CASTING

    It is a process in which molten liquid metal will be allowed to solidify in a pre-defined mold cavity.

    Casting is the primary manufacturing process.

   To hold molding sand while ramming, depending upon the type of pattern number of mold boxes is decided.The drag box kept upside down

After this ramming is done through a sand rammer.

It is a solid metallic object made up of metal.

Again put upside down

The distinction between cope and drags is called pamting line (PL) from the front view.

PL is coinciding with the pattern, the way is done to easily remove the pattern from the cavity.

Next step

To remove the pattern and empty cavity and Mould Molten metal.

Pattern made up of wooden material.

The  Pattern is removed using a draw spike by inserting it into a wooden pattern and some expansion takes place and the pattern is easily removed.

If a Metallic pattern is there then threads must be provided.

During moulding if the velocity is high then mould erosion takes place.

If the velocity of pouring metal is high then there is chances of removal of sand particles around the cavity in which the metal is poured.

Since the metal is poured into the cavity it mixes with the molten metal and there are chances of erosion of the metal.

One side liquid at very high temperature and at another side mold sandwich is at low temperature.

Due to this temperature difference heat transfer rate is high and thus the solidification rate is also high which results in fine grain structure on the surface of the casting material.

At center solidification rate is slower thus there is a presence of coarse grain

Gas defect 

    Liquid metals have much solubility for gases than do solid metal.

    When a metal begins to solidify, the dissolved gases are expelled from the solution.

    Gases may also result from reactions of the molten metal with mold materials.

    Gases either accumulate in regions of existing porosity or they cause microporosity in the casting.

    This defect caused by the gas is called a gas defect.

    This is the reason why LPG gases are not manufactured by the casting process.

    If these cylinders are produced by a casting process then it can cause an explosion.

ADVANTAGES

1. More Complex objects can be easily produced.

2. Any type of material can be cast i.e., hard and soft, ductile, and brittle.

3. Tools used in this technique are less expensive than compared to other processes.

4. Large size objects can be produced by casting only.

LIMITATIONS

1. The surface finish of the casting objects is very poor.
2. It is very difficult to produce the casting without any defect i.e., gas defects.
3. It is a laborious process and time-consuming process.
4. Mechanical Properties of casting objects are not uniform through its cross-section.