Nature of Mechanical Machine Design - Mechanical Engineering ...

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Standards and Standardization• Once upon a time there were no standards or even uniformity among the sameproducts, for example, bolts, nuts and screw threads. Finding a replacement was notan easy task. This lack of standards and uniformity was costly and ineffective for agreat variety of reasons.• Standardization is the term applied to the obligatory norms to which variousindices of a product should correspond. These indices are types, grades, parameters(dimensions), and quality characteristics, test methods, rules of marking, packingand storage of products, raw materials and semi-manufactured goods.• Standardisation is the key to ‘cost effectiveness’ and ‘quality’. Standardisations ofspecifications for machine elements promote their quality and increase their servicelife. It curtails the time needed for their designing, quickens their entry into serviceand simplifies repairs as new standard ones easily replace worn or damaged parts.• An important feature of standardization, in present day mechanical engineering isthe principle of interchangeability without which lot and mass production isimpossible.UPRM –Spring 2005 INME 4012 - Lecture 1 12
Standards and Codes• A standard is a set of specifications for part, materials, or processesintended to achieve uniformity, efficiency and a specified quality. One ofthe important purposes of a standard is to place a limit on the number ofitems in the specifications so as to provide a reasonable inventory oftooling, sizes, shapes and varieties.• Code: A code is a set of specifications for the analysis, design,manufacture and construction of something. The purpose of a code is toachieve a specified degree of safety, efficiency, and performance or quality.• Interchangeability is the property of machine parts or units making itpossible to utilize them in assembly (or replace them during repair/service)without any additional machining (fitting) while preserving the technicalrequirements for the given unit, mechanism or machine functioning.• For parts to be interchangeable their dimensions need not ideally coincide.It is enough that the actual size of each part lies within the assigned limits.UPRM –Spring 2005 INME 4012 - Lecture 1 13
Page 1 and 2: Nature of Mechanical Machine Design
Page 3: Adoptive Design• Adoptive design
Page 6 and 7: What is Machine Design• Machine d
Page 8 and 9: Nature of Machine Element Design•
Page 10 and 11: A Design Process1. Identification o
Page 14 and 15: Standards and Codes• In mechanica
Page 16 and 17: The Criteria for Evaluating Machine

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