Consider the following materials:
2. Plaster and Ceramic
A mould can be made of
Moulds can be classified on the basis of material i.e. green sand mould, plastic mould and metal mould.
The success of a casting process depends mainly on the following properties of the moulding sand:
Which of the these are valid?
Permeability: It is expressed as the gas flow rate through the specimen under a specified pressure difference across it.
Strength: It refers to compressive strength.
Deformation: It indicates the change in length of a standard specimen at the point of failure.
Flowability: it refers to the ability of the sand to flow around and over the pattern when the mould is rammed.
Refractioness: It measures the ability of the sand to remain solid as a function of temperature.
Match the List-I with List-ll:
The relative ability of the liquid metal to fill in the mould at a given temperature is knowns as
The optimum temperature after melting is decided by a property, called fluidity, of the metal. Fluidity refers to the relative ability of the liquid metal to fill in the mould at a given temperature. Fluidity is higher when viscosity is lower.
Which of the following gating ratio represents pressurised gating systems?
Gating ratio = Sprue area: Runner area: Ingate area
If total ingate area is not greater than the area of sprue, gating systems are known as pressurised gating system.
Option (a), (c) and (d) represents unpressurized gating system.
Which of the following methods increases turbulence in liquid metal flow in mould?
Following are the suggested methods to reduce turbulence in liquid metal flow in mould:
(i) Keep the system filled by proper design of pouring basin and a tapered spure.
(ii) Use a sprue base or well.
(iii) Reduce metal velocity by an enlarged runner.
(iv) Use a streamlined system by providing radius for sprue entrance and exit, runners and ingates.
If metal is freezing against a flat mould wall and heat flow is normal to mould surface, then how the thickness (x) of solid metal deposited related with time (t)?
Three pieces being cast have the same volume but different shapes. One is sphere, one a cube, and the other a cylinder with a height equal to its diameter. Which piece will solidify the fastest?
Shapes having highest surface area will solidify fastest.
Expendable moulds are destroyed to remove the casting when the process of solidification is over. Select the expendable moulds from the following lists:
1. Metal moulds
2. Sand moulds
3. Ceramic moulds
4. Plaster moulds
Which of the following pattern-materials is used in precision casting?
1. Plaster of paris
3. Anodized aluminium alloy
4. Frozen mercury
Investment casting employs a shell made of ceramic, plaster, or plastic that is formed around a wax pattern. The wax pattern is melted and removed in a furnace and metal is poured into the shell to create the casting.