ASTM D1871-04(2010)

To contribute to the mechanical properties required in a product, tire bead wire must have good adhesion to the rubber matrix. This allows the rubber to absorb part of the energy, distributing it uniformly between the reinforcing material and the rubber compound. This test method is considered satisfactory for acceptance testing of commercial shipments of wire since it has been used extensively in the trade for this purpose. This test method may be used for purchase specification requirements or manufacturing control of bead wire.

If there are differences of practical significance between reported test results for two laboratories (or more), comparative tests should be performed to determine if there is a statistical bias between them, using competent statistical assistance. As a minimum, test samples should be used that are as homogeneous as possible, that are drawn from the material from which the disparate test results were obtained, and that are randomly assigned in equal numbers to each laboratory for testing. Other materials with established test values may be used for this purpose. The test results from the two laboratories should be compared using a statistical test for unpaired data, at a probability level chosen prior to the testing series. If a bias is found, either its cause must be found and corrected, or future test results for that material must be adjusted in consideration of the known bias.

The characteristics of single filament steel wires that affect the adhesion property are wire diameter, coating composition, and coating mass. The storage conditions, age, and vulcanization conditions of the rubber compound will affect the test results and must be specified by the supplier of the rubber compound.

1.1 This test method cover procedures for testing the strength of adhesion of single-filament wire to vulcanized rubber compounds. The method applies to, but is not limited to, wire made from brass, bronze, or zinc coated steel wire. The adhesion strength is expressed as the magnitude of the pull-out force for the single filament of wire.

1.2 This test method is applicable to single-filament wires used in reinforced rubber products as single filaments and is normally used to evaluate the adhesion of samples of wire to a standard rubber applied under specified conditions. It is primarily used to evaluate tire bead wire and may be applied, with modifications and by agreement between supplier and customer, to various wire types used in rubber product reinforcing.

1.3 This test method is written in SI units.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. See 6.5.1.