RFT in Reactive Dyeing

A Journey towards

RFT (Right First Time) Processing in Exhaust Dyeing

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Aiming at Blind Dyeing in Dye-houses Industry Trends Garment Manufacturers and Retailers

Consumers Choice Fabric performance Colour fastness

Increasing

Increasing Decreasing

Number of fashion Trends Range of fabrics Colour changes Environmental pressure Colour Fastness Requirements Order size Repeat orders Lead times

Value for money

Which ultimately trends in increasing Production Cost and reducing Profit margins

Effects on Dyehouse Increasing

Energy costs Water and effluent costs Labour costs Number of Competitors Retailer’s knowledge of process costs

Create additional pressure on Production Costs ‘Performance for Profit’

q How much is performance affecting the profitability? -Impact of Right First Time performance -Benefits of true dyestuffs & user friendly Processes -Achieving high standards of process control

q Can we meet retailer needs with cost-effective approaches? -Optimize dyestuffs Selection to meet exactly customer needs

Main Focus of Standard Operating Procedures 1.

Review Industry Trends

2.

Impact of RFT

3.

Dyeing Performance

4.

Optimizing dye selection

5.

Process Technology for different Substrates

6.

Process Selection

7.

Process Control

8.

Control Parameters

9.

Test procedures

10.

Determine effectiveness with ‘on-line’ control

11.

Usage of software to make technology user friendly

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Control Options

q

Assignable variables

Measurable factors that influence dye performance can be controlled: 1. Liquor ratio 2. Internal fabric pH 3. Fixation temperature 4. Specific gravity (salt concentration) 5. Addition profile 6. Fixation pH 7. Time

q

Random variables

Factors that require intervention of management to effect control of Impurities in: 1. Cotton 2. Water supply 3. Chemicals eg QC of raw materials 4. Controlled Coloration concept

RFT (Right First Time) Performance & Setting Specifications

q

Measures of performance

Shade Reproducibility - Lab to bulk CMC 2:1 delta E 1.0 - Bulk to bulk CMC 2:1 delta E 1.0 Level Dyeing - Average throughout batch, piece to piece CMC 2:1 delta E 0.3 Colour Fastness - Customer specific - Washing, Repeat Washing, Rubbing, Light

q

Non-conformance - Off shade-Lab to Bulk-needs shading addition - Off shade-Bulk to Bulk-needs shading addition - Unleveled-side to side variation, shading or patchy - Fails in Q.C Test-staining, fading - Combinations of the above

The Benefits Of Right-first-time Financial

Non-financial

Lower Costs per Batch Increased Output Improved Profit Margin

Enhanced Customer Service Improved Quality of Goods Reduced Effluent Load

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Cost Management in Dye-houses Cost control comes from optimization & profit comes from improved performance Model of costing for average colour Cotton Knit Processing 1.

Dyes

25%

2.

Chemicals

15%

3.

Wage & Salary

15%

4.

Capital Investment & Other Overhead

13%

5.

Energy

15%

6.

Water

10%

7.

Depreciation

7%

Capacity : 2 batches/day working 7 days a week

Cost of Non-conformance-for Cotton Exhaust Processing

Process

Productivity

Cost

Profit

Blind Dyeing

100

100

100

Small Addition

110

80

48

Large Addition

135

64

-45

Stripping & Re-dying

206

48

-375

Cost of Shading (30% of original batch cost) RFT Rate % Cost Additional Cost Total Cost Batches

50 167 12 179 7.0

70 143 9 152 8.4

80 125 6 131 9.8

90 111 3 114 11.2

100 100 0 100 14

10% 9 1.4

20% 17 2.8

30% 23 4.2

40% 29 5.6

-10 2.5

-20 5.0

-30 7.5

-40 10

Increasing Productivity Increase in Productivity Reduction in total cost % Additional batches/week

Reducing dye costs % dye costs Saving on total cost %

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70% Plant Utilization @ 90% RFT Number of batches/week at % utilization

9.8

New Total Cost at % utilization

80.5

Actual number of RFT batches

8.8

Additional cost at 90% RFT rate

9.0

Total cost

89.3%

70% Plant Utilization @ 70% RFT Number of batches/week at % utilization

9.8

New Total Cost at % utilization

80.5

Actual number of RFT batches

6.9

Additional cost at 70% RFT rate Total cost

12.0 92.5%

Reducing dye costs and lower RFT (70 to 60%) %Cost Reduction

10

20

30

40

Saving on total cost % Additional cost at 60% RFT

2.5 24

5.0 25

7.5 28

10 29

Summary

q Increasing RFT from 70 to 90 % reduces costs by 32% q Increasing Productivity by 30% reduces cost by 23% q Reducing dye costs by 30% only saves 7% q Combined effect of increasing RFT from 70 to 90% with increase in Productivity of 30%,

even with 30% higher dye costs reduces total cost of production by 44% q As a bonus additional ‘opportunity’ margin can be generated from increase in productivity.

Impact of RFT on Cost 250

Effect on Cost

200

150

S e r ie s 1 100

50

0 50

55

60

65

70

75

80

85

90

95

100

R F T P e r f o r m a n ce

Conclusions

q Performance of dyestuff combinations is critical to cost and profitability of dyeing operation. q Selection of the most suitable combination is essential for success. PDF created with pdfFactory Pro trial version www.pdffactory.com

Scouring and Bleaching Process 95-105°C

30’

10’

80°C X 10’

10’

80°C

40°C

10’

overflow

Acetic Acid Peroxide Killer-Enzymatic (Catalase based)

Chemicals 1.0 g/l Anionic Detergent ( Remove dirt )

Pre-dyeing Check:

Ø Fabric temperature should be lower than

0.5 g/l Nonionic Detergent ( Remove Oil & Fat ) dyeing temperature. Ø No H2O2 is left in fabric. 1.0 g/l Sequestrant-High alkali stable Ø pH of fabric should be within 5.0-6.0. 1.0g/l H2O2 Stabilizer-Organic 3.0 g/l Hydrogen Peroxide(50%) 3.0 g/l Caustic Soda 38°Bé ( NaOH 38°Bé )

Audit and Trials Equipment 1. 2.

Hardness Test Papers pH Meter or pH Papers

3. 4. 5.

Thermometer preferably an Infra Red one. Peroxide Test Papers Hydrometer 1.000-1.100

6.

Universal Indicator Solution

Fibre pH A simple & quick spotting test with pH indicator solution is done. A slightly acidic state avoids premature fixation during migration phase of dye application. So, Ideal pH of fibre after neutralization is to be 5.0-6.0

Residual Hydrogen Peroxide Hydrogen Peroxide in dyebath can reduce dye yields and result in poor shade reproducibility. So, carry over of residual Hydrogen Peroxide to Zero.

Fibre absorbency Simple drop test with any temporary colouring liquid (i.e Potassium Permanganate Solution) can confirm fibre absorbency property.

Salt Concentration Confirm Salt concentration with a Hydrometer & SG Charts. Specific gravity is influenced by temperature, so always confirm with a thermometer with Tolerance +/- 5% from target SG Note: ‘portion-wise’ salt process does not allow this test

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Liquor Ratio Confirming Liquor Ratio Assumed volume X Expected salt Concentration Actual Volume = --------------------------------------------Measured Salt Concentration Controlling Liquor Ratio and Salt concentration optimizes shade reproducibilty ensuring highest RFT production performance.

Dye-bath Temperature Accurate control of dyebath temperature ensures best possible shade reproducibility. Every after certain period calibrate controller, adjustment needed with an Infra-red one if required.

Reproducibility between lab and bulk

q q q q q q q q

Same fabric ? Same pretreatment (weight loss, ...) ? Same liquor ratio ? Same salt quality and concentration at same temperature ? Soda ash quality ok ? Same caustic soda concentration ? Temperature indicator at lab equipment and dyeing machine ok or regularly calibrated? Right lab method for simulating the bulk process

As per different impurities content in greige cotton, scouring recipe to be adjusted to achieve required scoured fabric. For this reason, depending on shade depth, required specification for scoured fabrics (ready for dyeing) to be numerically pre-determined. Such as: a) Fabric GSM b) Whiteness value of Scoured fabric depending on shade depth. c) Absorbency grade of Scoured fabric of specific GSM. d) Different metal ions contents & total hardness.

Water quality & Standard Textile Process water Water contamination is constantly varying, so check it timely. Is water treatment effective? Is water free from vegetable, suspended solids & other mineral impurities? Hardness contaminants in dyehouse water can adversely effect level dyeing, shade reproducibility & wash off performance. Ø pH: 6-8 Ø Hardness: max. 5 °dH Ø Suspended matter: