Dref Friction Spinning

Friction Spinning or Dref Spinning is a textile technology that suitable for spinning coarse counts of yarns and technical core-wrapped yarns. Dref yarns are bulky, with low tensile strength making them suitable for blankets and mop yarns, they can be spun from asbestos, carbon fibres and make filters was water systems. Yarns such as Rayon and Kevlar can be spun using this method. The technology was developed around 1975 by Dr. Ernst Fehrer.

There are three current technologies used today for spinning fibres:

Friction spinning is the fastest of all these techniques though the yarn is irregular and bulkier, making it suitable only for some applications.

The mechanism of yarn formation consists of three distinct operations: feeding of fibres, fibre integration and twist insertion.

The individual fibres are transported by air currents and deposited in the spinning zone. The mode of fibre feed has a particular effect on fibre extent and fibre configuration in yarn and on its properties. There are two methods of fibre feed:

The fibres are fed directly onto the rotating fibre mass that outer part of the yarn tail.

The fibres are first accumulated on the in-going roll and then transferred to the yarn tail.

The fibres assembles through a feed tube onto a yarn core/tail within the shear field, is provided by two rotating spinning drums and the yarn core is in between them. The shear causes sheath fibres to wrap around the yarn core. The fibre orientation is highly dependent on the decelerating fibres arriving at the assembly point through the turbulent flow. The fibres in the friction drum have two probable methods for integration of incoming fibres to the sheath. One method, the fibre assembles completely on to perforated drum before their transfer to the rotating sheath. In the other method, fibres are laid directly on to rotating sheath.

There has been much research on the twisting process in friction spinning. In friction spinning, the fibres are applied twist with more or less one at a time without cyclic differentials in tension in the twisting zone. Therefore, fibre migration may not take place in friction spun yarns. The mechanism of twist insertion for core type friction spinning and open end friction spinning are different,which are described below.

In core type friction spinning, the core, made of a filament or a bundle of staple fibres, is false twisted by the spinning drum. The sheath fibres are deposited on the false twisted core surface and are wrapped helically over the core with varying helix angles. It is believed that the false twist in the core gets removed once the yarn is emerged from the spinning drums, so that this yarn has a virtually twist-less core. However, it is quite possible for some amount of false twist to remain in the fact that the sheath entraps it during yarn formation in the spinning zone.

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Wikipedia