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    Prediction of problems in injection moulded plastic products with computer aided mould design software : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Technology in Manufacturing and Industrial Technology at Massey University
    (Massey University, 1996) Cayzer, Peter Ian
    Several new technologies to assist plastic injection moulding companies have been developed in the last twenty years. A number of computer software programs are now available which could revolutionise mould design. The most exciting aspect of the Computer Aided Mould Design (CAMD) software is the effect it has on reducing the lead time required to produce a working mould from a product concept. The application of the new technology for designing moulds, however, has been slow in New Zealand. One of the main reasons for the slow progress is the perceived value of the software or consulting services. Many injection moulding companies who design and manufacture moulds do not realise the great potential of CAMD software to save many hours of mould changes and volume of polymer material, even when the program is used after the mould has been made. However, the true benefits are only seen when the mould is designed using CAMD before the mould has been manufactured. Moulds manufactured correctly the first time save a great deal of time, energy and money. The value of the software is not completely understood by injection moulding manufacturers. They perceive the immediate benefits, however, the ongoing benefits are not recognised. A project was carried out to demonstrate the potential of CAMD software in determining moulding problems in existing injection moulded products. Four products, two of which were supplied by an injection moulding company, that had moulding problems, were simulated using Moldflow, a CAMD software package. The results of the simulation were compared with the actual moulding problems. It was found that the Moldflow simulation results described the problems occurring in the moulds accurately. Moulding problems included warpage, air traps and weld lines in poor positions and flow marks. Warpage is a major problem in injection moulded products. Even simple products can warp if not designed correctly. The only problems Moldflow did not identify, and does not claim to, were the flow marks caused by jetting and splashing of plastic as it entered the cavity. The designer must be aware of the problems caused by jetting and design gates to avoid it. Moldflow, and other CAMD software, are beneficial tools for the mould designer. The advantages of CAMD include short mould development time, shorter lead times from concept to production, reduction in the amount of material used, fewer changes to machine settings and predictable, repeatable quality. These benefits are not only savings in the mould design and manufacture, they also continue on into the processing of the product since less material is used in the product and machine down time caused by moulding problems is greatly reduced.
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    Mould design and manufacturing using computer technology : a thesis presented in partial fulfilment of the requirements for the degree of Master in Technology at Massey University
    (Massey University, 2000) Lam, Yuk-sun
    This thesis presents a research work carried out at the Institute of Technology and Engineering of Massey University. The overall goal of the project is to develop an integrated mould design and manufacturing system for teaching and research. The development involves establishing a computer-aided design, computer-aided manufacturing, CNC machining, and injection moulding program for Technology and Engineering undergraduate and postgraduate students. An integrated CAD/CAM/CAE and CNC system has been established through this project. Four laboratory courses together with the tutorials have been developed and established. This design and manufacturing system and the corresponding laboratory courses provide a great support for Engineering Design and Manufacturing programmes. The laboratory courses give the opportunities to the students to gain the experience from concept design, through hands-on project, to the final physical product. The research work presented went through four stages. Before this project started, the Institute of Technology and Engineering (ITE) had a stand alone CNC milling machine, a CNC lathe, an injection moulding machine, a limited number of PCs and a few CAD licenses. The first stage was to develop an integrated CAD/CAM/CAE and CNC system based on the existing facilities in ITE and the limited funding provided by the fund of innovation and excellence in teaching. The second stage was focused on product design. It was realized that a product is needed for the development of this project. This product must have the features to demonstrate the applications of computer-aided technologies in product design, analysis and manufacturing. The product must also be a plastic component in order to smoothly integrate plastic injection moulding technologies within the programme. Stage three was to build and produce the die set of the product, which involves mould design and analysis, simulation, testing, tooling, and actual CNC machining. The final stage was to develop the laboratory courses, write the tutorials and produce a demonstration program. Four lab courses and the tutorials were developed, which cover CAD, CAM, CNC, and injection moulding. These labs provide students with hands-on and practical experience. The project has been successfully completed. The demonstration program is now used for ITE's open day and other occasions such as visitors from industries, high schools and other organisations. The four lab courses are now taken by 3rd and 4th year B.Eng and B.Tech students in the Institute of Technology and Engineering.
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    Injection moulded radiata pine fibre reinforced polymer composites : properties and applications : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology in Product Development at Massey University
    (Massey University, 2004) Sethuram, Vishwanath
    New Product Development (NPD) is important for an organization's growth, profitability and competitiveness. The product being developed depends on an organization's unique context and could either be market-driven or technology-driven. Technology-driven product development begins with a new proprietary technology, and the firm then identifies products where the technology can be applied. Models like Technology Stage-GateTM have been suggested for developing new technology-driven products. But this process has the drawback of isolating the technology development process from the product development process. The present project began with the observation that New Zealand had an enormous amount of Pine wood fibre resource at her disposal, and there was growing research and use of wood fibre reinforced polymer composites worldwide for applications like automotive interior components, decking, furniture, and so on. Development of commercial products with this material was limited to thermoforming, extrusion, and compression moulding process. Although there was limited research initiated into injection moulding of pine wood fibre reinforced polymer composites, there was no documentation of the effect of varying the melt temperature on the mechanical properties of the material. There was also no documentation, either of commercial injection moulded products that have been manufactured with this material, or of the process that could be employed to develop commercial products with the new material. This led to the broad research aim of identifying a commercial product idea that could be manufactured by injection moulding the composite material that was developed using wood fibre and medium density polyethylene powder (rotational moulding grade) and to document the process adopted to achieve this. Some of the objectives were to document the properties of the composite material that was developed without either pelletising, or modifying the properties of the wood fibre by chemical means. The effect of change in fibre content, melt temperature and fibre length were studied. The fibre content ranged from 10% to 40% (in steps of 10%), and the experiments were conducted at four melt temperatures (155° to 215°C, in steps of 20°C), and for two fibre lengths (up to 4mm, and between 4mm and 8mm). The results of the experiments were statistically analysed using the 'Analysis of Variance' method, for their significance. A new development model, "Technology Driven - Fuzzy Front End" (TD-FFE), was used to manage the "fuzzy" stage of developing the new material, identifying new product ideas, and analysing the product concepts. The model is discussed in detail. Brainstorming technique was adopted to identify new product ideas for the material. The effect of the increase in fibre content on the tensile properties of the composite material was found to be more significant, compared to the effect of melt temperature. The interaction between fibre content and melt temperature on the tensile properties of the composite material was also found to be significant. The results of testing the composite material indicated that addition of wood fibre to the polymer increased the viscosity of the polymer melt. The density of the composite was found to increase with increase in fibre content (up to 40%). The tensile properties of the material increased steadily with increase in fibre content up to 30%, after which it decreased. The maximum ultimate tensile strength was found to be about 20MPa (when moulded at 175°C). The brainstorming technique was not found to be very suitable for the current project as the number of new product ideas identified were very limited since there were constraints on the material and manufacturing method to be used. Nevertheless, the method identified a building foundation insulation and boxing product. The performance of the product was simulated using COSMOS software and from the results of the static stress analysis, it was concluded that the composite material had the required tensile strength to withstand the pressure exerted by wet concrete. A broad analysis to determine the financial viability of the product was also conducted. It was found that it was cheaper to manufacture the new product than assemble the formwork boxing in the traditional method. It offered additional benefits like improving the insulation of the house, and the feel (or appearance) of the foundation, and also could reduce the construction time of the foundation. It is hence recommended that the product concept be investigated in greater detail by conducting consumer and market research to determine its commercial feasibility, and take it through to production and into the market.