This is a national standard method for evaluating the surface quality and performance of bare wires, such as copper and aluminum, after bending. Its core principle involves tightly winding a wire of a specified diameter (typically ranging from 0.3 mm to 10 mm) around a test rod of a predetermined diameter, either through repeated winding or a single winding process. Subsequently, the wire's winding performance is assessed by observing whether any surface defects, such as peeling or cracking, occur. This standard should be applied in conjunction with the general provisions section (GB/T 4909.1). Conducting this test typically requires specialized equipment, such as a wire winding tester or a cable winding bare wire torsion tester. Such devices are equipped with interchangeable mandrels of various sizes and allow for controlled winding speeds to meet the different testing requirements specified in the standard.