Carpet yarn has properties that set it apart from other textile yarns, and it asks different things of the tube it is wound onto. In this article we look at what BCF yarn is and how it shapes tube selection.
What is BCF?
BCF stands for Bulk Continuous Filament. It is the most widely used yarn type in machine-made carpet production.
Broadly, it is produced as follows: colour is dosed into a synthetic polymer, chiefly polypropylene; the melt is extruded through spinnerets into filaments; rapid cooling brings about crystallisation; the drawing unit imparts strength; and the texturing unit gives bulk. The resulting yarn is wound onto a tube at the winder.
What makes carpet yarn different?
Two properties of BCF yarn stand out where the tube is concerned.
Bulk. Because the yarn is bulked, it occupies more space at the same weight. This affects package diameter and winding geometry.
Coarseness. Carpet yarn is worked at far coarser counts than apparel yarns. With coarse yarn, winding tension and full package weight both rise.
To these must be added the twisting and heat-setting stages. Carpet yarn generally passes through twisting; at these stages the yarn is transferred from one tube to another.
What is expected of the tube
High compressive strength
Because full package weight and winding tension are high, the tube's resistance to radial pressure is decisive. A tube that ovalises spoils the winding and causes unwinding problems at the next stage.
Stacking strength
Carpet yarn packages are normally stacked in the warehouse. Tubes in the lower rows are under constant load. Wall thickness must take this load into account as well.
Protection of the ends
With coarse yarn the full winding width is used. Tube ends must be cleanly cut and free of crushing so that the edge layers sit correctly.
Suitability for heat-setting conditions
After twisting, the yarn may be exposed to heat and moisture during heat-setting. The tube is expected to hold its shape under those conditions. This point varies with your process flow and is worth discussing when dimensions are being set.
The knitting side
In knitting yarns, yarn counts and winding conditions differ from carpet; but the fundamental expectations of the tube remain the same: correct inner diameter, sufficient wall strength and a smooth surface.
On the knitting side, the shape of the tube end and surface friction can additionally matter, so that the yarn unwinds without trouble.
Carpet and knitting tubes at Kafkas Masura
Our carpet and knitting tubes are made of paperboard and produced in custom sizes, to order. Inner diameter, length and wall thickness are determined together with you, according to your yarn count, winding tension, full package weight and storage conditions.
Contact us to request a sample or to confirm dimensions.