Pressing a Range of Wools in Instrumented Minimum Volume Presses

Abstract

Two instrumented presses are described in which eleven different types of wool, including coarse and fine fleeces and offsorts, were compressed to their minimum total volumes using a heat, press, out-of-press cool sequence. The final volume was the actual volume of all components with air excluded. Extrusion of grease and dirt during pressing resulted in higher yield products of lower weight and in-press densities over 1300 kg/m³. Frictional forces and transverse/in-line pressure ratios were deduced from side- and end-pressure measurements at 90°C and at 20°C for each of the two stages of biaxial pressing of these wools at final pressures of 3.1, 7.8, and 12.6 MPa. Densities of the compressed wools were monitored over a nine month storage period unrestrained under ambient conditions, and remained close to 1000 kg/m³ for those produced at the higher pressures.