The Ideal Rotor Spinning Process for a High Short-Fiber Content Rieter
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John Spatafora Harald Schwippl Technology & Process Analytics Head Technology & Process Analytics Rieter Machines & Systems Rieter Machines & Systems July 2020 The Ideal Rotor Spinning Process for a High Short-Fiber Content Rieter . The Ideal Rotor Spinning Process for a High Short-Fiber Content 2 Rieter . The Ideal Rotor Spinning Process for a High Short-Fiber Content Contents 1. Introduction 4 2. Process Shortening for a High Short-Fiber Content 5 3. Trial Setup 6 4. Optimal Process Sequence 8 4.1. Sliver Evenness and Adhesive Strength on the Intermediate Product 8 4.2. Evenness of the Rotor Yarn 10 4.3. Tenacity and Elongation of the Rotor Yarn 11 4.4. Hairiness and Abrasion of the Rotor Yarn 13 4.5. Running Behavior of the Rotor Spinning Machine 14 5. Advantages of the RSB Module with Two Draft Zones 15 6. Effects on the End Product 17 7. Process Recommendation 20 8. Economic Viability 21 9. Summary 22 3 Rieter . The Ideal Rotor Spinning Process for a High Short-Fiber Content 1. Introduction Unevenness in staple fiber yarns has Improvements of Yarn Unevenness Since 1957 TM been improving constantly in recent de- 100% Cotton, USP 50% (Uster Statistics Percentile) cades despite high production speeds at the individual process steps – from fiber 22 preparation through the end-spinning machine (see Fig. 1). 20 On the one hand, the improvement in 18 unevenness is due to innovations in me- chanical engineering, such as optimiza- 16 tions in drafting system design or newly developed technology components. On 14 Mass variation[%] CVm the other hand, the increasingly precise definition and coordination of raw ma- 12 terial, process sequence and yarn count 10 plays an important role. 1957 1964 1970 1975 1982 1989 1997 2001 2007 2013 2018 Uster Statistics Publication Year In recent years, studies have consistently proven that a shorter process – in partic- 100% Cotton, ring yarn, carded, Ne 20 ular in the rotor spinning process – is not 100% Cotton, ring yarn, combed, Ne 60 only of interest due to the yarn conver- 100% Cotton, ring yarn, combed, Ne 30 sion cost, but can also be appealing for quality reasons. The key criterion here is 100% Cotton, rotor yarn, carded, Ne 20 that the shortened drafting process has a positive effect on cotton with a high Fig. 1: Unevenness has been improving in recent decades. Source: Uster Statistics short-fiber content. This study demonstrates what influence the process sequence and the number of draft zones within the drafting system have in the rotor spinning process when using raw material cotton with different short-fiber contents. The impact on yarn quality – such as evenness, tenacity and hairiness – with different yarn counts is also explained in the study. In addition, the extent to which the tech- nical values of the yarn are reflected in the end product will also be explored. To do this, knitted fabrics were produced using yarns from the different process sequences. A process recommendation for the rotor spinning system and an evaluation of the economic viability are derived from these findings. 4 Rieter . The Ideal Rotor Spinning Process for a High Short-Fiber Content 2. Process Shortening for a High Short-Fiber Content How can the process sequence be opti- Short-Fiber Content versus Commercial Fiber Length mized for yarn quality? One could pre- 100% Cotton, bale sume that a process shortening will result 100 in a lower or at least an unchanged yarn 90 quality. In rotor spinning, however, there 80 are also cases in which process shorten- 70 ing can mean optimization if the raw ma- 60 terial has a high short-fiber content. 50 40 The higher the short-fiber content, the 30 -1.845 more positive the effect of reduced draft- content [%] Short-fiber y = 12882x 20 R2 = 0.5611 ing system work, as package warping on 10 y = 315302x -3.094 fiber web is avoided. In addition, a short- R2 = 0.6975 0 er process also reduces conversion costs 14 16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 as fewer machines are used. Fiber length (UQL) [mm] The short-fiber content in the raw ma- terial is dependent on the following Short-fiber content SFC (n) [%] Short-fiber content SFC (w) [%] parameters: Instrument: AFIS • Commercial staple of the relevant raw Fig. 2: Short-fiber content depending on the fiber length Source: TIS Data 03/2020 material origin (see Fig. 2) • Addition of recyclable raw material waste from the blowroom and card • Addition of noil from the combing pro- cess 5 Rieter . The Ideal Rotor Spinning Process for a High Short-Fiber Content 3. Trial Setup In order to be able to precisely deter- Short-Fiber Content mine the influence of the short-fiber con- Blend of virgin cotton and comber noil tent on the yarn quality and to eliminate 90 variables that influence the raw material 81% and therefore weaken the validity of the 80 results, a West African cotton with a com- 70 65% mercial staple of 1 7/32” was used and 60 54% short fibers in different quantities pre- 50 cisely mixed in. 43% 40 27% The increase in the short-fiber content 30 came from the addition of noils. As Fig. 3 SFC (< 12.7 mm(n)) [%] 20 shows, the noil addition of 50% resulted in a raw material short-fiber content of 10 approximately 54%, for example. 0 0 10 20 30 40 50 60 70 80 90 100 The comparison was built up on three Noil [%] production lines. One line as classical Instrument: AFIS process with two draw frame passages, Fig. 3: Development of short-fiber content with varying amounts of noil Source: TIS Data 03/2020 one line as shortend process with one single draw frame passage and one line as a direct process thanks to a module at- tached to the card, see Fig. 4 on the next The following raw material blends were tested: page. With all three processes three dif- Virgin Cotton Noil Short-Fiber ferent yarns were spun (Ne 30, Ne 20 (1 7/32”, 4.2 Mic) (19/32”, 4.35 Mic) Content and Ne 12) with different proportions of 1 100% 0% 27% short fibers (from 100% virgin cotton to 2 70% 30% 43% 100% noil). The short fibers were always blended in the blowroom. 3 50% 50% 54% 4 30% 70% 65% 5 0% 100% 81% 6 Rieter . The Ideal Rotor Spinning Process for a High Short-Fiber Content In the trial, the optimal process sequence for the above-mentioned raw materials was examined. To do this, three diff erent production lines were defi ned: Three diff erent rotor spinning processes Classical process VARIOline Card Draw frame Autoleveler draw Rotor spinning machine frame Shortened process VARIOline Card Autoleveler draw Rotor spinning machine frame Direct process VARIOline Card with RSB module Rotor spinning machine Fig. 4: Three processes were defi ned for the trial All of the optimal settings in the spinning plan were identifi ed and thus at the same time off er the basis for calculating the economical viability later. Machine Type Infeed count Doubl. Draft Delivery count Twist Delivery [tex] / [Ne] [fold] [fold] [tex] / [Ne] [αm] / [T/m] Blowroom A 11 – B 12 – B 36 – A 79 Card C 70 1 1 6 000 / 0.10 Virgin cotton 135 kg/h 12 000 / 0.05 Noil blends 100 kg/h Draw frame SB-D 15 6 000 / 0.11 5 5 6 000 / 0.10 Virgin cotton 750 m/min First passage Noil blends 450 m /min Draw frame RSB-D 40 6 000 / 0.11 5 5 6 000 / 0.10 Virgin cotton 700 m/min Second passage Noil blends 400 m/min Card with module RSB module 12 000 / 0.05 1 2 6 000 / 0.10 Rotor spinning machine R 66 6 000 / 0.10 1 113 49.2 / 12 167 / 681 125 m/min 85 000 rpm Rotor spinning machine R 66 6 000 / 0.10 1 188 29.5 / 20 167 / 969 98 m/min 95 000 rpm Rotor spinning machine R 66 6 000 / 0.10 1 281 19.7 / 30 184 / 1 300 77 m/min 100 000 rpm 7 Rieter . The Ideal Rotor Spinning Process for a High Short-Fiber Content 4. Optimal Process Sequence 4.1. Sliver Evenness and seen clearly when the drafted fiber web module still achieves the requirements Adhesive Strength on the which has not yet passed the web funnel of evenness. This indicates that the op- Intermediate Product is placed on a dark sheet. timal process sequence is dependent on the short-fiber content (see Fig. 5). In recent years, it has been clearly prov- With 100% virgin cotton, there is an en that process shortening not only re- even draft without drafting faults. Al- In the direct process with RSB module no duces the yarn conversion cost, but, ready with the addition of 50% noil, fiber drafting faults and fiber package build-up depending on the end-spinning process package build-up can be seen. In extreme are seen in any of the raw material vari- and raw material, it can also significant- instances of 100% noil, it is clear that ants. The fiber web looked the same in ly improve the quality. Prerequisites for neither the classical process with two all raw material categories, with no vis- this are drafting systems that include an draw frame passages nor the shortened ible fiber package build-up. The higher efficient draft as well as a draft control process with one draw frame passage the short-fiber content, the higher the in the shortened process.