 Research
 Open Access
Suitable traverse ratios for step precision winding
 Milind Vasudeo Koranne^{1}Email author and
 Kuldeep Mhedu^{1}
https://doi.org/10.1186/s4069101600620
© Koranne and Mhedu. 2016
 Received: 7 September 2015
 Accepted: 15 March 2016
 Published: 28 April 2016
Abstract
Step precision winding produces a yarn package that is free from ribbon formation and marginal variation in coil angle. In open step precision winding, traverse ratios used during package build are such that the resultant package is open suitable for end user applications like warping and dyeing. It is always a critical task for a manufacturer of step precision yarn winding system to find values of traverse ratios which are open and definitely ribbon free without any appearance of diamonds or honeycomb. Traverse ratios used in any commercial step precision yarn winding system are not accessible to the user. The authors have carried out basic work of finding suitable open wind traverse ratios for step precision winding and have come out with a novel approach of “SAFE ZONES” for finding suitable open traverse ratios. This paper discusses this novel approach that is very useful for manufacturers of step precision winding systems.
Keywords
 Traverse ratio
 Ribbon formation
 Diamond/honeycomb appearance
 Safe zones
Introduction
Phenomenon of cross winding delivered yarn onto packages takes place on several yarn spinning/rewinding/processing machines. Among different modes of winding like random, precision and step precision winding, step precision winding offers distinct advantages. Step precision winding combines positive characteristics of random and precision winding to form a pattern free package with coil angle varying over a narrow range (Koranne 2013).
In step precision winding, package starts winding in precision mode with a nonpattern forming traverse ratio giving coil angle very close to desired. Upon winding, coil angle keeps on reducing. After some interval, when coil angle has decreased to some extent, traverse ratio is instantaneously shifted to a new lower value that will bring coil angle closer to desired mean value. On continuing winding, coil angle again decreases and after certain interval traverse ratio is again instantaneously shifted to a new a nonpattern forming value to restore mean coil angle. Thus, a step precision wound package is wound with several nonpattern forming traverse ratios that are decreased progressively in steps to build a package with coil angle varying over a narrow range.
For applications like dyeing, warping and weft supply packages for shuttleless looms, open wind traverse ratios are taken. Manufacturer of a winding system has to take utmost care to select all traverse ratios that are open not giving “diamond” and/or “honeycomb appearance”. To build a package with minimal variation of coil angle, traverse ratios taken during winding of entire package need to be sufficiently large in number closer to one another. With use of a few traverse ratios, coil angle varies over a wide range. At change over from one traverse ratio to next lower one; if coil angle variation is large, traverse length on package suddenly change from a higher to lower value that adversely affects appearance of side flanks of packages. This may be permissible for applications like assembly winding where close winding giving high package density (and thereby high yarn content on package) is of main importance. But for other applications like dyeing, warping and weft supply packages for shuttleless looms, it is always advantageous to have several nonpattern forming open wind traverse ratios (Koranne 2013).
Several patents are available on step precision winding (German Patent 1999, 1992; United States Patent 1987, 1995, 2000, 2002) but none exactly describe the procedure of finding out nonpattern forming open traverse ratios that are acceptable visually also from the point of view of diamond or honeycomb appearance. Traverse ratios selected for step precision winding on commercial winding systems are not accessible to the user of winding system.
In cross wound packages, yarn is laid in form of helices reversing at extremes. Traverse ratio (also known as winding ratio/crossing ratio) is an important parameter associated with cross wound packages that is defined as number of coils laid on the package in a double traverse. If traverse ratio is expressed in form of fraction X/Y (with X and Y as natural numbers without any common factor except 1), Y indicates number of double traverses after which yarn comes to same place. With a smaller value of Y, yarn comes to same place after fewer double traverses causing overlapping of yarn wraps one above the other forming undesirable ribbons (patterns). For example, a traverse ratio of 11/3 would form ribbons as wraps of yarn after every three double traverses overlap on one another. Such ribbon forming number shall be termed as “nominal traverse ratio”. To avoid ribbon formation, traverse ratio for winding should be incremented or decremented from 11/3 so that yarn is displaced at least equal to its diameter that would eliminate overlapping and lay yarn adjacent to one another giving “close wind”. If number is taken such that the displacement of yarn is substantially more, say four times yarn diameter, it becomes “open wind”. Such nonribbon forming numbers derived from “nominal traverse ratios” shall be called as “actual traverse ratios”.
For end user applications like dyeing, warping and shuttleless loom weft supply open wind traverse ratios are usually selected in which wraps of yarn are seen substantially away from one another forming an open package facilitating flow of dye liquor during package dyeing or allowing withdrawal of yarn without tension peaks or slough off.
It is very essential to find out methods to determine suitable traverse ratios for step precision winding when task of manufacture of a step precision winding system is undertaken. The study reported in this paper discusses a novel approach developed to find out several suitable open wind traverse ratios for step precision winding. The outcome of this paper is very useful for manufacturers desirous to develop open step precision winding systems.
Methods
Machine used to conduct trials
The experimental work of verifying suitability of calculated traverse ratios was carried out on a three spindle laboratory model Peass make rewinding machine model UFLEX with propeller traverse (traverse stroke remains constant). The machine has one spindle for assembly winding and the other two are for soft package winding/rewinding of dyed packages. This machine allows package winding in two modes—(1) precision winding and (2) step precision winding.
Out of several methods attempted, suitable traverse ratio table could be derived from two methods for a range of coil angle for package diameter range of 69–200 mm. This is reported in trial 1 and trial 2.
Trial 1
It is a common practice to find a suitable traverse ratio for precision winding from a traverse ratio that is prone to pattern formation (will be called as nominal traverse ratio and henceforth abbreviated as NTR) by giving some displacement to yarn at the end of pattern repeat. A head wind precision traverse ratio is a number little smaller than NTR where as an after wind precision traverse ratio is a number little larger than NTR. Using this method, a table was prepared with calculated traverse ratios from NTRs for fractions from 1 to 11 and a range of gain values from 2 to 5 mm (head as well as after wind). Trial was conducted on Peass UFlex rewinding machine to find its suitability. Suitability was assessed on visual basis (There is no defined test method to determine suitability of a traverse ratio. A number that did not give appearance of ribbons, diamond or honeycomb and yarns were seen adequately on actual winding trial was considered to be a suitable traverse ratio).
Trial parameters were as follows
Bare package diameter 69 mm, Full package diameter 200 mm, Winding speed 500 m/min, Yarn used 20 s Ne cotton yarn, Coil angle range 10°–18°, Overfeed 15 %
For a given coil angle, suitable traverse ratios (among calculated traverse ratios) were found by practical run on machine. The machine permits input of traverse ratio up to four decimal points. To measure coil angle, photocopy of protractor was taken on a transparent plastic sheet. This sheet was put on package to measure angle at which yarn coils cross each other. Coil angle is half the crossing angle.
Trial 2
Some indivisible fractions with denominator from 1 to 50 arranged in descending order
Sr. No.  Fractions \(\frac{A}{Y}\)  Sr. No.  Fractions \(\frac{A}{Y}\)  Sr. No.  Fractions \(\frac{A}{Y}\)  Sr. No.  Fractions \(\frac{A}{Y}\)  Sr. No.  Fractions \(\frac{A}{Y}\) 

1  19/20  8  47/50  15  14/15  22  43/46  29  37/40 
2  37/39  9  31/33  16  41/44  23  14/15  30  12/13 
3  18/19  10  46/49  17  27/29  24  41/44  31  35/38 
4  35/37  11  15/16  18  40/43  25  27/29  32  23/25 
5  17/18  12  44/47  19  13/14  26  40/43  33  34/37 
6  33/35  13  29/31  20  38/41  27  13/14  34  45/49 
7  16/17  14  43/46  21  25/27  28  41/45  35  11/12 
Trial was conducted to verify traverse ratios for step precision winding of cylindrical packages for different coil angles with empty package diameter 69 mm, traverse length 150 mm, full package diameter 200 mm, over feed 10 to 25 %, and yarn tension 30 cN.
Results and discussion
Through trial 1, it became possible to develop a table for a particular coil angle for diameter range of 69–200 mm by selection among a large number of ratios; head and after wind from NTR of fractions up to 11 and yarn displacement ranging from 2 to 5 mm. Such tables were developed for a range of coil angle.
Common table for “Trial 1” section, coil angle range 10°–11°
Sr.No.  NTR  Yarn disp. (mm)  Actual traverse ratio  Package diameter in mm  Sr.No.  NTR  Yarn disp.(mm)  Actual traverse ratio  Package diameter in mm  

For 10°  For 11°  For 10°  For 11°  
1  7 7/9  −2  7.7719  69  25  3 7/8  −2  3.8717  139.88  126.89  
2  7 5/9  −5  7.5413  71.81  26  3 7/9  −4.5  3.7713  143.60  130.27  
3  7 1/8  2  7.131  75.95  69  27  3 7/10  −2.5  3.6968  146.50  132.89 
4  6 10/11  −2.5  6.9038  78.44  71.16  28  3 3/5  −2  3.5951  150.64  136.65 
5  6 7/9  −2  6.7727  79.96  72.54  29  3 6/11  −2.5  3.5427  152.87  138.67 
6  6 2/3  3.5  6.64  81.56  73.99  30  3 5/11  3  3.4578  156.62  142.08 
7  6 3/7  3  6.638  81.59  74.01  31  3 2/5  4.5  3.4105  158.79  144.05 
8  6 2/9  3  6.2293  86.94  78.86  32  3 1/3  −5  3.3143  163.40  148.23 
9  6  −2.5  5.9486  91.04  82.59  33  3 3/11  2  3.2748  165.37  150.01 
10  5 3/4  2  5.7598  94.03  85.29  34  3 1/5  −2  3.1956  169.47  153.73 
11  5 3/5  −3.5  5.5866  96.94  87.94  35  3 1/8  −2.5  3.1217  173.48  157.37 
12  5 5/11  −2  5.4511  99.35  90.12  36  3 1/9  3  3.1147  173.87  157.73 
13  5 4/11  −5  5.3553  101.13  91.74  37  3 1/11  2  3.0929  175.10  158.84 
14  5 1/10  5  5.1087  106.01  96.16  38  3  −2.5  2.9743  182.08  165.17 
15  4 9/10  3.5  4.9059  110.39  100.14  39  2 9/10  −2  2.898  186.88  169.52 
16  4 6/7  3.5  4.8655  111.31  100.97  40  2 9/11  4.5  2.8221  191.90  174.08 
17  4 2/3  3  4.6826  115.66  104.91  41  2 7/9  2  2.7799  194.82  176.72 
18  4 4/7  2.5  4.577  118.32  107.33  42  2 3/4  −3.5  2.7418  197.52  179.18 
19  4 3/7  −4  4.4199  122.53  111.15  43  2 5/7  3.5  2.7189  200  180.69 
20  4 1/3  −4.5  4.3111  125.62  113.95  44  2 2/3  3  2.6758  183.60  
21  4 1/5  −2  4.1942  129.12  117.13  45  2 3/5  4.5  2.608  188.37  
22  4 1/8  −3.5  4.1188  131.49  119.27  46  2 6/11  −2  2.5439  193.12  
23  4 1/9  −2  4.108  131.83  119.59  47  2 1/2  2  2.5086  195.83  
24  4  5  4.0685  133.11  120.75  48  2 5/11  −2  2.453  200 

It is possible to find suitable traverse ratios by this method through actual trial and error. This method is tedious and time consuming.

The interval of switch over from one traverse ratio to the other is around 3 mm over the entire package build except near whole numbers at some places. Suitable traverse ratios may be head wind or after wind.
The approach in trial 2 was more logical with theoretical base. Suitable traverse ratios were found for coil angle range of 10°–14° for bare package diameter of 69 mm to build packages up to 200 mm and different yarn displacements (0.4, 0.6 and 0.8 mm). The following is the results of the actual winding trial on Peass UFlex rewinding machine.
Number of attempts in searching suitable ratios greatly reduced.
The suitable traverse ratios derived from NTRs were with yarn displacement of 0.4 mm. Search was begun first from the lowest angle i.e. 10° and the suitable ratios were found. The traverse ratios those gave satisfactory winding for 10° were also found suitable for subsequent next angle.
At smaller package diameter, NTRs with relatively smaller value of Y (between 20 and 25) lead to satisfactory winding giving suitable traverse ratios.
At subsequent diameters, satisfactory actual traverse ratios were obtained those are derived from nominal traverse with Y value lying between 30 and 45 barring few exceptions.
The interval of switch over from one traverse ratio to the other is around 2 mm over the entire package build except near whole numbers at some places. This interval increases at whole numbers especially at larger diameters due to nonavailability of suitable traverse ratios.
The table developed was transferred to Peass UFlex rewinding machine through software and winding trials were conducted and packages for the entire range of coil angles were produced to confirm winding trial in continuous run.
Traverse ratio table for 10°, “Trial 2” section
Sr. No.  Traverse ratios  Diameter for 10°  Sr. No.  Traverse ratios  Diameter for 10°  Sr. No.  Traverse ratios  Diameter for 10° 

1  7.8617  69  22  4.6561  116.31  43  3.3234  162.96 
2  7.6396  70.89  23  4.5674  118.57  44  3.2811  165.06 
3  7.4479  72.71  24  4.4410  121.95  45  3.2257  167.89 
4  7.3232  73.95  25  4.3609  124.19  46  3.1794  170.34 
5  7.1078  76.19  26  4.2811  126.50  47  3.1080  174.25 
6  6.8934  78.56  27  4.2186  128.38  48  3.0644  176.73 
7  6.7034  80.79  28  4.1387  130.85  49  3.0605  176.96 
8  6.4480  83.99  29  4.0809  132.71  50  3.0269  178.92 
9  6.2598  86.51  30  4.0643  133.25  51  2.9755  182.01 
10  6.1079  88.67  31  3.9399  137.46  52  2.9267  185.04 
11  5.8972  91.83  32  3.9061  138.65  53  2.8973  186.92 
12  5.7434  94.29  33  3.8610  140.27  54  2.8717  188.59 
13  5.6051  96.62  34  3.7940  142.74  55  2.8444  190.40 
14  5.4863  98.71  35  3.7574  144.13  56  2.8084  192.84 
15  5.3609  101.02  36  3.7095  145.99  57  2.7749  195.17 
16  5.2431  103.29  37  3.6332  149.06  58  2.7435  197.40 
17  5.1387  105.39  38  3.5860  151.02  59  2.7096  199.87 
18  5.0809  106.59  39  3.5142  154.11  60  3.3234  162.96 
19  4.9060  110.39  40  3.4826  155.51  61  3.2811  165.06 
20  4.7939  112.97  41  3.4410  157.38  62  3.2257  167.89 
21  4.7305  114.48  42  3.3822  160.12  63  2.6756  200 
Range of variation of coil angle 10°–14° (“Trial 2” section)
Sr. No.  Degree  Minimum variation in coil angle in degree  Minimum variation in coil angle in degree 

1  10°  0.01  0.57 
2  11°  0.01  0.52 
3  12°  0.01  0.53 
4  13°  0.02  0.57 
5  14°  0.02  0.55 
Conclusions
This paper described the methods of finding open wind traverse ratios for step precision winding that give ribbon free winding without any diamond or honeycomb appearance. Based on fundamentals of yarn winding, “SAFE ZONES” were identified. It was found that suitable traverse ratios can be derived very conveniently within “SAFE ZONES”. Traverse ratios were identified that are closer to one another. During transition from one whole number to the other, difficulties do arose in finding suitable traverse ratios especially during change in the region of change from traverse ratio 2 to 1 where the interval became wider resulting into ring formation for coil angles of 13° and 14°. The variation in coil angle did not exceed 0.57°. The outcome of this work is very useful for manufacturers desirous to develop step precision winding systems.
Declarations
Authors’ contributions
MVK conceived and designed the experiments. KM performed the experiments, analyzed the data in consultation with MVK. All authors read and approved the final manuscript.
Acknowledgements
The authors would like to thank Peass Industrial Engineers Private Limited, Navasari, Gujarat, India for their help.
Competing interests
The authors declare that they have no competing interests.
Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
Authors’ Affiliations
References
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