Who Are Fabric Materials Supplied to Continuous Scale

Planning of clothing design, pattern making and cutting

Jelka Geršak , in Design of Clothing Manufacturing Processes (Second Edition), 2022

6.5.1.3 Defining fabric width

Fabric width (i.e., the usable width for which the cutting-marker is planned) should be determined in detail prior to planning the cutting-marker. The maximum width of the cutting-marker is constrained by the usable width of the fabric. The usable width is the width of the narrowest place minus the width of any unusable selvedge (i.e., considered to be the fabric's width with selvedge excluded—the net fabric width). Usable width can be equal to the net width of the smaller, for example, where a technological process causes fabric deformations parallel to the selvedge (i.e., resulting from tensile and thermal stresses in the process of heat-setting), producing unsmooth edges or a slightly wavy selvedge. Where the waves are dissipated towards the centre of the fabric width, usable width is smaller than net width, generally by the width of the deformation, which could seriously harm the clothing's appearance if included in the cutting-marker. When, for example, a jacket's pattern-pieces are cut near the fabric's selvedge, a wavy selvedge causes a significant difference in the fabric, which is reflected as visible transversal stripes on the back part of the jacket—in the seam of the finished article of clothing (see Fig. 6.8).

Fig. 6.8. Transversal streaks in the back area of the jacket seam (A and B) as a consequence of deformations, that is, fabric creasing in the selvedge zone.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780081026489000025

Quality requirements for clothing materials

Jelka Geršak , in Design of Clothing Manufacturing Processes, 2013

8.3.3 Width

There are two definitions of fabric width: the overall width, and the usable width. The overall width is defined under standard ISO 3932:1976 as the distance, at right angles to the length of the fabric, between the outermost warp threads in the piece. Under the same standard, usable width is defined as the distance, at right angles to the length of the fabric, between the outermost warp threads of the body of the fabric. In accordance with EN 1773:1996 the usable ² width of a piece is also defined as the width of the fabric excluding any selvedge materials, marks, pinholes or other non-homogeneous areas of the fabric. Faults in the fabric occur when the usable width of the delivered piece is less than that specified in the contract. No tolerance is allowed below the usable stipulated width in the contract. The maximum width must not exceed the usable stipulated width +   4 cm (DTB, 2006).

There are several methods of testing the width of the fabric: In cases where the cloth has selvedge, testing is carried out by measuring the smallest distance between the two selvedges (the latter not being included in the measurement); in cloths without selvedge, the smallest distance between the two edges of the cloth is measured and 1 cm is deducted from each side; cloths with stenter-pin holes or marks are measured at the minimum width between the holes or marks on the cloth without tension. Where there is dispute, measurements are made according to ISO standard 3932:1976.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780857097781500086

Quality requirement for clothing materials

Jelka Geršak , in Design of Clothing Manufacturing Processes (Second Edition), 2022

8.4.4 Width

There are two definitions of fabric width: the overall width, and the usable width. The overall width is defined under standard EN 1773, 1996 and ISO 22198, 2006 ^c as the distance between the outermost edges of the sample measured perpendicular to the longitudinal edges. Under the same standards, usable width is defined as the width of the fabric excluding any selvedge materials, marks, pin-holes or other nonhomogeneous areas of the fabric (Note: For some end uses or specifications, the usable width may be defined differently, as agreed between the interested parties). Faults in the fabric occur when the usable width of the delivered piece is less than that specified in the contract. No tolerance is allowed below the usable stipulated width in the contract. The maximum width must not exceed the usable stipulated width +   4   cm (DTB, 2020).

There are several methods of testing the width of the fabric: In cases where the cloth has selvedge, testing is carried out by measuring the smallest distance between the two selvedges (the latter not being included in the measurement); in cloths without selvedge, the smallest distance between the two edges of the cloth is measured and 1   cm is deducted from each side; cloths with stenter-pin holes or marks are measured at the minimum width between the holes or marks on the cloth without tension. Where there is a dispute, measurements are made according to ISO standard 22198:2006.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780081026489000086

Methods and machinery for the dyeing process

G.P. Nair , in Handbook of Textile and Industrial Dyeing, 2011

8.10 Semi-continuous and continuous open-width dyeing machines

Semi-continuous and continuous open-width fabric dyeing machines are necessary to produce bigger lengths of uniform, high quality shades economically. A comparison of the features of continuous dyeing with those of batch dyeing is given in Table 8.8 (Nair, 1999b; Nair, 2002; Nair and Pandian, 2008f). In these machines, which are produced by a large number of manufacturers, the dye application padding mangle is the most important component for shade uniformity, avoiding selvedge to selvedge or centre to selvedge shade variation. In these machines any of the following dyeing processes may be used:

Table 8.8. Continuous dyeing vs batch dyeing

Features	Continuous dyeing	Batch dyeing
Shade uniformity	High degree over width and length and reproducibility	Possibility of batch to batch shade variation
Quality of dyeing	Better	Good
Suitability for garments and uniforms	Suitable	Not suitable
Crease defects	Can be controlled	Difficult to control
Production	High due to short through times	Less due to long dyeing times as it is broken-up in between
Labour requirement	Less	More
Process cost	Less	More

Source: Adapted from Nair (1999b); Nair and Pandian (2008f).

•

Cold Pad-Batch

•

Pad-Dry-Pad-Steam

•

Pad-Steam (all in all)

•

Pad-Dry-Thermofix

•

Pad-Steam (Wet/Wet)

•

Pad-Steam-Pad-Develop

•

Pad-Steam-Pad-Thermosol.

The units of equipment are as follows:

•

Padding mangles for application of dyes and chemicals

•

Air passage unit for dye/chemical penetration

•

Infrared unit for pre-drying

•

Hotflue or float drier for drying/thermofixing/thermosoling

•

Booster for application of chemicals

•

Batching and batch rotation unit for colour fixation at room temperature

•

Reactor steamer for steaming/air passage

•

Units for rinsing/oxidation/soaping.

The semi-continuous dyeing process is very popular, useful and economically viable. It employs reactive dyes in the 'Cold Pad-Batch' process for dyeing cellulosics. The steps involved in this technology are pad with dye and alkali–batch–dwell–rinse–soap. The units of equipment used are padding mangle (padder), batching unit with batch rotation and soaper for rinsing, soaping and drying. The equipment used for the first stages, namely, padding and batching, is popularly known as a cold pad-batch (CPB) dyeing machine.

The continuous dyeing process involves more steps and uses units such as padders, boosters, Infra Red (IR) pre-driers, driers, steamers, air passages and washers (Shore, 1979; Ellis, 1984; Hyde 1998). The colours that can be used include reactive, vat, sulphur, azoic, pigment and disperse dyes. Table 8.9 (Nair and Pandian, 2008f) provides a list of the leading machine manufacturers and their machine models, a selection of which are discussed below.

Table 8.9. Semi-continuous and continuous dyeing machines

S. No.	Manufacturers	Models (Semi-continuous (SC) and Continuous (C) dyeing Machines)
1	Benninger*, Switzerland	Ben-Colour (SC and C)
2	Brückner, Germany	Pad-Dry/Thermosol line (C)
3	Brugman, Netherlands	Pad-Steam range (C)
4	Reisky-Dhall, Brazil-India	Continuous Pad Dry/Pad Batch dyeing range (SC and C)
5	Dhall, India	Cold pad-batch machine (SC) Continuous Over dyeing range for denim (C)
6	Erbatech, Germany	Scout-color Padder (SC) Supraflor Carpet dyeing machine (C)
7	Fleissner, Germany	Continuous Carpet dyeing range (C)
8	Goller, Germany	Goller-Colora (C)
9	HTP Unitex (Mezzera), Italy	Pad Steam dyeing line (C)
10	Küsters*, Germany	DyePad (SC and C)
11	Memnun, Turkey	Dyeing machine for indigo blue (C)
12	Monforts, Germany	Thermex 5500 (SC and C) Econtrol continuous dyeing (C)
13	Morrison, USA	Cold pad-batch range (SC) Pad Steam range (C) Thermosol Pad Steam range (C)
14	Swastik, India	CP Dyeing (SC) Continuous dyeing plant (C)
15	Yamuna, India	Continuous dyeing plant (C)

*

Benninger has taken over Küsters Textile and Subsidiaries of Küsters Far East and Küsters Shanghai in 2007 but no changes for Küsters-Zima, USA and Küsters Calico, India

Source: Adapted from Nair and Pandian (2003c); Nair and Pandian (2003d); Nair and Pandian (2005g); Nair and Pandian (2008f).

Ben-Colour of Benninger, Switzerland

Figure 8.18 shows Ben-Colour, the continuous pad-dry and pad-steam dyeing range that has modules or sections for colour padding, penetration and IR-pre-drying, drying and/or thermofixation, cooling, chemical/colour padding (one- or two-bath), steaming, rinsing and oxidation/soaping and finally drying.

8.18. Sections of Ben-Colour continuous dyeing machine (Benninger).

The possible applications are as follows:

•

pad-dry/pad-steam-wash process with reactive or vat dyes on cotton

•

pad-thermosol-pad-steam-wash process with reactive or disperse dyes for cotton/polyester blends

•

pad-thermosol-pad steam-wash process with vat and disperse dyes for cotton/polyester blends

•

pad-dry-thermofix-wash process with reactive dyes on cotton

•

pad-dry-pad-develop-wash process with azoic dyes on cotton

•

cold pad-batch-wash dyeing process with reactive dyes on cotton.

The fabric feed system incorporates a fabric accumulator for automatic roll change to prevent colour differences resulting from machine stoppages. The dyeing padder has a flexible Bicoflex roll to guarantee a uniform pick-up, independent from production speed and fabric weight. Linearity of the nip line is ensured despite the freely adjustable nip pressure. Figure 8.19 shows the construction details of Bicoflex roll. Its features include the following:

8.19. Construction details of Bicoflex roll (Benninger).

•

Uniform linear liquor application from beginning to end of dyeing operation;

•

Uniform squeezing pressure within the range of fabric including thick and narrow webs (without selvedge pressure);

•

No side-to-centre shading due to smooth treatment of selvedges;

•

Reproducibility of all dyes and chemical applications;

•

No cambering of the squeeze rolls;

•

Simple operation and control due to clear design;

•

Low energy consumption and short return of investment;

•

Reduction of setting-up times through the effective roll washing system;

•

Completely reliable and maintenance-free operation;

•

Special displacement elements and lay-on rollers in the U-shaped troughs or in economic troughs permit low liquor content, resulting in fast liquor exchange and preventing any undesired changes in concentration. All troughs can be raised, lowered and tilted pneumatically. Further, the well-known wedge-shaped trough can be installed for special applications. Fabric is guided in this case from top to bottom through a horizontal roller nip. Alternatively, passing through the trough is possible.

•

Padded fabric is pre-dried in Thermray infrared pre-dryer having the following features:

•

High drying capacity without migration;

•

Robust metal fibre IRG-gas radiators with 2, 4 or 6 burner rows with individual burner switches to control performance;

•

Special burners with rapid warming and cooling capability;

•

Durable metal fibre burner can reach a temperature of 1050°C;

•

Burner regulated from 50 to 100% by controlled gas flow and frequency-controlled burner air (optional);

•

Flap control to regulate exhaust air;

•

Multi-circuit safety system for stopping the machine. No moving parts needed. Immediate cooling of the special burners by admitting and exhausting cooling air.

The pre-dried fabric moves next to the drying and/or thermofixation unit, Thermfix, shown in Fig. 8.20. This Hotflue Thermosol is built with 'optimised drying conditions with leading technology'. In this unit, crease-free fabric transport and low tension are ensured by frequency-controlled individual AC-drives. Load cell technology is used for measuring the fabric tension. Individual single AC-drives guarantee reproducible low tension conditions which are maintenance-free and reliable. There are no clutches, chains or belts. Cleaning and maintenance are also minimised, as the lint sieves can be easily cleaned even during operation. All guide- and drive-rollers are equipped with enclosed lifetime lubricated bearings which are mounted outside the insulated dryer chamber. The grease used is resistant to HT and is suitable for thermosol processes. Grease drops on the fabric are a thing of the past. In areas where dye-deposition can occur, the rollers are Teflon-coated. High uniformity of air flow, air temperature and air humidity over the length and width of the fabric in the Thermfix chamber are ensured by two diagonally located frequency-controlled circulation fans (1). Air flows from the fabric chamber through the lint sieve (2) and is heated (3) either by oil-to-air or steam-to-air heat exchangers or direct gas heating. From the mixing tube (4) air enters the big distribution chamber (5). Air is distributed over the length and width and uniformly pressed through nozzle elements (6) into the fabric chamber (7). These nozzle elements have vertical air exit for uniform air and temperature distribution without heating of rollers. In each chamber, air quantity and temperature are controlled. The conditions are set appropriate for fabric weight, fabric construction, fabric composition (cotton, cotton/polyester, polyester, etc.), pick-up, etc., to prevent migration. Each chamber is suitable for drying (pad-dry) or for thermosetting (pad-thermosol) processes. It is important that the exhaust air should be removed in a controlled fashion in order to optimise the drying conditions. Frequency-controlled radial fans (8) are used to adjust the amount of exhaust air, while an automatic closed loop control with an electronic moisture probe in the exhaust air stream is available as an option. The feeding air enters the fabric chamber through the side slide gates (9). The entire chamber body is fully insulated, and the side walls are all built in the form of doors which are equipped with special slots to prevent heat transfer. This excellent insulation guarantees the lowest possible heat loss and is one of the reasons for the low overall energy consumption of the range.

8.20. Thermfix Hotflue Thermosol (Benninger).

After drying and/or thermofixation, the fabric moves on to the cooling zone, and then on to the Ben-booster unit (Fig. 8.21a) positioned outside the steamer for chemical padding to ensure uniform liquor application. The dipping length is kept short and no heating is required but good penetration into the fabric is achieved. Replacing the steamer inlet water lock with the booster would result in heating of the fixation liquor, which would decompose the hydrosulphite used in chemical pads for vat dyes. The booster's squeezer consists of two ground soft rubber rollers, where it is possible to cover a large pressure range with a parallel nip. The data presented in Fig. 8.21b show that a wide range of liquor pick-up is achievable with this booster squeezer: indeed, any specific liquor pick-up can be set for all fabrics. In the one-bath pad-steam process such as that used for sulphur dyes on cotton, this padding Ben-booster will have colour along with chemicals.

8.21. (a) Ben-booster and (b) its squeeze vs pick-up (Benninger).

The colour and chemical padded fabric is then subjected to saturated steam fixation in a Reacta steamer. This unit has modular sections, each able to contain 25   m of fabric and with either a horizontal or a vertical feed. To prevent water dripping, the inlet lips of the dyeing steamer are indirectly heated and the escaping steam clouds are extracted to prevent formation of condensate. Air-free operation is ensured by monitoring the temperature outside and below the bottom level of the steamer. Any deviation in temperature immediately leads to an increase in the steam supply. The exact saturation of the steam is achieved in the steam conditioning unit. Pressure is reduced independently of the flow rate and the throttled steam is then cooled and saturated in a water cooler. A control valve adjusts the steam supply corresponding to the temperature. A water lock at the steamer exit is indispensable for airtight closure, and the passage of hot cloth through this water lock heats the water. Chemicals also accumulate here. In the case of vat dyes, HT and higher levels of hydrosulphite and caustic soda lead to stripping of colour or at least to tailing. For this reason, the water lock on Benninger's steamer has a temperature-controlled fresh water supply to ensure ample dilution and constant conditions.

The next element of the dyeing line is the washing section for rinsing and oxidation/soaping. This stage is essential for proper completion of the dyeing process and for obtaining good dyeing results. The various groups of dyes require different after-treatment processes (Table 8.10), which the washing section should be able to accommodate.

Table 8.10. Dyeing after-treatments

Substrate	Dyes group	After-treatments
Cotton or viscose	Reactive Vat Sulphur	Rinsing – soaping – rinsing or hot counter-flow washing Rinsing – oxidising – soaping – rinsing rinsing – neutralizing – oxidising – soaping – rinsing
Cotton/polyester blends	Reactive/disperse Vat/disperse	Rinsing – soaping – rinsing Rinsing – oxidising – soaping – rinsing
Polyester	Disperse	Rinsing – reduction-clearing – soaping – rinsing

Source: Adapted from Nair and Pandian (2008f).

Benninger uses the tried and tested Ben-Extracta washing compartments, which are able to fulfil the requirements of all process stages. Rinsing processes are carried out in single loop washing compartments and dwell processes in double loop compartments. The treatment steps differ for different classes of dyes, with some requiring more steps. For this reason, some washing compartments may be divided into independent sub-compartments. These divided Beco-flex washing compartments allow two separate treatment steps in one compartment. The Extracta press rolls ensure good bath separation.

The last section of the dyeing range is dedicated to drying the dyed and rinsed fabric on a cylinder drying range.

Benninger's dyeing ranges are equipped with a good level of automation. Water and chemical feeds are automatically controlled based on cloth weight and production parameters via inductive flow meters and control valves. Important machine settings are monitored and controlled by a Siemens PLC control system used for both drive and process control. The latest technology AC-drive system guarantees low tension and crease-free cloth transport. Further automation is an option in the shape of an independent recipe management programme or connection to a host computer system.

Continuous pad dry/pad batch dyeing range of Reisky-Dhall, Brazil-India

Figure 8.22 shows the parts and fabric movement of this range. Its main features are as follows:

8.22. Parts and cloth movement in continuous pad dry/pad batch dyeing range (Reisky-Dhall).

•

Suitable for dyeing cotton, synthetics and blended fabrics in open width.

•

Equipped with Reisky-Dhall Dyeing Padder with two hydraulic controlled deflection rolls to guarantee even and uniform dyeing across entire width.

•

Can be used as cold pad batch dyeing and pad-dry range; versions available for fabric widths up to 3200  mm.

•

Scrays are provided at inlet and outlet for continuous operation.

•

Large diameter, i.e. 200   mm, guide rolls are provided for creaseless operation; E+L cloth guiders.

•

Colour dosing pumps developed by Prominent, Germany.

•

Gas fired Infrared Pre-Drier is provided to avoid colour migration.

•

Moisture Controller developed by Pleva, Germany is incorporated for precise and uniform control of moisture addition by steam inside Hot Flue Drier.

•

Total package, i.e. PLC, Touch Screen, Invertors, Motors, etc., are from Adolf B Bockemueht GmbH & co, Germany (ABB) or equivalent, for total process control and easy operation.

Scout-color Padder of Erbatech, Germany

This padder is for semi-continuous dyeing and has the following features:

•

Advanced tension control system allows all cellulosic fabrics and blends to be dyed with reactive dyes in open-width form. Formation of creases or pills is avoided. Fabrics of high elasthane contents can also be dyed without any problems.

•

Equipped with a modern automated self-cleaning system that allows a fast and economic processing even for smaller production lots.

•

Pad-batch dyeing method brings additional advantages in terms of water and energy consumption.

DyePad of Küsters, Germany

This DyePad is very useful for both semi-continuous and continuous open-width dyeing. It has the following features:

•

Claimed to be 'the Brand-new Machinery Generation', it provides 'optimised dyeing with an increased operation range' incorporating innovations 'at the Swimming Roll Küsters, the rubber covering (BlueNip), the modular fabric guiding system, the drive system and the modern integrated control system'.

•

Two horizontal, parallel Swimming Rolls with a doubled correction potential (Fig. 8.23). The S-Rolls are covered with the new BlueNip rubber covering, which is equipped with a universally applicable surface suitable for all dyeing processes. The BlueNip rubber covering also has high chemical resistance.

8.23. S-Rolls (Küsters).

•

Equipped with a reverse fabric guide suitable for both woven and knitted fabrics and optimised troughs with integrated heat exchanger.

•

'Maintenance-free drive system and the new decentralised control system as well as the high profitability turns the Küsters DyePad into a padder which is tailor-made for all market requirements', besides taking all relevant ecological aspects into consideration.

Econtrol continuous dyeing of Monforts, Germany

Figure 8.24 shows the Econtrol continuous dyeing range. Its features are as follows:

8.24. Econtrol continuous dyeing range with process details (Monforts).

•

Simple, rapid, innovative and economical continuous dyeing process for cellulose fibres with reactive dyes using minimum chemicals, developed by Monforts and BASF (Now DyStar). Process does not require process chemicals such as urea, sodium silicate, sodium hydroxide and salt: sodium bicarbonate is sufficient, thanks to the development of the Thermex Hotflue dryer with moisture content control and injection.

•

Machine configuration (Fig. 8.24) consists of: fabric inlet; padding mangle for dye application; wetting unit to provide adequate moisture in Hotflue chamber; Thermex Hotflue for dye fixation; unit for measuring and controlling chamber climate; steam injection unit; outlet section and washing unit. IR-drier can be incorporated for beneficial use while dyeing heavy fabrics.

•

Additional advantages include the absence of batching/rotating stations, extended machinery life due to avoidance of harsh chemicals such as salt and silicate and energy efficiency by optimum humidity control.

•

In short, 'a simple, economic, efficient, environmentally friendly, energy saving and controlled process of continuous dyeing'.

Universal continuous dyeing range of Yamuna, India

An abridged diagram of this machine is shown in Fig. 8.25. This machine has been designed by the author for continuous dyeing using all classes of commonly used dyes such as vats, reactives, sulphurs, azoics, pigments, mineral khaki (MK) and disperse dyes (Nair, 2007). The features of this range are as follows:

8.25. Universal continuous dyeing range (Yamuna).

1.

Single/double colour padding with a scray in between for giving dwell of the padded fabric. This step is helpful, especially for MK dyeing of thick fabrics, for full and proper penetration of colour and for colour economy.

2.

Pre-drying with IR heaters, as an option, for preventing migration and for boosting dryer productivity. A three-pass, four-section float dryer is ideal for final drying or for drying and thermosoling for disperse dyes.

3.

Chemical treatment (development) compartments, generally two, for hot caustic soda treatment in MK dyeing.

4.

Chemical pad with two-bowl mangle and jacketed shallow trough having continuous pad liquor feeding arrangement.

5.

Steamer with steam lock at entry and water lock at delivery, with control of temperature, speed and fabric tension.

6.

A five-compartment range for washing, oxidising, soaping and rinsing; closed ones for soaping and rinsing with proper fabric squeezing (mangling) between compartments and after the fifth compartment.

7.

Double stalk cylinder drying range with expander assembly at entry and batching/plaiting arrangement at exit.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9781845696955500088

Calculations in the knitting process

N. Gokarneshan , ... C.B. Senthil Kumar , in Mechanics and Calculations of Textile Machinery, 2013

20.6 Fabric calculations

Weight per linear yard in lbs

$\begin{array}{ll}\hfill & =\frac{\mathrm{Total}\mathrm{needles}\times \mathrm{Courses}\mathrm{per}\mathrm{inch}\times 36}{\mathrm{Stitches}\mathrm{per}\mathrm{foot}\times 3\times 840\times \mathrm{Cotton}\mathrm{count}}\hfill \\ \hfill & =\frac{\mathrm{Total}\mathrm{no}.\mathrm{of}\mathrm{needles}}{\mathrm{Wales}\mathrm{per}\mathrm{inch}}\hfill \end{array}$

Weight per square yard in lb

$=\frac{\mathrm{Weight}\mathrm{per}\mathrm{linear}\mathrm{yard}\times 36}{\mathrm{Fabric}\mathrm{width}\mathrm{in}\mathrm{inches}}\left(\mathrm{for}\mathrm{flat}\mathrm{fabric}\right)$

$\begin{array}{ll}\left(\mathrm{or}\right)\hfill & =\frac{\mathrm{Weight}\mathrm{per}\mathrm{linear}\mathrm{yard}\times 36}{\mathrm{Fabric}\mathrm{width}\mathrm{in}\mathrm{inches}2}\left(\mathrm{for}\mathrm{tubular}\mathrm{fabric}\right)\hfill \end{array}$

$\begin{array}{l}\mathrm{Fabric}\mathrm{width}\mathrm{in}\mathrm{inches}-\mathrm{Number}\mathrm{on}\mathrm{needles}\times \mathrm{waste}\mathrm{spacing}\hfill \\ =\mathrm{Needles}\times 4-\mathrm{yarn}\mathrm{diameter}\mathrm{per}\mathrm{wale}\hfill \end{array}$

$\frac{\mathrm{Width}\mathrm{of}\mathrm{old}\mathrm{fabric}}{\mathrm{Width}\mathrm{of}\mathrm{new}\mathrm{fabric}}=\frac{\mathrm{New}\mathrm{yarn}\mathrm{number}}{\mathrm{Old}\mathrm{yarn}\mathrm{number}}$

Stitch density

$=\frac{\mathrm{Constant}}{\mathrm{Stitch}\mathrm{length}\mathrm{in}\mathrm{inches}}$

Length constant

$=\mathrm{Courses}\mathrm{per}\mathrm{inch}\times \mathrm{Stitch}\mathrm{length}\mathrm{in}\mathrm{inches}$

Width constant

$=\mathrm{Wales}\mathrm{per}\mathrm{inch}\times \mathrm{Stitch}\mathrm{length}\mathrm{in}\mathrm{inches}$

Area constant – (Stitch length in inches)² × stitch density

$\begin{array}{ll}\hfill & =\mathrm{Courses}\mathrm{per}\mathrm{inch}\times \mathrm{Wales}\mathrm{per}\mathrm{inch}\times {\left(\mathrm{Stitch}\mathrm{length}\mathrm{in}\mathrm{inches}\right)}^2\hfill \\ \hfill & =\mathrm{Length}\mathrm{constant}\times \mathrm{width}\mathrm{constant}\hfill \end{array}$

Loop shape factor

$\begin{array}{ll}\hfill & =\frac{\mathrm{Length}\mathrm{constant}}{\mathrm{Width}\mathrm{constant}}\hfill \\ \hfill & =\frac{\mathrm{Courses}\mathrm{per}\mathrm{inch}}{\mathrm{Wales}\mathrm{per}\mathrm{inch}}=1.3\hfill \end{array}$

Weight per sq. inch of fabric in lb – stitch density × stitch length in inches × weight in lb. of 1 inch yarn

Fabric width

$\begin{array}{ll}\hfill & =\frac{\mathrm{Number}\mathrm{of}\mathrm{needles}}{\mathrm{Wales}\mathrm{per}\mathrm{inch}}\hfill \\ \hfill & =\frac{\mathrm{Number}\mathrm{of}\mathrm{needles}}{\mathrm{Width}\mathrm{constant}/\mathrm{stitch}\mathrm{length}\mathrm{inches}}\hfill \end{array}$

(Width constant = Wales per inch × Stitch length in inches)

$=\frac{\mathrm{Number}\mathrm{of}\mathrm{needles}\times \mathrm{Stitch}\mathrm{length}\mathrm{in}\mathrm{inches}}{\mathrm{Width}\mathrm{constant}}$

Weight per running yard

$\begin{array}{ll}\hfill & =\frac{\mathrm{Weight}\mathrm{per}\mathrm{sq}.\mathrm{yard}\times \mathrm{Width}\mathrm{of}\mathrm{the}\mathrm{fabric}\mathrm{lb}}{\mathrm{Width}\mathrm{constant}}\hfill \\ \hfill & =\frac{36\times \mathrm{Constant}\times \mathrm{Weight}\mathrm{in}\mathrm{lb}\mathrm{of}1\mathrm{inch}\mathrm{of}\mathrm{yarn}\times \mathrm{Number}\mathrm{of}\mathrm{needles}}{\mathrm{Width}\mathrm{constant}}\hfill \\ \hfill & =36\times \mathrm{Length}\mathrm{constant}\times \mathrm{Weight}\mathrm{of}\mathrm{lb}\mathrm{of}\mathrm{one}\mathrm{inch}\mathrm{of}\mathrm{yarn}\mathrm{in}\mathrm{lbs}\times \mathrm{Number}\mathrm{of}\mathrm{needles}.\hfill \end{array}$

Weight per square yard in rib structure (in ozs)

$\begin{array}{l}=2.06\times \mathrm{Courses}\mathrm{per}\mathrm{inch}\times \mathrm{Wales}\mathrm{per}\mathrm{inch}\times \mathrm{Stitch}\mathrm{length}\mathrm{in}\mathrm{inches}/\mathrm{Worsted}\mathrm{count}\\ \end{array}$

Cover factor or tightness factor

$=\frac{1}{\mathrm{Stitch}\mathrm{length}\mathrm{in}\mathrm{inches}\times \mathrm{worsted}\mathrm{count}\left(\mathrm{indirect}\mathrm{system}\right)}$

$\begin{array}{ll}\mathrm{Or}\hfill & \frac{\mathrm{Tex}}{\mathrm{Stitch}\mathrm{length}\mathrm{in}\mathrm{inches}}\left(\mathrm{direct}\mathrm{system}\right)\hfill \end{array}$

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780857091048500201

The principles and elements of textile design

Jacquie Wilson , in Handbook of Textile Design, 2001

4.3.3 Centring

For the most economic fabric usage it is better for fabrics to be symmetrical in both the vertical and horizontal directions. This means that laying-up plans for cutting out pattern pieces can be more easily worked out. If a fabric has a pile, it is important that the pile lies the same way on all garment pieces.

Centring is when a fabric design is organised in such a way that it is balanced about the middle line of the fabric in a vertical direction.

4.3.3.1 Example A

Consider a striped fabric that consists of two colour stripes of equal width. The required finished fabric width is such that an exact number of the design repeat fits (see Fig. 4.5). It would be better to have half a white stripe at either side as in Fig. 4.6 or a grey stripe at either side as in Fig. 4.7.

Fig. 4.5. Striped fabric not centred.

Fig. 4.6. Stripe centred with white stripe at either side.

Fig. 4.7. Stripe centred with grey stripe at either side.

4.3.3.2 Example B

Consider a simple half-drop print design as in Fig. 4.8. This is not symmetrical about the vertical axis and so will give problems in cutting. Fig. 4.9 shows the same design centred and, as such, it can be more easily laid-up in layers, for cutting into individual pattern pieces.

Fig. 4.8. Simple print design — not centred.

Fig. 4.9. Simple print design — centred.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9781855735736500096

Manufacturing of textiles for civil engineering applications

T. Gries , ... O. Stolyarov , in Textile Fibre Composites in Civil Engineering, 2016

1.4 Three-dimensional textile structures

A significant achievement over the last several decades in textile technology has been the development of 3D textile structures (3D textiles) that have new, unique properties compared to conventional, planar textile structures. The main impact of 3D textile development has been seen in the limited use of conventional planar textiles, mostly woven as reinforcing fabrics for particularly critical structural elements. Unlike planar textile reinforcements, 3D textile structures have the advantage that the yarn can be built-in in three directions in space, including the through-thickness direction. Development of textile fabrics with reinforcing elements in their structures, and having the shape of the reinforcing structure, is quite cost-effective technology. The use of such structures makes it possible to reduce labor costs related to the manufacture of composite materials owing to the creation of integrated systems of reinforcing elements (Gries and Roye, 2003; Roye and Gries, 2007).

Three-dimensional structures can be defined based on either the manufacturing process or the dimensionality of the internal structure. Thus, Buesgen (1993) defined three-dimensional textiles: "textiles or fabrics are three-dimensional textiles when they appear in a three-dimensional geometry without any transformation step and/or when they exist in at least three different layers of yarn systems which are oriented in all three directions (three-dimensional structure)." Roye et al. (2004) defined a 3D textile as a textile that has three directions in yarn architecture and/or textile architecture, regardless of whether it is made in a one-step process or multiple-step process. Thus, in general, a 3D textile is a structure having yarns oriented in three orthogonal directions.

Fabrication of 3D structures can be carried out in either one-step or multiple-step processes; however, production in multiple-step processes involves many additional operations such as cutting, laying, and joining. Therefore, the development of a one-step process for three-dimensional structures is currently a priority. All major textile technologies, including weaving, knitting, and nonwoven technology, are suitable for the production of three-dimensional textile structures.

1.4.1 3D-woven structures

Weaving technology can be used in the narrow-fabric form as well as in the broad-width-fabric form for the manufacture of 3D textiles. These textiles are suitable for an array of different applications, including:

•

High energy absorption

•

Low crack propagation

•

Good impact behavior

•

High tensile strength

These structures can be used for the manufacture of frameworks in building. These framework structures can be woven and directly extruded to be used in applications such as door and window frames.

1.4.2 3D-knitted structures

Knitting technology is widely used in the production of 3D structures. Three-dimensional-knitted structures can be manufactured by both weft-knitting and warp-knitting techniques; however, the warp-knitting technique is the most popular in manufacturing 3D structures for composite reinforcement. Warp-knitted spacer fabric is one of the special types of 3D textiles for use in structural applications. In forming 3D warp-knitted fabrics, two warp-knitted structures having the same or different structures are simultaneously and independently produced on each side of the machine. They are connected together during fabric production by another set of yarns, together forming a 3D structure (Roye and Gries, 2007).

Spacer fabrics show specific characteristics thanks to their special structures. Spacer fabric is a sandwich structure consisting of two outer surfaces and a connection layer, as illustrated in Figure 1.13. Spacer fabrics are produced on double-needle-bar Rachel machines. The upper and lower surfaces of spacer fabrics are produced on the front and rear needle beds, respectively. The needle bars operate in alternation (Raz, 2000). The upper and lower surfaces of the spacer fabric consist of rovings laid at angles of 0° and 90° connected by warp-knitting yarn. In addition, there are spacer yarns located in the through-thickness direction that bind the two outer surfaces of the fabrics to each other.

Figure 1.13. Spacer fabric components.

Spacer fabrics may have open or closed structure or a gridded, mesh-like structure. Various mesh sizes can be obtained by regulating the distance between inlay yarns in two directions. Spacer fabrics with open structures find appropriate application for concrete reinforcement owing to better flow of the concrete mixture into the fabrics. The upper and lower surfaces of spacer fabrics can be produced from the same or different inlay yarns. As a spacer yarn, single, continuous yarns are used. Selection of different inlay yarns allows spacer fabric with different predetermined characteristics to be obtained. The length of spacer yarns between two surfaces can be varied up to 60   mm (Raz, 2000). With this range of length, different fabric thicknesses can be realized depending on composite geometry.

Along with high-strength textile yarn used as inlay yarn, metal wire may be used as a 3D warp-knitted textile for structural reinforcement in hybrid metal or plastic products (Janetzko et al., 2009). The main advantage of spacer fabrics for concrete applications is in the final shape of the component. The high-strength inlay yarns are located in the outer layers of spacer fabrics where the highest tensile and compressive forces occur. The two layers of the spacer fabric can be designed to have different forms, even allowing different distances between the layers, as shown in Figure 1.14. It is also possible to leave out free areas if the concrete element is designed with holes. A spacer fabric with open structure has been designed for façade elements, as shown in Figure 1.15 (Hanisch et al., 2006).

Figure 1.14. Warp-knitted spacer fabric with varying distances between outer layers.

Figure 1.15. Warp-knitted spacer fabric with open structure.

The factors affecting the properties of spacer fabrics include the thickness; the number of inlay yarns per width and the number of spacer yarns per unit area; the properties of inlay and spacer yarns; the spacer yarn laying angle; and the pattern of the warp-knitting yarn.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9781782424468000021

Process control in weaving

V.K. Kothari , in Process Control in Textile Manufacturing, 2013

11.2.2 Control of fabric quality

The quality of any given fabric is usually measured by both its defects and its general properties. These include fabric specifications such as fabric width, ends and picks per unit length, weight per unit area, as well as the required functional properties of the fabric. The process of yarn preparation should minimise yarn faults, which could otherwise result in unacceptable fabric appearance or defects. Defects incurred during the weaving process itself must also be kept to a minimum, as the cost of fabric defects can be very high, with potentially substantial reductions in the value of the product. The tolerance limit of non-repairable faults per 100  m of fabric has been considerably reduced (from 15 to 5) in recent years, and is forecast to reach as low as 3 in the future. ⁴

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780857090270500114

Process control in knitting

S.C. Ray , in Process Control in Textile Manufacturing, 2013

10.3 Quality control of knitted fabrics

Some important factors to check with regards to quality control of knitted fabrics are:

•

loop length,

•

GSM,

•

courses per inch,

•

fabric width,

•

wales per inch,

•

fabric defects,

•

stitch density,

•

fabric tightness factor,

•

yarn count,

•

fabric construction (design),

•

yarn type.

Loop length is the most important specification for fabric quality in knitting. Most scientific studies regarding quality control of knitting and knitted fabrics are based on loop length. The manufacturers of knitted products are also gradually becoming more aware of the value of consistent loop length. The consumers of knitted fabrics are very much concerned about loop length, as are traders of knitted fabrics, making it financially one of the most important quality control factors. For this reason loop length is discussed in more detail later in the chapter.

The physical properties of the yarn, and ultimately the properties of the knitted fabric, are influenced by the yarn count, fibre composition and the settings of the spinning machinery used to make it.

The GSM of knitted fabric can be adjusted very easily by varying yarn count, without altering the stitch density or loop length. Today, most trading of circular weft knitted fabric is based on GSM and width. If count is not specified, manufacturers of knitted fabric can achieve the target GSM using coarser yarns with lower stitch density. The consumer is subsequently deprived of the desired quality of fabric. Furthermore, count variation between the feeders will not only produce uneven fabric but could also result in defective fabric.

Courses per inch (cpi), wales per inch (wpi) and stitch density are basic parameters of knitted fabric; variation of these specifications within the fabric will result in uneven thickness. The courses per inch and wales per inch are interrelated ⁴ and mainly depend on loop length governed by machine gauge, stitch cam setting, yarn properties and yarn input tension. These three parameters should be strictly controlled to produce high quality, even fabric.

The fabric tightness factor is the measure of compactness of the knitted fabric. It is calculated using yarn count and loop length and is directly proportional to the coarseness of the yarn, but inversely proportional to the loop length. Therefore, the tightness factor can be increased by using coarser yarn or smaller loop length, and vice versa.

Generally, the variety of structures available using circular weft knitting is limited, but there is scope to produce complex designs using Jacquard and multiple cam tracks on a knitting machine. One of the unique features of flat bed weft knitting and warp knitting is the variety of ornamented structures that can be created. It is important to check that the desired design has been produced correctly by analysing the design after processing.

10.3.1 Controlling GSM in knitted fabrics

As mentioned above, GSM is broadly dependent on stitch density (cpi × wpi), loop length and yarn count. In general, if the stitch density is high, if the yarn diameter is large, or if the yarn is heavy, the GSM will increase proportionally. However, if the loop length is high then the GSM will decrease, as stitch density decreases at a higher rate to the increase in loop length. For double jersey fabric, the additional factors of knitting timing and the gap between the two beds can also cause variation. ^{3 , 5}

GSM is affected by variation in a large number knitting parameters. Therefore, in order to control GSM, these parameters need to be controlled. Depending upon the requirements of the consumer, GSM is mainly controlled by changing the stitch cam setting, the yarn input tension and the yarn count.

10.3.2 Testing the quality of knitted fabric

Some of the specifications which need to be considered with regards to testing the quality of knitted fabrics include:

•

fabric yield,

•

fabric extension,

•

fabric appearance,

•

air permeability,

•

fabric pilling,

•

fabric bow and skew,

•

dimensional changes,

•

abrasion resistance,

•

angle of spirality,

•

bursting strength.

Knitted fabrics are used to create various end products, all of which require a high quality fabric to work from. The fabric will have to undergo further processing before it reaches the consumer, therefore it is necessary to assess the fabric throughout to maintain quality and consistency.

Fabric yield is expressed as a percentage of the ratio of weight of fabric produced (output of the knitting machine) compared with the weight of yarn used (input of the knitting machine). As some wastage of yarn is unavoidable in continuous processing, the yield will almost always be less than 100%. However, due to moisture gain (higher moisture content in the ultimate fabric than the moisture content in the yarn used for knitting), the loss in yield due to wastage of yarn is mostly compensated for. Steps must be taken during the knitting process to ensure that yarn wastage is kept to a minimum.

Knitted fabric properties such as fabric extension under a predetermined load, pilling, abrasion resistance and bursting strength are tested and compared with standard values. These values are set by the manufacturer, based on assessment of performance in the end use of the fabric. For example, pilling is a very common defect in the end application. It is therefore recommended to produce fabric on a laboratory scale to test pilling tendency for different yarns, before moving on to large scale production.

In order to identify the presence of defects such as unevenness (thick and thin places), bow and skew, and spirality, the fabric is passed over an inspection table. Arrangements are then made with regards to the removal/rectification of the defects and any further action which needs to be taken.

10.3.3 Important quality aspects of fabrics from consumers' point of view

The dimensions of some relaxed, knitted fabrics can change when they are subjected to wet treatments, such as scouring, bleaching, dyeing and compacting. This change in dimensions, has the ability to affect many of the knitted fabric parameters, including courses per inch, wales per inch, stitch density, GSM and fabric width/circumference. With the exception of loop length, the parameters of knitted fabrics will continue to change throughout post knitting operations. With this in mind, the parameters of knitted fabrics are only measured in their finished state (usually after compacting).

Shrinkage during subsequent wet treatments, that is, performed by the consumer, also needs to be taken into account. The tolerances for a change in GSM (plus or minus) are only 4–5% of the ordered GSM value. For example, against the ordered value of 150 GSM, the manufacturer is required to produce a fabric with a GSM in the range of 144–156, otherwise orders may be cancelled.

Consumers of knitted fabrics are also concerned with the final width of the fabric (in a two-fold state for circular fabrics and in an unfolded state for flat fabrics). The tolerances here (plus or minus) are again only 4–5% for wide width fabrics, which are cut and opened, before being transformed into the end products. However, for body size fabrics for innerwear (e.g. vests), the reasonable tolerances (plus or minus) are only 0.5 in, irrespective of the diameter. So if the consumer requires fabric for making a vest 36 inches in circumference, the manufacturer must supply knitted fabric with a circumference in the range of 35.5–36.5   in. In addition, the finished fabric must not shrink more than 3% during subsequent wet treatments and throughout the life of the end product. In recent years the leading consumers, particularly from Europe and the USA, have also specified requisite yarn parameters, such as CV% of yarn count, number and magnitude of yarn faults, etc. in addition to the yarn count, unevenness percentage, tensile properties, and the acceptable limit of spirality in the finished fabric.

It has become apparent that more norms and standards for knitted fabrics are to be established in the near future, keeping in mind the satisfaction of consumers on the one hand and the performance of the end product on the other.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780857090270500102

Principles and methods of textile spreading

I. Viļumsone-Nemes , in Industrial Cutting of Textile Materials, 2012

4.5.5 Fabric plies with faults appearing in stripes across the fabric

Textile faults often appear in the weft direction of a woven fabric or in the direction of the wales in a knitted fabric and are visible throughout the entire fabric width. In this case, the following actions are necessary:

•

The marker is placed on the spread to determine the location of the fault.

•

If the fault is not located close enough to the splice area (see Fig. 4.26), the fabric ply may be moved from the beginning of the spread and placed on the first splice mark of another splice area.

4.26. Fabric piece with a fault in an uneconomical splice position.

•

The piece of fabric is laid in a new position to see if the faulty piece which has to be cut off is shorter than in the original position. When the most economical position of the splice has been found, the ply is spread from the first mark of that splice (see Fig. 4.27, lower fabric ply). The fabric is then taken back to the beginning of the spread and laid up to the second mark of the selected splice (see Fig. 4.27, upper fabric ply).

4.27. Fabric piece with a fault in an economical splice position.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B978085709134550004X

galvandowerent.blogspot.com

Source: https://www.sciencedirect.com/topics/engineering/fabric-width