Page 42 Advertisement 1

New Zealand Listener, Volume 32, Issue 805, 24 December 1954, Page 42

S HRINK FIT At an engineering works in the Midlands, a 2,000 ton hydraulic forging press had to be overhauled because of wear. The firm decided that a good way of effecting repairs would be to "shrink fit" new parts in place of worn ones. A metal part to be fitted by this process is deliberately made a precise amount too large. When extreme cold iS applied the part shrinks and can be fitted into another The metal expands as the temperature rises to normal and a very tight fit is thus ensured. The firm therefore consulted LCI: Billingham Division who make "Drikold"_a solid refrigerant which, with a temperature of minus: 110PF: iS a convenient means of producing extreme cold. The main part of the problem was to shrink a hollow steel cylinder weighing 7 tons and fit it into the body of the press. The firm made the neces- sary preparations. and provided lifting tackle; whilst an ICI man supervised the shrinking; This was done by clos- ing the cylinder at one end and flling it with 80 gallons of methylated spirit and 1,400 lb of Drikold Five and a half hours later, at a temperature of minus 95"F. the cylinder had contracted by 30 thousandths of an inch; It was then hoisted into position. This completed one of the biggest shrink fitting jobs ever undertaken: ICL IMPERIAL CHEMICAL INDUSTRIES (NZ) LTD: GneBoa I0 DI $ E D S A L T Guards health and assists to See hw it prevent and guard unS against Goitre