A study conducted proficiency testing of laboratory test for the strength of corrugated fiberboard boxes

Abstract

The objective of this research project was to comply testing information on compression strength of corrugated fiberboard boxes from industrial laboratories in Thailand to use as a guideline to conducted proficiency testing. The information was obtained by delivering the prepared samples to 26 industrial laboratories. The testing results were analyzed by robust z-score and relative standard deviation methods. It was found that the testing results of 23 laboratories were satisfactory (|z| £ 2.0), of 2 laboratories were questionable (2<|z| < 3) and of 1 laboratory was unsatisfactory (|z| ³ 3). The normal distribution of z-score was considered well-established and the proficiency testing could use these 3 criterions together with other statistic methods.

                The repeatability of these results was then analyzed with %RSD method. It was found that the results from 17 laboratories was acceptable and from 9 laboratories was unacceptable. This could be because the laboratories were not under control conditions or the equipment was older than 15 years and not well maintained. The laboratories were advised to improve on performances for the proficiency testing in the future.