Influence of Headbox Nozzle Contraction Ratio on Sheet Formation and Anisotropy, 1994 Engineering Conference Proceedings
A.Nordstrom, B. Norman
According to traditional knowledge, the degree of fiber orientation in a paper sheet is determined by the speed difference between mix and wire(s) during forming. A low speed difference then yields a low degree of fiber orientation. With an increased speed difference, the degree of fiber orientation increases, and formation first improves, but deteriorates at higher differences. It is then not possible to optimize formation for products requiring a high degree of anisotropy.
For TMP, an unconventionally high headbox nozzle contraction ratio can generate a high degree of fiber orientation already in the headbox. Further, the state of flocculation in the jet is improved. It is then possible to forma sheet with high anisotropy and still an optimized formation.
Influence of Headbox Nozzle Contraction Ratio on Sheet Formation and Anisotropy, 1994 Engineering Co