Aplicación de herramientas CAD/CAM para el diseño y fabricación de prototipos de moldes de inyección de plásticos

The study, development and production of injection molds comes with the implementation of CAD and CAM tools available on the market; using these tools, a prototype injection mold for thermoplastic materials was designed and built, based on a mold is injection in the laboratory of the University of Pamplona, in which a couple of modifications were made in order to experiment with its design. The prototype was manufactured through a 3D scan of the original mold to provide the CAD / CAM files with the simulated 3D printing technique for performing an experimental study with the prototype for adjusting temperature and pressure sensors and for coatings metallic materials for use in the injection molding process.El estudio, desarrollo y fabricación de moldes de inyección se facilita con la implementación de las herramientas CAD y CAM que ofrece el mercado, aplicando estas herramientas se diseñó y construyó un prototipo de molde para la inyección de materiales termoplásticos, con base en un molde del laboratorio de inyección de la Universidad de Pamplona, al cual se le hicieron modificaciones para experimentar con su diseño. Se fabricó el prototipo por medio de un escaneo 3D del molde original para obtener los archivos CAD /CAM con la simulación de la técnica de impresión 3D, para realizar un estudio experimental con el prototipo para la adaptación de sensores de temperatura y presión, y para recibir recubrimientos de materiales metálicos para su utilización en el proceso de moldeo por inyección

Micro-nanostructured polymer surfaces using injection molding : a review

Micro injection molding is in great demand due to its efficiency and applicability for industry. Polymer surfaces having micro-nanostructures can be produced using injection molding. However, it is not as straightforward as scaling-up of conventional injection molding. The paper is organized based on three main technical areas: mold inserts, processing parameters, and demolding. An accurate set of processing parameters is required to achieve precise micro injection molding. This review provides a comparative description of the influence of processing parameters on the quality of final parts and the precision of final product dimensions in both thermoplastic polymers and rubber materials. It also highlights the key parameters to attain a high quality micro-nanostructured polymer and addresses the contradictory effects of these parameters on the final result. Moreover, since the produced part should be properly demolded to possess a high quality textured polymer, various demolding techniques are assessed in this review as well

INJECTION MOLDING OF FLAX FIBER BIOCOMPOSITES BY SIMULATION AND OPTIMIZATION

Flax (Linum usitatissimum) fibers have the advantages of low density, low cost, and recyclability and are considered as a potential material to reinforce plastic materials. Though Canada is one of the largest seed flax growing countries in the world, the utilization of flax fibers as reinforcement in composites is not as developed as in Europe. Indeed, in Canada, a large amount of flax straws are left in the fields and burned by farmers each year. Therefore, development of technologies to make use of flax straws for reinforcement in composites and for other purposes has huge benefits to both the material industries and flax farmers in Canada. This thesis presented a study of flax fibers reinforced biocomposites by injection molding through modeling and optimization. The focus of the study was to understand the relationships between the properties of biocomposites and the processing conditions through the experiment and improve the qualities of biocomposites by optimizing the processing conditions. In this thesis, biocomposites were successfully produced by injection molding with a proposed processing scheme. The influence of flax fiber loading and processing conditions, including injection temperature and pressure on the mechanical properties (tensile properties and flexural properties), and water absorption of biocomposites was investigated. The study also experimentally investigated the effect of the processing conditions (fiber content and temperature) on the rheological properties of biocomposites. In order to implement the simulation analysis of injection molding for biocomposites, the Cross-WLF model was employed to obtain the rheological information of biocomposites. Further, a systematic approach on simulation analysis and optimization of injection molding was proposed to minimize the shrinkage and warpage of biocomposites. Several conclusions are drawn from this study: 1) With respect of the influence of the processing conditions on the properties of biocomposites, (a) Fiber content is the most significant impact factor influencing the mechanical properties of biocomposites compared with the other two processing conditions and the tensile properties and flexural properties of biocomposites dreamingly increased with flax fiber content; (b) lower injection temperature led to higher tensile properties and flexural properties; (c) Water absorption of biocomposites was significantly dependent on fiber content and injection temperature; (d) Injection pressure had no significant effect on either mechanical properties or water absorption. 2) In the study on the rheological characteristics, (a) The shear viscosity of biocomposites increased with fiber content, but at very high shear rates (from 5,000 to 10,000 S−1), the shear viscosities of biocomposites with various fiber content (from 0 to 30%) tended to be the same; (b) The shear viscosity of biocomposites decreased with temperature, and at higher shear rate, all the shear viscosity variations as function of shear rates followed the same rate for different temperatures; (c) At high shear rate, the shear viscosity mostly depended on the shear rate rather than fiber content and temperature; (d) A method was presented to determine the seven parameters of the Cross-WLF model for biocomposites. 3) For minimizing the shrinkage and warpage of injection molded biocomposites, (a) The significant factors on the shrinkage and warpage of biocomposites by injection molding were injection temperature, packing time, and packing pressure; (b) The optimization of the injection molding of biocomposites for reducing the shrinkage and warpage of biocomposites was successful by integrating design of experiment (DOE) and simulation technique. The contribution of this thesis includes: 1) In the field of biocomposites reinforcement, the study has shown a great promise to use flax fibers to enhance the mechanical properties of thermoplastics, in particular an increase of 41.83% in tensile strength and an increase of 47.13% in flexural strength. In addition, this work has provided a mathematical relationship between the processing condition of injection molding and the mechanical properties of biocomposites, which would be important to control the manufacturing process to reach desired mechanical properties. 2) In the field of optimal design and manufacturing of flax fiber biocomposites, this work has provided: (a) an effective method to determine the parameters in the rheology model of the biocomposites melt, which has been an important step in simulating the process, and this method has a generalized implication to other types of biocomposites; and (b) a systematic approach to optimize the injection molding process for minimizing the shrinkage and warpage of biocomposites, which are the two most important quality issues in biocomposites

Implementação de controlo estatístico a um processo de injeção de plásticos

Este trabalho consistiu na implementação de controlo estatístico a um processo de injeção de plásticos, da indústria de componentes automóveis. A indústria de componentes automóveis destaca-se como sendo bastante competitiva, devido às dimensões das peças produzidas, sendo crucial garantir a filosofia “fazer bem à primeira”. Da vasta gama de setores de componentes, destacam-se componentes eletrónicos, interiores, exteriores e motores. O processo de injeção de plásticos pode ser diferenciado em três fases: a primeira fase consiste na liquefação do material através do seu aquecimento, a segunda fase ocorre quando o material é injetado para as cavidades do molde onde vai obter a forma desejada e a última fase consiste na ejeção da peça do molde. Na Fase I do SPC foram implementadas cartas ̅− para estimação dos parâmetros do processo a serem utilizados na Fase II e cálculo da capacidade do processo. Na Fase II foi aplicada a carta EWMA, carta mais sensível à deteção de pequenas alterações na média do processo. Após aplicação das cartas de controlo houve a necessidade de aplicar um teste estatístico t-Student para testar as médias das duas fases uma vez que o comportamento exibido pelas cartas na Fase II demonstrou não estar de acordo com a Fase I. Aquando da recolha diária de dados, foram identificadas algumas diferenças entre os valores das cavidades de um dos componentes. De modo a perceber qual a origem dessas diferenças foi aplicado um desenho de experiências com o objetivo de estudar dois fatores a três níveis: percentagem de matéria-prima reciclada e segunda pressão. Foram realizadas nove experiências com seis replicações cada. A determinação dos fatores significativos e melhor combinação de níveis foi feita através da aplicação de análise de variância. A realização deste trabalho permitiu concluir que, o sistema de medição utilizado não é o mais adequando ao caso. A aplicação das cartas de controlo demonstrou que o processo não se encontra estável para a aplicação da Fase II ao processo. Por sua vez o desenho de experiências revelou que a percentagem de matéria-prima reciclada não é um fator significativo. Porém a segunda pressão apresenta-se como fator significativo quando se considera como resposta a dimensão do componente

Shrinkage and ejection forces in thermoplastics reinforced with glass fibres and nanoclays

Tese de doutoramento em Ciência e Engenharia de Polímeros e CompósitosThe process of injection moulding is a complex theme of study, and the manufacture of the moulds requires knowledge about materials, processing and design methods. The larger challenge for designers and engineers is to obtain one product within established tolerances. The prediction of shrinkage enables the engineers to know the final size and shape of the parts. There are commercial codes to simulate the injection moulding process and, thus, help to design runner system, cooling system, weld lines, air traps, and shrinkage. However, there is no software known that could determine the ejection force and, therefore, help to design the ejection system. In this work, a study of shrinkage and ejection force was carried out using deep tubular parts of several materials. This work develops a model to predict the shrinkage and ejection force of mouldings in polypropylene composites reinforced with glass fibre or nanoclays. The experimental part of this work consists in producing the parts with an instrumented mould with monitorisation of the temperature, pressure and ejection force. The final dimensions were also measured after 48 hours to calculate as-moulded shrinkage. Several other tests were done to characterize the material namely DSC, DMA, TMA and rheometry. The tensors of orientation of fibres were determined due to its influence on the shrinkage. The content of fibre, the length and diameter of the glass fibres were evaluated. The coefficient of friction between the steel and polymer was determined to calculate the ejection force. The simulations using the Moldflow software provided the temperature profile across the thickness of the part. The mathematical model that was developed is based on the thermomechanical model to calculate the residual stresses and shrinkage in composites, developed by Kaspar Jansen, and a thermomechanical model to calculate the ejection force in tubular mouldings produced in unreinforced materials, developed by António Pontes. The proposed model is an attempt to predict the shrinkage and ejection force combining those previous models. The results of the model were compared with the experimental results and were found to be in a good agreement.O processo de moldação por injeção é complexo e o fabrico de ferramentas para produzir uma peça requer conhecimento sobre materiais, processamento e metodologias de projeto. O maior desafio para os projetistas e engenheiros é obter uma peça moldada dentro das tolerâncias estabelecidas. A previsão da contração permite aos projetistas prever a dimensão final e a forma das peças produzidas. Há softwares comerciais para simular o processo de injeção e prever, desta maneira, o sistema de alimentação, arrefecimento, linhas de soldadura, retenções de ar, e a contração, mas, não existe software conhecido, para prever a força de extração e, portanto, o sistema de extração. Neste trabalho, um estudo da contração e força de extração foi realizado em moldações tubulares profundas para diversos materiais. O objetivo deste trabalho é desenvolver um modelo para prever a contração e força de extração moldadas em compósitos de polipropileno com fibra de vidro e nanoargila. A parte experimental deste trabalho consiste em produzir peças num molde instrumentado com sensores de temperatura, pressão e força de extração e após 48 horas procedeu-se a medição das moldações para efetuar o cálculo da contração pós moldação. Diversos outros testes foram realizados para caracterizar o material como DSC, DMA e TMA e reometria. Os tensores de orientação das fibras foram determinados, pois influenciam a contração. A quantidade de fibra, o comprimento e diâmetro da fibra de vidro foram também medidos. Os coeficientes de atrito entre o aço e o polímero foram medidos, pois são necessários para calcular a força de extração. Os campos de temperatura ao longo da espessura da peça foram obtidos através das simulações com o software Moldflow. O modelo matemático foi baseado no modelo termomecânico para prever as tensões residuais e contração em materiais reforçados com Fibras de Vidro Curtas desenvolvido por Kaspar Jansen e no modelo termomecânico para prever as forças de extração e contração em peças tubulares com materiais não reforçados desenvolvido por António Pontes. O modelo proposto é uma tentativa de prever a contração e a força de extração combinando os modelos anteriores de Kaspar Jansen e António Pontes. Os resultados de previsão do modelo desenvolvido foram comparados com os resultados experimentais e apresentaram uma boa concordância

A theoretical and experimental study on biochar as an adsorbent for removal of acid gases (CO₂ and H₂S)

Biochar, a carbon-rich material that is obtained from forestry wood residues through thermochemical conversion in the absence of oxygen (i.e. pyrolysis), is a potential alternative to commercial adsorbents for acid gas treatment. Acid gases (CO₂ and H₂S) are present in landfill gases, fossil fuel gases, and mining operations. These gases must be treated to improve environmental safety and limit operational issues such as pipeline corrosion. Common processes for removal of acidic gases from landfill, flue, and natural gas streams include amine absorption processes, which are energy and space intensive due to required regeneration, and solid adsorbents (which can be costly to produce and dispose of). In this work, CO₂ adsorption using biochar as a solid adsorbent was investigated. Use of biochar as an adsorbent for acid gas removal is relatively novel. The specific objectives included; characterize the biochar structure (i.e. chemical, physical, and morphological) through a series of analyses; determine the operating conditions for obtaining maximum adsorption capacity; modify the biochar surface to determine impact on adsorption; and develop a molecular model to simulate the adsorption process to determine if it can be used as a tool in experimental design. Chapter one gives an overview of the conceptual framework of acid gas purification and outlines the objectives, the scopes, and the significance of this study along with a summary of the thesis chapters. Chapter two provides a literature review to identify different types of biochar production methods, reaction conditions (e.g. temperature and residence time), and woody biomass as one of possible feedstock materials. The biochar was compared with commercial adsorbents and the results indicated biochar could be used as a feasible alternative to activated carbon as it is environmentally friendly and a low-cost adsorbent. In addition, the impact of production conditions on biochar properties were investigated and it was found that carbon, hydrogen content, and surface area were significantly affected by pyrolytic temperature. The reported isotherms in the literature were compared and the Freundlich isotherm was the best fit with the biochar. The application of molecular modeling to describe adsorption process and different simulation methods were studied. The biochar for this research was produced from three different woody biomasses: softwood (sawdust and bark (Balsam fir)) and hardwood (Ash wood) through fast pyrolysis at 400-500⁰C and then compared in terms of chemical and physical properties in chapter three. Chapter four looks at the impact of three operating conditions, temperature, inlet feed flow rate, and CO₂ concentration, on biochar adsorption capacity and the interaction of these parameters were evaluated using response surface methodology. The operating conditions for maximizing CO₂ uptake were determined and the Freundlich isotherm best represented the equilibrium adsorption and the pseudo first-order was selected as a kinetic model. Thermodynamic analysis indicated the adsorption process was spontaneous and exothermic. Further, we found that biochar derived from “waste” materials had better adsorption capacity relative to commercial zeolite. Chapter five describes chemical modification of the biochar using two novel methods of amine functionalization and the maximum adsorption capacity was measured at the conditions obtained in chapter four. The results indicated functionalization decreased the pore volume, surface area, and subsequently the adsorption capacity of the biochar. In order to enhance capacity, the biochars (unmodified and chemically modified) were thermally activated via air diluted with nitrogen at a moderate 560⁰C. Some nitrogen functionality retained in the biochar structure even after activation. The synthesized N-enriched biochar followed by thermal activation was found to have much higher adsorption capacity as compared with commercially available activated carbon (Norit CA1) and recent carbon based adsorbents in the literature. Chapter six is dedicated to molecular modeling and linking the experimental results with simulations. The effect of various functional groups on adsorption of CO₂/H₂S on biochar surface was investigated. It was found that the presence of functional groups promotes CO₂ adsorption on the surface with exothermic adsorption energy. As expected, the DFT calculations showed amine functional groups enhanced CO₂ adsorption with more exothermic adsorption likely because of stronger bonding compared to other functional groups. The thermodynamic outcomes (Enthalpy and Gibbs free energy) validated that the affinity of the chars for CO₂ is on the same order of magnitude as H₂S. The simulated thermodynamic parameters and IR vibrational frequencies were calculated and both showed reasonable agreement with experimental results (chapter four and five). The results of this study would be helpful for developing future work, on the scale-up of the adsorption system, further modification of the biochar, CO₂ sequestration, regeneration, and atomic-level design of carbon surfaces

Process simulation and optimisation of thin wall injection moulded components

Integrally moulded hinges and tension bands are important features in packaging components for plastic closures and their function is critically dependent on the flow induced micromorphology in the hinge section. Polymer characteristics and processing of the hinge also have an influence on the hinge properties obtained. This study is aimed at obtaining interrelationships between polymer characteristics, in-cavity flow, microstructure development and hinge properties, to produce hinges with enhanced functional properties. Three different virgin polypropylene (PP) grades were investigated (homopolymer PP-H, random copolymer PP-RC and impact copolymer PP-IC) and injection moulding simulation was carried out using Moldflow software. In-cavity data acquisition has been carried out for different sets of injection moulding conditions, using high performance transducers and a data acquisition system. A comparison between Moldflow simulation and practical injection moulding data suggests that, for thin wall injection moulded components the real time pressure data are in close agreement during the injection stage. During the packing stage there is some disagreement between these data, since the thickness of hinge and tension band sections are 0.4 mm and 0.5 mm respectively, suggesting that these dimensions are extending the capability of the software.An extensive study using a design of experiments (DoE) approach was carried out on both practical and predictive data. Injection velocity and melt temperature were the most influential factors on the component mechanical properties. From the optical micrographs it is observed that PP-RC has a finer micro-structure compared to PP-H and PP-IC and some micrographs confirm Moldflow simulation results in which hesitation effects are evident, as the flow converges into the thin hinge and tension band sections. PP-clay nanocomposites (PP-CN) were prepared using a twin screw compounder. Transmission electron microscopy (TEM) has shown some evidence of dispersion and exfoliation of the clay particles in the PP matrix. However, X-ray diffraction (XRD) results show a reduction in inter-layer spacing of PPCN s possibly due to clay compaction. The addition of nano-clay however has not resulted in any significant improvements in the mechanical properties of hinges and tension bands. The high degree of molecular orientation induced in the hinge and tension-band sections appears to mask any improvements attributed to the addition of nano-clay. From the reprocessed and post consumer recyclate (PCR) study conducted on hinges and tension bands, it is seen that with an increase in both the re-processing and PCR content there is a decrease in the component strength of around 14%, giving scope to potentially use PCR in future packaging applications. Investigations conducted on colour pigments (violet and green) reveal that the onset of crystallisation for green pigmented mouldings is considerably higher (16°C) than for natural and violet mouldings. Optical micrographs also reveal a finer microstructural texture for green components, indicating a high nucleating capability of the green pigment. Irrespective of the colour, both for hinges and tension bands, the yield stress values were around twice as high as the values quoted in the manufacturer s data sheet for isotropic PP, due to the high levels of molecular orientation in the hinge and tension band sections. In order to industrially validate the findings from the DoE study, commercial closures were produced in industry on a production tool then characterised. In the case of tension bands, there was a good agreement between the results obtained from lab scale and industrial study due to the relatively simple geometry. For hinges this agreement is not so clear. Finally a comparison of mechanical properties of the 3 PP grades shows that PP-H has a higher yield stress compared to PP-IC and PP-RC and yield stress is significantly higher (yield strain values are lower) than values quoted by the manufacturer. The PhD study has confirmed the process conditions that are able to optimise all the interactive effects to improve functional properties in high volume parts in the packaging industry

Study of the behavior of a thermoplastic injection mold and prediction of fatigue failure with numerical simulation

Tese de doutoramento em Engenharia MecânicaO objetivo deste trabalho é a criação de uma metodologia de análise da resistência à fadiga de moldes de injeção de termoplásticos. Uma metodologia capaz de satisfazer o mercado atual que exige a diminuição do tempo de entrega e custos de moldes de injeção, sem comprometer a sua fiabilidade. Para o desenvolvimento desta metodologia, foram utilizados modelos digitais. Com estes modelos é possível executar-se várias iterações sem os custos de um modelo físico. Além do menor custo dos modelos digitais, também é possível compreender o comportamento de cada molde no decorrer da fase de projeto. Com o aumento da complexidade dos componentes injetados, o estudo da resistência à fadiga tende a ser cada vez mais importante. Neste trabalho serão apresentados cuidados a ter na preparação dos modelos digitais, de forma a obter-se resultados fiáveis. No desenvolvimento desta metodologia, usaram-se dois softwares de simulação numérica para gerar os modelos digitais. Um deles dedica-se ao estudo reológico de peças termoplásticas e outro ao comportamento estrutural dos moldes de injeção. A execução de simulações numéricas requer uma boa caracterização dos materiais usados. No caso dos termoplásticos, os fabricantes têm uma grande base de dados com a informação necessária para as simulações numéricas. No entanto, para as simulações estruturais, os fabricantes tendem apenas a fornecer os dados das curvas monotónicas, os quais não fornecem qualquer informação sobre o comportamento à fadiga. Portanto, neste trabalho foram estudados modelos empíricos que se adaptam aos aços usados em moldes de injeção, a partir dos quais é possível gerar as curvas S-N e e-N. De modo a avaliar qual o modelo empírico que se adaptaria melhor a esta área, foram realizados ensaios experimentais com provetes feitos em EN 1.2311. A partir destes ensaios, escolheu-se o modelo empírico mais conservador. Com base no modelo empírico escolhido, foi desenvolvida uma aplicação capaz de gerar as curvas S-N e e-N, a partir das informações fornecidas pela aciaria. Além da caracterização dos materiais, também é importante que as condições de carregamento do modelo numérico estrutural sejam o mais aproximadas possível do que irá ocorrer no modelo físico. Como as cargas deste modelo numérico podem ser previstas a partir do modelo numérico reológico, a criação de uma ponte entre estes dois modelos numéricos é imprescindível. Logo, neste trabalho foi construída uma aplicação capaz de converter os dados gerados pelo software comercial Moldflow em ficheiros capazes de serem lidos por softwares comerciais de simulação numérica estrutural. Usando esta aplicação para a conversão dos dados, foram realizadas simulações e comparadas com os respetivos modelos físicos. Verificou-se que é possível replicar o comportamento do molde em modelos digitais. No entanto, os modelos digitais dos moldes de injeção estudados tenderam a apresentar resultados conservadores quando comparados com os modelos físicos. Por fim, foi desenvolvida uma aplicação capaz de usar dados calculados a partir de softwares comerciais de cálculo numérico estrutural para a determinação da resistência dos moldes à fadiga. Aqui foi tido em conta o modelo para geração das curvas de fadiga dos materiais validado. Os modelos de cálculo à fadiga na aplicação baseiam-se na regra de Palmgren – Miner para a determinação dos ciclos até à nucleação da fissura. O cálculo das tensões alternadas foi realizado a partir de dois métodos, o critério da tensão de corte octaédrica e o método de Sines. Para testar a aplicação foram escolhidos cinco moldes que apresentaram falhas por fadiga. Em seguida, foi aplicada a metodologia proposta neste trabalho para a determinação da resistência dos mesmos à fadiga. A partir da aplicação desta metodologia e das ferramentas desenvolvidas para o seu emprego, foi possível verificar que esta é capaz de prever as zonas onde ocorreram as falhas, bem como outras com probabilidade de nucleação de fissuras. Portanto, no decorrer deste trabalho foi possível criar uma metodologia e ferramentas de apoio para o cálculo de moldes à fadiga. Assim, projetistas de moldes podem ter uma boa perspetiva da resistência à fadiga de moldes de injeção ainda em projeto, tendo por base métodos científicos.The objective of this work is to create a methodology to analyze the fatigue resistance of thermoplastic injection molds. A methodology capable of satisfying the current market that demands a decrease in the delivery time and costs of injection molds, without compromising their reliability. To develop this methodology, digital models were used. With these models it is possible to execute several iterations without the costs of a physical model. Besides the lower cost of digital models, it is also possible to understand the behavior of each mold during the design phase. With the increasing complexity of injected components, the study of fatigue resistance tends to be more and more important. In this work, care will be presented in the preparation of the digital models, in order to obtain reliable results. In the development of this methodology, two numerical simulation software’s were used to generate the digital models. One of them is dedicated to the rheological study of thermoplastic parts and the other to the structural behavior of injection molds. The execution of numerical simulations requires a good characterization of the materials used. In the case of thermoplastics, manufacturers have a large database with the information needed for numerical simulations. However, for structural simulations, manufacturers tend to provide only monotonic curve data, which do not provide any information about fatigue behavior. Therefore, in this work, empirical models that fit the steels used in injection molds were studied, from which it is possible to generate the S-N and e-N curves. In order to evaluate which empirical model would best fit this area, experimental tests were performed with specimens made in EN 1.2311. From these tests, the most conservative empirical model was chosen. Based on the chosen empirical model, an application capable of generating the S-N and e-N curves from the information provided by the steel mill was developed. Besides the characterization of the materials, it is also important that the loading conditions of the numerical structural model are as close as possible to what will occur in the physical model. Since the loads of this numerical model can be predicted from the rheological numerical model, the creation of a bridge between these two numerical models is essential. Therefore, in this work was built an application capable of converting the data generated by the commercial software Moldflow into files capable of being read by commercial structural numerical simulation software. Using this application for data conversion, simulations were performed and compared with the respective physical models. It was found that it is possible to replicate the mold behavior in digital models. However, the digital models of the injection molds studied tended to present conservative results when compared to the physical models. Finally, an application capable of using data calculated from commercial numerical structural calculation software was developed for determining the fatigue resistance of molds. Here the validated model for generating the fatigue curves of the materials was taken into account. The fatigue calculation models in the application are based on the Palmgren - Miner rule for the determination of the cycles until crack nucleation. The alternating stresses calculation was performed from two methods, the octahedral shear stress criterion and the Sines method. To test the application, five molds that presented fatigue failures were chosen. Then, the methodology proposed in this work was applied to determine their fatigue resistance. From the application of this methodology and the tools developed for its use, it was possible to verify that it is able to predict the areas where the failures occurred, as well as others with a probability of crack nucleation. Therefore, during this work it was possible to create a methodology and support tools for the calculation of fatigue molds. Thus, mold designers can have a good perspective of the fatigue resistance of injection molds still in project, based on scientific methods