CASTING Multiple Choice Questions

Multiple Choice Questions

1. The metal is subjected to mechanical working for
a. Refining grain size
b. Reducing original block into desired shape
c. Controlling the direction of flow lines
d. All of these

2. The temperature at which the new grains are formed in the metal is called
a. Lower critical temperature
b. Upper critical temperature
c. Eutectic temperature
d. Recrystallisation temperature

3. The dowels are
a. Wooden nails
b. Box nails
c. Wire nails
d. None of these

4. Which of the following material can be used for making patterns?
a. Aluminum
b. Wax
c. Lead
d. All of these

5. Aluminum is the best material for making patterns because it is
a. A light in weight
b. Easy to work
c. Corrosion resistant
d. All of these

6. When a pattern is made in three parts, the bottom part is known as a cope.
a. True
b. False

7. A taper provided on the pattern for its easy and clean withdrawl from the mould is
known as
a. Machining allowance
b. Draft allowance Page 2 of 5
c. Shrinkage allowance
d. Distortion allowance

8. If an aluminum pattern made from a wooden master pattern is to be used for grey
from casting, then the shrinkage allowance allowed on the wooden pattern should
be
a. 10 mm/m
b. 16 mm/m
c. 20 mm/m
d. 26 mm/m

9. The shrinkage allowance for cast iron pattern is
a. 10 mm/m
b. 16 mm/m
c. 20 mm/m
d. 26 mm/m

10. The draft or taper allowance on casting is generally
a. 1 to 2 mm/m
b. 2 to 5 mm/m
c. 5 to 10 mm/m
d. 10 to 15 mm/m

11. The metal patterns as compared to wooden patterns require less
a. Shrinkage allowance
b. Machining allowance
c. Draft allowance
d. Distortion allowance

12. The machining allowance provided on patterns depends upon
a. Type of casting metal
b. Size and shape of casting
c. Method of casting used
d. All of these

13. The surface to be machined is marked on the pattern by
a. Red colour
b. Yellow colour
c. Black colour
d. Blue colour

14. Riddle is used for Page 3 of 5
a. Smoothing and cleaning out depressions in the mould
b. Cleaning the moulding sand
c. Moistening the sand around the edge before removing pattern
d. Reinforcement of sand in the top part of moulding box

15. The adhesiveness is the property of a sand due to which
a. It evolves a great amount of steam and other gases
b. The sand grains stick together
c. It cling to the sides of a moulding box
d. None of these

16. If the sand is too fine, its permeability will be high
a. True
b. False

17. The purpose of a riser is to
a. Deliver molten metal into the mould cavity
b. Act as a reservoir for the molten metal
c. Feed the molten metal to the casting in order to compensate for the
shrinkage
d. Deliver the molten metal from pouring basin to gate

18. Which one of the following material will require the largest size of riser for the
same size of casting?
a. Aluminium
b. Cast iron
c. Steel
d. Copper

19. The directional solidification in casting can be improved by using
a. Chills and chaplets
b. Chills and padding
c. Chaplets and padding
d. Chills, chaplets and padding

20. In permanent mould casting method
a. Molten metal is poured in a metallic mould, retained in the mould long
enough for the outer skin to solidify and finally mould is turned over to
remove molten metal still in molten condition Page 4 of 5
b. Molten metal is poured and allowed to solidify while the mould is
revolving
c. Molten metal is forced into mould under high pressure
d. None of these

21. In a ___________, the molten metal is poured and allowed to solidify while the
mould is revolving.
a. Die casting method
b. Slush casting method
c. Permanent mould casting method
d. Centrifugal casting method

22. In a hot chamber die casting machine
a. Melting pot is separate from the machine
b. Melting pot is an integral part of the machine
c. Melting pot may have any location
d. High temperature and pressure is used

23. Cast iron and steel pipes are produced by
a. Slush casting
b. Investment casting
c. True centrifugal casting
d. Die casting

24. Which of the following statement is wrong?
a. The hot chamber die casting machine is used for casting zinc, tin, lead and
other low melting alloys.
b. The cold chamber die casting machine is used for casting aluminium,
magnesium, copper base alloys and other high melting alloys.
c. The castings produced by centrifugal casting method have open and coarse
grained structure.
d. All of the above
25. In a cold chamber die casting machine, only non-ferrous alloys with _______ are
casted.
a. Low melting temperature
b. High melting temperature
26. The centrifugal casting method, is used for casting articles of
a. Symmetrical shape about vertical axis Page 5 of 5
b. Symmetrical shape about horizontal axis
c. Irregular shape
d. Non-ferrous metal used

27. Match the correct answer from Group B from the manufacturing process given in
Group A.
Group A (Manufacturing process) Group B (Product)
(a) Pressure die casting (a) Automobile piston in aluminium alloy
(b) Gravity die casting (b) Engine crankshaft in spherodial graphite iron
(c) Sand casting (c) Carburetor housing in aluminium alloys
(d) Shell moulding (d) Cast titanium baldes

28. Fin s casting defect which is due to thin projections of metal not intended as a part
of casting.
a. Correct
b. Incorrect

29. Shift is a casting defect which
a. Results in a mismatching of the top and bottom parts of a casting
b. Results in general enlargement of a casting
c. Occurs near the ingates as rough lumps on the surface of a casting
d. Occurs as sand patches on the upper surface of a casting.

30. A casting defect which occurs near the ingates as rough lumps on the surface of a
casting is
a. Shift
b. Sand wash
c. Shift
d. Swell

31. A casting defect which occurs due to improper venting of sand is known as
a. Cold shuts
b. Blow holes
c. Shift
d. Swell 

Self-sculpting smart sand could assemble itself into solid replicas of objects

Research currently underway at MIT’s Distributed Robotic Laboratory (DRL) could lead to an innovative replicative manufacturing technique with the disruptive potential equal to that of 3D printing. Imagine a sand-like material that could autonomously assemble itself into a replica of any object encased within. Incredible though this may sound, the DRL researchers have already managed to build a large scale proof-of-concept, with 10-mm cubes acting as the grains.

Before we go into how these cubes - or "smart pebbles" - work, let’s sketch out the general concept. The idea is to create objects using a subtractive method, where excess material is removed just like when carving in stone. Each grain of smart sand would be a self-contained micro computer. These tiny machines would use an elaborate algorithm to communicate with the neighboring particles in order to establish the exact position and shape of the input object so that it can be replicated.

The already mentioned smart pebbles demonstrate this principle in a more easily understandable 2D setting. First the pebbles establish which of them border on the perimeter of the object to be replicated. Once identified, these particles pass on a message to their neighbors, and effectively specific particles selected by the algorithm are notified that an identical (or scaled) arrangement should be recreated a safe distance away, so that the two shapes do not overlap.

Once the perimeter of the copy is identified, the pebbles within that area bond to each other, while the redundant material simply falls away. The resultant object would be solid, but it could be easily deconstructed simply by putting it back into the heap of smart sand. The constituent grains would detach from each other and the whole process could be repeated with an entirely new shape.

Each smart pebble cube used for testing was equipped with a set of electro-permanent magnets on four sides. The magnetic properties of such magnets can be switched on and off using electrical impulses, but unlike electromagnets, they do not require electricity to sustain these properties over time. With each particle neighboring on eight other particles in a 2D scenario, the magnets allow for selective bonding with any of the neighbors. However, the magnets also play a role in communication and power sharing.

Each smart pebble was also fitted with a rudimentary microprocessor capable of storing 32 kilobytes of code and boasting two kilobytes of working memory. With such limited processing power at the disposal of a single unit, the main computational heft had to fall on the distributed intelligence algorithm that constitutes the core of the current DRL endeavors.

"How do you develop efficient algorithms that do not waste any information at the level of communication and at the level of storage?" asks Daniela Rus, a computer science and engineering professor at MIT. The answer to that question is likely to be found in a paper that Rus co-authored with her student, Kyle Gilpin, and which is going to be presented in May at the IEEE International Conference on Robotics and Automation.

The algorithms developed at DRL have already been shown to work robustly with 3D scenarios, where the bed of smart sand would be divided into layers, each constituting a separate 2D grid. Now the only thing that stops smart sand from joining 3D printing in revolutionizing the world of rapid manufacturing is getting the scale right.

But according to Robert Wood, an associate professor of electrical engineering at Harvard University, this is not an issue. Wood reckons recreating the functionalities of the smart pebbles in smaller scale is feasible. Yes, it would require quite a lot of engineering, but the goal is well defined and reachable. “That’s a well-posed but very difficult set of engineering challenges that they could continue to address in the future.”, he says. If Wood is right, the future of subtractive manufacturing is bright.

Watch the video below to find out more about the algorithm behind smart pebbles.