This set of Casting, Forming and Welding Multiple Choice Questions & Answers (MCQs) focuses on “Finishing Patterns & Storing of Patterns”.
1. Finishing allowance to a pattern is generally provided to avoid various defects in the casting.
Explanation: Finishing allowance is generally provided for a machining process, the finish and accuracy achieved in sand casting are usually poor and therefore when the casting is functionally required to be of better surface finish, so the machining is required that is accomplished by providing finishing or machining allowance.
2. Finishing also includes removal of scales from the surface of the casting.
Explanation: When the casting is made in the mould cavity, some of the oxides layers called as scales adhere tightly to the surface of metal casting, which should be removed for making casting strong and durable. So to achieve this, proper finishing and cleaning are done with the help of tools to make casting free from scales.
3. Subsequent machining for products finishing does not require extra material to the metal casting, as it removes negligible amount of material from the casting.
Explanation: It is very necessary to include extra material to the metal casting to compensate it for subsequent machining which removes very fine particles to vanish roughness and to make casting smooth and aesthetically pleasant. Then the casting becomes ready for industrial application.
4. Which of the following ranges show the approx range of finishing depth (in mm) required for finished casting?
a) 2 to 20
b) 20 to 30
c) 30 to 35
d) 35 to 40
Explanation: The range of finishing depth basically depends on dimensions, the type of casting material and the surface finish required, but for the approximation, it comes in the range of 2 to 20 mm. In this range, casting can achieve greater surface smoothness and shiny surface with good appearance.
5. For finishing allowance, great care is taken while adding extra material to the molten metal.
Explanation: After extraction of casting from the mould cavity, the finishing allowance provided would ultimately have to be removed by machining. Hence, great care is taken while adding extra material as to maintain the cost of material. So it is always examined before finalizing for the production of casting.
6. Which of the following parts is used to keep the casting in for reducing the finishing allowance?
c) Drag flask
d) Conical flask
Explanation: In finishing allowance, the entire casting is put in the drag flask to reduce the finishing allowance such that the dimensional variation and other defects due to the parting plane are reduced to a minimum. This part is widely used in the casting process to make the casting economical and sustainable.
7. Which of the following technologies is used in metal casting for reducing the product development time?
b) UV radiation
c) Eddy current coiling
d) Rapid prototyping
Explanation: Rapid prototyping is used for decreasing the product development time in metal casting, in which parallel horizontal layers of material are formed with the help of equidistant layers in a computer through CAD software. This all is achieved by rapid prototyping without application of any finished pattern.
8. After providing the finishing allowance to the metal casting, it is not necessary to include shake allowance as it can be covered by finishing allowance.
Explanation: The purpose of shake allowance is totally different and opposite from finishing allowance. Shake allowance includes reducing of pattern dimensions, before implementing this, the casting made is generally large that is caused by the pattern removal which enlarges the mould cavity. So, shake allowance is provided, it is also called a negative allowance.
9. A Fillet is provided in the finishing of a pattern which is very small for shallow castings.
Explanation: Intersecting surfaces forming junctions of metal thickness are usually joined with fillets in order to avoid high stress concentrations in the metal casting. Shallow castings commonly have much smaller fillets, while the deep pockets and other interior complex corners may have larger fillets.
10. In finishing of a pattern, fillets are provided to eliminate the stresses completely from the metal casting.
Explanation: Stresses cannot be eliminated completely, only it can be reduced or distributed to the more part of the material. Fillet Radius makes the casting stronger because it redirects stresses from being concentrated at a sharp internal corner and distributes them over the broader volume of the fillet material.
11. Why is it important to take careful measurements/steps while storing the pattern?
a) They loose their shape and size
b) They get rusted
c) They get warped
d) All of the mentioned
Explanation: On long storage, if careful measurements are not taken then pattern materials tends to alter their dimension and the physical condition gets worse.
12. Temperature and humidity should be _________
a) Very low
b) Very high
c) Be controlled accordingly
d) Is not a matter of concern
Explanation: Neither too high nor too low temp is required but it is a factor to be controlled as to avoid pattern rusting or warping.
13. Time to time cleaning of stored pattern should be done by ___________
a) Distilled water
b) Dry cleaning
c) Treated with proper chemical fluids
d) Vegetable oils
Explanation: No dust or chemical or moisture should be left over the surface of the pattern for longer periods hence time to time dry cleaning is a must.
14. To ease the storing and assembly which of the following method is used by industries?
a) Colour pattern
b) Scanned copy/Photo
c) Coding and numbered
d) No measurements are taken
Explanation: Coding with numbers are the easier ways to distinguish the assemblies of patterns and ease its storing.
15. Which of the following method(s) is obsolete for storing fragile patterns?
a) They must be stored in kerosene
b) They must be stored in wax plated shelves
c) They must be stored in a wood wardrobe
d) They must be stored in foam
Explanation: Foam has the ability to absorb shocks and sudden impacts to a very higher extent. Hence, Fragile patterns are stored while wrapped in foam.
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