Mechanical Extraction
Mechanical removal of the woody core fragments from the fibrous bast layer constitutes the primary goal of the scutching and hackling stages. Efficient shive separation ensures that the final linen yarn is free from dark, brittle particles that would cause breakage or visual defects. This process relies on the physical difference in density and flexibility between the wood and the fibre.
Cleaning Mechanism
Rotating blades and spiked rollers strike the flax straw to shatter the internal xylem and knock it away from the external bundles. During shive separation, the distance between the striking elements and the transport belt is adjusted based on the maturity and thickness of the flax. If the clearance is too wide, the wood remains attached to the fibre, while a clearance that is too narrow will damage the long filaments.
Hackling machines further refine the material by combing out the smaller fragments that survived the scutching process. Dust extraction systems then pull the airborne shive away from the production line to maintain a clean environment.
Purity Standard
Acceptance criteria for premium flax roving specify a maximum weight of residual wood per kilogram of fibre. Because shive separation is never one hundred percent perfect, the remaining particles must be small enough to pass through the spinning nozzles without causing an ends-down event. High purity levels are required for the finest linen yarns used in luxury textiles.
