Introduction

Meaning of Mould Cavity
Hollow space, or cavity, in the mold, which is used to impart the desired form to the product being molded. 

Moulding

Moulding process involves shaping foundary sand around a suitable pattern in such a way that the pattern can be withdrawn to leave a cavity of the required shape in the sand. To facilitate this procedure the sand mould is split into two or more parts. For casting of simple shapes, a two-part mould can be used, each half being contained  in a box like frame. The upper frame is called cope and the lower frame  as the drag.

Classification of Mould

1. On the basis of Materials

• Green sand mould
• Plastic mould
• Metal mould

2. On the basis of Method of making

• shell mould 
• investment mould 

Classification of Pattern Allowances

1. Shrinkage allowamces
2. Draft allowances
3. Machining allowances
4. Shake allowances
5. Distortion allowances

Properties of Metals
Metals : - metals are element substances that give up electronos to form metallic bonds and conduct electricity. Properties of Metals 1. Tensile strength 2. Toughness 3. Ductility 4. Malleability 5. Hardness

 Tensile Strength: - 

It is the properties of the material to withstand stretching forces. It can be found by stretching a specimen of a material on a testing machine by applying known values of the tensile load and measuring the resulting extention of the specimen until the material fractures.

Materials may have different values of strength when tested in tension, compression and shear.

Toughness

This is the ability of metal to withstand shock loading. Toughness may be measured by subjecting a test specimen to sudden loads using a machine design for the purpose. The machine is capable of measuring the amount of energy required to break the test  pieces.

Ductility

 is when a solid material stretches under tensile stress. If ductile, a material may be stretched into a wire. Malleability, a similar property, is a material's ability to deform under pressure (compressive stress). If malleable, a material may be flattened by hammering or rolling.

Both of these properties are aspects of plasticity. Plasticity is how far a solid material can be plastically deformed without fracture. Also, these material properties are dependent on temperature and pressure. This was investigated by Percy Williams Bridgman as part of his Nobel Prize–winning work on high pressures.

Ductility and malleability do not always go together. Gold has high ductility and malleability, but lead has low ductility and high malleability.The word ductility is sometimes used to embrace both types of plasticity.

Gold, copper, aluminium, and steel have high ductility.

Hardness

 is a measure of how resistant solid matter is to various kinds of permanent shape change when a compressiveforce is applied. Some materials, such as metal, are harder than others. Macroscopic hardness is generally characterized by strong intermolecular bonds, but the behavior of solid materials under force is complex; therefore, there are different measurements of hardness: scratch hardness, indentation hardness, and rebound hardness.

Hardness is dependent on ductility, elastic stiffness, plasticity, strain, strength, toughness, viscoelasticity, and viscosity.

Common examples of hard matter are ceramics, concrete, certain metals, and superhard materials, which can be contrasted with soft matter.

Malleability

 is a substance's ability to deform under pressure (compressive stress). If malleable, a material may be flattened by hammering or rolling.

Malleability is a physical property of matter, usually metals. It usually applies to the family groups 1 to 12 on the modernperiodic table of elements. It is the ability of a solid to bend or be hammered into other shapes without breaking. Examples of malleable metals are gold, iron, aluminum, copper, silver, and lead.

Malleability is the ability of a metal to be hammered into thin sheets. Gold and silver are highly malleable. When a piece of hot iron is hammered it takes the shape of a sheet. The property is not seen in non-metals. Non-malleable metals may break apart when struck by a hammer. Malleable metals usually bend and twist in various shapes.

Ductility is a related type of plasticity. Ductile materials can be stretched into wires.