Manufacturing Technology I Set 11

Answer: false

Explaination:
in co2 moulding, poor collapsibility of the mould is a major disadvantage. although some additives are used for the improvement in the properties of

Answer: true

Explaination:
in co2 moulding, over-gassing and under-gassing can affects the properties of cured sand adversely. when the continuous passing of co2 is done for long time, this may results into sticking of pattern with the mould which cannot be removed easily, so proper care should be taken while passing of co2 gas.

Answer: true

Explaination:
because then there will be no torque developed and flux cutting.

Answer: rotor will be driven against rmf

Explaination:
as the rotor rotates at larger speed than the stator, the rmf speed is less than the rotor speed and it tries to rotate in the opposite direction to rmf.

Answer: all of the mentioned

Explaination:
it will operate as induction motor.

Answer: ns

Explaination:
the rotor emf and current are zero at the speed of synchronous speed of the machine.

Answer: 34.5 mm/s

Explaination:
for aluminum, the specific energy required is u = 2.9 j/mm3 therefore,

Answer: electrical energy

Explaination:
all arc welding utilizes the transfer of electrical energy to heat energy. an arc is a sustained electric discharge through this ionised gas column called plasma between the two electrodes. in order to produce the arc, the potential difference between the two electrodes (voltage) should be enough to allow them to move across the air gap. the larger air gap requires higher potential differences. if the air gap becomes too large for the voltage, the arc may be extinguished.

Answer: flux

Explaination:
flux is a substance used to prevent the formation of oxides and the other unwanted contaminations, or to dissolve them and facilitate removal. during welding the flux melts and becomes a liquid slag, covering the operation and protecting the molten weld metal the slag hardens upon cooling and must be removed later by chipping or brushing.

Answer: spot welding

Explaination:
spot welding is the simplest and most used resistance welding process. welding may be performed by means of single (most common) or multiple pairs of electrodes (as many as a hundred or more), and the required pressure is supplied through mechanical or pneumatic means.

Answer: neutral flame

Explaination:
in neutral flame oxygen is in the same proportion with acetylene. neutral welding flames are commonly used to weld: mild steel, stainless steel, cast iron, copper, aluminium, etc.

Answer: 30 v

Explaination:
voltage = ocv – (     i     )×ocv, where “ocv” is open circuit voltasgcec, “scc”

Answer: v = f(l)

Explaination:
v= a+bl, where ‘v’ is the arc voltage and ‘l’ is the length of arc in cm, a & b are constants.

Answer: construction of torch is different

Explaination:
construction of the torch is the only difference between plasma arc welding and tig welding. both the tig and paw are uses tungsten electrodes.

Answer: ionized

Explaination:
in plasma arc welding the gas is ionized. electrode used is made of tungsten and filler metal is used addition to it.

Answer: 1.4

Explaination:
n = (p×total efficiency)/(q×a), where p represents power, q represents heat transfer, and a represents the cross-sectional area.

Answer: co2

Explaination:
co2 is used only in dc power supply. it cannot be used in ac power supply. argon and helium can be used with ac supply.

Answer: electric resistance

Explaination:
in the making of an upset butt welding, there are jaws made of copper, into which the part to be welded is put, and hence a solid contact is made. at this point of contact, while the current flows, it gets transformed into heat because of electric resistance.

Answer: mechanical pressure

Explaination:
in spot welding process, the metal or the alloy parts which are to be welded, are heated in their in their zones. to bring these parts in contact with one another, mechanical pressure is applied, causing them to connect.

Answer: 12 mm

Explaination:
in spot welding process, to bring the heated parts in contact with one another, mechanical pressure is applied. this pressure can be of three types, by using foot lever, by providing air pressure or by using a hydraulic cylinder. the use of these methods allows steel or other metal parts to be welded up to a thickness of 12 mm.

Answer: true

Explaination:
in flash butt welding process, there is a light contact between the edges. a high voltage is supplied when the flashing action takes place. in this process, the metal that is forced out, is called as flash.

Answer: rubbing

Explaination:
friction welding is a solid-state joining process that produces coalescence in materials, using the heat developed between surfaces through a combination of mechanically induced rubbing motion and applied load. the resulting joint is of forged quality.

Answer: forgeable

Explaination:
as a rule, all metallic

Answer: cost saving

Explaination:
since dissimilar materials can be joined, a significant cost savings are possible because engineers can design bimetallic parts that use expensive materials only where needed. expensive forgings and castings can be replaced with less expensive forgings welded to bar stock, tubes, plates and the like.

Answer: butt joint

Explaination:
friction welding produces forged quality joints, with a 100% butt joint weld through the contact area. furthermore, in friction welding heat affected zone is much narrower as compared to other welds, which indeed reduces the cost of post-weld heat treatments (stress relieving processes).