AERO ENGINE BEARINGS

Evening Star, Issue 25226, 13 July 1944, Page 6

AERO ENGINE BEARINGS

LIFE PROLONGED BY NEW PLATING METHOD A wartime development of which little has yet 'been heard, but which conceivably may have a very important effect on extending almost indefinitely the life of the bearings of automobile, aero, and other engines, has been recently revealed, says the ' Dunlop Bulletin."' Such an announcement is one which will intrigue most motorists, for engine bearings that have a life of almost that of the rest of the motor mean reduced cost of upkeep, etc. Strange to say, the medium by which the life of bearings can be extended is a corrosion-resistant silver-white pure metal, softer than lead, which was discovered away back in 1867, when samples were priced at about £4.000 an ounce Fifty years later, the price was still high, £6O per ounce, with no takers The metallic element is _ indium, found in small quantitie in zincblende, and obtainable from commercial zinc. Prior to the war, the metal had little practical application. Indium confer its own peculiar properties upon the actual wearing surface, and although it is softer than lead, it gives greater hardness to an alloy when combined with a number of non-ferrous metals. It melts at 311 deg. Fahrenheit, and this low melting temperature enables a "flash" plating, only a few hundredthousandths of an inch thick, to be diffused into the surface of the lead or other bearing metal by heating in an oil bath at about 350 deg. Fahrenheit. The indium then fuses and immediately alloys with the surface of bearing, the metals of which are unaffected by this moderate heating. The life of bearings of aero engines, which formerly wero considered to have given good service if they stood up to aJbout 200 hours' flying, has, it is stated, under the in-dium-plating technique, been extended to thousands of hours.

Although the price of indium entitles it to be rated almost" as a precious motal, such small quantities of it accomplish such large results that a wide use of indium-treated bearings by automobile manufacturers after the war seems almost a certainty.

It appears that shortly before the outbreak of the war, overeas automobile manufacturers wore beginning to recognise the value of indium diffused into the surface of heavy-duty_ bearings of various types. War experience has now proved its value, not only for prolonging the life of bearings, but also for preventing tarnish and corrosion of metals. For instance, it has been found effective in protecting the leading edge of aero steel propeller blades.

While evacuated, horticultural expert heard that in his absence local children were stealing his specimen blossoms. When he returned home there were no blooming plants left. ,r My daughter caught her soldier husband flirting," complains a mother. That, Ave understand, is the usual way to patch a, husband.