Casting and Forging

These flashcards cover key terms and concepts related to casting and forging processes as outlined in the lecture notes.

Casting

A process in which a metal is heated to a molten state and poured into a mould to create an object of the same shape.

Moulding Sand

The principal material used in casting, classified into Natural moulding sand, Synthetic sand, and Special sand.

Permeability

The property of sand that allows gases and water vapour to escape through the mould.

Refractoriness

The ability of moulding sand to withstand high temperatures without fusing.

Adhesiveness

The property that allows sand to adhere to surfaces, preventing it from falling when moulding boxes are lifted.

Cohesiveness

The ability of sand particles to stick together, allowing the pattern to be withdrawn without damaging the mould.

Flowability

The ability of sand to behave like a fluid, allowing it to flow and pack properly around the pattern.

Collapsibility

The property of sand moulds that allows them to collapse after solidification of the casting.

Pattern

A model of the desired casting used to produce the cavity or impression in moulding sand.

Shrinkage Allowance

Extra size added to a pattern to compensate for the shrinkage of the metal as it cools and solidifies.

Machining Allowance

Extra material provided on the surfaces of the casting to be removed during machining for desired surface finish.

Draft Allowance

Taper provided on the vertical surfaces of a pattern to facilitate easy withdrawal from the mould.

Rapping Allowance

A negative allowance made slightly smaller to compensate for the increase in mould cavity size when freeing the pattern.

Distortion Allowance

Adjustment made to the pattern to compensate for expected distortions during the cooling and solidification of the casting.

Cores

Bodies of sand placed in the mould to create hollow portions in the casting.

Blowholes

Cavities in the casting formed by entrapped bubbles of gases.

Scabs

Projections on the casting that occur when a portion of the mould lifts and metal flows.

Swell

Enlargement of the mould cavity caused by molten metal pressure.

Warpage

Unintentional deformation in a casting due to internal stresses or different rates of solidification.

Forging

A process involving heating metal stock to a desired temperature and then reshaping it through hammering or pressing.

Smithing

A hand forging operation where small parts are produced using open fire and hand hammers.

Directional Properties

Properties that indicate the flow lines in forged components, resulting in increased strength.