Steps to be taken for quality improvement of textile processing

Introduction Quality is of prime importance for every industry or business, to get increased sales & better name amongst Consumers & fellow Companies. Generally Quality control Standards for export are set strictly, as this business also holds prestige of the country, whose company is doing export. Quality standards like ASTM, AATCC, BS, DIN & JIS & ISO must be recognized & agreed by all levels of management. However quality expectations for exports are related to type of customer segments & retail outlets. For textile & apparel industry product quality is calculated in terms of quality & standard of fibres, yarns, fabric construction, colours fastness, Surface designs & final finished garments products. Present paper was aimed at investigating important testing parameters for textile products & steps to be taken to improve these testing parameters.

Different testing parameters: a) Tensile strength b) Tear strength c) Seam properties d) Pilling e) Colour fastness to light

a) Tensile strength It is the strength of fabric which denotes breaking force required to rupture fabric. A tensile tester is used to determine strength in which central part of width of specimen is gripped in clamps. It determines effective strength of specified width with assistance of adjacent yarns. Fabric assistance depends on type of fabric & construction variables.

Recommendation for Improvement: Tensile strength is a property that cannot be improved once a fabric is produced. For future production, a higher thread count or use of stronger yarns should result in a fabric with better tensile strength properties.

b) Tearing Strength Tear force required to propagate a single-rip tear of defined length from a cut in fabric when a sudden force is applied. This test is performed by measuring work done in tearing fabric through a fixed distance on tearing strength tester. This test is mainly applicable for woven fabrics not for knitted fabrics.

Reasons for poor tear strength: Basically yarn is weak; hence fabric constructed with such yarns will produce a weak fabric with less strength. In rare cases during various treatments fabric may become weak.

Recommendation for Improvement: Tearing strength is a property that cannot be improved once a fabric is produced. For future production, yarns with longer fibre length & higher twist may result in higher tear strength properties. Since core of fabric is having problem there are no definite remedies to improve upon. Marginal improvements may be possible with washing or some treatment. c) Seam properties To determine seam maximum force of sewn seams is when force is applied perpendicularly to seam. Test applies to standard seam applied to fabric samples or Production seam as received in finished garments. Major contributors to seam strength are fabric type & weight, thread type & size, stitch & seam construction, stitches per inch & stitch balance. Seam Strength in woven & knit is same as fabric breaking and bursting strength respectively.

Reasons for poor seam properties: Yarn slippage occurs in fabric along a seam when stress is applied results in pulling out of yarns but thread & stitch doesn't rupture. Seam slippage is usually caused by poor fabric design (too loose of a weave) or too narrow of a seam margin. Not using enough stitches per inch & a poor stitch balance can also contribute to seam slippage.

Recommendation for improvement: If fabric construction or weave is loose then drastic improvements are difficult. Seam Slippage can be marginally improved by increasing the SPI (Stitches per Inch) & Seam margin. If it is failing by Single needle stitch, then can try with Double needle stitch.

d) Pilling resistance: Pilling is serious problem of textile industry. A finished fabric may have pleasing handle & smooth surface but when converted into garment & while wearing & as well as washing pills are formed due to rubbing action. First entanglement of loose fibres which protrude from surface takes place; this further appears like a ball anchored to fabric surface through unbroken fibre.

Recommendation for improvement: Selection of fibres: Manufacturing of yarn & fabric based on low pilling tendencies. Prevention of abrasion during batch processing by using suitable lubricant in pre-treatment as well as in dyeing process is necessarily required. Shearing & cropping with brushing to eliminate surface fibre & protruding fibres Singeing on both surface to remove surface fibres.

e) Colourfastness to light: It is resistance to degradation of fabric dyes & prints due to light is an important requirement of a garment because without such resistance, garment may change colour & such colour may not be acceptable to a consumer from an aesthetic point of view. Samples are placed in special holders & exposed to artificial daylight produced by a special light source which mimics action of sunlight, but in a more intense manner so as to speed up fading effect. A standard (blue wool reference) is also exposed with sample & colourfastness is being assessed by comparison of colour change of exposed portion to unexposed portion of test specimen using scale or blue references used.

Recommendation for Improvement; Here regarding colour fastness to light, there are certain controllable & uncontrollable factors. Uncontrollable factors are Light, Environmental factors such as temperature & relative humidity & controllable factors are chemical reaction of fading reaction, degree of dye association with fibre, diffusion characteristics of fibres, chemical nature of fibres, contaminants, delustrants, UV stabilizers & finishes. Thus by improving certain processing conditions & by using good type of stabilizers & finishes improves light fastness.

Tab-1: Average water consumption by fibre type Sl. noFibre typeConsumption (l/kg)Remarks

19661975

01Wool15055075300

02Cotton10030050200

03Synthetic-polymer2520010100

Tab-2: Water consumption by processSl. noFibre type Process Consumption (l/kg)

01Cotton Scouring 10-80

Bleaching 10130

Jig dyeing 10-60

Winch dyeing 100450

02Wool Hank dyeing 40-65

03Synthetic-polymer Fabric dyeing 65190

04Acrylic Garment dyeing 100-230

05Wool Sock dyeing 265465

06NylonSock dyeing 125150

Hose dyeing 100-240

07Wool Loose stock dyeing 40-60

08Cotton Continuous dyeing 60-80

Yarn dyeing 100-140

Printing 140200

Fabric dyeing 100180

Garment dyeing 80140

Tab-3: Measures to reduce water consumptionSl. noMeasures to be taken

1) Development of efficient standard operating procedures (SOP)

2) Following SOP exactly, assisted by automation

3) Installation of machines operating at low liquor ratios

4) Operating at minimum liquor ratio by processing full machine loads

5) Monitoring liquor levels, assisted by automation, to avoid overfilling

6) Improved production scheduling to avoid unnecessary machine cleaning & downtime

7) Replace direct heating by heat exchangers to avoid liquor volume increases

8) Control rate of flow of cooling water through heat exchangers

9) Return cooling water from closed-coil systems

10) Use of water-soluble lubricants to eliminate separate scouring

11) Combine processes or use one-bath methods whenever possible

12) Avoid after-treatment or excessive rinsing, especially overflow rinsing

13) Allow drainage time between rinses

14) Adopt counter-current rinsing methods in continuous processing

15) Reuse relatively clean rinsing water for processes not requiring high-quality water

16) Partial purification and bath reuse

17) Total water purification and recycling

Tab-4: Water usage & pollution loads in cotton finishing processesSl. noProcessWater usageApprox. BOD(mg/l)BOD(%)Pollution load(%)

(l/kg) (%)

01Desizing 205450022>50

02Scouring 41110005410-25

03Bleaching 18046100053

04Mercerising 7230