Mullen bursting strength tests quantify linerboard's durability and resistance to rupture under rough end use handling (pushing, pulling and dropping). Consistency of sheet properties such as Mullen strength are important for finishing paper at the winder, converting it to its final form, and to the end customer's satisfaction. Even when the average board strength is within specification, high Mullen variation can indicate that portions of the sheet are outside of the customer's accepted range.

A linerboard mill in the southeastern United States partnered with Precision Roll Grinders to evaluate the benefits of tight-tolerance calender roll grinds. With PRG-ground rolls installed, the Mullen variation of the sheet improved 6%, dropping from a variation value of 8 to a variation value of 7.5. With the Mullen variation of the paper improved across the sheet, the board was able to hold up better to external forces, such as those commonly experienced during rough and extreme handling at the end use of the product.

Contact Precision Roll Grinders today to learn how tight-tolerance grinding can drive similar performance improvements for your machine.