No description available.

This thesis is missing page 48, all other copies of this thesis are missing the page as well. -Digitization Centre / Metal injection molding (MIM) employs the advantages of injection molding and powder metallurgy and provides a high productivity means to form intricate, low-cost, high performance metal parts. One of the most unique characteristics of MIM is the binder system and the consequent debinding step, which is considered to be major process improvement barrier in the MIM process. A MIM part with a thick section suffers from a long debinding cycle and it is difficult to avoid defects. Therefore, it is always of interest to find out a method to quickly debind a thick part without defects. PowderFlo® feedstock combines metal powder with an aqueous agar-gel binder system and requires simple air-drying followed by thermal debinding. However, previous studies on this agar-gel binder feedstock mainly focus on sintering, while the debinding step has lacked sufficient attention. A debinding study on agar-gel binder system is conducted in the present project. The metal compacts are formed via compression molding and injection molding, followed with thermal debinding in order to understand the effects of process parameters on debinding with respect to thickness to determine a good debinding schedule. The thickness transition between thick and thin section is particularly important in the debinding to find a protocol to make parts with both thick and thin sections. Thermal debinding experiments show that the initial heating rate is the most significant factor due to it may cause visible defect directly and an increase of initial and secondary heating rates may retard binder removal. The air-drying time has less influence on binder extraction for thicker section. Extending the holding time for water and polymer removal is beneficial to obtain better dimensional control. The overall debinding process parameters have larger effects on thicker parts. For the thickness transition, it is suggested to avoid the combination of too thin and too thick section, increase the joint area, and provide uniform packing during molding. / Thesis / Master of Applied Science (MASc)

No description available.

Published Article / Titanium has fired the imagination of engineers and designers for decades by its 'ideal' combination of high strength, low density and good corrosion resistance. However, its application has unfortunately been limited to those niche markets where performance is more important than cost, such as in the aerospace, military, medical and off-shore oil drilling fields. Extensive efforts have been and still are being expended on ways to make this metal cheaper. There are promising new processes but these have yet to be demonstrated commercially. Nevertheless, there has been a global surge in interest in titanium over the past decade, and in South Africa the government has recently made this a particular focus for research and development funding. With the increased availability of higher quality titanium powder, metal injection moulding offers an attractive method for producing small, intricate components at a reasonable cost. This paper will present an overview of the metal injection moulding process and discuss the particular challenges related to the use of titanium and titanium alloy powders. The state of the global and local industry and markets will also be reviewed.

No description available.

Published Article / Metal injection moulding (MIM) offers advantages for mass production of components over conventional production methods for parts with complex shapes and large production runs. The MIM process includes mixing a fine metallic powder with a polymeric binder to produce a homogeneous feedstock. This enables the production of metallic components in a similar manner to plastic injection moulding. After undergoing a process of binder removal the components undergo a conventional sintering cycle. As significant shrinkage occurs (as much as 30%) this must be considered when designing the die cavity. This paper describes the design and manufacture of a die to produce tensile specimens. Extensive injection moulding trials to produce acceptable tensile components were undertaken. The complexities and possible implications of the design of a mould on the process are discussed. The outcomes of this research will be used by the CSIR for further development and application of the MIM technology for manufacture of high value components, such as dental implants.

Na presente pesquisa, produziu-se amostras de ferro puro poroso como biomaterial degradável visando a aplicação em stents, pelo processo de moldagem por injeção de pós metálicos (MPI). Os efeitos da fração volumétrica de ferro puro na mistura de injeção e da temperatura de sinterização na porosidade, microestrutura, propriedades mecânicas, propriedades de superfície, de degradação in vitro e de biocompatibilidade, foram investigados. Os resultados obtidos foram comparados com o ferro puro fabricado por fusão e com o aço inoxidável AISI 316-L. Encontrou-se que o grau de porosidade remanescente nas amostras sinterizadas foi o principal fator influenciando as propriedades mecânicas e de superfície, influenciando indiretamente os demais resultados. O ferro puro produzido por MPI exibiu valores de limite de escoamento entre 59 e 114 MPa e limite de resistência máximo de 210 MPa, com alongamento entre 10 e 50 %. A alta ductilidade é uma propriedade especialmente requerida em materiais para potencial aplicação em stents. Suas taxas de degradação em solução de Hank foram superiores às do ferro puro fabricado por fusão. O material fabricado com mistura de injeção contendo fração de ferro de 66 % (acima da fração crítica) mostrou o maior alongamento e boa taxa de degradação, um resultado interessante, pois segundo a literatura, valores acima da fração volumétrica crítica não são amplamente explorados. Os testes de biocompatibilidade mostraram excelente hemocompatibilidade do ferro puro fabricado por MPI com as células do sangue. Todas as condições testadas mostraram um nível de citotoxicidade abaixo do recomendado pela norma vigente, mas este dependendo da concentração de íons de ferro empregada e do grau de porosidade. Entre todas as condições de ensaio investigadas, as amostras contendo fração volumétrica de ferro de 62 % inicialmente na mistura de injeção e sinterizadas a 1120 oC, apresentaram a melhor combinação de propriedades para aplicação em stents. Concluiu-se que a MPI é um método tecnicamente viável como rota de produção de tubos de parede fina precursores para fabricação de stents biodegradáveis. / In the present research, an attempt was made to produce porous pure iron, as a metallic degradable biomaterial potentially for stent application, via the MIM route. The effects of iron powder loading and sintering temperature on the porosity, microstructure, mechanical properties, surface properties and in vitro degradation behavior of MIM iron were investigated. The results obtained were compared to those of cast iron. It was found that the amount of porosity remained in the as-sintered specimens had a major effect on their surface and mechanical properties. The MIM pure iron showed yield strength values between 59 and 114 MPa and maximum tensile strength of 210 MPa, with elongation values between 10 and 50 %. A high ductility is a specially required property of stent materials. Its degradation rates in Hank’s solution were superior to the degradation rate of cast iron. The material made from the feedstock containing 66 % of iron powder, above the critical powder loading, showed the highest elongation and a good in vitro degradation rate. This result is interesting, once according to the literature, powder loadings above the critical value are not well explored. The biocompatibility tests showed excellent hemocompatibility of MIM pure iron with blood cells. All conditions tested showed toxicity level below the values determined by current standards, but depending of Fe ions concentration and porosity level. Between all the conditions tested in the present investigation, the 62 % powder loading sample, sintered at 1120 oC, showed the best combination of properties for stent application. In conclusion, MIM is a promising method to be developed as a new route to produce thin-wall tubes for biodegradable stents.

現今是資訊發達且多變的環境，企業要生存必須因應環境的變化。目前在機械業界中最熱門的金屬射出成形(Metal injection mold) 技術，使得零組件成形與加工技術有革命性的改變。現今全球具規模的金屬射出成形產業的供應商將近30年的歷史，過去五年都維持在約15%以上成長，個案P公司是由粉末冶金產業開始，其主力產品是汽車零件，在2008年下半年金融風暴的襲擊，汽車產業衰退，該公司在此情況，精進金屬射出成形的技術，並研發節省能源設計的新材料，提供給汽車產業和其他市場的使用；另一個案T公司在金屬射出成形產業有十多年，主要是製造形狀複雜、高精密度的機械零件。本研究希望藉由產業環境分析與個案分析，找尋金屬射出成形產業的利基點，與企業在發展和成長過程，探討出未來經營策略或可行的方案。 本研究的理論基礎主要是參考Michael Porter的產業分析(1980)對於MIM產業的總體環境和產業分析，瞭解其發展趨勢；接著引用Porter的五力分析(1985)，分析個案企業面臨外在產業的環境，與其競爭優勢；最後採用Weihrich,Heinz (1982)提出SWOT矩陣策略配對，將個案公司內部的優勢、劣勢與外部的機會及威脅以矩陣結構的方式分析，利用最大之優勢和機會、及最小之劣勢與威脅，以界定出其目前所處的情況，進而研擬出個案公司適當的因應對策。 經過產業分析和個案分析後，本研究得到以下結論:(一)、影響粉末冶金、金屬射出成形產業的因素為全球經濟環境、石油價格和科技技術。(二)、粉末冶金產業的生命週期已進入成長期，金屬射出成形正邁入成長期。(三)、形狀複雜高精密度的小型機械零件，以傳統加工方式不易生產，用MIM的技術可以量產出這些複雜的形狀，減少加工的步驟，為其利基點。(四)、目前以MIM技術生產持續降低成本，縮短交期、增加其競爭優勢。(五)、產品廣泛應用在各種需要金屬零件的產業界，如個案P公司生產汽車齒輪的數量，供應全球汽車產業需求量超過三分之ㄧ，而個案T公司生產小而複雜的零部件提供給手工具、3C產品和資訊等產業，都有獲利的空間。 對於金屬射出成型產業的建議為 (一)、在各國節約能源和環保愛地球，研發技術人員需開發輕金屬零件，以因應市場需求。(二)、因歐美市場汽車需求量降低，而大陸市場汽車需求量大，因此大陸正積極的發展金屬粉末射出成形產業，並尋求台灣零件的供給，是我們拓展市場的機會。(三)、對於3C和資訊產業的產品，因其產品生命週期短，需要有專案的技術人員以最短的開發和交樣時間，以ERP管理，降低庫存，並與客戶一起開發，節省資源，降低風險。 關鍵字: 金屬射出成型(MIM)，SWOT矩陣策略。 / In the fast growing IT world of today, Metal Injection Molding (MIM) technology transform the traditional manufacturing method of the metallic parts to a revolutionary fabrication process in the machinery industries. MIM actually has been developed for more than 30 years, and in the latest 5 years, the annual growth rate is about 10 to 15%. End products are commonly component items used in various industries and applications. Company P has been using powder metallurgical technology to produce auto parts. Although its business was affected by the slowdown of auto industries due to the financial storm in the second half of 2008, its advancement in the MIM technology, including the development of the energy saving material, had helped the company to survive in the downturn of auto industries. Another Company T in the case study has used the MIM technology to provide the diversified geometrically complex metal parts for more than 10 years. This study was using the tools of analysis and case studies to find the niche of metal injection molding industry for the enterprise to explore the appropriate managing strategies during they were developing and growing process of the business. The theoretical background of this study is referring to the industry analysis and 「Five Force analysis」 made by Professor Michael Porter of Harvard University in 1980 and 1985. It gives an overview and the overall environmental and competitive analysis and used for studying the development trend of the MIM industry. Using the SWOT matrix for strategy matching proposed by Weihrich in 1982, the company’s internal strengths, weaknesses and external opportunities and threats, could be analyzed and expressed in an explicit form. Then, maximize the strengths and opportunities and minimize the weaknesses and threats to define the present situation, and then develop the best applicable strategies for the company. Through industry analysis and case studies, this study concludes the followings: (1) Powder metallurgy and metal injection molding industry are affected by the global economic environment, oil prices and the technological advancement. (2) The life cycle of powder metallurgy industry is at its growth period, but the metal injection molding is at the end of embryonic period and moving to growth period. (3) Since it’s not easy to use the traditional fabrication process to make the complicated or asymmetric shaped metallic parts, the metal injection molding technology has the advantages of making the complicated parts with less fabrication steps. (4) Powder metallurgy and metal injection molding could continuously reduce costs and shorten the delivery time to increase their competitiveness. (5) The products could be widely used in various kinds of industry where the metallic parts are needed. Company P is producing one-third of the gears used in the world-wide auto industries and Company T is making the small and complex parts for the hand tools, 3C and IT industries with profits. Finally, the suggestions for metal injection molding industry are listed as follows: (1) Under the regulations of the environment protection, we should develop the energy conserving and carbon-reducing materials to meet the requirements. (2) China is developing the metal injection molding technology aggressively to meet the demand of its automobile market, which provides a great business opportunity of the auto parts supplier of Taiwan, (3) Since the life cycle of 3C and IT products is very short, the engineering team should design and fabricate the products in a very short time to the market. Also, it is necessary to use ERP management to reduce inventory and co-work with customers to develop products, conserve resources and reduce the risk.

Na presente pesquisa, produziu-se amostras de ferro puro poroso como biomaterial degradável visando a aplicação em stents, pelo processo de moldagem por injeção de pós metálicos (MPI). Os efeitos da fração volumétrica de ferro puro na mistura de injeção e da temperatura de sinterização na porosidade, microestrutura, propriedades mecânicas, propriedades de superfície, de degradação in vitro e de biocompatibilidade, foram investigados. Os resultados obtidos foram comparados com o ferro puro fabricado por fusão e com o aço inoxidável AISI 316-L. Encontrou-se que o grau de porosidade remanescente nas amostras sinterizadas foi o principal fator influenciando as propriedades mecânicas e de superfície, influenciando indiretamente os demais resultados. O ferro puro produzido por MPI exibiu valores de limite de escoamento entre 59 e 114 MPa e limite de resistência máximo de 210 MPa, com alongamento entre 10 e 50 %. A alta ductilidade é uma propriedade especialmente requerida em materiais para potencial aplicação em stents. Suas taxas de degradação em solução de Hank foram superiores às do ferro puro fabricado por fusão. O material fabricado com mistura de injeção contendo fração de ferro de 66 % (acima da fração crítica) mostrou o maior alongamento e boa taxa de degradação, um resultado interessante, pois segundo a literatura, valores acima da fração volumétrica crítica não são amplamente explorados. Os testes de biocompatibilidade mostraram excelente hemocompatibilidade do ferro puro fabricado por MPI com as células do sangue. Todas as condições testadas mostraram um nível de citotoxicidade abaixo do recomendado pela norma vigente, mas este dependendo da concentração de íons de ferro empregada e do grau de porosidade. Entre todas as condições de ensaio investigadas, as amostras contendo fração volumétrica de ferro de 62 % inicialmente na mistura de injeção e sinterizadas a 1120 oC, apresentaram a melhor combinação de propriedades para aplicação em stents. Concluiu-se que a MPI é um método tecnicamente viável como rota de produção de tubos de parede fina precursores para fabricação de stents biodegradáveis. / In the present research, an attempt was made to produce porous pure iron, as a metallic degradable biomaterial potentially for stent application, via the MIM route. The effects of iron powder loading and sintering temperature on the porosity, microstructure, mechanical properties, surface properties and in vitro degradation behavior of MIM iron were investigated. The results obtained were compared to those of cast iron. It was found that the amount of porosity remained in the as-sintered specimens had a major effect on their surface and mechanical properties. The MIM pure iron showed yield strength values between 59 and 114 MPa and maximum tensile strength of 210 MPa, with elongation values between 10 and 50 %. A high ductility is a specially required property of stent materials. Its degradation rates in Hank’s solution were superior to the degradation rate of cast iron. The material made from the feedstock containing 66 % of iron powder, above the critical powder loading, showed the highest elongation and a good in vitro degradation rate. This result is interesting, once according to the literature, powder loadings above the critical value are not well explored. The biocompatibility tests showed excellent hemocompatibility of MIM pure iron with blood cells. All conditions tested showed toxicity level below the values determined by current standards, but depending of Fe ions concentration and porosity level. Between all the conditions tested in the present investigation, the 62 % powder loading sample, sintered at 1120 oC, showed the best combination of properties for stent application. In conclusion, MIM is a promising method to be developed as a new route to produce thin-wall tubes for biodegradable stents.

Na presente pesquisa, produziu-se amostras de ferro puro poroso como biomaterial degradável visando a aplicação em stents, pelo processo de moldagem por injeção de pós metálicos (MPI). Os efeitos da fração volumétrica de ferro puro na mistura de injeção e da temperatura de sinterização na porosidade, microestrutura, propriedades mecânicas, propriedades de superfície, de degradação in vitro e de biocompatibilidade, foram investigados. Os resultados obtidos foram comparados com o ferro puro fabricado por fusão e com o aço inoxidável AISI 316-L. Encontrou-se que o grau de porosidade remanescente nas amostras sinterizadas foi o principal fator influenciando as propriedades mecânicas e de superfície, influenciando indiretamente os demais resultados. O ferro puro produzido por MPI exibiu valores de limite de escoamento entre 59 e 114 MPa e limite de resistência máximo de 210 MPa, com alongamento entre 10 e 50 %. A alta ductilidade é uma propriedade especialmente requerida em materiais para potencial aplicação em stents. Suas taxas de degradação em solução de Hank foram superiores às do ferro puro fabricado por fusão. O material fabricado com mistura de injeção contendo fração de ferro de 66 % (acima da fração crítica) mostrou o maior alongamento e boa taxa de degradação, um resultado interessante, pois segundo a literatura, valores acima da fração volumétrica crítica não são amplamente explorados. Os testes de biocompatibilidade mostraram excelente hemocompatibilidade do ferro puro fabricado por MPI com as células do sangue. Todas as condições testadas mostraram um nível de citotoxicidade abaixo do recomendado pela norma vigente, mas este dependendo da concentração de íons de ferro empregada e do grau de porosidade. Entre todas as condições de ensaio investigadas, as amostras contendo fração volumétrica de ferro de 62 % inicialmente na mistura de injeção e sinterizadas a 1120 oC, apresentaram a melhor combinação de propriedades para aplicação em stents. Concluiu-se que a MPI é um método tecnicamente viável como rota de produção de tubos de parede fina precursores para fabricação de stents biodegradáveis. / In the present research, an attempt was made to produce porous pure iron, as a metallic degradable biomaterial potentially for stent application, via the MIM route. The effects of iron powder loading and sintering temperature on the porosity, microstructure, mechanical properties, surface properties and in vitro degradation behavior of MIM iron were investigated. The results obtained were compared to those of cast iron. It was found that the amount of porosity remained in the as-sintered specimens had a major effect on their surface and mechanical properties. The MIM pure iron showed yield strength values between 59 and 114 MPa and maximum tensile strength of 210 MPa, with elongation values between 10 and 50 %. A high ductility is a specially required property of stent materials. Its degradation rates in Hank’s solution were superior to the degradation rate of cast iron. The material made from the feedstock containing 66 % of iron powder, above the critical powder loading, showed the highest elongation and a good in vitro degradation rate. This result is interesting, once according to the literature, powder loadings above the critical value are not well explored. The biocompatibility tests showed excellent hemocompatibility of MIM pure iron with blood cells. All conditions tested showed toxicity level below the values determined by current standards, but depending of Fe ions concentration and porosity level. Between all the conditions tested in the present investigation, the 62 % powder loading sample, sintered at 1120 oC, showed the best combination of properties for stent application. In conclusion, MIM is a promising method to be developed as a new route to produce thin-wall tubes for biodegradable stents.