Lab Project: Yarn Processing

Transcription

1 TT520- Oxenham Lab Project: Yarn Processing Fall 2008

2 Students Involved Carding and Drawing Clinton Coletrane Leslie Eadie Jonathan Halbur Spinning Rachel Davis Brian Edwards Physical Testing Colin Holloway Jennifer Woodson *assistance from Nazan Erdumlu Knitting Prasad Muthusami Sam Watson Mounting Ahmer Ghani Brian Hamilton Page 2 of 51

3 Table of Contents Yarn Preparation Opening, Carding, Drawing with Testing and Results... 4 Combing / Roving with Testing and Results... 7 Spinning Rotor Spinning Ring & Compact Spinning Testing and Results Knitting Processing Testing and Results Mounting Final Conclusions References Appendix I. ASTM Test Methods II. Physical Testing Raw Data III. Knitting Evaluation Raw Data IV. Mounting Samples Page 3 of 51

4 Yarn Preparation The raw material used for this project was 100% Fibermax cotton. This cotton was graded prior to purchase and had the following specifications (Table 1): Color 31 Leaf 3 Staple 35 Micronaire 3.3 Strength 28.5 Table 1: Specifications for Fibermax cotton The cotton was put through the following processes: 1. Monocylinder cleaner B4/1. This machine has a peg beater that is used to separate fiber tufts. The trash that is taken out of the fibers falls down through to a separate section of the machine. This machine runs at rpm 2. Mixing opener B3/3R. this machine contains a saw tooth beater and spiked apron lattice 3. ERM cleaning machine B5/5 (fine opener cleaner) 4. Card 1. This card has a delivery speed of 145m/min and the slivers coming out were 70gr/yd The main operations in the first four processes are opening and cleaning. In a typical blowroom, one would blend multiple bales of cotton so as to achieve the highest degree of blending possible. For this lab, only Fibermax cotton was used, which should decrease the need for substantial blending. However, the cotton still must be opened and cleaned. As the cotton went through the blowroom, the degree of opening and cleaning increased as it went from the blunt peg beaters (Figure 1) found on the monocylinder cleaner B4/1 to the fine card wire seen on the card. If opening and cleaning of the fibers was not done slowly using the three Page 4 of 51

5 machines prior to the card, the sharp card wire would rip and tear the cotton fibers from the tufts rather than separating and orienting them. Figure 1: Peg beater inside the cleaner From this point on, materials were split, a portion going to produce carded yarn and the remaining portion going to produce combed yarn. Processes for the carded yarn: 1. Draw frame RSB851. Slivers coming out of this machine were 60gr/yd. the machine had the following settings (Table 2): Roll Settings 39mm front; 41mm back Break Draft 1.28 Draw Ratio 7 Delivery Speed 250 m/min Table 2: Settings for draw frame Page 5 of 51

6 Figure 2: Draft zone inside the draw frame 2. Draw frame RSB851 (with auto-leveler). 8 slivers (60gr/yd) were fed into this machine and the sliver coming out was 60gr/yd. 9 cans were filled with 75 yards of sliver each and one with 200 yards (for testing). This machine had the following settings (Table 3): Roll Settings 41mm front; 42mm back Break Draft 1.16 Delivery Speed 250m/min Draft Ratio 8 *Calculations were done to set the auto-leveler which was finally set to 682 Table 3: Settings for draw frame Page 6 of 51

7 Figure 3: Autoleveler on the second drawframe The purpose of the drawframe is twofold. A specific sliver count must be achieved that is suitable to go to the roving frame, and in achieving that specific count the uniformity of the sliver is also increasing. By running six slivers into the drawframe (Figure 2), the final effect of any variation seen in any of the slivers is reduced. In addition, the autolevelers (Figure 3) found on both drawframes allows the input sliver count to be automatically controlled and adjusted so as to insure uniformity of the output. Processes for the combed yarn: 1. Prep-draw. Settings were the same as for the carded going through the first draw frame, but this time draw was set to Lap winder 3. Comber 4. Breaker draw. There were 2 breakages observed during this process, but when delivery speed was slowed down, no more breakages were observed. 5. Draw frame RSB581 (with auto-leveler). 8 slivers (60gr/yd) were fed into this machine and the sliver coming out the machine was 60gr/yd. Settings on the machine were the same as for carded, except the auto-leveler was set to 647 after calculations were done to Page 7 of 51

8 determine output. Two breakages were observed on the draw frame. 9 cans were filled with 75yards of sliver and one with 200 yards of sliver (for testing). The sliver being prepared for combing goes through the same initial drawframe as the carded sliver does, having the same two functions. However, after the initial drawframe, the sliver that will be combed is wound into a lap on the lap winder for use on the comber. Both the lap winder and comb use doublings similar to those found on the drawframes. As a result, a higher degree of uniformity in the output from the comb should be achieved. When combing (Figures 4 & 5), the removal of both trash content as well as short fiber content found in the laps is desirable. The resultant combed sliver should be more uniform and oriented than the carded sliver. As a result of the increased orientation and the resultant lack of cohesion, the comber s drawframe adds a small degree of crimp to the fibers to help increase inter-fiber cohesion. Figure 4: Comber Figure 5: Close up of working parts of the combing machine Once the carded sliver and combed sliver had been appropriately drawn, samples were tested in the physical testing lab on the Uster Tester 3 and AFIS machines. The Uster Tester 3 machine provides information describing the uniformity of the two slivers, namely the Page 8 of 51

9 coefficient of variation (CV). In addition to the CV, the Uster Tester 3 machine also gives a histogram that sums variant lengths. From the histogram, the lengths where there is the most variation, can be determined. The AFIS machine was used to determine the fiber length distributions and nep content of the combed and carded slivers. For each of the machines, combed and carded sliver was tested three times so as to provide accurate and useful data. Sliver Type %CVm Carded Sliver 3.86 Combed Sliver 3.26 Table 4: %CVm results from Uster Tester 3 As the data in Table 4 shows, combing the sliver did decrease the coefficient of variation (CV%) by a small degree, as would be expected. This can be attributed to the removal of short fiber content from the sliver during the combing process. In addition to the removal of short fibers, the comber also doubles the input slivers and then redraws them after combing. The doubling and redrawing of the slivers also reduces the coefficient of variation by reducing the effect of variation seen in any one of the slivers fed into the comber. Although there was a decrease in CV% in going from the carded to the combed sliver, neither sample had what would be considered a good CV%. Given the high quality cotton used from the bale, the CV% would have been expected to have lower values. One reason a slightly higher variation than normal existed is because the samples were allowed to condition for 48 hours. As the sliver relaxes, the coiler pattern becomes more defined within the sliver structure. This can be seen from the peak on the histogram at 1 yard. Further analysis from the histogram shows a number of peaks at the range from inches. These peaks are drafting waves, and are a result of the drafting frame and the natural variation in cotton fiber length within the sliver. Page 9 of 51

10 Carded Sliver Combed Sliver Nep Content(9000 fibers) (45) Short Fiber Content%(w) (5.65) Average Length (in.) Table 5: Sliver results from Uster AFIS As is indicated by the data in Table 5, both nep content and fiber length distribution of the combed sliver was lower than that of the carded sliver. This is to be expected as the main purpose of the combing machine is to remove both short fiber content and waste, such as neps, from the carded sliver. Depending on the degree of uniformity desired in the combed sliver, the desired level of trash removal can be increased or decreased. Thus, to a certain degree, one can control the values of nep content and fiber length distribution in the combed sliver. As for the carded sliver, nep content is mainly a result of the operating conditions seen in the card and the fine opener prior to the card. These two processes utilize teeth so fine that snagging and fiber breakage can occur, thus resulting in neps. The fiber length distribution of the carded sliver is a function of the initial quality of the cotton that was used. However, the averaged combed data looks worse than it actually is because one test showed a nep content of 86 and a short fiber content (SFC) of 7.3. This was far worse than the other two and the average of the two runs can be seen in parenthesis. Page 10 of 51

11 Spinning The purpose of this exercise was to spin yarns using three different techniques: open end spinning, ring spinning, and compact spinning. Open end spinning is used because it is approximately ten times faster than ring spinning. It also requires less labor because the equipment is more automated. Alternatively, ring spinning equipment is less expensive and the yarns produced are stronger. Whereas, compact spinning takes place on the same equipment as ring spinning, a few extra elements are added to the machine that makes the yarns much less hairy. Rotor Spinning For rotor spinning (a method of open end spinning), the Reiter R20 was used. The machine must be warmed up prior to its use. Stray fibers should also be cleaned from the rotor with a blast of compressed air. With the Reiter R20, the sliver is fed from the can into the machine via a feed roll. In this case, an OB20 M4 combing roll, at 700 rpm, was used to open the fibers in the sliver and to allow trash to fall out. With cotton, it was necessary to use an aggressive combing roll such as this. The fibers were then fed out of the combing roll and into the fiber channel. From the fiber channel, the fibers were transported to the rotor (Figure 6). For this exercise, a 32 mm rotor was used that spun at 92,100 rpm. The rotor had a standard groove and a diamond coat finish. Centrifugal force forced the fiber into the groove and each rotation of the rotor put one turn of twist into the yarn. The fibers then exited the rotor and entered the nozzle (or navel). The nozzle used in this exercise had eight grooves, while others may have spirals or lobes. It was also ceramic (Figure 7), which would not be the best choice if synthetic fibers were being spun because steel nozzles dissipate heat more efficiently. The nozzle provides false twist, which is beneficial because it creates spinning stability. Grooved nozzles may increase hairiness, so a smooth nozzle may be used when the yarn is going to be woven. The yarn then passed through an Uster electronic yarn clearer, a paraffin waxing device, and onto a package. The threading, and rethreading, of the machine is performed by a robot. All settings for this machine are adjusted via computer controls. Page 11 of 51

12 Figure 6: Interior of rotor spinning chamber Figure 7: Inside of front face plate of rotor spinning machine. Combing takes place inside the face plate. Ceramic navel inserts false twist into yarn exiting the rotor, while loose fibers enter rotor from opening around base of navel Page 12 of 51

13 The goal was to produce a yarn with an English cotton count of 18/1. The draft was set at 125, so that for every yard of sliver, 125 yards of yarn was produced. The delivery speed was then set based on the following calculations: turns/inch = [ (cotton count)] (twist multiple) = [ (18)] (4) = turns/inch turns/meter = (turns/inch) (39.37 inches/meter) = (16.97) (39.37) = turns/meter delivery speed = (rotor rpm) / (turns/meter) = (92,100) / (668.13) = 138 meters/min First, 120 yards of each the combed and the carded yarn was spun for testing on the Scott Tester (Figure 8). The Scott Tester measures the force (in pounds) required to break the yarn (Figure 9). A 120 yard segment of the yarn is reeled into 40 loops for testing. Yarn count is determined on a scale. By multiplying yarn count and the break force, the break factor can be calculated. The break factor of the combed yarn was 2,123 and the break factor of the carded yarn was 1,894. A break factor of greater than 1,200 suggests that the yarn is adequate for knitting, while a break factor of greater than 2,000 suggests that the yarn is sufficient for weaving. Upon verification that the cotton count was within 3% of 18, the machine was restarted and the rest of the sliver was spun into yarn. Page 13 of 51

14 Figure 8: Scott Tester tests the breaking strength of the yarns Figure 9: Yarn breaking on Scott Tester Three cans of carded sliver and three cans of combed sliver were spun because variation exists between positions on the machine. Carded sliver was spun in positions 2, 4, and 6. Combed sliver was spun in positions 14, 16, and 18. The total length of yarn produced from each can of sliver is provided in Table 6 below. It is significant to note that the waxing device on position 4 malfunctioned and was not spinning. Also, the yarn broke once at position 18. This meant that in three hours of machine operation, there was only one break. Position Meters Table 6: Total length of yarn produced from each can of sliver Page 14 of 51

15 Ring and Compact Spinning For ring and compact spinning, the Seussen Fiomax E1 was used (Figure 10). This machine, like others, must be warmed up before it is used. The roving is hung overhead. The end of the roving is fed through the drafting rollers, from which it exits. To thread the machine, a guide yarn is wound around the bobbin, through the traveler, and is then fed through the drafting rollers where it attaches to the drafted roving. Compact spinning is carried out on the same machine, but the drafting rollers are different they are designed to eliminate the majority of the hairiness that is associated with ring spun yarns and make the yarn structure more compact (Figure 11). The ring on this machine was 45 mm. The traveler that was initially used was a #5. This machine has very little automation and yarn breaks must be pieced by hand. Figure 10: Suessen Fiomax E1 ring frame with compact spinning attachments and overhead roving Page 15 of 51

16 Compact Spinning Ring Spinning Figure 11: Compact spinning on left; groove under mesh provides suction that compacts the yarn. Ring spinning on right; tubes underneath pull away waste fibers. To determine the draft setting for the machine, the desired count (18) was divided by the break draft (1.19). The calculated main draft was The closest machine set-up was a total draft of To accomplish this, the N W gear inside the machine was changed to a 35 tooth gear and the H2 gear was changed to a 45 tooth gear. To account for twist, the square root of the desired count was multiplied by the twist multiple (4). The calculated turns/inch was The closest machine setting was To achieve this, the D W gear was changed to a 30 tooth gear. The Z1 and Z2 gears were also changed to 60 and 56 tooth gears, respectively. All gears were changed manually (Figures 12 & 13). Page 16 of 51

17 Figure 12 & 13: Gears for the ring spinning machine (gears must be changed manually) The data produced once the yarn was tested, as described previously, on the Scott Tester is provided below (Table 7). Four rovings, one of each spinning / preparation combination, were spun. Yarn Breaking Force (lbs.) Count Break Factor Carded Compact Combed Compact Carded Ring Combed Ring Table 7: Four rovings, one of each spinning / preparation combination Page 17 of 51

18 The average yarn count from above was calculated to be This is 5% difference from the desired count of 18. Since a 3% difference is allowed, the machine settings needed to be adjusted. The traveler was changed to a lighter #3 to improve the count (Figure 14). After switching travelers the average count was This is within the 3% tolerance. However, the tension was still too high, so the machine was slowed down slightly and was run until all twentyfour bobbins were full. No yarn breaks were recorded. Figure 14: Replacing the traveler on the spindle Page 18 of 51

19 Testing and Results Conditioning of Specimens (72 hours): Relative Humidity 64% Temperature 72 F Specimens: 1. Carded Ring Spun Yarn (Table 8) 2. Combed Ring Spun Yarn (Table 9) 3. Carded Compact Yarn (Table 10) 4. Combed Compact Yarn (Table 11) 5. Carded Rotor Spun Yarn (Table 12) 6. Combed Rotor Spun Yarn (Table 13) 7. Carded Compact Roving (Table 14) 8. Combed Compact Roving (Table 14) 9. Combed Ring Spun Roving (Table 14) 10. Carded Ring Spun Roving (Table 14) Testing Machines Utilized Uster Tester 3 This machine is used to provide testing on various yarn and roving types (Figure 15). Outputs found in printed reports provide detailed information on the test sample. The characteristics tested were yarn, hairiness, CV%, count, neps, as well as yarn thickness. These reports are very valuable within the industry for yarn comparisons. This may provide insight into how to achieve better quality in processing. In terms of roving, this machine can provide tests to determine CV% as well as a fully graphed chart of the variation within the roving. This is beneficial in that workers can quickly test their roving outputs and make changes accordingly. Pictured below is an Uster Tester, similar to the one utilized in this experiment: Page 19 of 51

20 Figure 15: Uster Tester 3 (Via USTER.COM) Procedures: Uster Tester 3 For each sample of yarn it was necessary to use the following steps to properly set up testing on the Uster Tester 3: 1. Yarn end of the package needs to be drawn through the yarn tensioner by means of a drawing in needle. Depending on the diameter of the yarn (maximum allowed is 2.5 mm), the material can be drawn through the ceramic eyelet. If the yarn is coarse yarn, the material must be drawn through the cross bored hole. 2. The yarn from the package is placed into the clamping plate of the yarn changer; the yarn ends should not protrude more than 2-3 cm. (Figures 16 & 17). For Ring Spun Yarns it should be ensured that the yarn tensioner is always positioned above the axis of the yarn package. The height of the yarn tensioner of the package holder can be adjusted with the threaded flange. For Yarns on Cylindrical Packages (OE, Rotor Spun) the yarn tensioner lies above the center of the package. The yarn should be drawn off such that the end of the yarn forms a P with the yarn package. Page 20 of 51

21 Figures 16 & 17: Yarns placed below yarn guides and into clamping arrangement 3. Before beginning the measuring procedure for the sample, it is necessary to type in a nominal count value of the yarn being tested. This is to be entered into the TEST PARAMETERS key. This is so that measuring tests of the yarn can be accurate, if it is unknown what the count is before testing, one should measure to ensure the best testing results. 4. After the yarn has been secured in the yarn tensioner, and count has been entered into the computer, make sure that the proper information regarding yarn type and test number has Page 21 of 51

22 been entered. If these steps have not been taken, it is not possible to hit the Start button and begin the test. 5. As the start button is pressed, a suction jet suctions yarn off into a waste bin. At the start of the measurement, the yarn is cut and accurately-defined yarn length is fed to the balance (Figures 18 & 19). The yarn is then cut once again, after which it is suctioned off into the waste bin until the measurement is completed. The weight of the material on the balance is determined automatically, and finally the sample is ejected. Figures 18 & 19: Specified yarn length is weighed on the balance 6. A multiple page report is then printed out that provides information on CV%, count, hairiness, neps, and thin and thick places (Figure 20). Page 22 of 51

23 Figure 20: Yarn thickness being tested on Uster Tester 3 For each roving sample, the following steps were taken on the Uster Tester 3 (Figure 21): 1. Use a rotating spindle that the roving bobbin can easily wind off; place the roving bobbin on this spindle. A spindle tensioner must also be used to control the speed at which the unwinding from the bobbin occurs. 2. Before the roving is placed into the measuring slot, the 100% adjustment must be carried out for the first test of a measuring series (in terms of this test, for each bobbin of roving from each test). Press the Start button and then quickly press it again to initiate the 100% adjustment. 3. This is followed by a request to insert the yarn in the measuring slot. 4. Make sure that the machine is clear of debris as well as into the finger tensioner, and over the roller into measuring slot 2, and is drawn off via the guide roller, and the rubber covered rollers. The roving can run off onto the floor, or kept if waste percentages are being calculated. Page 23 of 51

24 5. Once the yarn is measured, the roving must be taken out of the measuring field for at least 2 seconds because between each measurement, an automatic 100% calibration is carried out. 6. Similar to the above test for yarn, this test provides a print out of results that focus on CV% Figure 21: Roving thickness being tested on Uster Tester 3 Uster Tensorapid 3- This machine analyzes measured values from tensile testing. Yarn quality can also be tested and analyzed with the Uster Tensorapid (Figures 22 & 23). This machine can be utilized to determine tenacity, elongation, and work of rupture. Outputs in printed reports provide detailed information on the yarn test sample. The results from this test are useful in determining the suitability of a particular yarn for its end use in knitting or weaving. Page 24 of 51

25 Figure 22: Uster Tensorapid 3 (Via USTER.COM) Figure 23: Uster Tensorapid 3 Page 25 of 51

26 Procedures: Uster Tensorapid 3 For each sample of yarn it was necessary to use the following steps to properly set up testing on the Uster Tensorapid 3: 1. Yarn end of the package needs to be drawn through the yarn tensioner by means of a drawing in needle. Depending on the diameter of the yarn (maximum allowed is 2.5 mm), the material can be drawn through the ceramic eyelet. If the yarn is coarse yarn, the material must be drawn through the cross bored hole. 2. The yarn packages that are to be tested should be set up to the left of the machine on a suitable package holder. The yarn is then pulled through the pig tail (Figure 24) and placed into the clamping plate of the yarn changer, and should not protrude more than 2-3 cm. For Ring Spun Yarns it should be ensured that the yarn tensioner is always positioned above the axis of the yarn package. The height of the yarn tensioner of the package holder can be adjusted with the threaded flange. For Yarns on Cylindrical Packages (OE, Rotor Spun) the yarn tensioner lies above the center of the package. The yarn should be drawn off such that the end of the yarn forms a P with the yarn package. Figure 24: Yarn being pulled through pig-tail on Uster Tensorapid 3 Page 26 of 51

27 3. After the yarn has been secured in the yarn tensioner, and count has been entered into the computer, make sure that the proper information regarding yarn type and test number has been entered. If these steps have not been taken, it is not possible to hit the Start button and begin the test. Figure 25: Yarn tension being tested on Uster Tensorapid 3 4. A multiple page report is then printed that provides information on tenacity (gf/den), elongation (%), time to break the yarn (seconds), and work of rupture (gf.cm) (Figure 25) Page 27 of 51

28 Results *Three packages of each type of yarn were tested, and averages taken for the following results. Table 8: Carded Ring Spun Yarn PACKAGE 1 PACKAGE 2 PACKAGE 3 AVERAGE Tenacity (gf/den) Elongation (%) Work of Rupture (gf.cm) Regularity (CVm% 10yd) Hairiness Table 9: Combed Ring Spun PACKAGE 1 PACKAGE 2 PACKAGE 3 AVERAGE Tenacity (gf/den) Elongation (%) Work of Rupture (gf.cm) Regularity (CVm %) Hairiness Page 28 of 51

29 Table 10: Carded Compact Spun Yarn PACKAGE 1 PACKAGE 2 PACKAGE 3 AVERAGE Tenacity (gf/den) Elongation (%) Work of Rupture (gf.cm) Regularity (CVm% 10yd) Hairiness Table 11: Combed Compact Yarn PACKAGE 1 PACKAGE 2 PACKAGE 3 AVERAGE Tenacity (gf/den) Elongation (%) Work of Rupture (gf.cm) Regularity (CVm %) Hairiness Table 12: Carded Rotor Spun Yarn PACKAGE 1 PACKAGE 2 PACKAGE 3 AVERAGE Tenacity (gf/den) Elongation (%) Work of Rupture (gf.cm) Regularity (CVm %) Hairiness Page 29 of 51

30 Table 13: Combed Rotor Spun Yarn PACKAGE 1 PACKAGE 2 PACKAGE 3 AVERAGE Tenacity (gf/den) Elongation (%) Work of Rupture (gf.cm) Regularity (CVm %) Hairiness Table 14: Rovings (only regularity is tested) Regularity (CVm% 10yd) 7. Carded Compact Combed Compact Ring Spun Combed Ring Spun Carded Ring Spun 6.42 Page 30 of 51

31 Results and Discussion The results from the testing of the yarns and the rovings give an adequate indication as to the suitability of each yarn for its designated end use. Overall, the combed compact yarn and the combed ring spun yarn are the most consistent. The combed compact yarn received above average results in the work of rupture, regularity, and tenacity tests. The combed compact yarn was also not hairy, although this is consistent with compact spinning it is a trait which can be deemed as desirable or undesirable depending on the end use. The combed ring spun yarn, while a hairy yarn as compared to the others, was exceptionally regular, with high tenacity and work of rupture results. The test results for the carded rotor spun yarn indicated that in all areas regarding strength, with the exception of elongation, this yarn is deficient. The combed rotor spun yarn, when rated against the other yarns, would be an average quality yarn. Its only exceptional quality is in regard to elongation, where it outperformed all the other yarns tested. When making comparisons with regard to spinning method, the compact spun yarns, according to the tests performed, resulted in the most regular and uniform yarns. The rotor spun yarns, with the exception of elongation rated below all the other yarns tested in every test. In comparing the combed yarns against the carded yarns, after the different types of spinning were performed, the combed yarns had a high tenacity rating, regularity, and work of rupture rating whereas the carded yarns only indicated to have higher elongation ratings. In analyzing these yarns one can see that the extra time and capital invested in producing combed yarns definitely produces a yarn of higher quality. Although, is has already been noted: end use is the ultimate factor in determining the appropriateness for a yarn in weaving or knitting. Page 31 of 51

32 Knitting For further analyses purposes such as appearance, hand, and abrasion resistance, samples of the combed rotor spun, combed compact spun, carded compact spun, carded rotor spun, combed ring spun, and carded ring spun yarns were knitted on a Fiber Analysis Knitter (FAK). The FAK (Figure 26), made by Lawson-Hemphill, was used to knit the six yarn samples. Figure 26: Fiber Analysis Knitter (FAK) used for the knitting of six yarn samples The knit is a 28 cut gage. This means there are 28 needles per inch. One sample, approximately half a yard in length, was knitted for each yarn with a small section of blue yarn knitted between the samples. This allows for one continuous knitted sample with a distinguished separation between yarn types. Each sample was assigned a number, and the number was documented with the yarn type. This was done to ensure completely unbiased results. After all of the samples were knitted, the samples were cut from the original continuous knit sock into six individual samples corresponding to the six different yarn types (Figure 27). Page 32 of 51

33 Figure 27: Knitted samples As mentioned previously, the samples were marked with numbers rather than the type of yarn. This was done because a panel of judges was used for appearance and hand preferences of the samples. Seven judges were asked to rate the knitted samples based on appearance and hand. The backlight on a batching machine model no. H-450 made by Joseph Pernick MFG., Corp., (Figure 28), was used to aid in analyzing samples. This allowed each judge to easily see any defects or irregularities. Figure 28: Batching machine with backlight used to aid in analyzing samples Page 33 of 51

34 Each judge rated the samples individually. The judge first was asked to put the samples in order of preference based solely on personal preference of appearance. The judge was then asked to put the samples in order of preference based solely on personal preference of hand. The judge was finally asked to place the samples in order of personal preference based on both appearance and hand. The order for all three ratings was documented along with the reasoning each judge used for placing the samples in a particular order. Page 34 of 51

35 Number of Times Preferred in the Top Three Choices Results and Discussion Results based on appearance are shown below (Graph 1). Appearance Combed Rotor Spun Carded Rotor Spun Combed Ring Spun Combed Compact Spun Carded Compact Spun Carded Ring Spun Type of Spinning Graph 1: Number of times preferred in the top three choices based on appearance The above graph indicates that Combed Rotor Spun yarn is in the top three most preferred based solely on appearance from all of the judges. Four of the six different types of yarns were in the top three of four or more judge s votes. This showed that the appearance was subjective to the particular judge. Most judges preferred the uniform appearance of the combed samples despite the type of spinning process, and also the rotor spun sample despite whether or not it was combed. When asked for the basis of the decisions, most stated that they preferred the uniform appearance the most. Other preferences given were the most cover, evenness, and lack of neps and trash. Page 35 of 51

36 Number of Times Preferred in the Top Three Choices Results based on the hand of the fabric are shown below (Graph 2). Hand Combed Ring Spun Carded Ring Spun Combed Compact Spun Carded Compact Spun Combed Rotor Spun Carded Rotor Spun Type of Spinning Graph 2: Number of times preferred in the top three choices based on hand With the exception of one, all judges voted combed ring spun, carded ring spun, and combed compact spun as his or her top three choices in regard to hand. Nobody voted combed rotor spun or carded rotor spun as being in the top three choices for hand. It should also be noted that the rotor spun yarns have a wax on the yarn that was applied during processing that the other four yarns do not have on them, which may have been a factor in determining hand. When the judges were asked what they based their decision on, all responded with a liking for softness or hairiness. Some additional measurements were based on how thick the sample felt and the smoothness of the surface. The true test was the combination of both characteristics being judged. Page 36 of 51

37 Number of Times Preferred in the Top Three Choices Results for judging on both appearance and hand are graphed along with the preference of a combination of both characteristics (Graph 3). Appearance and hand are also graphed to help show what preferences the judges favored in making their decisions. Preferences Combed Ring Spun Carded Ring Spun Combed Compact Spun Combed Rotor Spun Carded Compact Spun Type of Spinning Carded Rotor Spun Combination of Appearance and Hand- Number of Times Preferred in the Top Three Choices Hand- Number of Times Preferred in the Top Three Choices Appearance- Number of Times Preferred in the Top Three Choices Graph 3: Number of times preferred in the top three choices based on both appearance, hand, and a combination of appearance and hand This is the most important method of analysis because it most closely resembles a real life decision when shopping for fabric or garments. This graph indicates that a combination of appearance and hand is the most subjective preference of all. Every type of yarn was voted into the top three choices at least once. Most judges showed a preference of hand over appearance as shown with carded ring spun. Carded ring spun yarn was not voted into the top three preferences by anyone according to appearance but, its softness overcomes its appearance and allows for it to be one of the most preferred samples overall. The balance of appearance and hand was different for everyone. Some judges were more willing to sacrifice one characteristic more than another. More technical tests of the knitted samples were performed with the Martindale Pilling Test. Page 37 of 51

38 Martindale Pilling Test This test method covers the determination of the resistance to the formation of pills and other related surface changes on textile fabrics using the Martindale Tester (Figure 29). The Martindale Abrasion and Pilling Tester used here was manufactured by James H. Heal & Company Ltd, Halifax, England. For the pilling resistance test the fabric samples, in sock form, were slit-open along the length of the fabric. With each of those fabrics two circular samples of 38mm and 140mm diameter were cut using a circular cutter. One standard felt of 140mm diameter and one fabric specimen of the same size were mounted on each of table of the tester. Then, a 38mm diameter disk of 3mm polyurethane foam and a 38mm diameter specimen of the same fabric were mounted in its respective holders. The holders were placed over the specimen such that the face of the specimen is rubbed against the face of the same fabric in the holder. The holders were held in position with pegs which normally tends to give a pressure as low as 3kPa. When the machine is switched on, it starts off in a particular straight line which gradually becomes a widening ellipse until it forms another straight line. The machine was run for 500, 1000, 2000 and 3000 cycles and number of pills on each fabric was counted and documented for each trial. The degree of the fabric pilling for the different samples were compared with visual standards which may be actual fabrics or photographs of fabrics showing a range of pilling resistance, and given a rating on a scale of 1-5 (1-high pilling and 5-no pilling) at the end of the test. The results of the testing have been tabulated below (Table 15). Type of Spinning Number of Pills 500 cycles 1000 cycles 2000 cycles 3000 cycles Combed Rotor Spun Combed Compact Spun Carded Compact Spun Carded Rotor Spun Combed Ring Spun Carded Ring Spun Table 15: Results from Martindale Pilling Test Page 38 of 51

39 Based on the number of pills and in comparison to the visual standards the samples were given a numerical rating. The results are given below (Table 16). Sample Rating Combed Rotor Spun (waxed) 4 Combed Compact Spun 3 Carded Compact Spun 3 Carded Rotor Spun (waxed) 4 Combed Ring Spun 2 Carded Ring Spun 2 Table 16: Ratings assigned to knitted samples after pilling test The results indicate that rotor spun yarns have better resistance to pilling over the other types of yarn and ring spun yarns have the least pilling resistance standards among the given types. It should be noted that rotor yarns are waxed during the spinning process while other yarn samples are not waxed, and hence the results are biased to a certain extent. Figure 29: Martindale Pilling / Abrasion Testing Machine Page 39 of 51

40 Mounting Samples of all of the rovings, yarns, and fabrics can be found in Appendix IV. The varying samples have been mounted amongst their counterparts so that variances between them can be seen. For the rovings and yarns, contrasting backgrounds of black and white are utilized to allow the eye to pick up different details. For example, it is much easier to detect the different levels of hairiness in the yarns and rovings against the black background while impurities tend to be easier to spot when the background is white. The fabric samples have been affixed so that the bottom is unattached to the paper, making the hand easier to determine. Scanning the mounted samples into a computer makes it possible for very precise viewing of the samples. In the scanned images of rovings and yarns, it is possible to make qualitative assessments that may be difficult to make with the naked eye. When looking at the scan of the rovings, against the black background, the two combed rovings certainly appear to be less hairy than the carded samples. This must be due to the removal of short fibers during the combing process. In fact, on closer inspection, it can be observed that the combed samples have much less short fibers than do the carded samples. The combed fibers also look more regular in width from top to bottom than do the carded rovings, and this assessment is consistent with the quantitative analysis that was done on the samples. Against the white background, two things stand out. First, the two combed samples have a bit more twist in them than the carded samples; this is intentional, as the combed rovings need the twist to boost cohesion. Second, the combed roving samples have less visible dirt than the carded samples. This makes sense as cleaning is one of the perks of cotton combing. Page 40 of 51

41 The yarn sample scans (Figure 30) provide insight into their qualities that may not be apparent at first glance. At the top of the mounting, against the black background, the two ring spun yarns are unmistakably hairier than the other four samples. This is to be expected and is consistent with the testing results. The combed compact spun yarn appears to be the least hairy of the samples. Regularity is difficult to access on such a short and thin sample, but the combed compact and combed ring-spun samples appear to be the most uniform as far as linear density is concerned. When making observations against the white background, the level of cleanliness in all of the combed yarns is once again apparent when contrasted with the carded samples. A B C D E F Figure 30: Scanned yarn samples A- Carded Ring Spun B- Combed Ring Spun C- Carded Compact D- Combed Compact E- Carded Rotor F- Combed Rotor Mounting provides a way to accentuate the visual aspects of the samples that were created during this lab. It takes away many variables when comparing the different yarns or rovings. The samples are juxtaposed to each other on the same board, lying in the same direction, against the same background, and likely receiving the same lighting. This means that the viewer is free to observe and make educated comparisons. Page 41 of 51

42 Final Conclusions The world of yarns is nothing if not bountiful, consisting of an array of options; be they natural or synthetic. This abundance in choices means that there should be a yarn suitable for any end use one might have in mind, for the end use is the real driver behind the determination of which yarn to select. Different fibers, processes, and process variables should all be explored as each can impact the qualities of the final product. This lab focused on the processes and the process variables, using cotton as a constant fiber choice. Cotton s journey from bale to yarn can consist of many different routes. Six such routes were explored in this lab, leading to six different yarns, which, in turn, became six pieces of fabric. The assessments of these yarns and fabrics, both qualitative and quantitative, showed how this one material can be customized to excel in a multitude of varying end uses. The characteristics of the six yarns are displayed graphically in the figure below (Graph 4). For someone making cotton processing decisions, the data presented below (Graph 4), can be a tremendous asset. It takes a collection of numbers and assessments for six different yarns and combines them into one comprehensible display. The carded compact yarn, for example, is situated completely toward the center of the octagon, not excelling in a single area. The combed ring spun yarn, on the other hand, resides almost exclusively on the two outermost octagonal grades, with elongation being its solitary downfall. Once it is determined which characteristics are required of the cotton s end use, these qualities can be matched with those produced by a particular process route. Page 42 of 51

43 Appearance Pills (after3000 cycles) Tenacity Elongation Work of Rupture Hand Hairiness Regularity Carded Ring Spun Combed Ring Spun Carded Compact Combed Compact Carded Rotor Spun Combed Rotor Spun Graph 4: Web comparing important aspects when determining an end use for a yarn Page 43 of 51

44 References Davis, Brian Long, Stan Oxenham, William Pegram, Jan Pleasants, Tim White, Teresa Knitting Lab Knitting Lab Professor Physical Testing Lab Rieter Lab Physical Testing Lab Page 44 of 51

45 Appendix Page 45 of 51

46 Appendix I: ASTM Test Methods ASTM D : Standard Test Method for Unevenness of Textile Strands Using Capacitance Testing Equipment This test method covers the indirect measuring of unevenness of textile strands by means of continuous runs using capacitance testing equipment. The test method provides a value of short-term unevenness, a single value expressing the complicated strand property that is unevenness. Properties of a strand vary along the length; these variations are termed strand irregularity. The variation of linear density is unevenness this is what this test method is concerned with. This test method is applicable to all yarns, rovings, slivers, and tops (exceptions apply). During testing, a yarn or roving will pass through the sensing device of the evenness tester at a constant speed. The Uster Tester 3 is equipped with an integrator that calculates the unevenness automatically. The value for the variations as determined by the Uster Tester 3 is designated as a CVm%, which is related to the unevenness of the strand. A low unevenness number is preferred, as higher unevenness numbers generally indicate the specimen will be difficult to process, have lower strength, and will have poorer fabric appearance. Page 46 of 51

47 ASTM D : Standard Test Method for Tensile Properties of Yarns by the Single- Strand Method This test method covers the determination of tensile properties of monofilament and spun yarns. This test method also covers the measurement of breaking force and elongation of yarns and includes directions for the calculation of breaking tenacity, initial modulus, chord modulus, and breaking toughness. Specimens are to be handled in such a way that changes in twist or stretching are avoided. During testing single strand yarn specimens are broken on a tension testing machine, in this case the Uster Tensorapid 3, at a predetermined elongation rate and the breaking force and the elongation break are determined. This test method determines the breaking tenacity and elongation of a yarn which are fundamental properties that are widely used to establish limitations on yarn processing or conversion and on their end-use applications. Elongation results provide an indication of the likely stretch behavior of garment stress areas (i.e. knees or elbows) and stretch behavior of reinforcement items (i.e. hose or tires). Also, the breaking strength is tested. The breaking strength of a yarn influences the breaking strength of a fabric made from the yarn. Page 47 of 51

48 Appendix II: Physical Testing Raw Data Page 48 of 51

49 Appendix III: Knitting Evaluation Raw Data Characteristic Person A Person B Person C Person D Person E Person F Person G Appearance- Top (Most Preferred) to Bottom (Least Preferred) Hand- Top (Most Preferred) to Bottom (Least Preferred) Combination of Appearance And Hand- Top (Most Preferred) to Bottom (Least Preferred) = Combed Rotor Spun 4= Carded Rotor Spun 2= Combed Compact Spun 5= Combed Ring Spun 3= Carded Compact Spun 6= Carded Ring Spun Page 49 of 51

50 Type of Spinning Appearance- Number of Times Preferred in the Top Three Choices Hand- Number of Times Preferred in the Top Three Choices Combination of Appearance and Hand- Number of Times Preferred in the Top Three Choices Combed Ring Spun Carded Ring Spun Combed Compact Spun Combed Rotor Spun Carded Compact Spun Carded Rotor Spun Page 50 of 51

51 Appendix IV: Mounting Samples Page 51 of 51