Pulsating Forming at Headbox Consistency in Bench Scale Provides Close Imitation of a Single-Wire Machine - Or How to Tune a Lab Device for Desired Web Structure, 2003 Spring Technical Conference Proceedings

The Moving Belt Drainage Tester (MBDT), first designed and constructed in Finland, has been demonstrated and discussed in a number of prior publications [1,2,3]. It was envisioned that the pulsations during handsheet forming should allow close imitation of Fourdrinier forming. Our recent studies with a more modern design using similar operating principles indeed show that some structural characteristics of mill-made paper can be nearly duplicated in laboratory forming from headbox furnish samples. We have adopted an accurate but low-cost method for determining the thickness direction profile of PCC, and this is one of the target characteristics to be compared with mill paper, along with basis weight and formation. To find the appropriate operating point of the MBDT device, it was necessary to construct “operating curves” by empirical modeling. These curves reveal some fundamental insights into pulsating forming and have remained a useful guideline for tuning the device with other furnishes. Having established experimentally that the MBDT provides a somewhat faithful simulation of single-wire forming, we envision that its usefulness will be largely based on the correct proportions of water, fiber, filler, and additives, so that their interactions can be more realistic than with conventional handsheet molds where high dilution is necessary.