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Tham khảo tài liệu 'engineering - materials selection in mechanical design part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Chapter 12------------------------- Case studies process selection 12.1 Introduction and synopsis The previous chapter described a systematic procedure for process selection. The inputs are design requirements the output is a shortlist of processes capable of meeting them. The case studies of this chapter illustrate the method. The first four make use of hard-copy charts the last two show how computer-based selection works. More details for each are then sought starting with the texts listed under Further reading for Chapter 11 and progressing to the specialized data sources described in Chapter 13. The final choice evolves from this subset taking into account local factors often specific to a particular company geographical area or country. The case studies follow a standard pattern. First we list the design requirements size minimum section surface area shape complexity precision and finish and the material and the processing constraints that it creates melting point and hardness . Then we plot these requirements onto the process charts identifying search areas. The processes which overlap the search areas are capable of making the component to its design specification they are the candidates. If no one process meets all the design requirements then processes have to be stacked casting followed by machining to meet the tolerance specification on one surface for instance or powder methods followed by grinding. Computer-based methods allow the potential candidates to be ranked using economic criteria. More details for the most promising are then sought starting with the texts listed under Further reading for Chapter 11 and progressing to the specialized data sources described in Chapter 13. The final choice evolves from this subset taking into account local factors often specific to a particular company geographical area or country. 12.2 Forming a fan Fans for vacuum cleaners are designed to be cheap quiet and efficient probably in that order. Case study 6.6 .