. The opal found in the mines of the Salto Jacuí appears in many colors. The white opal is the most common and is not valued, thus generating significant amount of waste. Through this study, that aims to establish a methodology for processing by the CNC machining waste of opal and white agate from the Mining District of the Salto Jacuí, a great value was added for design and technology. Whereas the most currently used in industries for agate, dyeing and cut into plates, are not applied to the opal, one can say that the introduction of CNC machining in this sector can assist in the exploitation of such material, to modify and value them as objects of adornment in the form of camafeus. The methodology used for this research consisted of steps of identifying locations for extraction of opal and white agate the state, evaluate the procedures used for further processing of these materials, study and analysis of the material by specific techniques, testing of CNC machining, analysis of cutters and materials used after the processes involved in machining and product development. Were conducted nine tests of machining and the subsequent analysis, identifying the results that, with the cutters suitable for the wear (larger diameter) or finishing (minor diameter of tip), when used together with parameters and machining strategies for well-defined, are sufficient to achieve the goal defined in this study.

Tendo em vista ganhos expressivos na inovação e na competitividade, o setor joalheiro nacional busca constantemente incorporar novos recursos a fim de eliminar erros e agilizar a fabricação de modelos. Dentre as diversas tecnologias passíveis de serem empregadas na produção de joias, a usinagem CNC, é amplamente utilizada por empresas de todos os portes. A usinagem, associada à microfusão, aprimora o processo de produção de joias em larga escala, pois reduz o índice de retrabalho, de perda de material e garante maior qualidade e produtividade mantendo a expressividade formal da peça original. O presente trabalho propõe um estudo acerca das tecnologias de modelagem do setor joalheiro, dando foco aos processos de fresamento. Com o auxílio da digitalização tridimensional, foi feita uma análise comparativa das etapas envolvidas no processo de fabricação de joias. Foi possível verificar, pelos resultados obtidos, que a influência da velocidade de avanço no acabamento das peças: velocidades mais baixas resultaram em superfícies com menor rugosidade aparente e permitiram a obtenção de seções mais estreitas. Além disso, os ensaios possibilitaram a definição das velocidades adequadas para a relação produtividade versus acabamento. Foram ainda determinadas relações entre as propriedades mecânicas do material e os parâmetros testados, comprovando-se que, dentre as ceras estudadas, aquela de maior dureza (63 na escala Shore D) resulta em melhores condições de acabamento. Este trabalho indica a viabilidade de otimização do processo de fabricação de joias, pois avalia as condições de usinagem em relação ao tempo, bem como a possibilidade de redução das operações de acabamento realizadas após obtenção dos modelos por usinagem. Análises realizadas por digitalização tridimensional indicam que o principal ponto de perda dimensional é a etapa de confecção dos moldes de borracha de silicone e injeção de cera, seguido pela usinagem dos modelos. Entretanto, se esse significativo desvio resultante da produção dos moldes e da injeção for corrigido, a qualidade superficial dos modelos obtidos por usinagem CNC passa a ser fundamental. Esses processos devem, portanto, ser reavaliados, a fim de reduzir os erros gerados nas etapas intermediárias da produção de joias em larga escala. / Given significant gains in innovation and competitiveness, the national jewelry sector constantly seeks to incorporate new features, in order to eliminate errors and streamline the manufacturing of models. Among the various technologies that can be used to produce jewelry, CNC machining, is widely used by businesses of all sizes. Machining process associated with casting, improves the large-scale production of jewelry, because it reduces the rework rate, material loss and ensures higher quality and productivity while maintaining the formal expressiveness of the original part. This research proposes a study about modeling technologies of the jewelry industry, giving focus to milling processes. Aided by three-dimensional scanning, it was performed a comparative analysis of the involved steps in the manufacturing process of jewelry. Based on obtained results, it was possible to verify the influence of feed speed in the finishing of parts: lower feed speeds resulted in surfaces with roughness less apparent and allowed to obtain narrower sections. Moreover, the tests enabled the definition of appropriated feed speeds to the ratio productivity versus finishing. Relationship between mechanical properties and tested parameters was determined, proving that among the studied waxes, the hardest one (63 in Shore D scale) results in better finish. This study indicates the optimization feasibility of jewelry manufacturing process, once it evaluates the machining conditions in relation to time, as well as the possibility of reducing the finishing operations carried out after obtaining models by machining. Analyses performed by three-dimensional scanning indicate that the greater dimensional loss is in the steps of silicon rubber mold production and wax injection, followed by the machining process of models. However, if this significant deviation from production of molds and injection is corrected, the surface quality of models obtained by CNC machining becomes crucial. Therefore, these processes must be reevaluated in order to reduce errors generated in intermediate stages on large-scale production of jewelry.