NON-MECHANICAL JOINTS 1 PROFESSIONAL ENGLISH IN USE FOR ENGINEERING

 

PROFESSIONAL ENGLISH IN USE FOR ENGINEERING UNIT 28. NON-MECHANICAL JOINTS 1

 

A Welding Welding means permanently joining two pieces of material by heating the joint between them. The heat melts the edges of the components being welded together, and once the material has become molten (liquid), fusion occurs. When the joint fuses, material from each component is mixed together, joining to form a solid weld. Metal is often welded. It is also possible to weld plastic. B Common gas and arc welding techniques Shielded metal arc welding (SMAW), generally called arc welding or stick welding, involves striking an electric arc between the workpiece and an electrode – an electrical conductor. The heat from the arc melts the base metal. The electrode consists of a wielding rod – a stick of metal of the same type as the workpiece – which provides filler. The welding rod is therefore consumable – it is used up. The rod is also coated with a material called flux. When heated, this produces a shielding gas, which protects the molten metal from oxygen. Without this gas, the hot metal would combine with oxygen in the air, and this would weaken the weld.     EXERCISES 28.1 Complete the extract from a technical document about welding using the words in the box. You will need to use some words twice. Look at A opposite to help you. base fuse metal residual weld discontinuities heat-affected molten stresses welded dissimilar materials pool together zone   It is possible for components made of different metals to be (1) ___________ __________. for instance, steel can be welded to copper and to brass. However, it is much more difficult to weld components made of two (2) ___________ _____________ than it is to weld those made of the same (3) ___________ _____________. While there is no difficulty in melting two different metals and mixing them together in a (4) ___________ 28.2 Match the two parts to make eleven correct sentences about welding techniques. You will need to use some parts more than once. Look at B opposite to help you. 1. Shielded metal arc welding uses 2. Gas welding uses 3. Gas metal arc welding uses 4. Gas tungsten arc welding uses 28.3 Match each of the substances (1-6) to the description (a-h) above that uses the substance. Look at B opposite to help you. 1. flux 2. argon 3. oxygen 4. tungsten 5. acetylene 6. carbon dioxide

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