Thus,the particular objectives of research are:1) Tostudy the various casting to identify the defects and grouping them.2) Tostudy the characteristics of the defects. 3) Tostudy of effect of various process parameters causing casting defects.
4) Todevelop a suitable casting model to analyze different process parameters. 5) Touse computer simulation to simulate the casting model. This paves the way tothe diagnosis of casting defects. 6) Tostudy the major defects analysis (causes and remedies) supported by simulation.7) Todevelop guidelines specific to different controlling parameters. 8) Toimplement guidelines in different foundries or in a medium sized foundry tocontrol rejection without the need of shop floor trials. RESULTS ANDCONTRIBUTIONS:In addition to the primaryunderstanding of sand casting process, A hierarchical methodology forsystematic categorization of major SC defects, such as shrinkage, sandinclusion, blow holes, flash, misrun, shrinkage, and slag inclusion wasdeveloped. The current study contributes to determine the optimum values of feedersize, neck size to overcome shrinkage supported by simulation and pouringtemperature, permeability, mould hardness, green compressive strength andmoisture content.
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Iterative process based on modulus of last freezing section and L16 and L27 taguchibased gray relation analysis approaches are used to optimize the outputparameters that is shrinkage, blow holes and sand inclusions. The obtainedresults of three different grades of cast iron grades (FG-300b,GG-25 andFC-250) having different geometries ofcasting components (Rotor oil filter, Three wheeler drum and verroc flywheel) havebeen compared and suggested guidelinesspecific to metal, process and geometry. The current methodology was validatedin medium scale foundry to achieve better quality characteristics. ORGANIZATION OFTHESIS:In Chapter 1,introduced sand casting process, and itspresent overview of status in the world as well as in India and majorchallenges faced by sand casting foundries especially quality issues. The quality of sand castings andparameters causing the defects were discussed.
The rationale, motivation,research objectives, and methodology of the current work are explained.Chapter 2 provides thedetailed review of literature on classification of casting defects analysis,defect prediction, categorization of defects. It covers the effect of parametersrelated to sub processes such as design, melting, chemical composition and sandpreparation on quality characteristics of casting components. The severaltechniques such as knowledge basedexpert systems, casting process simulation, prediction of castingdefects and optimization methods adapted by previous researchers have beenreviewed and included in the literaturereview. The aim of literature review has been testified to find out theresearch gap and to finalize material, geometry and parameters to minimizecasting defects produced in foundries.Chapter 3 contain the results of an industrial survey of sandcasting foundries, carried out in support of the research plan .This chapteralso presents a systematic approach for categorization of sand casting defectsbased compound attributes such as detectionstage, size, shape, appearance, location, consistency and severity ofoccurrence. In addition, the possible causes of each defect, related todesign, material and process parameters are also listed and in depth investigation of nature and source of major castingdefects such as shrinkage, blow holes and sand inclusions are studied.
Chapter4 explains experimental setup for studying sand casting process of threedifferent grades of cast iron grades (FG-300b,GG-25 and FC-250) having different geometries of casting components(Rotor oil filter, Three wheeler drum and verroc flywheel).Further, it explainthe selection of design parameters supported by simulation and melting; sandrelated parameters based on L16 (213) taguchi based gray relation analysisapproach. Chapter5 consists of describes proposed feeder and feeder neck design optimizationmethodology based on iterative process approach, which includes formulation ofobjective function to eliminate shrinkage porosity and formulation of variousconstraints like feeder efficiency and feeder yield . It also covers introductionof feed path based optimization supported by simulation which mainly presents feedpath (temperature gradient maps) computed and generated by Vector Element Method(VEM). It includes implementation and validation of the methodology usingindustrial component of different geometries (Rotor oil filter, Three wheelerdrum and verroc flywheel) and extendedsame methodology to optimize common feeder used for two adjacent casting toachieve better yield.Chapter 6 consists of experimentationcarried to determine optimal set melting and sand related parameters such aspouring temperature, permeability, mould hardness, green compressive strengthand moisture content to minimize major casting defects such as shrinkage, blowholes and sand inclusions based on taguchi based L27 (35)orthogonal array and grey relation analysis of industrial component ofdifferent geometries (Rotor oil filter, Three wheeler drum and verrocflywheel).
It also presents analysis of variances (ANOVA) for robust designparameters values and interaction effects within parameters. A number ofexperiments have been carried out to validate the result and reduce rejectionlevel from above 20 % to below 7% and achieved improved productivity .Chapter 7 summarizesthe conclusions, contributions and limitations of based on this research workas well as directions for further work in casting process. In the end, appendices,references, have been added which show the current status of related researchwork at various places, gathered from different professional journals andpublications to support the research.