STUDY OF THE EFFECT OF SOME PARAMETERS ON QUALITY OF GREY CAST IRON CASTINGS MADE BY V-PROCESS

Abstract

Vacuum moulding is the latest sand moulding process. It utilises physical bonding only in dry and free flowing sand without any convensional binders . The sand mass in moulding box is first vibrated and then enclosed with in thin poly-ethylene plastic films followed by compacting the sand by applying vacuum which sucks away air existing with in the viods of bulk of sand The future of any process depends upon the quality of the casting and cost of production. The objective of the present investigations is to•study the effects of parameters on the characteristics like mould hardness of sand mould, dimension a 1 accuracy, surface finish, tensile strength, impact strength, and hardness of casting. The material chosen for making castings was Grey cast Iron. (3.17. C, 2.5% Si).The pouring temperature is kept constant at 1325+_25 C. The material is chosen keeping in mind its extensive use in the machine tool industries, automobile industries and construction industries etc. Lot of work has been done on Aluminum alloys but application of 'J process on Grey cast Iron is done first time in this University. A statistical approach i.e. central composite rotatable experimental design was used to plan the various experiment for all the studies done in the present investigations. Various measurements were made on mould and casting for each specific characteristic of mould and castings. fused on these observations, the regression models were formulated and tested for adequacy with the help of these models, relationships of various (ii) • parameters for each a given characterstics were computed keeping some of the parameters as constant and varying the others. The complete study is based on five major factors vibration frequency, sand grain fineness, vibration time, vacuum. level, plastic film thickness and keeping all the five fagtor5,-,at, five levels in the ranges as suggested in various international and I,nd.ian ;3•ornaPs. i~eThe'vibration frequency' .' varied ? in the range of 600 ,cyc/min .to .2200, •cy.cimin, the vacuum . level , •is varied from 200, mmof tig to 600 mm , Gf Hg ,T,he,, ,plastid • film thickness ranges from '0.05 mm to 0.15 mm; the•' sand grain fineness ranges from AFSGFN 50 to 150 and the vibration time is varied in the range of 60 sec to 120 sec. Th9results shows that the surface 'finish is excellent in the thinner sections ,'the dimensional accuracy is very high • the mechanical properties viz, tensile strength,impact strength and hardness is also satisfactory. Special purpo'Se computer' prot rams'has 'been dieveloped for the calculation and analysis of the results. ...----------------------------