Mandrel Test

Section 6.3 of ASTM B470 covers the mandrel test for Type III (heavy bonding) bonded copper conductors. The conductor is wrapped six close turns over a mandrel of size specified in Table 3.After wrapping, the conductor is slipped off the end of the mandrel for examination. No separation of strands shall be visible to the […] Read more

Fraying

Section 6.2 of ASTM B470 covers the fraying test for bonded copper conductors used in hookup wire. The conductor, cut square at the end, is inserted into a blind hole of specified size and depth.The edge of the hole is broken to no more than 1/64 inch radius. The conductor is bent 90 degrees over […] Read more

Resistance Change with Temperature

Section 10 of ASTM B344 covers the accelerated life test performed in accordance with ASTM B76. This test evaluates the long-term oxidation resistance and durability of nickel-chromium alloys at elevated temperatures.The accelerated life test subjects the wire to repeated heating and cooling cycles under controlled conditions to simulate the service life of an electrical heating […] Read more

Tolerance on Electrical Resistance per Unit Length

Section 9 of ASTM B344 covers the test for change of resistance with temperature, performed per ASTM B70. This test measures how the alloy’s resistance varies with temperature.For electrical heating elements, stability of resistance at operating temperature is critical for consistent heat output. The test characterizes the resistance behavior across the operating temperature range.Determination is […] Read more

Physical Requirements

Section 5 of ASTM B344 covers the physical requirements for nickel-chromium and nickel-chromium-iron alloy wire for electrical heating elements. The material must be thoroughly and uniformly annealed.Wire of size 0.0035 inch (No. 39 AWG) and larger must meet a minimum elongation of 20% in a 10-inch gauge length. Wire from 0.0031 inch to 0.002 inch […] Read more

Continuity of Coating – Silver

Section 8.4 of ASTM B298 covers the continuity of coating test for silver-coated soft or annealed copper wire. This test verifies that the silver coating is continuous without bare spots or discontinuities.The silver coating classes range from Class A (minimum 1.25% by weight) to Class E (minimum 10.00% by weight). The continuity test ensures complete […] Read more

Enable Coatings

Section 13 of ASTM B267 covers the thermoelectric power test for resistance wire. This measures the thermal electromotive force generated at junctions between the resistance wire alloy and copper.Thermoelectric power (thermoEMF) is measured in accordance with ASTM B77. This property is important for wire-wound resistors used in precision circuits where parasitic thermoelectric voltages can introduce […] Read more

Permissible Variation in Electrical Resistance

Section 10 of ASTM B267 covers the temperature coefficient of resistance test for wire-wound resistor wire. This measures how the resistance of the alloy wire changes with temperature.The mean temperature coefficient of resistance (TCR) is a critical property for precision resistor applications. Different alloy classes have different TCR values, which determine the stability of the […] Read more

Thermal EMF with Respect to Copper

Section 9 of ASTM B267 covers the test for nominal electrical resistance per unit length for resistance wire. The nominal resistance per unit length for round wire is calculated from the nominal resistivity and the nominal cross-sectional area.For ribbon or flat wire produced by rolling from round wire, the cross section departs from a true […] Read more

Microscopical Examination

Section 11.2 of ASTM B187 covers the bend testing requirements for copper bus bar, rod, and shapes. The test specimen is bent around a mandrel of specified diameter to evaluate ductility.The test determines whether the copper product can be formed without cracking or surface defects. The mandrel diameter is related to the product thickness, with […] Read more

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