Geometric Spacing
Gilling and drafting machinery controls the movement of flax fibres using pinned bars that must be configured for specific sliver weights. In these combing systems, the pin pitch is the distance between the centres of two adjacent pins on a single faller bar. This dimension determines the density of the pin field and the degree of control exerted over the fibre bundle.
Mechanical Function
Faller bars are driven through the fibre strand to prevent the uncontrolled movement of shorter fibres during the drafting action. A narrower pin pitch increases the combing efficiency and is utilized for fine flax line processing. Conversely, a wider spacing is needed for initial drawing passages where the flax sliver is thick and contains coarse bundles.
Choosing the correct density prevents the pin bars from clogging and bending under the force of the machine.
Processing Boundary
Spinning factories change these faller bars depending on the linear density of the yarn being produced. When the pin pitch is too small for a heavy sliver, the pins cannot fully penetrate the fibre mass, which leads to poor combing and uneven drafting. When it is too large for a fine strand, the fibres escape control, creating thick and thin spots in the yarn.
This spacing therefore dictates the operational limits of each drawing frame passage and must be matched to the progressive thinning of the flax sliver.
