Source: http://www.textiletopics.ttu.edu

INTRODUCTION:

During the last two decades,components of ring spinning machines have been greatly improved. Changes indrafting systems, drive systems, and robotics have enabled large gains inproductivity, flexibility, and quality (Stahlecker, 1995; Seuberling, 1995; Hequet, et. al,1998).

Most of the technicaladvances in ring spinning were aimed at improving the performance of theexisting technology. In recent years, however, a bona fide innovation hasoccurred. It has been called compact or condensed spinning, because itminimizes width and height of the spinning triangle associated with ringspinning (see Figure 1).

Several experts havedescribed the technical principles of compact spinning that result in a moreorganized structure without peripheral fibers and with a better twistdistribution (Artzt, 2000; Meyer, 2000; Olbrich, 2000; Stalder,2000). As a result of this enhancedstructure, the compact yarn shows higher strength, reduced hairiness, andimproved evenness (see Figure 1).

The first compact spinningsystem to be commercialized is by the Rieter Corporation and is called Com4spinning. This system was designed and is marketed only for use withextra-long-staple cottons to make only the very fine yarn sizes (i.e., 50 Neand finer). However, compact spinning systems are also made by Suessen (theEliTe) and by Zinser (the Air-Com-Tex 700), both whichare designed to accommodate the full spectrum of staple lengths spun today.These compact spinning systems offer the possibility of using cottons with shorterstaple lengths to produce high-quality yarns that heretofore required long- orextra-long-staple cottons.

This paper reports resultsobtained from spinning various Texas upland cottons, along with some otherrepresentative U.S. upland cottons, on both conventional and compact spinningsystems. The spinning machines used were the Suessen Fiomax 1000 (forconventional ring spinning) and the Suessen EliTe 1000 (the Fiomax 1000 fittedwith the compacting system). The focus is twofold: (1) evaluate theperformance of these cottons on modern conventional ring spinning machines, and(2) evaluate the improvements in performance resulting from compact spinning.

Figure 1: SpinningTriangle and Yarn Structure; Conventional Ring Spun Yarn versus Compact Yarn.

PROCEDURE:

Thirty-one bales of Texas upland cotton were selected in a manner to ensure nine groupings of fibers with different values for fiber length and micronaire. Sampling strata and the resulting number of bales in each stratum are as follows:

The main cause of differing numbers of bales in each stratum (or cell) was the initial bale selection process being based on USDA classing data, but more exacting measurements taken at the International Textile Center shifted some of the bales to different categories. (Each bale was sampled at 10 layers throughout, with HVI measurements being done on each layer. Each measurement consisted of 4 replications of micronaire and 10 replications of length and strength.)

In addition to the Texas bales, 6 representative, high-quality bales were selected from other regions of the U.S. cotton belt: 3 bales from the Delta and 3 from California. Thus, all 6 of these bales fell into the long length category and care was taken not to get micronaire values higher than 4.90 from the Delta. The California cottons were all high-quality Acala varieties. The purpose of these 6 cottons, all of which are deemed appropriate for use on ring spinning systems, was to provide a better frame of reference for evaluating the performance of the Texas cottons.

A statistical summary of the HVI fiber data for all 37 bales used in the study is given in Table 1.

Table 1: Summary of main HVI fiber properties of the 37 bales

Preliminary experiments were done to evaluate the spin-ability limits of a representative Texas bale from each sampling strata. These experiments enabled an efficient selection of yarn sizes to make in the larger experimental design. Results from this made it clear that the compact spinning technology would open the ring spinning to cottons that are not generally considered suitable for this process. Indeed, all of the test cottons could be taken far beyond typical spin-ability limits on a conventional ring spinning system.

The experimental procedure used on all 37 cotton bales is outlined in Figure 2. The yarn sizes for each length group were chosen to enable useful comparisons between the conventional and compact yarns.

Figure 2: Experimental procedure.

The yarn produced at the close of these trials was tested for the following properties:

-          Evenness on UT3 (10 bobbins; 400 m/bobbin)

-          Single end break (10 bobbins; 10 breaks/bobbin)

-          Skein break (10 bobbins; 1 skein/bobbin)

-          Hairiness on Zweigle hairiness tester (10 bobbins; 100 meters/bobbin)

RESULTS AND DISCUSSION:

Evenness parameters

Analysis of variance on the yarn evenness data is summarized in Table 2. It accounts for the part of output variance from the yarn count within each length group (Length group x count), then tests for the effects of categorical factors (Spinning system, length group, and length group x Spinning system). Results indicate that, after controlling for the yarn count within length groups, there is no significant effect of compact spinning on yarn evenness parameters of the UT3.

Table 2: Testing compact spinning effect on yarn evenness

The 26 Ne yarn size was the only one spun for every cotton bale (Figure 2). Therefore, it is used to illustrate the yarn evenness parameters resulting from the spinning trials (Figure 3). The results are similar for the other yarn sizes.

The 25% and 50% quality levels of the USTER Statistics are shown by the horizontal lines on the graphs in Figure 3, in order to provide benchmarks for the results shown. To facilitate reading the results, the 31 Texas cottons are listed first on the horizontal axis, followed by the 3 Delta cottons and then the 3 California cottons.

Figure 3: 26 Ne conventional and compacted yarn evenness parameters

Conclusions from Figure 3 include the following:

-         Compact spinning did not make much difference in the yarn evenness data from the UT3.

-         Most of the Texas cottons compared well with the Uster Statistics; they fared worst for the thin places and best for the neps.

-         Most of the Texas cottons performed better than the Delta cottons and some of the Texas cottons compared favorably with the California cottons.

Yarn hairiness

The scatter plot showing UT3 hairiness indexes (H) for conventional versus compact yarns is given in Figure 4. The hairiness index values are highly correlated, but the values are significantly lower for the compact yarns (as shown by comparison with the equality line in Figure 4). In fact, the hairiness levels for the compact yarns are generally low enough to rank well into the best quartile of the Uster Statistics.

Figure 4: Relationship between compact and conventional spun yarn UT3 hairiness.

The scatter plot showing the Zweigle hairiness indexes (S3) for conventional versus compact yarns is given in Figure 5. Unlike the results with the UT3, the correlation between values for compact versus non-compact spinning is very low. The hairiness levels of the compact yarns are generally very low regardless of the levels exhibited by the conventional yarns. However, a few of the yarns in all length groups had S3 values that were quite high.

Figure 5: Relationship between compact and conventional spun yarn Zweigle S3.

The foregoing observations are corroborated by the analysis of variance results in Table 3. The effect of compact spinning is highly significant, as is the interaction between length groups and compact spinning (Group x Spinning System).

Table 3: Testing compact spinning effect on yarn hairiness

The interaction effect (Group x Spinning System) may be visualized by charting the average H or S3 values for each length group on each of the spinning systems. This is done for the H values in Figure 6, using the 26 Ne yarn as a reference point. This shows that yarn hairiness improvement is greater for the shortest fibers (length group 1). The experimental design explicitly targeted the distinct length groups. However, it is expected that there are other significant interaction terms that could have been explored (e.g., Strength Group x Spinning System, Short Fiber Content Group x Spinning System, Fineness Group x Spinning System, etc.) and that inclusion of these could alter the residual effect detected for the Length Group interaction term.

Figure 6: Interaction Spinning System x Length group, UT3 hairiness

Yarn tensile properties

The relationships between conventional and compact spun yarn tensile properties are represented on Figures 7 and 8 respectively for elongation and single-end strength. The analysis of variance results for these two tensile properties are summarized in Table 4.

Figure 7: Relationship between compact and conventional spun yarn Elongation (%).

Figure 8: Relationship between compact and conventional spun yarn single-end break strength (cN/tex).

Table 4: Testing compact spinning effect on yarn tensile properties.

These results show that compact spinning resulted in a highly significant improvement in both elongation and strength of yarns. While the slight deviations of the regression line slopes suggest a possible interaction between compact spinning and these tensile properties (Figures 7 & 8), the analysis of variance (Table 4) shows that the Length Group x Spinning System interaction term is not statistically significant at a 5% confidence level.

The average yarn strength values for each length group and for both conventional and compact spinning systems are illustrated in Figure 9. Again, 26 Ne yarn is used as reference point. While the gap between conventional and compact yarns is somewhat wider for the shortest fibers (length group 1), this difference was not statistically significant. As with the hairiness, it is quite likely that interactions with other variables affecting the yarn strength are occurring besides length groups. An alternative experimental design that allowed inclusion of these other variables might reveal a stronger residual effect for length groups.

Figure 9: Average yarn strength (cN/tex) by length groups, conventional and compact spun yarn

A charting of the yarn strengths and elongations from each cotton bale with conventional versus compact spinning is given in Figure 10. It clearly shows that the compact spinning resulted in a generally higher strength and greater elongation for the 37 bales of cotton.

Figure 10: 26 Ne conventional and compacted yarn tensile properties

It should be noted that the Texas cottons were specifically selected to include a wide spectrum of the cottons produced in this very large state, while the Delta and California cottons were selected to be representative of the average length of the upland cottons from these areas. The range of micronaire was selected in the same manner for all three locations. Clearly many of the Texas cottons perform equal to or better than the selected Delta cottons and some of the Texas cottons are comparable to the selected California Acala varieties.

CONCLUSION:

The yarn structure resulting from compact spinning technology appears to get very close to a maximum utilization of each fiber in the yarn bundle. This makes it possible to achieve higher yarn strength from any fibers used. However, the improvements in yarn strength appear to be greater for shorter stapled cottons than for the longer staple lengths. These results made it clear that some fibers that were inadequate for use in conventional ring spinning may be spun satisfactorily on the compact system.

As expected, compact spinning greatly reduced the hairiness of yarns. As with the tensile properties, the greatest reductions in hairiness occurred with the shorter stapled fibers.

Compact spinning did not result in significant improvements in any of the yarn evenness parameters tested with the UT3. Furthermore, this conclusion held for all staple length categories.

Taken together, these results suggest that compact spinning technology may enable us to extend the use of shorter stapled cottons into the manufacture of finer yarns than has heretofore been feasible. It exemplifies a technological innovation that, instead of making greater demands on fiber properties, actually compensates for the lack of certain fiber properties.

Finally, these results reveal that some of Texas cottons are among the best upland cotton fibers produced in the U.S. Thus, on average the Texas cottons performed as well as or better than the high-quality Delta cottons on both the conventional and compact ring spinning systems. And a subset of the Texas cottons performed as well as or better than the high-quality California cottons.

LITERATURE CITED:

Artzt P., 2000. The special structure of compact yarns - Advantages in downstream processing. Beltwide Cotton Conferences, January 4-8, San Antonio, TX (USA), National Cotton Council of America. Memphis, TN (USA), pp. 798-803.

Hequet E., Ethridge D., and Cole W. D., 1998. Evaluation of improvement in yarn quality with new ring spinning frame. Textile Topics (4: fall 1998): 2-8.

Meyer U., 2000. Compact yarns: innovation as a sector driving force. Melliand International, 6 (1): 2.

Olbrich A., 2000. The AIR-COM-TEX 700 condenser ring spinning machine. Melliand International, 6 (1): 25-29.

Seuberling J., 1995. Advanced standard in ring spinning. Melliand International (1): 25-26.

Stahlecker H., 1995. Fiomax: High speed spinning machine. Melliand International (1): 27-28.

Stalder H., 2000. New spinning process ComforSpin. Melliand International, 6 (1): 22-25.

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