From Raw Fibre to Finished Cone: How a Sewing Thread Is Made

Have you ever wondered how the sewing thread you use on your bag closer machines is made from a pack of polyester staple fiber into finished cones? It involves a long production chain. Let us walk you through the process step by step.

1. Blowing & Carding

Raw polyester fibre is opened, blended, and carded into a soft, continuous web, then formed into slivers. This is where the fibre gets cleaned and aligned — the base for everything after.

2. Drawing

Several slivers are drawn together and stretched to even out thickness. This step smooths out inconsistencies so the thread's size stays stable along its whole length.

3. Roving

The sliver is drawn thinner and given a light twist. It's a halfway stage, preparing the material for fine spinning.

4. Spinning

The roving is drawn down to the final, fine count and twisted into a single yarn. This is where the basic yarn — with its strength and diameter — is actually formed.

5. Winding

The yarn is wound onto large packages while defects and weak spots are removed. Clean yarn in means fewer breaks later at your machine.

6. Doubling

Several single yarns are combined together, side by side. This is where multi-ply threads — like the /4 or /5 in a spec — get their start.

7. Two-for-One Twisting

The combined strands are twisted together into a balanced ply yarn. This is what gives bag closing thread its roundness, cohesion, and consistent tension.

8. Cone Winding

The finished thread is wound into a cone shape that feeds smoothly through your machine, with even density and controlled tension.

9. Small-Cone Winding

Finally, some thread is wound into smaller packages for portable machines and field use — easy to carry, ready when you need a quick seal.

---

• Why the process matters

Each step is a small quality gate. A thread that has been properly drawn, twisted, and wound will run steadier and break less often on your line. When you see consistent strength and smooth sewing, that consistency was built step by step — long before the cone reached you.