Category: Casting And Welding

In electric arc welding, the heat required for melting the metal is generated by short-circuiting the electrodes. An intense heat is produced in the electric arc. Various types of mechanism are used to produce arc and to stabilize it. The selection of the mechanism, i.e., type of electric arc welding depends on the heat required…

There are two types of welding methods. The welding rod is held in left hand and blowpipe is held in right hand. Leftward welding is used for the metal plate thickness up to 3 mm. Welding proceeds from right to left. It is also known as forward or forehand welding. The inclination of welding rod…

The highest temperature obtained in oxyacetylene welding is 3,200°C. Acetylene can be used as a gas from a separate cylinder or through reaction of water on calcium carbide. Three different types of flames such as neutral, oxidizing, and carburizing are generated at the tip of welding torch by regulating the amount of acetylene and oxygen…

In this welding process, various types of gases are burnt in combination with oxygen and the flame is applied at the edge of metal plates to be joined. The heat of combustion of the gas melts the metal; filler material may or may not be applied to fill the groove. The molten metal fills the…

Broadly, welding processes can be divided into the following categories as shown in Figure 20.31. Figure 20.31 Classification of Welding Processes

For complete penetration, sound welded joints, and good strength, bevelling preparation of edges and cleaning are required. The type of groove or edge preparation depends on the thickness of the plate and the welding methods. Some of the edge preparation methods are shown in Figure 20.28. Figure 20.28 Edge Preparation in Welding The use of various types…

A weld is defined by the American Welding Society (AWS) as “a localized coalescence (the fusion or growing together of the grain structure of the materials being welded) of metals or nonmetals produced either by heating the materials to the required welding temperatures with or without the application of pressure, or by the application of…

The history of joining metals goes back several thousand years, with the earliest examples of welding from the Bronze Age and the Iron Age in Europe and the Middle East. Welding was used in the construction of the iron pillar in India, during the Ashoka empire. In ancient age, forge welding was in use but…

Wire Brushing: Wire brush of hardened steel wires, embedded in a wooden block, is extensively used for cleaning the casting surface. Tumbling: In this method, the castings to be cleaned are placed together with a number of small cast iron pieces called stars inside a large steel barrel. Both ends of the barrel are closed and the…

Casting defects are unwanted feature or irregularities in casting which make it of poor quality. These defects occur due to several reasons such as poor design of casting, excess moisture in mould, improper ramming of moulding sand, misalignment of cope and drag, etc. The various types of casting defects are shown in Figure 20.27. Figure 20.27 Casting…