The Institute of Paper Chemistry Runnability Tester

The Runnability Tester corrugates a strip of medium at a constant speed. The tension of the medium is progressively increased as the strip is corrugated. At some critical tension level a fracture will occur in the corrugated specimen. The length of the corrugated medium, expressed in number of flutes, which passes through the tester without fractures is taken as an index of runnability performance. The greater the index value, the better the anticipated runnability performance on a corrugator.


The tester consists of a pair of 9" diameter, 2" wide face, B-flute corrugating rolls mounted on an electrically heated hot plate. One of the rolls is motor driven at a nominal speed of 47 f.p.m. The other roll (or pressure roll) is pivot mounted on a lever arm which is hydraulically loaded to apply an effective nip pressure of 535 pounds -- i.e., 335 lb./in. based on a 1.6" wide specimen. To minimize roll wear, the hydraulic pressure is only applied when the medium is being corrugated.

The sample holder is positioned at the entrance of the nip so that a strip of medium (49" long by 1.6" wide) may be fed through the nip. Means are provided for applying a linearly increasing tension to the sample strip as the strip is corrugated. The tension is near zero at the start of the test and increases to a maximum near the end of the test. The application of tension to the specimen under test is activated by the sample strip itself.

After corrugating, the sample strip is placed on an illuminated transparent rack and examined by transmitted light to determine how many flutes were produced without fractures. The number of flutes formed before fracture in the strip of one hundred flutes is the runnability index.