ASTM A938 and ISO 7800 both cover the requirements for simple twist testing of wire. These torsion testing standards require that a wire specimen be twisted about the longitudinal axis until it fails. Upon failure, the total number of twists should be recorded. Additionally, most operators want to know the torque required for specimen failure and would like to see a plot of torque versus angle for the entire test. This plot will show where the wire yielded during the twist test as well as the failure point.
For wire torsion testing, we recommend our 55MT series of multi-turn torsion testing systems. The model 55MT1 is well-suited for small diameter wires. It can be configured with a very low capacity (0.225Nm) torque cell and special fixtures for gripping small diameter wire. The model 55MT2 is ideal for larger diameter wire and wire rod. With a capacity of 220Nm, it can test wire rod as large as 10mm diameter. Both models are offered with an axial preload assembly that allows for a constant tensile load to be applied to the specimen. This set-up prevents the specimen from overlaying on itself during twisting. These torsion testing systems also include a standard interlocked test enclosure for extra safety.
The 55MT series is paired with Partner™ Torsion Testing Software for accurate data acquisition, result calculations and control. Partner Software will automatically record the total twists at failure and generate a complete torque versus angle plot for detailed data analysis.