This set of Manufacturing Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Fundamentals Of Metal Casting”.
1. ‘V’ or ‘f’ marked surfaces on a casting indicates?
a) Camber allowance
b) Machining allowance
c) Draft allowance
d) Shrinkage allowance
Explanation: Surfaces of castings required to be machined, are made to dimensions more than that indicated on the working drawings. The extra amount of material provided on the surfaces is called machine finish allowance and V or f is indicated on these surfaces.
2. Considering the shrinkage allowance, the amount of pattern, when compared to casting is?
a) larger than casting
b) smaller than casting
c) same as casting
d) equal to casting
Explanation: Shrinkage allowance is a correction for solidification shrinkage of metal and its contraction during cooling. It is larger than the casting to provide space for total contraction.
3. The process of removing unwanted material from the casting is called?
Explanation: Fettling is the complete process of the cleaning of the casting. It involves removal o the cores, gates, risers, cleaning of the as surface and chipping of any of the unnecessary projection on the surfaces. Core can be removed simply by knocking of it with an iron bar or by means of a cone vibrator. Gates and risers can be removed by hammering, chipping, hack sawing, or by flame or arc cutting.
4. In the following type of foundry, melting unit, as well as balance equipment, are installed to the casting of the particular metal is?
a) jobbing foundry
b) ferrous foundry
c) mass production foundry
d) non-ferrous foundry
Explanation: A jobbing foundry is one that produces a casting or a small number of castings of a given kind as per order. Mass production foundries have automatic molding, pouring and finishing lines with a little or no manual handling. The melting unit, as well as balance equipment in the foundry, is installed in ferrous foundry to suit the casting of particular metal.
5. Which of the following is used for making the hollow cavities in the casting?
b) vent rod
Explanation: For producing a casting with internal cavities or passages, cores which are made of sand are utilized. Cores are placed in the mold cavity to form the interior surface of the casting and are removed from the finished part during fettling process.
6. What is the limitation of oil as a binder?
a) at lower temperature, bond between sand mix and oil becomes strong
b) at higher temperature, bond between sand mix and oil becomes strong
c) should be added in high volumes
d) quickly hardens
Explanation: At higher temperatures the bond between sand mix and oil becomes hard and brittle there by weakening the sand mix. So, care should be taken about the rate and temperature of baking of oil sands.
7. Cereals are added to the molding sand to improve which of the following?
a) hot strength
c) green strength
d) edge hardness
Explanation: The role of cereals on imparting an amount of green strength in oil sands has been mentioned. Cereals are used because they are less harmful than clays form the point of view of baked strength in oil sand cores. Starch is capable of imparting a higher green strength than dextrin for the same amount of moisture.
8. To improve the surface finish of castings, which of the following additive is used in the molding sand?
b) sea coal
d) wood flour
Explanation: Resins produces good bonding strength between the sand grains, oils are used as binders, wood flour is cellulose material used to overcome sand expansion defects and seal coal is finely ground soft coal used for surface finish of castings.
9. To permit the escape of gases generated in the mold, which of the following are provided?
a) vent holes
d) core print
Explanation: Chaplets are used to support the cores inside the mold cavity to take care of its own weight and overcome the metallostatic force, core print is used to create openings and various shaped cavities in the castings, and vent hole, a small opening in the mold to facilitate the escape of air and gases.
10. Which of the following is used for making the hollow cavities in the casting?
b) vent rod
Explanation: Chaplets are used to support the cores inside the mold cavity to take care of its own weight and overcome the metallostatic force, core is a separate part of the mold, made of sand and generally baked, which is used to create openings and various shaped cavities in the castings.
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