Rubber metal components

The rubber-metal system is made of sheets of rubber alternating with sheets of metal, as shown in Figure 4.32. Generally, the thickness of each layer of rubber is the same, as well as that of the metal. But the problem can be resolved whatever the thickness of the rubber-metal components. 

A disposable syringe may be made of plastic, glass, rubber, and metal components, and such multicomponent construction provides a potential for interaction that is greater than when a container consists of a single material. 

Let us note that this kind of test measures the behavior of the special rubber pieces supporting housings in case of earthquake. And, thus, special attention has been given to the cure process of these kinds of rubber-metal pieces in sandwich form in Chapter 4. It should be said that the motion due to earthquake is far from being vertical, as the horizontal component of the motion is essential and is also the most destructive. 

Improved adhesion is obtained by galvanizing, but this is only suitable for ABS polymers. When the plastic surfaces are pickled, the rubber elastic components are anodized. This produces pores and channels in which, for example, silver can be deposited chemically. The silver then forms the adhesive base for the copper layers subsequently deposited electrochemically, and these layers are then reinforced by the galvanized coating. Here, too, it is difficult to manufacture metal layer thicknesses of more than 10 fJLm because the different thermal coefficients of expansion of plastics and metals can easily lead to stresses, and thence to bubbles or cracks. 

One of the options available on a conveyor would be to have a mar-free machine. This would mean that all metal components are covered with a plastic or rubber compound, which would reduce the chances of the metal being. scraped while being sheared or conveyed. 

Non-metallic components Nanoparticles of diamond are being added as reinforcing agents to rubbers, plastics and resins. 

An increase of temperature in tribiological contact during friction is well known. It facilitates the phenomenon of selective transfer of polymer components, followed by their chemical reaction with the surface layer of metal coimterface, in the case of rubber-metal fiiction couple. The modification carmot only effect composition and structure of the surface layer of polymer but metal as well [2]. Our previous studies confirmed on the... 

Rubber expansion joints offer engineering advantages over metallic joints. Rubber expansion joints, which consist of flanged ends and a flexible section, can absorb within its free length more lateral movements, than any other similarly sized joint Expansion bellows are joints that have several sections. The flexible section of the rubber expansion joint/bellows is often a single fold which, because of the inherent flexibility of the rubber, can deal with large lateral movements with low force, a phenomenon which would require multiple folds in a similar metal component. 

The environment in which the component is to work will also affect the stresses to which the rubber-metal bond will be subjected. Some oil and solvent environments will penetrate a bond at the interface and thus may weaken or destroy the integrity of the bond until the stress becomes relieved by failure. 

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. 

However, at the same time it is possible to achieve sufficient bonding to steel without having problems with the self-adhesive silicone sticking to the mould, as is the case with conventional bonding agents for rubber to metal components. 

Rubber to metal bonded components have been designed and manufactured since the early days of the rubber industry and their technology and manufacture has been discussed elsewhere [1]. However, the design of the rubber to metal component in the modern car engine mount has provided other problems for the rubber manufacturer not related to... 

Particularly prone areas of bond stress in the early part of the components existence are concentrated by protrusions of metal components, such as bolt heads, into the rubber mass. An extensive load created in the area of such protrusions concentrates in their vicinity and localised bond failure can occur. This may not be evident to the observer but cavitation may have been created which can expand under stressing of the product in service, with resultant complete failure through rubber tear. 

A further interfacial factor can be the presence of non adsorbable or non desorbable contaminating films (as previously mentioned above) at the interface. Such materials can be oils, fatty acids, plasticisers from the rubber and metal processing oils from inadequately cleaned metal components. Some of these lubricants can be absorbed by the adhesive if it is solvent-based but in the case of the new waterborne rubber to metal systems this absorption cannot take place, for the systems are neither miscible or compatible with oils. These new waterborne systems have a critical tolerance level for surface contamination of the metal and if this is exceeded then wetting out of the metal by the adhesive will not, at the worst be possible, or at the best complete. 

Nowadays, rubber-metal composites are produced with bonding agents in which the polymer base is usually a halogenated polymer, for example, a mixture of chlorinated and brominated polybutadiene. After the film of bonding agents applied to the metal component has dried, the metal component is bonded to the rubber mixture during the vulcanization process. 

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