EFFECTS OF ROLL-BLADE AND ROLL FORMING ON FORMATION, RETENTION, MECHANICAL-PROPERTIES AND ANISOTROPY - A PRELIMINARY COMPARISON

For a TMP furnish, roll-blade was compared with twin-wire roll forming over a broad range of jet-to-wire speed differences. Roll-blade formi ng resulted in a better large-scale formation (3-30 mm wavelength) and a slightly poorer small-scale formation (0.3-3 mm wavelength) over th e whole speed difference range investigated. Retention and mechanical properties were either maintained or impaired. Tensile stiffness MD/CD -ratio did not increase with the mix-to-wire speed difference in the c onventional way. Instead, an excessive mix speed caused a decrease in the MD/CD-ratio, whereas an moderately excessive wire speed had no app reciable effect. This was attributed to an unusually high fibre orient ation anisotropy in the headbox jet.