As the wire reverses once, the convex-concave occurs on the cutting section once, thus the regular washboard shape occurs on the cutting section. Usually it is called as washboard strip. If not only black-and-white reversing strip, but also the washboard stripe occurs, this situation is not acceptable. The possible reasons caused as below:

1 The wire is loose or there is difference tightness between the two sides of wire on the cylinder. This causes the wire is vibrating with wide range during running, and the wire winding occurs at the moment of the wire reversing, so that over feeding or short feeding happens.

2 The bearing of guide wheels doesn’t rotate flexibly and stably that causes the resistance is not uniform during reversing or running in the axis direction.

3 The resistance is too much between the conducting block or the guide wheel and the wire that causes the different positive and negative tension in the working area (the area between the two guide wheels calls as the working area).

4 The guide wheel or the wire cylinder support causes the guide stay in wrong position, V face is not symmetric.

5 Non-uniform feeding related to the wire reversing causes the step on the oblique line or circular arc like the

washboard stripe.

In general, the reason that the washboard strip occurs mostly is: the wire runs up and down as two paths in the working area to lead to the amplitude of convex-concave washboard. Another special situation, the periodic regularity of washboard stripe does not depend on the wire reversing but X、Y screw. How to know this situation happens: Cut the oblique line with 450mm, the periodicity and the defect caused are clear at a glance.

The washboard stripe causes not only the bad roughness but also low efficiency, frequent short and open circuit. The prompt over-feeding can make the process stopping.