Rubber to metal bonding -applications

The production of tyres is among the most important of Automotive applications of adhesion. A modern steel-belted radial tyre contains several reinforcing materials, such as polyester and steel cords. The adhesion of the rubber compound to these cords is of critical importance for the performance and safety of the tyre. Other aspects of Rubber to metal bonding - applications are treated in other articles (see Rubber to metal bonding - basic techniques) here, the adhesion of rubber to the steel cords is discussed. 

Rubber to metal bonding - applications G LAKE Tyres bearings durability... 

The rubber toughened cyanoacrylates are particularly well suited for rubber to metal bonding applications, although they are slightly slower curing than the standard ethyl... 

The application of instrumentation to the automatic control of a sequence of operations, e.g., injection moulding processes. Once the mould has been loaded with inserts (assuming a rubber to metal bonded part) into the press, the operation of a push-button starts the controller which closes the press, injects the rubber, controls the cure cycle, recharges the injection unit, opens the press, operates the ejectors and presents the mould for cleaning and loading of inserts. 

The adhesives were applied according to manufacturers directions to scaled down models of an application. Failure of the vulcanized, rubber to metal bond was detected by a loss of resistance resulting from the establishment of a leak path under the rubber. The samples were connected electrically to the zinc anode. The temperature, specific gravity, electrical conductivity and pH of the solutions were monitored during the test. 

Rubber to metal bonding is a generic phrase covering a number of interdependent processes. The rubber bonded units that result from the process are used for the isolation of noise and vibration in automotive, engineering and chemical industry applications, such as in rubber lining of process equipment. 

The level of environmental resistance required and equipment available may determine whether to evaluate primer/cover coat systems versus one coat adhesive systems. And last, but not least, cost of both the adhesive and the application process is an important factor to consider in any industrial application, rubber to metal bonding being no exception. 

The different bond test methods yield results that do not always correlate closely in terms of bond strength or mode of failure [22]. Some of these contrasts in results reflect substantial differences in the manner in which the rubber to metal bond is stressed. This is likely to be more meaningful for some actual applications of bonded parts and less for others, depending on how the bond is stressed in such applications, e.g., shearing, tension or peeling. 

Bonds between rubber and substrates can fail for a number of reasons. Section 12.1 deals with some of the causes of rubber to metal bond failures. Section 12.2 examines the type of failures which are adhesion related, in fabric or cord reinforced power transmission belts. Section 12.3 discusses a phenomenon which causes service failures of rubber components, mainly in sealing applications. This phenomenon arises through a bond which is formed between the rubber (nitrile) and the metal mating surface of a valve or similar, which is of sufficient strength to rupture the rubber surface when the valve is opened. 

There is little practical value in complete hydrogenation since the end-product, at least in the case of the polybutadienes, can be prepared by the direct polymerization of ethylene. Partially hydrogenated materials, still capable of cross-linking by residual unsaturation, are of interest for a variety of possible applications including adhesives for rubber-to-metal bonding. 

Mr. Given s paper points up the fact that the conventional, slow speed, essentially static type measurement of rubber to metal bond strength is inadequate for many real life applications where high speed mechanical shock stresses are encountered. 

In summary, we have presented a method for the dynamic shear testing of post cure bonded and vulcanized in-place rubber-to-metal bonds at high speeds. This method is applicable for the testing of elastomeric energy absorbing bumper systems on automobiles in the five miles per hour range. This method has the capability of reproducible results with greater consistency than previous methods. 

Consideration is given to the different steps involved in rubber-to-metal bonding, including surface preparation of metal substrates, the application of primers and adhesives, and moulding, vulcanisation, curing and posttreatment processes. Factors which can lead to weak adhesion and bond failure are discussed, and approaches to the identification and correction of such problems are outlined. 

Other nitrile rubber epoxy adhesives have been described for rubber to rubber and rubber to metal bonds. Liquid carboxylated nitrile materials have been found useful in a number of applications. An adhesive comprised of carboxylated nitrile rubber, epoxy resins, imidazole, or tertiary amine and an organic peroxide has been described for bonding metals, paper, plastics, and inorganic materials. 

During World War II, synthetic rubber and resin-modified phenolics were used to bond aluminum sheets (available only in in. thickness at that time) into billets from which airplane propellers were carved, thus replacing laminated wood, which often shattered on impact with a bullet. Similar adhesives were used to bond rubber to metal in a variety of vibration-damping applications. The most successful widely known product of the new technology was the automotive bonded brake lining first introduced in 1947, and now regarded as a symbol of quality and integrity [12, p. 490]. 

Corrosion of the metal component of the bonded unit by salt environments can also be a major problem and thus due concern and allowance must be made for the service conditions in which the rubber to metal component will be resident. Corrosion of the bonded metal under the bonding system can also occur if the metal pre-preparation is carried out with acidic degreasing fluids. Care must be taken that degreasing fluids are and remain, neutral in pH throughout their use in the application. Recovery of used solvents and redistillation can significantly change the pH of a solvent. This can be a particular problem with chlorinated solvents, where after redistillation the distillate can be acidic in nature. 

The increased use of rubber in automotive, aerospace, and industrial applications has driven the requirement for strong and robust bonds between rubber and metal. Much literature has been published on the history and technology of bonding rubber to metal [1,2,3,4,5,6,7, 8]. The earliest historical methods of attaching rubber to metal involved attaching the rubber by mechanical means or by the use of ebonite. Mechanical... 

The last four decades have seen the introduction of many new rubber to metal adhesives designed to cover the ever increasing range of synthetic rubbers currently available for use in dynamic applications. These include one coat adhesives, adhesives for postvulcanisation bonding, specialty rubber adhesives for silicones, fluorosilicones, fluororubbers, acrylics, and hydrogenated nitrile rubbers, along with the recent introductions of water-based adhesives. 

Rubber to metal primers contain organic resins which react with most metal (steel, aluminum, stainless steel, copper, brass) surfaces during the vulcanisation process to form a chemical bond to the metal. They also contain polymers which allow for better film formation and act as an anchor for the subsequent application of the adhesive. 

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