Formula of Moulding Sand, Bentonite and Portland Cement toImprove The Quality of Al-Si Cast Alloy

Abstract

A binder is any material used to strengthen the bonding of moulding sand grains. The primary function of the binder is to hold the moulding sand and other materialstogether to produce high-quality casts. In this study, there were four binder compositions being tested, i.e. 5% bentonite + 5% Portland cement, 4% bentonite + 6% Portland cement, 6% bentonite + 4% Portland cement, and 7% bentonite + 3% Portland cement. Each specimen was measured for its compressive strength, shear strength, tensile strength and permeability. The highest compressive strength was obtained fromthe specimen composed of 6% bentonite+ 4% Portland cement. The highest shear strength was obtained from the moulding sand with 7% bentonite+ 3%Portland cement. The highest tensile strength was obtained fromthe specimen contained 5% bentonite+ 5% Portland cement. The specimen composed of 5% bentonite + 5% Portland cement had the lowest permeability of 131 ml/min, while that of 6% bentonite + 4% Portland cement had the highest permeability of 176 ml/min..

Analysis of Mechanical Properties and Permeability of Sand Moulding by Using Eggshell in Sand Casting

“…The result of this study was better compared with the other study entitled Analysis Binder Material Variations in Sand Moulding Malang against Strength and Permeability with composition of 10% starch, 82% sand, 8% water with the permeability value of 180ml/min. Combination of 5% bentonite and 5% of portland cement generated permeability up to 176 ml/min [2]. Previous study entitled Analysis of Variations in composition of Fly Ash and Bentonite as Binder of Sand Moulding against Permeability, Compressive Strength and fluidity of Green Sand Moulding with the composition of 7% bentonite and 2% fly ash, this molten had permeability of 231.67 ml/min.…”

“…Low permeability of sand moulding caused the air difficulty in flowing through the sand grain [2]. As the result when the molten metal poured, the air/gas couldn't flow properly and caused defects on the casting product.…”

“…Generally, the binder used in sand casting is single binder bentonite. Bentonite is used as a binder in manufacture of sand moulding due to its necessary properties that generate high binding capacity, being clay when wet, so it will facilitate the making process of moulding, it's being hard after drying [2].…”

The Analysis of Permeability and Mechanical Properties of Sand Moulding Using Mixed Material Clamshell (Placuna placenta) on Sand Casting

“…But the value that reached by sample 3 with composition of 11% clamshell was closer to the standard shear testing results, so the results of 11% clamshell was able to be be used for sand moulding manufacture in order to reduce the usage of bentonite. The content of water and binder in dry condition, usually was lower than in wet condition, for the drying process [5], [10]. Figure 3 showed that sample which had the highest mechanical properties was sample 3 with composition of 11% clamshell.…”

“…Generally, binder which is used in sand moulding is bentonite. The use of bentonite as binder in sand moulding manufacture of sand due to its necessary properties that generate high binding capacity, being clay in wet condition and harden in dry condition, thus, manufacture of sand moulding is easy to be set up [5].…”