Gap Specification
Radial distance between the rotating cylinder and the fixed concave surface determines the intensity of the mechanical action on the flax straw. Precise drum clearance prevents the destruction of delicate long fibres during the initial scutching process. If the space is too narrow, the wooden core of the plant is crushed into the fibre, making subsequent cleaning difficult.
Conversely, a gap that is too wide leaves excessive shive attached to the stalks. This setting remains the primary variable in controlling the ratio of long fibre to short tow production.
Calibration Procedure
Feeler gauges verify the uniformity of the opening across the entire width of the machine. Technicians adjust the drum clearance at four specific points to ensure that the cylinder does not wobble or tilt during operation. Uneven gaps lead to inconsistent fibre quality and uneven wear on the metal pins.
The alignment must be checked weekly during high volume production runs.
Material Influence
Optimal settings change based on the thickness and maturity of the retted flax arriving from the field. Coarser stalks require a larger opening to allow the heavier shive to drop away without snapping the bundles. When the mill receives a batch of fine, dew retted straw, the operators reduce the distance to ensure the mechanical beaters reach every layer of the material.
