Press release BoxID: 142031 (KARL MAYER Textilmaschinenfabrik GmbH)
  • KARL MAYER Textilmaschinenfabrik GmbH
  • Brühlstraße 25
  • 63179 Obertshausen
  • Contact person
  • Ulrike Schlenker
  • +49 (6104) 402-274

An exciting success story

The AccuTense yarn tensioner is set on a course for success, especially for processing glass fibres, technical yarns, aramids, high-strength, twist-free yarns and monofilaments for producing filter fabrics for the papermaking industry

(PresseBox) (Obertshausen, ) The KARL MAYER Group produces state-of-the-art warp preparation machines and is the only manufacturer that can supply all the components to make up full production lines. The range of machines produced by this well-known manufacturer includes direct beaming, warping and sizing machines, as well as a wide variety of creels and yarn tensioners.Two years ago, this company expanded its range of yarn tensioners by acquiring the Accu-Tense range of yarn tensioners. The company took over all the patents, associated rights and production technologies of Textrol Inc. in September 2005. This transferred all the business and expertise from this family run, American company to the KARL MAYER Group, which went on to make further improvements to the equipment. The result was that the accuracy of the AccuTense computer-controlled yarn tensioner has been improved and the business has been expanded.

Technical features
The AccuTense products are induction yarn tensioners, which use the principles of the eddycurrent brake, which is based on the concept of magnetic induction. If a piece of metal moves relative to a magnetic field, a current is induced in it. This current generates a flow in the form of eddies, which in turn produces a magnetic field having the opposite effect to the original field. This phenomenon is also known as Lenz’s Law.

The following structural and geometrical factors have an influence on the braking force of the eddycurrent brake:
- the permeability of the material
- the intensity of the eddy current
- the effective conductor length
- the distance between the exciter-induced regions
- the resistance that opposes the eddy current in the metal

Two factors also have an effect on the yarn tension during warping. These are:
- The speed of the conductor in relation to the exciter field, a value which is determined by the warping machine during warping.
- The magnetic exciter field, Be. Before the warping process begins, the operative specifies this field by inputting the required yarn tension at the touchscreen of the control unit or the operating console of the warping machine.

Every yarn in the creel runs over a yarn tensioner, which is located immediately in front of the package. The yarns are guided via a transport disc. With its grooved construction made from a flexible material, its synchronous rotation and its gentle deflection points via the large radius, this guarantees that the yarn is handled gently and without slipping. The yarn is not bent and there is no friction whatsoever, which ensures that a top-quality beam is produced.

A wide range of yarns and counts can be processed - from metal wire for technical textiles, through high-strength aramid and glass, to simple polyester. The enduses of the AccuTense products are virtually unlimited. Every type of well-known fibre material has already been tested successfully using these induction yarn tensioners. Their other advantages include an almost constant yarn tension, irrespective of the speed, and the yarn tension can be changed during the warping process. It is also possible to equalise the creel lengths by zone-wise programming, and a non-contact stop motion can also be incorporated.

The improvements
The company’s own exceptionally high quality standards during production and the modifications that it has made to its testing equipment ensure that all the AccuTense yarn tensioners on a creel operate synchronously and without deviation. At one time, this was only possible within a specified region of the stress/strain curve and meant that the yarn tensioners had to be calibrated to come within a specific window, which included to the mean strain value that could be expected for that particular application. Deviations in the strain curves for the individual yarn tensioners within the calibrated zone could deviate by as much as 15% from the maximum strain value of the components.

The AccuTense products currently available produce a virtually identical sress/strain curve over the entire operating range specified. The deviations in yarn tension from one take-off point to another now vary by no more than +/- 5% from the final value of the setting range. This is 1.75 cN for an AccuTense 35 tensioner with a setting range of 3 to 35.

The consistent yarn tension and gentle handling of the yarns have enabled the AccuTense tensioners to make inroads into those areas which involve processing extremely fine yarns for technical applications, where the focus is on a high strength. For example, one of its main applications is in the production of circuit boards for the electronics industry.The production of these base components for the electronics industry requires a combination of the appropriate fine resin formulation and high-quality textile carriers, such as fine glass fabrics, and every process in the manufacturing sequence must be carried out to the highest level of precision.

New applications for the AccuTense yarn tensioners also include the production of geotex-tiles, conveyor belts and glassfibre wallpaper, and the processing of high-strength ballistic materials. New applications are likely to emerge, which will guarantee the continued success of this technically sophisticated range of yarn tensioners, which have proved themselves time and time again.