Metal bonding, rubber process

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. 

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. 

Several years ago the subject was regarded as a "black art". Now the technology allows the production of a uniform, high quality product that is free from failure. Much of the science behind the technology remains cloaked in uncertainty, but it is sure to become an important part of future developments. Today, environmental concerns have an impact on all aspects of commerce. Rubber-to-metal bonding is no exception, so the process is changing to reflect these concerns. 

Vulcanization, thus, is a process of chemically producing network junctures by the insertion of crosslinks between polymer chains. A crosslink may be a group of sulfur atoms in a short chain, a single sulfur atom, a carbon to carbon bond, a polyvalent organic radical, an ionic cluster, or a polyvalent metal ion. The process is usually carried out by heating the rubber, mixed with vulcanizing agents, in a mold under pressure. 

Further detail may be found in articles on Pre-treatment of metals prior to painting, Pre-treatment of copper, Thermal spray processes and Rubber to metal bonding - pre-treatments. 

Many widely used Tests of adhesion can be applied to the rubber to metal bonds Blister test. Fracture-mechanics test specimens. Non-destructive testing of adhesively-bonded structures. Peel tests. Shear tests. Tensile tests and Wedge test. This particular article is concerned with those aspects that are of practical concern in the rubber-processing industry. 

Rubber to metal bonding processing effects J A LINDSAY Importance of good mould design... 

There are several drawbacks to the use of self-bonding compounds which are worthy of mention. To make a self-bonding compound, one must modify the properties of the bulk rubber compound in order to affect the chemistry of the reactions which are required to take place only at the rubber to metal interface. Processing is adversely affected since the compounds want to bond to the mould and metals alike, and the environmental resistance of the rubber to metal bond is generally poor compared to that which is obtained with the use of a conventional rubber to metal adhesive system. 

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. 

Bonding rubber to metal is a complex and multifaceted combination of metallurgy, surface science, adhesion science, rubber chemistry, and process engineering, with a multitude of interactions. In all aspects of bonding, scrupulous cleanliness, adherence to process controls and meticulous attention to detail are essential if good adhesion is to be attained on a consistent production basis. 

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