Plate Parameter
A geometric metric of refiner plates calculates the total length of bar edges that pass each other per second to define the shear action on wood fibres. This value, known as cutting edge length, establishes how the mechanical energy is distributed across the refining surface. Planners use it to choose between plates designed for shortening fibres and plates designed for fibrillation.
The calculation incorporates the rotational speed, the number of bars, and the angle of the refining sectors.
Shear Calculation
The mathematical determination of this value relies on the grid pattern of the rotor and stator plates. As the rotor turns, the overlapping patterns of the bars create a combined cutting edge length that determines the intensity of the treatment. A high value means the energy is divided among many contact points, which favors gentle brushing and fibrillation.
Conversely, a low value concentrates the force on fewer edges, causing the fibres to be cut shorter. This control is necessary for achieving the correct balance of tear and tensile strength in packaging board.
Refinement Influence
Plate wear decreases the sharpness of the bar edges over time. When the edges round off, the actual cutting action drops and the process becomes inefficient.
