RUBBER TO METAL.

Press, Volume LXVIII, Issue 20551, 20 May 1932, Page 15

RUBBER TO METAL.

NEW METHODS OF ATTACHMENT. AMERICAN EXPERIMENTS. At a recent conference of the American Society for Testing Materials it was reported that among the most important recent developments in the rubber industry is the discovery, perfected within the last two years, of processes for 'bonding soft rubber directly to metals. Formerly the attaching of rubber to metal was limited to such articles as solid rubber tyres. which were made by vulcanising a soft rubber tread to a hard rubber base, and simultaneously vulcanising the hard rubber to tho steel rim. This method was expensive and technically unsatisfactory, since tho heat necessary in using the hard rubber had a deleterious effect on the soft rubber of the tread. The need for lining metal tanks led to the discovery of two methods by which soft rubber can bo fastened directly to tho metal without tho use of hard rubber. One of these methods involves the cleaning of the metal and the application of a coating of a special cement. The soft rubber is then applied in sheets and rolled dowro, after which heat, in the form of live steam, is applied to vulcanise it. Fixing Bubber on Metal. The other method requires no cemont and is finding its greatest application in the manufacture of rubber.and steel motor mountings in modern automobiles. This method involves the plating of the steel with brass and the vulcanisation of the soft rubber dirootly to the braßs plating by a special process. Tho assembled mountings, built up of* plated steel and uncured rubbor compound, are placed in a mould and vulcanised in a press under accurately determined conditions of temperature and time. Tho degree of adhesion of the rubber to the metal obtained by the process is so great that even the toughest )of rubber compounds will break or tear before they will separate from the two parallel plates four inches square are fastened together in this way with vulcanised rubber, they can be made to withstand a load of 5000 pounds or more before the plates will be separated. When the break occurs, which is usually from a stress' of three tons or more, tho rubber tears, but thcro is no separation between the rubber and the plates. 1 Variety of Uses. " Along witli this development has come a widespread advance in the use of rubber cements' and a'dhesives. Practically everything that was formerly clamped, sewed, or«nailed can now bo fastened together with rubber adhesive more quickly and less expensively, according to tho rubber engineers. For the elimination of noise in automobiles an entirely new typo of material, known as "anti-squeak" tape, has been developed. It consists of a heavy fatiric impregnated with a sticky rubber compound, and is used in tho manufacture of automobile bodies Avherever squeaks would otherwise occur. The manufacture and patching of balloons has opened' an important new field for the use of rubber cement and tape. At first rubbor cements for this purpose were made of ordinary coagulated rubber, but new mixtures have now been devised which result in a vulcanising seal. These special "balloon" cements have an especially severe duty to perform, not only because of the stresses and strains, but because they are exposed to the "action of the sun's ultraviolet rays, which have a bad effect on rubber. The special cements are protected against this action.