Overall process of Denim

1. Welcome to my presentation
on
Denim
Submitted to:
Shamsuzzaman Sheikh
Assistant Professor, Dept. of
Textile Engineering
Submitted By:
Md. Tariqur Rahman
Student ID: 135042
Dept. of Textile Engineering
1/14/2019 1

2. Contents
• Introduction
• What is denim?
• Types of denim
• Special commercial fabrics
• Raw materials of denim
• Process sequence of denim
• Dyeing of denim manufacturing process
• Process sequence of indigo dyeing
• Different units of Re-beamer
1/14/2019 2

3. Conts.
 Flow chart of indigo dyeing
 Chemistry of denim dyeing
 Process control of indigo dyeing
 Sulphur bottoming
 Control of Sulphur bottoming
 Darkest indigo shades
 Light indigo shades
 Dark indigo shades
 Sulphur topping
1/14/2019 3

4. Conts.
• Sizing in denim manufacturing process
• Sizing operation influenced by following factor
• Sizing agents
• Sizing units in denim manufacturing
• Weaving in denim manufacturing
• Typical denim weave
• Types of selvedge
• Defect in denim weaving
• Denim wash
1/14/2019 4

5. Conts.
• Stone wash
• Finishing in denim manufacturing
• Types of dry process
• Inspections procedure
• Quality standard
• Off line quality control
• Cost analysis
• Production planning & control
1/14/2019 5

6. Introduction
Denim is one of the most fashionable clothing items of all time. People
love practical, comfortable and stylish things and denim is definitely
characterized by these. Denim is a type of cotton textile known for its
use in blue jeans and other clothing. It uses a sturdy twill weave
characteristics diagonal ribbing. Originally used for women’s cloth.
1/14/2019 6

7. What is Denim?
Typically denim fabrics are woven from coarse indigo dyed cotton yarn.
 They are hard weaving high density fabrics with a high mass per unit
area.
 Denim is produced more in the world than any other type of cloths.
 It is made for a variety of application and in a wide range of qualities and
shades.
 Even today classic denim is still dyed with indigo.
 It is a special process in which only the surface of warp yarn is dyed and
the weft stays white.
1/14/2019 7

8. Types of Denim
The most popular variants are
 Stone Wash and Double Stone Washed Denims
 Chambrays
 Fancy Multicolor Denims
 Denim with metal effect yarns
 Elastics Denims
 Printed Denims
 Jacquard Patterned Denims
 Denim with Fancy Yarns
1/14/2019 8

9. Special Commercial Denims
 Basic or Regular Denim
 Ring Denim
 Slubs Denim
 Cross hatch Denim
 Stretch Denim
 Poly Denim
1/14/2019 9

10. Raw Materials of Denim Fabrics
o Minimum staple length: 2.7 cm
o Proportion of short fibres: under 40%
o Micronaire value: 4.0 to 4.5
o The usual count range of denim warp yarns is 50 to 90 Tex and weft
yarns is 75 to 120 Tex
o Twist factor: 4.5 to 5.0 for warp yarns, 4.2 for weft yarns
o Low yarn hairiness
o Yarn strength and uniformity
1/14/2019 10

11. Process sequence
 Garments loading with stone
 Desize
 Rinse
 Stone wash
 Rinse
 Soften
 Tumble Dry
 Unload
 Extract
1/14/2019 11

12. Dyeing in denim manufacturing process
• Rope dyeing
The indigo rope dyeing technology for denim production is considered
a superior dyeing technology, where better uniformity of dyeing is
achieved than other indigo dyeing technologies like slasher dyeing was
started in USA.
1/14/2019 12

13. Process sequence in indigo rope dyeing in
denim
• Pre-scouring
The following agents normally used in pre scouring
1. Caustic Soda
2. Wetting agent
3. Sequestering agent
• Hot wash and cold wash
After hot wash, the yarn ropes are fed through a cold wash bath to
bring back to its room temperature.
1/14/2019 13

14. • Dyeing
The ropes are then fed into the indigo dye baths and skyed after each
dip. There is a need of repeated dipping of 6-8 dye baths with multi dip
and multi nip facility to increase the penetration. The dyeing is done on
room temperature, and oxidation is done bye air.
• Washing
After the dyeing process the ropes of yarns are rinsed several water
baths to remove any unfixed dyes. Rubbing fastness of indigo can be
improved through washing.
• Drying and Colling
After the washing, the ropes are dried by hot cylinder and coiled in can.
1/14/2019 14

15. • Re-beaming
Once the warp yarns are rope dyed, it is then necessary to change the
yarn alignment from to a sheet form a rope form to a sheet form before
entering the next process, which is slashing or re-beaming.
1/14/2019 15

16. Different units of Re-beamer/ long chain
beamer
• Tension stand
• Accumulator
• Open sheet accumulator
• offset roll rope accumulator
• Deep groove pulley rope
accumulator
• Beater bar and comb
• Stop motions
• Drop wire stop motions
• Electric end break detector
• Camera Scan system
1/14/2019 16

17. Flow chart of Indigo dyeing in slasher/ sheet
dyeing range
• Pretreatment (1 bath)
• Washing ( 2 bath)
• Dyeing ( 6-10 bath)
• Washing ( 2-3 bath)
• Pre-dyeing
• Sizing (1-2 bath)
• Drying
1/14/2019 17

18. Chemistry of denim dyeing
The used colour technologies on warp dyeing machines “today” are:
• Indigo
• Sulphur
• Indanthrene
• Reactive
• Direct
• Naphthol
• Pigment dyeing
1/14/2019 18

19. • Pure indigo/Regular indigo
• Sulphur bottoming/Dark indigo
• Sulphur topping/Blue black
• Pure Black
• Sandwich/ Black-Blue-Black
1/14/2019 19

20. Process control in indigo dyeing
• Pretreatment
Pretreatment is conducted in the 1st tank. The most common pretreatments
are:
1. Sulphur bottoming
The purpose of Sulphur bottoming are
• Originally to produce a dark shade on denim using less indigo for lower
costs
• In the USA Sulphur bottoms were dyed using a combination of blue and
black dyes.
• In denim operations outside the USA the bottom is normally dyed with
Sulphur black.
1/14/2019 20

21. 2. Scouring with sodium hydroxide
• Cotton fibres contain impurities like waxes, pectins and minerals that
will interfere with indigo dyeing and result in streaks.
• Sodium hydroxide at concentration (<5%) are applied at high
temperature (>850 C) in order to remove impurities and melt natural
cotton waxes.
3. Causticizing
• Causticizing generally refers to using sodium hydroxide at below
Mercerizing Concentration (18%)
• Cold causticizing of cotton yarn results in faster indigo dye fading from
laundry abrasion, darker indigo colour with the same % of indigo and
unique washdowns.
1/14/2019 21

22. 4. Mercerizing
• Mercerizing is the use of strong sodium hydroxide (18-30%) to swell
surface fibres.
• Mercerized yarns are more ring dyed and darkly than non-
mercerized.
• Mercerizing is normally conducted at low temperatures, but hot
mercerizing can be employed for a more abraded appearance after
garments laundering.
1/14/2019 22

23. Sulphur bottoms
• Bottoming of indigo dyed yarns produces a darker , brighter effect
with indigo.
• The purpose of bottoming originally was to produce a darker color
with less indigo.
• While large amounts of Sulphur dye can be applied in first box, most
of the Sulphur is removed by hydrosulphite in the indigo dye.
• Unlike other Sulphur dye applications, a PH of 12 with sodium
hydroxide is needed to retard the dyeing for colour consistency.
• A temperature of 600 C or less should be used to lower the affinity
factor for consistent colour.
1/14/2019 23

24. Control of Sulphur bottoming
• The typical methods used for dyeing Sulphur bottoms result in denim
shade differences.
• When applied as light colours, sulphur dyes should be dyed at
temperatures <600 C If dextrin reducing agents are used which require
850 C, there will be variation
• Sulphur bottoms are an exception to the normal PH for Sulphurs (11),
requiring 12.
1/14/2019 24

25. Darkest indigo shades
• Very dark shades of indigo are in demand currently around the world.
• Many companies use 4% or more indigo on weight of yarn, which is
expensive.
• 2% will produce same depth if low levels of caustic are used (0-0.4%).
• For dark indigo that does lose colour 2% applied normally, with an
indigo bottom.
1/14/2019 25

26. Light indigo shades
• Dyeing indigo in light shade results in a sky blue impossible with any
other dye.
• This is useful for shirting fabrics that are not strong enough for stone
washing, bleaching or cellulase treatments.
• Special procedures are necessary in order to avoid colour fastness
problems.
1/14/2019 26

27. Dark indigo colour
• There was am example of a typical method used for dark shade
below.
• In order produce same depth colour as 1.2% in the USA, in Latin
America 2.0% is used and in Asia from 2.4-2.8%.
• The USA method results in more surface ( Ring Dyeing), which loses
colour faster.
1/14/2019 27

28. Sulphur topping
• In topping, the Sulphur dye is applied after the indigo dye.
• Sulphur topping permits much darker colour than Sulphur bottom,
but is duller.
• Sulphur topping colours include black, blue-black, yellow-brown, and
green.
• Sulphur topping are used to produce slub apparence in normal air.
1/14/2019 28

29. Sizing in Denim manufacturing process
Requirements of sizing
• Adequate friction resistance and yarn strength
• High and uniform residual stretch and a uniform warp yarn tension
1/14/2019 29

30. Sizinig operation influenced by the following
factors
• Type of fibres (Natural, regenerated, synthetic fibres)
• Type of spinning (Filament, OE, Ring, Twisted yarns)
• Spinning characteristics
• Yarn count
• Yarn condition
• Yarn Quality
• Viscosity
• Liquor pick up
1/14/2019 30

31. Sizing agents
• Carboxymethylcellulose and carboxymethyl starch
• Modified starch
• Native starch
• Polyacrylates
• Polyester
• Polyvinyl Alcohol
1/14/2019 31

32. Sizing unit in Denim manufacturing
• Creels-unwinding zone
• Size boxes – sizing zone
• Drying cylinders- Drying zone
• Bust rods – Spliting zone
• Head stock – weavers beam preparation zone
• Controls and instrumentations
1/14/2019 32

33. Weaving in Denim manufacturing process
• Weavers beam with let off motion
• Back rest
• Drop wire (to detect warp breakage)
• Heald frame
• Shading
• Reed
• Feel of the colth (beating)
• Take up
1/14/2019 33

34. Typical denim weaves
• Regular twills (3/1 RHT, 3/1 LHT)
• Zigzag or Wavy twills
• Broken twills
• Herringbone Twills
1/14/2019 34

35. Types of selvedges
• Tucked selvedges
• Leno selvedges
• Fused selvedges
1/14/2019 35

36. Defects in Denim weaving
• Open reed
• Slack end
• Clocked yarn
• Sloughed filling
• Miss pick
• Under shot
• Filling floats
• Hang pick
• Kinky filling
• Harness misdraw
• Double end
• Burl
• Knot
• Thick place
• Warp float
• Dropped picks
1/14/2019 36

37. Denim Wash
• Gives aesthetic finish
• Enhances the appeal
• Provides strength
• With time the fabric will fail in a manner similar to that which
artificially distressed attempts to replicate.
• With dry denim however such fading is affected bye the body of the
person who wears the jeans and the activities of their daily life.
• This creates what many feel to be a more natural, unique look than
pre distressed denim.
1/14/2019 37

38. Stone Wash
• During washing this stones scrap of dye particles from the surface of
the yarn of the denim fabric which shows a faded, worn out and
brilliance effect in the denim fabric.
• Due to ring dyeing of denim fabric and heavy abrasion during stone
washing, the fading is more apparent but less uniform.
• Stone washing makes the denim garments more supple so that it fits
comfortably.
1/14/2019 38

39. Finishing in Denim manufacturing
Typical finishing line of denim
fabrics
• Input J-box with pulling unit
• Brushing and beating unit to
remove dust from fabric
• Singeing unit
• Impregnation tank with squeezer
• Weft skewing unit
• Can dryer
• Clip tentering unit
• Compressive rubber belt unit
• Shrinkage unit
• Felt Calendar
• Exist j-box
• Surface winder
1/14/2019 39

40. Types of Dry Process
• Hand Sand
• Sand Blast
• Whisker
• Laser whisker
• Destroy
• PP spray
• Tagging
• Grinding
• Crinkle
• 3D crinkle
• PP rubbing
• Resin spray
• Heat pressing
• Pocket marking
• Seam marking
1/14/2019 40

41. Sequence of singeing
• The cleaning step in front of the singer
• The singeing itself and
• The cleaning step afterwards
1/14/2019 41

42. Sizing parameter:
Capacity of cooking tank:1000 Ltr
Cooking temperature:85c
Cooking time:25-50 mins
Pick up:5-10%
Cylinder temperature:110-130c
Squeezing pressure:
Lowest:12-17 kN
Highest:15-20 kN
Stretch:0.7-1%
Viscosity:12-13 see1/14/2019 42

43. Inspection procedure
As the fabric is produced by the air jet loom it is then collected by the
quality inspector and the fabric is thoroughly inspected in front of a
white light board.During this inspection the holes ,oil marks,reed
marks,loom bars,temple mark,double end,double pick,tight warp,lose
warp,faulty denting,faulty drawing are checked.if the fabric is within
the acceptance level then it is sent to the garment section for further
treatment.
1/14/2019 43

44. Quality standard
Amber denims Ltd.follows the four point grading system to inspect the
body of the fabric.In the four point system the faults are found by
inspection and are given points against the fault.Then the total number
is calculated.
Size of defects Penalty point
3 inches or less 1
Over 3 inche but not over 6 inch 2
Over 6 inche but not over 9 inch 3
Over 9 inch 4
1/14/2019 44

45. Off line quality control
GSM test
Shrinkage test
Shade check
Wash fastness test
Fastness to water
Rubbing fastness test
Perspiration test
Durability test
Dimensional stability test
1/14/2019 45

46. Cost analysis
Costing of a product includes
Yarn cost
Weaving cost
Dyes and chemical cost
Cost of dyeing
Cost of finishing
Cost of cutting
Labour cost
Office and administrative cost
Others cost
Factory cost
1/14/2019 46

47. Production planning & control
Basic procedure of production planning and control
Taking order from marketing division
Analyzing the order
Planning for dyeing the yarn
Planning for weaving the fabric
Planning for finishing the fabric
1/14/2019 47

48. Thanks to all
Query please…????
1/14/2019 48