Knife-Over-Roll Configuration Design
topic
Knife-over-roll systems position a fixed knife blade above a driven backing roll that supports the substrate, with the gap between knife tip and substrate surface controlling coating weight from 50 to 800 grams per square metre for viscous compounds at knife clearances of 0.05 to 2.0 millimetres, with the backing roll hardness of 60 to 85 Shore A rubber determining the nip geometry and the substrate deformation under knife pressure that affects penetration depth into open fabric constructions.
Role
Provides controlled coating weight application for a broad range of compound viscosities and substrate types through the simplest and most robust knife coating configuration, with backing roll hardness selection being the critical design choice governing whether the compound penetrates through an open textile substrate as required for full impregnation or stays at the surface as required for barrier coating without substrate saturation.