MACHINING 2 PROFESSIONAL ENGLISH IN USE FOR ENGINEERING

 

PROFESSIONAL ENGLISH IN USE FOR ENGINEERING UNIT 24. MACHINING 2

 

A Guillotining and punching Thin materials can be cut by applying pressure in order to shear them – that is, cut them with a scissoring force (in engineering, called a shear force). Sheets of metal can be sheared using a machine called a guillotine, which has a long blade. Usually, sheets are guillotined when long, straight cuts are required. B High-temperature metal cutting techniques Flame-cutting generally uses oxygen (O2) and acetylene (C2H2). The two gases are blown through a torch – basically a tube – as a mixture called oxyacetylene. The acetylene burns in the oxygen to produce a flame hot enough to melt steel. C Laser cutting and UHP waterjets Laser beams (concentrated light) can cut materials accurately, in small quantities, by melting them. Laser cutting is especially suitable for plastics. Ultra-high-pressure (UHP) waterjets – jets of water fired at extremely high pressure – can cut almost any material, including metal. An advantage of UHP waterjet cutting is that the edge quality of workpieces is high – that is, the cut edges are smooth. This means that no secondary operations EXERCISES 24.1 Match the cutting processes (1-4) to the descriptions (a-e). you will need to use some of the descriptions more than once. Look at A opposite to help you. 1. blanking 2. guillotining 3. piercing 4. punching 24.2 Complete the descriptions of the photos using words from B and C opposite. This torch burns (1) _________ (C2H2) in a flow of (2) _________ - a mixture called (3) _________. The torch can be used for (4) _________- _________. 24.3 Answer the questions below, about non-mechanical machining techniques. Look at B and C opposite to help you. 1. In machining, what does EDM stand for? 2. What alternative term can be used instead of EDM? 3. What type of tool is used in both flame-cutting and plasma cutting?

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