Covering Technology

Covering is one of the most frequent operations at SOFILA, as it is hardly ever offered by spinners and offers a finished yarn of recognized quality. We have mastered this technique perfectly, whether on rigid or elastic yarns.

Conventional covering

Conventional covering consists of covering a wire (“the core”) with one (or two) other wires (“the covering”). This covering can be single (one covering) or double (two coverings).

The core thread passes through a hollow spindle on which the covering thread is placed: this spindle turns regularly and allows the covering thread to make turns around the core, which can go as far as covering it completely (SOFILA is capable of making coverings with almost 2000 turns per meter of covering).
The aim of this operation is either to totally protect the core thread, generally using a stronger covering thread, or to cover the core thread so that it is no longer visible in the fabric.

There are many applications :

  • Elastic covering (elastane core, polyamide or viscose covering, etc.) to give elasticity to the thread, and therefore comfort to the fabric.
  • Application in the clothing or lace sector (low elasticity) or the medical sector (high elasticity).

Conventional covering can also be carried out on a rigid core

The process is more delicate and requires a high level of expertise. SOFILA produces many rigid covered yarns, particularly for technical applications, thus making it possible to protect very fragile materials, or to cover a very technical material (generally non-dyeable) with a more standard material (which is dyeable, for example polyamide).

Fiber (Hamel) covering

Fiber covering is a specific form of conventional covering, but is carried out on a dedicated and adapted machine.

The fiber yarns used (cotton, linen or even synthetic materials in fibrous form) are made up of multiple fibers, which can sometimes fly away under the effect of rotation. This “contamination” must absolutely not end up in the finished yarn where it could create a visual defect. To avoid this, the machines are equipped with vacuum systems and the finished yarn is perfectly cleaned of any contamination. Sofila is one of the few players in the sector still to offer this operation, making it possible to offer elastic fiber yarns with an elastane core.

Caracteristics :

  • This makes it possible, in particular, to provide comfort in clothing fabrics (cotton) or in protective equipment (aramid fibers).

Air jet covering

Air jet covering also consists of covering a core thread, not by regular turns around the core but by frequent and regular interweaving of the covering and the core.

A fast and economical process, suitable for general public applications

This process, frequently used by SOFILA, allows much higher manufacturing speeds to be reached, with a satisfactory technical result. The disadvantage of this technology is the performance of the covering over time: the core is only lightly covered and deteriorates over time. This process is preferred for applications aimed at the general public and when an economical solution is required.