TO MAKE an impellerthe fan-like part of the pumps that push ore-slurry down a pipelinethe folk at Weirs foundry in Todmorden, West Yorkshire, begin with a polystyrene cast coated in ceramic paint. They place it in a flask tightly packed with sand, into which a molten alloy is poured. The polystyrene burns away, leaving a metal copy. A 15-tonne impeller takes just a minute to cast but needs 11 days to cool. Metal ores are hard on machinery, so every three weeks one of these giant metal parts must be shipped from Britain to a copper mine in Chile. The worn impeller is sold for scrap. Some 200 miles to the south, in Bushey, a suburb of London, another British firm is manufacturing high-tech tools for export. Smiths Detection, part of Smiths Group, an industrial mini-conglomerate, specialises in devices that can detect toxic gases in seconds, including hand-held ones that run on AA batteries. The American military has issued more than 57,000 of them. source: http://www.economist.com/news/britain/21569717-two-firms-tug-war-between-british-heritage-and-global-customers-victoria-line