Abstract
The study investigated foundry properties of bed sand from river Gurara located in Niger State, Nigeria for use in production of foundry casting moulds using bentonite or kaolin clay as binders. A quantity of representative sand sample collected according to AFS procedure was washed, sun dried, classified on vibrated sieves and used for the experiment works. Specimens bonded with 0.5-3% of either bentonite or kaolin clay were prepared in accordance with AFS standard and tested for refractoriness; permeability; green/dry compressive strengths; moisture content; green hardness and shatter index using equipment including moisture teller, universal strength machine, shatter index and Rockwell hardness testers. The BS classification sieve result showed it consisted of 42% medium and 27% fine sand that will produce castings with fine surface finish. The physiochemical analyses done with XRF machine showed the sand was made up of 88% silica with metal/alkali oxides including Fe 2 O 3 (3.02%), K 2 O (3.02%), Al 2 O 3 TiO 2 (2.12%). It had refractoriness of 1,500 o C making it suitable for casting moulds for non-ferrous metals, light/heavy grey iron and some grades of steel. Tested foundry properties including permeability (167-136No); green compressive (26-38KN/m 2 ), dry compressive strength (200-360KN/m 2 ); hardness (65-80); shatter index (88-70) for kaolin bonded specimen and (130-116); (18-34KN/m 2 ); (182-238KN/m 2 ); (48-54No); (110-76N0) for bentonite bonded specimen when compared with existing foundry standards also confirmed suitability of sand bonded with these clay for the applications mentioned. Keywords: Gurara river, bed sand, Kaolin, Bentonite, Foundry Keywords: Claims, Delivery, Administration DOI : 10.7176/IEL/9-2-05 Publication date :March 31 st 2019
Highlights
One of the ancient methods of metal forming is casting in foundry which involves such basic production processes as mould preparation, melting of metal, pouring into prepared mould, solidification, shake-out and fettling
The study revealed through physiochemical property tests that river Gurara bed sand had high silica content that imparted high refractoriness to it
This made it suitable for casting many non-ferrous metals and selected classes of ferrous metal that melt below 1,500oC.The sand responded well to bentonite and kaolin clay binders to impart good mechanical properties on sand mould
Summary
One of the ancient methods of metal forming is casting in foundry which involves such basic production processes as mould preparation, melting of metal, pouring into prepared mould, solidification, shake-out and fettling. The processes include permanent mould, centrifugal, die-casting, investment castings; sand and shell castings. Sand casting is the most widely used of the processes as it accounts for about 80% of cast product and can be employed for both ferrous and non-ferrous metals (Fatai et al, 2011). The study of foundry sand constitutes one of the main sections of foundry technology and sand tests have become essential parts of daily control of foundry operation. Property requirements of materials are determined by moulding and casting conditions (Fatai et al, 2011). Proper choice of compositional moulding mixture is of prime importance
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