Ultrasonic Washing

An innovation in the range of textile finishing is the energy-efficient ultrasonic washing of narrow fabrics and broadcloth. The principle of the new technology is based on cavitations and mechanic impact by ultrasound.

In ultrasonic washing the ultrasound penetrates directly into the fabric at a rate of 20,000 oscillations per second, mechanically beating, as it were, the unwanted substances out of the fabric. The particularly sophisticated aspect of ultrasonic washing is the fact that the superfluous substances are not only removed from the fabric purely mechanically but also by cavitation. The action of the ultrasound on the fabric produces periodic compression and expansion of the liquor absorbed by the fabric. As a result of this fluctuating pressure, microscopically small cavities are formed in the liquid. The subsequent implosion of these gas and water vapour filled cavitation bubbles creates locally extreme conditions, so that the bursting bubbles produce shearing forces, which remove the superfluous substances from the fabric at high speed.

Schematic representation of a ultrasonic washing module

Schematic representation of a ultrasonic washing module

The fabric is drawn in through the intake (1) into the bath (2), containing slightly warmed water that may be strengthened with detergent. Here the fabric absorbs liquid in the form of water. The oscillations transmitted by the ultrasonic unit (3) wash out the sizing agent, spinning oils and excess dye particles from the material with the water. The fabric is continuously passed between a roller, which acts as an anvil, and the sonotrode, which is the tool that mechanically transmits the ultrasound. By then guiding the fabric again into the water bath, the loosened substances are flushed out. The nip roller at the delivery (4) ensures that the washing liquor absorbed by the fabric is squeezed out and transports the fabric to the next process stage.

Depending on the type of fabric or the degree of soiling, the process can be repeated in a second ultrasonic washing module connected directly to the first module. Even the simple process of passing through an ultrasonic washing module can replace several baths of conventional, high-temperature systems.

An ultrasonic washing system is only a quarter of the size of conventional systems. This means that there is automatically less material in the system during the process. Instead of 4-8 passes previously, it is sufficient for ultrasonic washing if the material only passes 1-3 times through the system, which has an extremely positive effect on processing times and reduces water consumption by roughly half. Another advantage of ultrasonic washing compared with conventional methods is that almost no heating up times are required for the washing liquor or tool. This not only additionally shortens the process but also makes a significant contribution towards reducing energy consumption. In order to achieve comparable washing results (washing efficiency), the ultrasonic system needs only roughly one third of the energy of a conventional system.

The fact that the process is intrinsically very efficient and environmentally friendly, is also demonstrated by the fact that the use of ultrasound technology means that significantly less or, depending on the material, even no chemicals are required in the liquor. The small size, reduced use of materials and shortened processing times considerably enhance the flexibility of a washing system, so that it can even be used efficiently for smaller production quantities.

Ultrasonic washing is intended to complement, in particular, the conventional washing of narrow or even wide fabrics in long, heated water baths by the use of energy-saving ultrasonic units.

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Product Ultrasonic Washing Modules