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Saving energy in singeing processes

Control of singeing intensity depending on the remaining hairiness after singeing

The challenge in terms of sustainability:

During the singeing process, protruding fibres on textile surfaces are removed with an open gas flame. Gas consumption per material quantity is the crucial factor with regard to process costs. The aim is to use this resource as efficiently as possible.

The initial situation:

The singeing result has ever since been judged subjectively by eying the material surface. Process parameters, especially the burner capacity, are only roughly set. In case of doubt, the technologist or the operator prefer to stay "on the safe side". The burner power is adjusted too high resulting in unnecessary gas consumption. This waste can be avoided by determining the singeing result online, i.e. during machine operation with a speed up to 150 m/min. A measuring unit has been developed offering the possibilty to measure the amount of hairiness after the singeing process.

The solution:

The system consists of a light source (LED) and a monochrome CCD camera. The light source is slightly tilted and illuminates the fabric surface tangentially so that the camera does not register the shadows of the protruding fibres but the refracted light. This type of measurement is called dark field measurement, because the background remains black whereas the objects are shown bright. Camera and light source are installed in a dust and waterproof enclosure (IP67). The lenses of the camera are protected by scratch-resistant sapphire glass. Both parts of the unit feature air nozzles which keep the optics dust-free. The camera signal (up to 2 cameras are possible) is sent to an industrial PC via Gbit Ethernet cable. The industrial PC is located in the main cabinet and runs an analysis program, which determines the bottom limit (fabric surface) and top limit (topmost visual point of hairs) of the fibres. The distance in-between is the length of the hair. After this, a variety of statistical data is calculated, where for the evaluation of the hairiness the mean value and the standard deviation are used. The mean value reflects the grade (how short are the hairs in general), the standard deviation reflects the quality (the constancy of the hair length) of the hairiness. We define hairiness as the sum of the mean value and the standard deviation.

The sustainable strengths:

By means of our hairiness tester we are - for the first time - able to measure and influence the important variable, i.e. the hairiness, directly. The measured value is used to control the process parameters, or in more detail: intensity of the burners is adjusted depending on a preselected hairiness value.
Advantages:

  1. It is ensured, that the whole batch has the same hairiness value.
  2. In the future, similar articles will be singed with the same parameters (repeatability)
  3. The gas consumption is only as high as necessary. If the desired hairiness is achieved with a lower intensity, the settings are adjusted accordingly.

The inventors:

Herr Rainer Ebbinghaus
Herr Heiko Wilke

Brief profile of the company:

Name: Osthoff-Senge GmbH & Co. KG
Headquarters: Wuppertal
Year established: 1912
Employees: 55
Solutions: Singeing machines, fabric cleaning devices, desizing and cold bleaching machines
URL: http://www.osthoff-senge.com