Slot Die Manifold Design Principles for Uniform Liquid Coating Width
Uniform liquid coating width depends on matching coat-hanger manifold contours to non-Newtonian fluid rheology while constraining die body pressure flexure.
Shear Thinning Slurry
Meaning
Non-Newtonian fluids containing suspended solid particles exhibit variable resistance to flow depending on the applied deformation rate. A shear thinning slurry undergoes a decrease in viscosity when subjected to increasing shear strain, such as during pumping or agitation. This property allows highly concentrated mixtures to be transported more easily once fluid motion is initiated.
Understanding this behavior is essential for designing piping systems and selecting appropriate pumps for industrial processes.
Rheological Behavior
At rest, the suspension behaves like a thick paste due to particle interactions. Once the pump starts, the shear thinning slurry flows like a low viscosity liquid. This facilitates efficient pipe transport.
Viscosity Audit
Rotational viscometers measure viscosity across a broad range of shear rates during pilot scale formulation tests. This audit defines the flow curve and determines the minimum pump pressure required to transition the slurry into its low viscosity state. Accurate data prevents pipe blockages during commercial operations.
Flow Failure
Underestimating the viscosity of the resting mixture leads to undersized pumps that cannot initiate flow. When a shear thinning slurry is handled by inadequate equipment, the system stalls and blocks the entire transport line. The resulting maintenance demands extensive downtime for manual system flushing.