White Paper: Tension Effects and Solutions for Modern Warping Processes
COMMON TENSION VARIATIONS IN WARPING
Modern warping of yarn is used to prepare beams for many fabric formation processes. Several yarn compositions can be warped to beams, such as nylon, polyester, wool, cotton, as well as processed yarns such as twisted or texturized yarns. The warping machines typically run at 600 to 1200 yards per minute and pull yarn from a creel structure.
Typical creels will hold from 500 to 1500 yarn packages. Due to the differences in yarn composition and number of packages, the creel structure can be many different sizes and geometries. Regardless of the details, the purpose of the creel and associated accessories is to deliver yarn to the warper with uniform tension across the sheet and at the desired tension level. There are a variety of problems that can occur in a creel/warping production line.
SLACK ENDS are the result of the tension being too low (probably zero). In this case the slack end may not be noticed while running but as soon as the warper stops, the end will be sagging significantly from the horizontal yarn sheet.
TIGHT ENDS are the result of the yarn travel being impeded in some fashion such that the yarn tension is significantly higher than desired. This defect in tension is difficult to see by the operator as the end will always be included in the yarn sheet. However, it may be found by looking at the beam surface profile. A tight end will result in a low spot in the beam surface.
MISSING ENDS are the result of one or more yarn ends lost in the yarn sheet. Every style has a unique end count for the beam being produced. This is a difficult defect to locate unless the ends are physically counted periodically. This results in down time.
TENSION VARIABILITY across the yarn sheet can be the result of creel geometry, eyelets, tension devices, package alignment, package size and more. Modern warping will typically use large metered packages in the creel to avoid problems created by package size. With the exception of the tensioning device, the other causes of this problem can be easily remedied.
Slack ends will create a situation on the fabric formation machine where the slack end eventually will drag on the floor. It is necessary to cut and shorten this end several times as the beam is consumed. In addition, the stitch construction for this loose end will be different to the point of causing finishing problems. Tight ends will eventually become so tight that it will break causing a defect in the material being produced. This will also happen numerous
times during the beam. The stitch construction for tight ends will also cause finishing problems. Missing ends will at best require the addition of one or more yarn packages at the machine to replace the missing ends. This is a problem In itself as the operator needs to have the exactly same yarn merge for this substitution. In some cases, a missing end will require the entire beam to be scrapped due to the sensitive nature of the process using the beam. Slack ends, tight ends, and tension variability will have an effect on the finishing process. All of these yarn problems will show up as streaks in the final material being finished. This is the type of problem everyone wants to avoid because when it is discovered, there has been much investment and the fabric is never first quality.
To read more, download the complete white paper.
You will learn:
The Source of Tension in the Creel
Smart Systems to Minimize Tension Problems