This set of Foundry Multiple Choice Questions & Answers (MCQs) focuses on “Requirements of the Base Sand”.
1. The Natural Sand needs only water to mix before making moulds.
Explanation: The Natural sand is obtained from sources like deserts, lakes, riverside beds etc. It has a certain quantity of natural binders such as clay. The water (of about 5% to 8%) is mixed before making of the mould is necessary to make it easy for molding.
2. Which of the following is not included in the Natural Sand?
a) Organic Matter
Explanation: Natural Sand is usually imported from the banks of the water sources. Hence the water content, clay and organic matter are expected from the sand content. However, the chances of the Graphite content are minimal.
3. Synthetic Sand possess greater refractoriness.
Explanation: The Synthetic sands contain uniform grain size. They acquire proper mold ability with less moisture. They have high permeability and hence greater refractoriness (above 3000oC).
4. ____________ sand has higher clay content than ordinary sand.
a) Silica Sand
b) Loam Sand
Explanation: Loam Sand us composed of Sand particles and very fine clay particles. It is found in the successful farming regions known for fertile land. As it is softer than ordinary sand, it has higher clay content.
5. Natural Sand contains 50% clay.
Explanation: Natural Sand has binding materials in very less quantity. The Binding materials are to be externally added and the quantity required is less. Loam sand has 50% clay and is very softer than Natural Sand.
6. ______________ requires less proportion of binders.
a) Natural Sand
b) Synthetic Sand
c) Loam Sand
d) Silica Sand
Explanation: Synthetic Sands are made by adding binders. Synthetic Sand properties are enhanced by adding external chemical agents which technically lessens the proportion of binders.
7. Natural Sand is mixed with bentonite gets its properties improved and is called Synthetic Sand.
Explanation: When Natural sand is mixed with a binder such as Bentonite, the properties of the Natural Sand such as green strength, compressive strength is increased but it also retains its original properties. It becomes semi-synthetic sand.
8. Synthetic Sand is formulated sand.
Explanation: Synthetic sand consists of Natural Sand, Binder and Moisture. It is done in order to acquire certain desirable properties not possessed by natural sands. They are prepared using all these components. Hence it is called as the formulated sand.
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