1. Core oil and binders change their chemical properties at what temperature?
a) 200°F – 300°F
b) 300°F – 400°F
c) 400°F – 500°F
d) 500°F – 600°F
Explanation: Whenever any material is heated to a temperature high for its properties, there is a change in its chemical and physical aspects seen. Core oils and organic binders used in backing the core, change their physical properties at 400°F – 500°F.
2. What does an unbacked core generate?
a) Greenhouse gases
b) Mold gases
c) Mold liquids
d) Ultraviolet rays
Explanation: An unbacked core causes to generate an excessive amount of mold gases which then produce blowholes in the castings.
3. Using what are core ovens heated?
a) Gases or oils
b) Infrared heating
c) Ultraviolet heating
d) Solar heat
Explanation: Core ovens are heated in a well-defined temperature range. They are heated using gases and other oils.
4. Drawer type core ovens are used for baking large sized cores.
a) True
b) False
Explanation: Drawer type core ovens are used for baking small sized cores. These types of core ovens need proper fuel to be able to energize it to work, hence, they use gas or oil-fuels.
5. Which of the following type of air is circulated over rack type core oven?
a) Cool air
b) Hot air
c) Compressed air
d) Odourless air
Explanation: On a rack type core oven, for proper baking of the core, hot air is circulated over the cores. Odourless air or compressed air or cool air cannot be of much help here.
6. How are core manufactured in casting?
a) Cores are manufactured from a pattern in the same way as of mold
b) Cores are manufactured by machining process
c) Cores are manufactured by traditional methods
d) Cores are not manufactured, they are found naturally
Explanation: The manufacturing of cores is similar to mold making and ramming.
7. What are the core boxes?
a) Used to support cores
b) Used to create cores
c) Used to store cores
d) Used to Eject cores while ejection of casting after solidification
Explanation: Core boxes are those elements or tools which are used to create cores.
8. In the case of coldbox core _____________
a) The core mix is heat treated in order to cure it
b) Core mix immediately gets cured after sand is blown
c) Time is given to the core mix to be cure
d) Cold water is poured onto the core mix
Explanation: Due to high production rates, the coldbox are left alone to cure by itself after the sand is blown into the corebox.
9. In the case of shell, hotbox or warmbox ______________
a) Hot water is poured onto the sand mixture
b) The sand mixture is heated to set the core
c) Steam is provided to the core mix
d) The corebox is left in the room temperature
Explanation: The sand mixture needs to be heated in order to set the core. Once, it is set the core is removed from the corebox.
10. What will happen if the parting line in the corebox is not closed properly?
a) Coresand may blow out of the box to create fins on the cores
b) The cope and drag part clamped will detach and break the core
c) Air inclusion occurs as the atmospheric air involves the solidification of core
d) Nothing will happen, as the parting line has no role in core making
Explanation: Obviously, the sand will overflow out causing unwanted contours called fins, which may increase the cost of machining to remove them and time is consumed.