Metal Casting and Welding

Mechanical working processes are performed on metals

• to achieve optimum mechanical properties in the metal

• to improve the mechanical strength of the metal

• to make metal dense

• All of the above

Hot working process is the plastic deformation of metal which is carried out

• at temperature below the recrystallisation temperature

• at temperature above the recrystallisation temperature

• at temperature equals to boiling point of water

• none of the above

Castings are usually

• costlier than forgings

• cheaper than forgings

• at the same rate as forging for similar metal

• None of the above

What is the process, in which the metal is caused to flow through a restricted orifice to create an extremely elongated strip of uniform and comparatively smaller cross-sectional area, called?

• Rolling

• Drawing

• Extrusion

• Spining

Which of the following is not a part of carriage of the centre lathe?

• Tool post

• Apron

• Compound rest

• Gear box control

Why are the plasticisers added with polymers?

• To hold other constituents of plastic together

• To reduce the cost and enhance the strength and hardness of plastics

• To improve flexibility and to reduce the temperature and pressure required for moulding of plastics

• None of the above

Specific gravity of the plastics is usually

• less than the specific gravity of metals

• More than the specific gravity of metals

• similar to the specific gravity of metals

• Unpredictable

Which of the following is an example of thermoplastic material?

• Camera bodies

• Auto mobile parts

• Electric plugs

• Electric insulation

Which plastic materials contain strong cross linkings in their molecular structure?

• Thermoplastic materials

• Thermosetting materials

• Both a. and b.

• None of the above

Which plastic materials contain strong cross linkings in their molecular structure?

• Thermoplastic materials

• Thermosetting materials

• Both a. and b.

• None of the above