The following points highlight the nine main properties of moulding sand. The properties are: 1. Permeability 2. Cohesiveness 3. Adhesiveness 4. Plasticity 5. Refractoriness 6. Chemical Resistivity 7. Binding Property 8. Flowability 9. Green Strength. Property # 1. Permeability: The passage of gaseous materials, water and steam vapour through the moulding sand is related to porosity or in other words [...]
The following points highlight the six main tests done to determine the essential qualities of sand. The tests are: 1. Grain Fineness Test 2. Permeability Test 3. Sand Mould Strength Test 4. Moisture Content Test 5. Clay Content Test 6. Hardness Test. 1. Grain Fineness Test: Granular particles of various sizes and shapes provide variable interstices (space between grains) and [...]
Pattern allowances in order to produce a casting of proper size and shape depend partly on product design, mould design, shrinkage and contraction characteristics of the metal being cast, etc. Actually, it is very difficult to predict precisely any rule mathematically, and a process of trial and error is best to achieve adjustment of pattern dimensions to obtain desired results. [...]
In this article we will discuss about:- 1. Definition of Moulding Sand 2. Types of Moulding Sand 3. Chief Constituents. Definition of Moulding Sand: The principal raw material used in moulding is the moulding sand because it provides several major characteristics that may not be obtained from other materials. Moulding sand is defined as granular particles resulting from the breakdown [...]
Small or medium-sized castings are made in flask— a box shaped container without top and bottom, which confines the sand moulds (Refer Fig. 3.28). It is made in two parts, held in alignment by dowel pins. The top part is called the cope and the lower part is called the drag. If the flask is made in three parts, the [...]
The following points highlight the fifteen main patterns used for casting of materials in an industry. The patterns are: 1. Single-Piece or Solid Pattern 2. Split Patterns 3. Loose Piece Pattern 4. Gated Pattern 5. Match Plate Pattern 6. Follow Board Patterns 7. Sweep Patterns 8. Segmental Pattern or Part Pattern 9. Skeleton Pattern 10. Shell Pattern 11. Built-Up Pattern [...]
In this article we will discuss about:- 1. Introduction to Casting Process 2. Aims in Making a Casting 3. Types 4. Patterns 5. Design 6. Technical Aspects of Making Sound Castings 7. Inspection 8. Defects. Introduction to Casting Process: Casting process is based on the property of a liquid to take up the shape of vessel containing it. Molten metal [...]
In this article we will discuss about:- 1. Definition of Sand Moulds 2. Classification of Sand Moulds 3. Feeding of Metal. Definition of Sand Moulds: A sand moulds may be defined as-a preformed sand container into which molten metal is poured and allowed to solidify. After casting it is removed from the sand mould, sand mould is generally destroyed. The [...]
Some of the casting defects are described below: 1. Surface Roughness: Too coarse a moulding sand or when pouring temperature is high leads to rough or pebbly surfaces on castings. In steel castings, roughness is produced due to occurrence of surface reaction at mould-metal interface in which iron is oxidised and iron oxide reacts with silica to forms rough compound. [...]
In this article we will discuss about the process and characteristics of sand casting. Process of Sand Casting: The importance of sand casting is increasing day-by-day as the scientific research has brought about lot of applications and adaptations in the field of casting industry. This is probably the easiest and most convenient way of giving the desired shape to the [...]