Rubber to metal bonding: testing

The test consists of immersing rubber-to-metal bonded test-pieces in distilled water and salt water for 30 days at ambient temperature. The changes in weight before and after the test are noted. 

Means of effecting good bonds between rubber and metal are discussed in articles on Rubber to metal bonding - basic techniques, Rubber to metal bonding - pretreatments and Rubber to metal bonding - testing. 

For further information, see the articles Rubber to metal bonding - testing and Soivent-based adhesives. 

Specific tests of adhesion are described in more detail under the following articles Blister test, Climbing drum peel test, Fracture mechanics. Napkin ring test. Peel tests. Rubber to metal bonding - testing. Shear tests. Tensile tests. Wedge test and in Refs. [1-5] see also Standards for adhesives and adhesion and Appendix. 

It is possible to clean and phosphate in a single operation. This process of acid phosphate cleaning combines the degreasing with a transformation of the metal surface by removal of oxide and the phosphating of the metal. The process can be used for metals such as steel, aluminium and zinc. This process produces an excellent surface for the adhesion of lacquers but it is not suitable for rubber-to-metal bonding. Tests have shown that the corrosion resistance of the components are not satisfactory. 

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. 

BRMA Publication Testing of Rubber to Metal Bonded Components, 1982. 

BS 903 PA21 Physical testing of rubber Part A21 Determination of rubber to metal bond strength Section 21.1 Adhesion to rigid substrates, 90-degree Peel method. 

A BRMA publication [17]. which gives recommendations for testing rubber to metal bonded components in general, suggests conditions for carrying out dynamic tests. Aubrey et al. [18] made a systematic study of the most commonly used methods and developed a procedure for industrial laboratories to predict strength and lifetime of bonded components. 

In service, rubber-to-metal bonds are often required to withstand harsh environments, so it is logical that tests for strength will be required after exposure to simulated aging conditions. Any of the environmental exposure tests (see Chapter 1. ) can in principle be applied, and it is generally preferable to subject the bond to stress during the exposure. 

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. 

A rubber to metal bonded part can be thought of as a chain which holds rubber and metal together. Any chain is only as strong as its weakest link. So it follows that when a rubber to metal part fails, it will fail in the weakest section of the part. A test method exists which specifically covers adhesion of rubber to metal, ASTM D429-2002 [21]. The vast majority of bond failures can be attributed to one or a combination of the following ASTM designations ... 

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. 

Butt, tensile test using compression moulding (see Figure 3.22). This is not widely used in rubber to metal bonding. 

With the advent of the energy absorbing bumper systems on automobiles, a need has developed for bonding and testing post cure bonded and vulcanized in place rubber-to-metal bonds. 

This paper will deal with the adhesives used in both types of bonding and the technique of fabricating the rubber-to-metal bonds. A special test will be described using high speed stress strain equipment to simulate impacts in the five- to 10-miles per hour range. 

The dynamic shear testing of rubber-to-metal bonds was done with a Plastechon Universal tester. This machine is an electro-hydraulic floor model with a 20,000-lb capacity. (Fig. 1.) It has additional interchangeable actuator/piston sleeve assemblies available in 2,500, 5,000 and 10,000-lb capacities. The speed range of the tester varies with the capacity. The range under 20,000-lb actuator service is from 2.0-3000 in/min, with speed range being... 

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. 

Beyond the particular process of cure in this case, the important problem which should not be neglected is the bonding of the rubber to the metal. This problem of adhesion of rubbers to metals is very weU covered in Reference [27] where a full description of the various tests is given. Another case of interest appears with the cure of a rubber when the cure is bound to various fabrics in order to get proofed materials such as hose. 

Standard Test Methods for Rubber Property - Adhesion to Rigid Substrates, Method D - Adhesion Test - Post Vulcanisation (PV) Bonding of Rubber to Metal, 2002. 

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