Warp knitting and warp preparation specialist Karl Mayer has introduced its new Rot-O-Tense motor driven yarn tensioner which controls the yarn tension that has been set at the creel as an independent unit.

Right from the early stages of the production process, textiles for use in special applications have to be produced on machines with very specific features. Special warp preparation technology is needed to produce warps from high-strength technical yarns, such as glass or aramid, for example, and these have to be able to guarantee high tension levels, gentle handling of the materials, maximum efficiency and top quality.

Karl Mayer’s claims that its new tensioner is both accurate and reliable and is also very flexible in use. Rot-O-Tense autonomously controls the yarn tension that has been set by the operator at the creel as an independent unit. Each yarn tensioner independently monitors in real time, the actual value and adjusts it to suit the desired value that has been set, independently and steplessly over a wide yarn tension range. This enables each take-off point to have its own yarn tension value which is useful if different yarns are required in the warp.

The operating range of the Rot-O-Tense theoretically begins at a yarn tension of 0 cN and goes up to 330 cN. The system can achieve variable yarn running speeds of 0 to 1200 metres per minute, irrespective of the yarn tension, which Karl Mayer says opens up new opportunities for the customer.

Operating principles

Karl Mayer explains that the new Rot-O-Tense yarn tensioner owes its excellent performance to the use of high-quality control electronics, which are located in each yarn tensioner, processing the information on the yarn tension obtained by the measurement sensor. If the actual and desired values correlate with each other, the status is maintained. If there are any deviations, the yarn tension is automatically adjusted in real time.

The required adjustment is carried out by a motor-driven AccuGrip wheel, which is either made to actively rotate or brake, depending on the type of adjustment needed. To produce the desired, low tension, the yarn has to be removed and driven from the package. If a higher yarn tension is required, the motor acts as a brake. Karl Mayer says that this is an ingenious technique and its well-thought-out principles open up new opportunities for yarn handling. The design features of the AccuGrip wheel with its profiled discs ensure that the yarn is delivered very gently, without any sliding friction and without any of the associated abrasion. If required, the grip-wheel can be replaced by a yarn guiding device or used in conjunction with a yarn guiding device.

According to the company, Rot-O-Tense is ideal for processing polyester, polyamide and polypropylene, glass, aramid, carbon, acetate, rayon, wool and cotton and it can handle virtually every type of yarn in practically any count. Even though the yarns are handled gently, yarn breakages may still occur and packages may also run out, in which case the system automatically detects the missing or loose yarn and stops the machine.

Communication principles

Depending on the machine being used, which stands in front of the creel, any yarn breakages are transmitted by a bus system and analysed. Their occurrence can be displayed using X-Y coordinates for the row and level, either at the touch screen or at a separate display. Information on the nature of the disruption can also be requested. To ensure that the number of warp yarns on the final beam corresponds exactly to the specifications of the production job, missing yarns are displayed and yarns that have been incorporated inadvertently are also recorded. In this case, the machine is stopped.

Rot-O-Tense can be used with Karl Mayer’s warp preparation machines for warp knitting - DS - Direct warping machines, DSE - Elastane warping units and DSST - Draw warping units.