Indigo or slasher dyeing


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Indigo or slasher dyeing

  3. 3. IntroductionIntroduction
  4. 4. Denim is the oldest, most widely used, most fashionable and most versatile fabric of the world. At present denim is mainly used for producing garments particularly trousers for the young people. The gross production of denim fabric is approximately 3,000 million metres per year. Denims are produced from 4 oz. to 16 oz./ sq. yds in weight. Technically Denim is defined as a 3/1 warp faced twill but also produced from weaves like: Left hand twill, right hand twill, broken twill, cross hatches, cords, dobby's, structures, etc . Denims are made from yarn dyed warp and undyed weft. Traditionally, denim was dyed with various shades of indigo, yarn-dyed, different costs, and over-dyed with various types finishes at fabric as well as garments state. Denims are manufactured different types of after treatments or washes like stone wash, bleach wash, hand wash, acid wash, over dyed, printed denims and even embossed. Denim fabrics are used as jeans trousers both for men and ladies. It is extensively used in the world as casual garments, Shirts, jackets, children wears are also made of denim fabrics. Its versatility, finds applications in furniture upholstery, bed covers, curtains, etc. Denim now-a-days is a very demandable product. To make a denim fabric the required yarn for the definite construction should be dyed then make a weavers beam to go to weaving to make fabric.
  5. 5. TYPE OF FABRIC :TYPE OF FABRIC : Normal Fabric Ring Fabric Half Cross Fabric Cross Latch Fabric FABRIC IDENTIFICATION : Normal Fabric = 6 OE * 6 OE / 66 * 35 Ring Fabric = 6, 9, 12 * 7 OE / 66 * 35 Half Cross Fabric = 6 slub * 7 OE / 66 * 35 Cross Latch Fabric = 10 slub * 10 slub / 66 * 35 TYPE:
  6. 6. 'Some typical denim fabric construction: Description Wt oz/yd2 Construction: Finished Fabric Desig n 100%Cotton indigo Half Cross Denim 6 89X55/20RsX16R+16R s 2/1 RHT 1 00%Cotton indigo Ring OE 8 77X49/13RX12R 2/1 RHT 100%Cotton indigo Vertical Slub 7.25 68X49/1 ORsX20K i2/IRH T 100%Cotton light Indigo Slub Lucky 6.50 79X49/1 6RX14Rs 2/1 RHT 98.5%cotton 1 .5%lycra park indigo stretch slub 11.50 65X46/7.5RsX8+70D 3/1 RHT 100% Cotton indigo normal 12 10 OE+10 OE*12 OE/69*44 2/1 RHT 100% Cotton indigo 12.10 9 Rs+ 9 R * 7Rs + 7R/ 72 *48 3/1 RHT 100% Cotton indigo 11.65 8 Rs + 9R* 8Rs (MC) / 68 *50 3/1 RHT 100% Cotton indigo 9.8 9 OES+ 9 OE* 10 OE / 75 * 43 2/1 RHT
  7. 7. Most of the denims are produced with 100% cotton and cotton-based blends with Lycra®, Polyester, Tencel®, Bamboo, Jute, Nylon, and Linen etc. An ideal cotton mix for denim should have the following quality parameters. 2.5% span length > 25mm Strength (g/tex) >18 Micronaire > 4.5 to 5.0 Maturity Coefficient >0.75 Uniformity Ratio> 49% Trash> 4.9% In Bangladeshi mills, in most cases substantial quantity of waste yarns are used. This is mainly done to reduce the cost of production. A well established mix for denim yarns are as follows; i. 80% waste, which consists of (i) Dropping-1, (ii) Dropping-2, (iii) Flat strip, (iv) Comber noil. ii. 20% Fresh Cotton FIBRE
  8. 8. YARN (i) Rotor yams are the best and most widely used yarns in Denim production. Because of their very high speed rotor yams are much cheaper than ring spun yams. Off course rotor can only produce yarns of up to 30Ne. Though cheap rotor yarns are associated with greater imperfections than corresponding ring yarns therefore knit goods are produced from ring yarns. (ii) Count range from 6 to 16 Ne but most widely used range is 7 to 12 Ne. For slub yarn the range is 9 to 20 Ne. (iii) Quality- Counf CV-<1.2, Single yarn strength> 12.8 gm/tex, Elongation> 6.0,U% <9.5. (iv)As huge amount of slub yarns are used today the idea of too much strict U% is not considered. The diameter of slub varies froml.SD to 2.2D (Where D is the normal dia of yarn). The periodicity of slub also varies widely. Test results show mat the distances between two adjacent slubs varies within certain range. Some of the usual range distances between two adjacent slubs are from 6cm to 10cm, 7 cm to 20 cm, 30cm to 60cm. Some more information on yarns are given in weaving section later
  9. 9. Fig: Creel stand with creel
  10. 10. Fig: Unwinding of creel
  11. 11. Fig: Warpers beam The thread from the packages in the creel is wound on to a beam to make warp beam.
  12. 12. PARTICULARS OF A DIRECT WARPING MACHINE Setup parameter >• * Range Set value Warping Length 1 -99,999m Based on quantity yarn count, warping beam, capacity Cone/Cheese no. in the creel ! 325-410 Based on customer fabric construction Machine speed l- 800m/min 650 m/min; Based on yarn count and quality Length correction % 1 156% Stop motion I m- second Don't need Supply Pressure 1-8 bar 5 bar Beaming Pressure 1-160 40psi Press Pressure 1-160 30psi Carrier Pressure 1-160 50/55 psi Hydraulic Pressure 0-40 16Psi
  13. 13. Normally the process of dyeing dictates the technology of denim manufacturing. The following twoDyeing methods are most popular processes for manufacture of denim SLASHER DYEING: Slasher dyeing dyes the yarns in the warp beam form. It is a continuous process which combines dyeing & sizing in a single operation. Dyeing is done by continuously passing warp yarns through several (at least 5) troughs of indigo dye liquor. The dyed yarns are then sized & wound onto a warp beam to be ready for use in the weaving process. Slasher dyeing is usually of inferior quality as compared to rope dyeing shade evenness or side-to-side shade variations. With the slasher dyeing, the penetration of dyestuff is poorer, and it is easily reveals an uneven pick-up along its width with the distortion of the pad-roll.
  14. 14. Fig: Diagram of Slasher Dyeing
  15. 15. FLOWCHART OF DYEING & SIZING: Warper’s Beam ↓ Pretreatment (Scouring) bath ↓ Dryer- wash bath (1, 2, 3) ↓ Color box - 1 ↓ Dryer - 1 ↓ Color box- 2 ↓ Dryer - 2 (Air oxidation is done here) ↓ Color box - 3 ↓ Steam box ↓ Color box - 4 ↓ Yarn pass between a set of guide roller for oxidation ↓ Color box - 5
  16. 16. ↓ Oxidation ↓ Color box - 6 ↓ Guide Roller ↓ Color box - 7 ↓ Oxidation ↓ Color box - 8 ↓ Oxidation ↓ Wash box (1, 2, 3) ↓ Dryer ↓ Sizing box ↓ Dryer ↓ Accumulator ↓ Leasing ↓ Winding ↓ Weaver’s beam •Type- Sliding creel •Arrangement- Two creels are placed parallel to each others. •Creel capacity-16 warp beams can be placed in each creel. •Electronic motor is available to slide the creel as well as mount the beams. Beam creel section:
  17. 17. Fig: Beam creel Capacity of cooking tank: 1000 Ltr Cooking Temperature: 85º Cooking time: 25-50 mins Pick up: 5-10% Cylinder temperature: 110- 130ºc Squeezing Pressure: By top roller Delivery squeeze pressure: Lowest: 12-17 kN Highest: 15-20 KN Stretch: 0.7-1% Refractro reading: 7-11% Viscosity: 12-30 sec Sizing Temperature: 85-90ºc Sizing BATH: No of dry cylinders used in this bath = 12 Sizing parameter:
  18. 18. Fig: Sizing Tank Scouring: Natural fibers contain oil, fats & waxes together with other impurities. During manufacturing oil & adventitious dirt are collected. And these are affected the absorbency of the cloths & leads to uneven dyeing. Oil, fats & waxes are all insoluble in water; they dissolve in organic solvents such as Chloroform, Ether and Petrol etc. Scouring is the process to remove all these impurities to make a more absorbent, hydrophilic & clean fabric. OBJECT: 1. 01. To remove natural & added impurities like oil, wax, gum, fatty material as completely as possible. 2. 02. To get a clean & even fabric surface for the next process. 3. 03. To increase the absorbency of the fabric, i.e. to make the fabric hydrophilic, so that it can absorb dye molecule, water & other processing easily. Scouring Recipe: NaoH= 36-145 gpl or g/l Wetting agent (Lionil EH) = 0.5g/l Temperature=85ºc Water = 1400 liter Squeezing roller pressure = 4-5 bar
  19. 19. FUNCTION OF THE CHEMICALS USED IN SCOURING: 1. Alkali: It converts the oil into water soluble fatty acid & soap. 02. Wetting agent: A soluble or dispersible material that reduces the surface tension between the material & liquid. Detergency effect helps to clean the material. 03. Sequestering agent: It reacts with metallic ions & thus makes the metallic compounds to become a part of complex anion. DYEING: Dyeing is consists of 2 dyes. The indigo blue & Sulphur black is used in the dyeing process of denim. Sometimes brown color is used instead of indigo blue in the factory according to the requirement of buyer. DYEING RECIPE: For leuco preparation here is a ratio which is followed: Indigo : 100 g/l Caustic Soda : 73 g/l Reducing agent : 93 g/l Dispersing agent : 0.5 g/l Sequestering agent : 0.5 g/l Wetting agent : 0.3 g/l
  20. 20. For black preparation the following ratio is followed: Black : 35 g/l Caustic Soda : 15 g/l Antioxidant : 15 g/l Sequestering agent : 0.5 g/l Wetting agent : 0.5 g/l Dyeing Process: Dyeing process that is maintained as follows: Pure Indigo- Continuous Indigo Dyeing Bottoming- Sulphur(Bottom) & Indigo(Topping) Topping- Indigo(Bottoming) & Sulphur (Topping) Black Denim-Continuous Sulphur Black Dyeing Color Denim.
  21. 21. LIST OF SOME CHEMICALS ARE USED & AND THEIR FUNCTION: Pimazol ws: Use as pre-wetting agent to reduce the surface tension of the liquor and allow to penetrated in to the fibers. Sodium Hydrosulphite / Hydrose: It is a reducing agent. It converts the insoluble vat dye to soluble leuco form & also to remove dissolved oxygen from water. Na2S2O4 + H2O + [O] = 2NaHSO3 Specification: ISO 9001, ISO 14001, OHSAS 18001 Purity = 90% min Country = China Caustic Soda: It is scouring agent and removes impurities from the fiber. It is used here as pH controlling agent. NaHSO3 is produced in the vatting bath which has the tendency to destroy leuco compound. To remove NaHSO3, alkali is used. NaHSO3 + NaOH = Na2O3 + H2O Specification: “Caustic Soda Flakes’’ NaOH =96%min Country = China
  22. 22. Ladiquest: It is a sequestering agent and use to remove the hardness of water. Specification: Name = 1097 – U liq Country = Thailand Setamol-Ws: It is a dispersing agent. It is used to disperse the dye molecule properly in the dye solution. Specification: Manufacturer = BASF Country = India Persoftal BD (Paste): It is a softener, used to soften the fabric in the finishing process. Antioxidant: It is used to protect oxidation of dye molecule in dye bath. It is used as reducing agent while Sulphur black is used. It is also known as monohydrate glucose. Acetic Acid: It is used to reduce the percentage of pH in dye bath. Specification: Name = Acetic acid Glasiroyal Composition: Acery = 99% Water = 0.7-1 % Acetic anhydride = 0.3%
  23. 23. SIZING Sizing Mills coat yarn with polyvinyl alcohol and starch for strength, and paraffin to make it easier to weave into cloth and handle in sewing. It is a film- forming polymeric materials, which is applied to a warp sheet for the purpose of protecting it during the weaving process. Objects:- •To increase the strength of yarn Up to 20% after the size application. •To improve the hairiness, thick and thin places, Neps knots in the warp yarn. •To protect the warp yarn from breakage during weaving process. Which is subjected to abrasion width varies loom parts such as reed heald shaft Shuttle, Splitting rod. Sizing composition depends on the following factors: •Types of fibers •Types of yarn •Yarn quality •Quality particulars of fabric to be woven •M/c condition & ambient condition of the loom shade •Cost of various ingredients
  24. 24. The Starch & Softener are used in the sizing bath are given below: Starch: Emsland E-55 (Modified starch) Emsland E-14 Softener: Mutton Tallow Fin Fix Trefin Wax Starch: These are products from grains & tubers. These are mixture of carbohydrate, oil, nitrogenous substances & mineral matter. Carbohydrate is a polymer consisting of 25% amylase and 75% amylopectin. Structurally it is a highly branched glucose polymer. Starches are cheap & easily available & have proved to valuable adhesives over a many years especially for cellulosic yarns. This is manufactured mainly from maize, wheat, rice etc. When starch is boiled with water, the starch granules swell & break up forming a smooth & homogenous gelatinous mass.
  25. 25. EMSIZE E-55: Application: is a low add –on starch sizing agent for spun yarns Characteristics: Application: is a low add –on starch sizing agent for spun yarns Characteristics: Kind of product: Potato starch derivatives Appearance: Off white powder Moisture content: < 20% pH value (5% conc): 6-8 Viscosity: Preparation of the solution: The required quantity of product is added to cold water. Under stirring the slurry should be heated up till 95ºc and kept for at least 10 minutes at this temperature. Preparation in an autoclave has to be heated up to 110ºc and kept for at least 10 mins at this temperature.
  26. 26. EMSIZE E-14: Application: Emsize is a starch sizing agent for spun yarns Characteristics: Kind of product: High modified polymer Appearance: Off white granules Moisture content: 9-14% pH value (5% conc): 9.5-11.5 Viscosity: Preparation of the solution: The required quantity of product is added to cold water. Under stirring the slurry should be heated up till 95ºc and kept for at least 20 minutes at this temperature. Preparation in an autoclave has to be heated up to 110ºc and kept for at least 10 mins at this temperature. Both the starch has the following common properties: excellent sizing effect transparent flexible film high adhesion power compatible with other sizing agents washed out quickly without enzymes good biological degradability
  27. 27. Modified starch: It is manufactured from natural starches mainly maize. Advantage: They are water soluble. Can gelatinize easily & quickly They penetrate well into the yarn because of their small particle Size, & pick up percentage increases for this reason Mutton tallow: It is prepared from the sheep & is chemically composed of the glycerides of stearic, oleic & palmitic acids.
  28. 28. After warping, dyeing and sizing a weaver's beam is produced. The weaver's beam, after drawing and denting is then mounted in the loom to produce the fabric. Weaving of denim fabric is not much different from weaving all other fabric except the idea about the warp and weft way shrinkage percent. It is well known that fabric shrinks after relaxation and also after any wet process treatment. In order to accommodate the aspect of both way shrinkages it is necessary to use a very decisive EPI and PPI in the loom state so that after relaxation and wet treatments the fabric will conform to the customers supplied fabric details. It was found that in general that the fabric shrinkage percent in the length direction varies from I2%-15% while in the width direction the shrinkage percent lies around 4.5% to 5.5 %. The higher shrinkage in the warp direction is mainly due to greater warp tension during weaving and also due to the coarser weft yams than that of the warp yarns. In order to comply with the customer's requirements it will be necessary to choose both EPI and PPI very precisely so that the final EPI and PPI of the ultimate fabric conform to the buyer's requirement.
  29. 29. The typical reed and picks of some commonly produced fabric is given below; Construction Finish EPI Loom State EPI Finish PPI Loom State PPI Finished Cover Factor warp Cover factor Weft Cover factor 9Rs+9R*7Rs+7R/ 72*48 72 68 48 44/45 26.59 24 18.14 8Rs+9R*8Rs(MC)/68 *50 68 63 50 50 26.04 23.33 17.68 8Rs*10Rs+10R/76*5 4 76 71 54 50 27.56 26.87 17.08 9Rs+9OE*12Rs+10+ 70D/ 78*54 78 64 54 48/49 27.16 26 16.28 8Rs+10R*8Rs+7OE/ 72*50 72 71 50 47/48 26 24 17.68 9OEs+9OE*10 OE/75*43 75 68 43 37/39 26.47 25 13.6 10Rs+10OE*6OE+70 D/ 76*50 76 71 50 44/45 26.93 24.03 20.41 8Rs+7R+10R*9R/72 *48 72 66 48 41/44 26.69 24.94 16
  30. 30. We know Cover factor, Kc =( K1 + K2 – K1*K2/28 ) Where, warp Cover factor, K1 = EPI/√ count And weft Cover factor, K2 = PPI/√ count Denim fabrics are highly sensitive to the fault incidence. Therefore maximum care is necessary at all levels to avoid fabric faults. Normally the loom stoppages are regarded as a serious matter in accumulating fault level. Loom stoppages in turn depend on a large extent on the yarn quality. A recommendation based on research study has suggested the following yarn breakage norms in the warping and sizing department;
  31. 31. Warping Ring yarn Rotor yarn Dyeing Ring yam Rotor yarn End break per million metres l<08 <0.5 End break per million metres 0.2 0.3 Loss of extension <0.5% <0.4% Loss of extension <1.3 <1.3 Imperfection also plays an important role in the production of a fault free denim fabric. The norms for some of the important indicator of yarn quality for denim are given below. ^ Parameter Norms for Rotor Yarns Norms for Ring Yarn Count CV < 1.2% < 1.7% Single Yam Strength > 12.8gm/tex > 14.0gin/tex Elongation > 6.0 > 6% U% j < 9.5 < 10% Total Imperfection < 10 (at 280%) <35'9(At200%) N:B: The CV% can not be applicable to the slub yarns.
  32. 32. GSM Calculation Yarn count = Length (cm) X 0.0059 Wt(gm) Yarn weight = Sample weight X 100X100 / Sample Length X SampleWidthX 33.9063 For example, Construction = 71 X 51 Total yarn = 11 Length of fabric = 3.45cm Weight of fabric = 0.03 gm Count =11X3.45X0.0059 / 0.03 =7.46 Weight = 0.4 X 100 X 1OO X 3.45X2.886X33,9063 =11.83 oz / yd2 Crimp % : Warp Length – Actual Warp Length Production / Warp Length * 100
  33. 33. Shrinkage % : Actual Production – Finishing Production / Actual Production * 100 Fig: Front view of a weaving mc
  34. 34. Fig: weaving mc (Picanol omni plus 800)
  35. 35. Fig: J Box of a finishing mc
  36. 36. Fig: Brushing unit of a finishing mc
  37. 37. Fig: Singing unit of a finishing mc
  38. 38. Fig: Scew roller of a finishing mc
  39. 39. Fig: Drying cylinder of a finishing mc
  40. 40. Fig: Calendering unit of a finishing mc
  41. 41. Fig: Spreading unit of a finishing mc
  42. 42. After weaving, the woven denim fabrics undergo for various finishing processes depending on the end uses. This is because denim fabric produced in a loom is somewhat dirty and very stiff and difficult to make garment from them. Apart from this, the technical specification like width and threads per inch cannot always be achieved straightway from the loom. Therefore some physical and chemical treatments are carried out before delivering the fabric to the customer/garment factory. These processes are discussed under finishing section. Finishing of denim is carried out in both fabrics as well as garment state. The fabric finishing is carried out in the weaving factory where the fabric is produced but the garment state finishing is carried out in the garments washing plant.
  43. 43. Finishing section placed along a line: Finishing Line Fabric Finishing The typical flowchart of the denim fabric finishing is as below Loom state fabric ↓ Brushing ↓ Singeing ↓ Brushing ↓ Softening ↓ Correction of skewing ↓ Compressive shrinkage ↓ Palmer (Calendaring cum drying) ↓ Inspection ↓ folding
  44. 44. Description of the processes: Brushing: The purpose of this process is to remove the lint, fluffs and loose impurities. This is achieved by subjecting the fabric to kind of roller beating action.Singeing: The objective of this process is to burn out the protruding fibres from the surface of the fabric. Only blue side singed and it is done twice. Softening: The aim of this process is to modify the feel of denim fabric and to facilitate the movement of the threads during skewing and shrinkage process. This is just a softening process where the fabric is passed continuously through a solution containing 5gm/Htre softener. Sometimes softener is used as foam form. Use of foam reduces the quantity of heat required to dry the fabric.
  45. 45. CORRECTION OF SKEWING: The 3/1 twill weave is in the classical denim fabric is inherently unstable weave and has a tendency to twist anticlockwise considering blue side as face side to stable configuration when it is put in water. Due to this unstable condition the weft yarns lies with warp yarn at an angle different from 90°. This is regarded as skewing and if it is not corrected then there will be deformation and leg twisting in the jeans made out of it. Therefore skewing is corrected in this section where the fabric is basically passed either over a roller or through two sets of rollers. The basic idea of correction the skewing is that warp yarns deliberately pulled at one end so that the weft yarn can lie with warp at 90° .In the former case the fabric is pulled by a pair of squeeze rollers and the correction roller is either pushed up or down. In the later case two sets of rollers are set at the two extreme ends, the rollers are capable of pulling fabric at different speeds. What ever is the method of correcting the skew ness, in all cases attempt is made to compact the fabric sufficiently so that the tendency of skewing is eliminated.
  46. 46. Compressive shrinkage: The lengthwise shrinkage potential of denim fabric varies from 12% to 18% depending on the quality and construction. It is necessary to correct this type of high potential shrinkage before making a garment. Compressive shrinkage is a very widely used finishing process used for shrinking the denim fabrics deliberately. This is basically a mechanical finishing treatment. The basic working principle of this process is that if a strip of elastic rubber is extended and then a fabric strip is held pressed against the extended rubber. If, now the rubber is allowed to relax, it will relax while the fabric strip will also relax as it is held pressed against the rubber. In the real case, an endless rubber sheet is pressed by a large circular cylinder. The fabric is fed between the cylinder and the rubber sheet. By varying the amount of feed it is possible to control the amount of shrinkage. The extent of relaxation of the fabric can be controlled by controlling the amount of feed.
  47. 47. Machine that are used in Tube line are given below: J - Box Brushing Unit Singing / Burning Washing / Softing Skew Roller Dry Cylinder Shrinkage by rubber belt with 33º pressure  Calendering / Palmer Folding Softening Agent Softener (Persaftier ISD) Wetting Agent ( Lionil ) Acetic acid
  48. 48. Machine Specification : Machine name: Morrison Company Name : Morrison Textile Machinery Company Origin : USA Maximum Capacity : 40000 yds / day Manufacturing Date : 2005
  49. 49. 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 bar, temple mark, double end, double pick, tight warp, loose warp, faulty denting, faulty drawing are checked. If the fabric is within the acceptance level (by the four point system) then it is sent to the garments section for further treatment. Quality Standard Sinha 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 no. is calculated. The following table shows the four point system.
  50. 50. Fig: Inspection mc
  51. 51. Four Point Grading System Size of defects Penalty Points 3 inches or less 1 Over 3 inch but not over 6 inch 2 Over 6 inch but not over 9 inch 3 Over 9 inch 4 Following Table shows common faults and response by inspection section at Sinha Denims Ltd
  52. 52. No. Faults Response 1. Reed Mark Uneven warp & weft tension 2. Mis pick Uneven weft yarn tension 3. Snarl Uneven air pressure 4. Hole Uneven knotting 5. Slubs Yarn fault 6. Thick thin place Uneven tension 7. Weft contamination Wrong weft yarn supply 8. Double end Wrong denting 9. Wrong denting Double end 10. Double pick Wrong air tension 11. Wrong drawing Operator fault 12. Loose warp Wrong beam winding 13. Tight warp Do 14. Oil line/ stain Carelessness 15. Chemical Do 16. Dirt stain Do 17. Crease mark Do 18. Uneven tension Wrong operational set up
  53. 53. MACHINE SPECIFICATION: Machine Name : Modular Design Inspection Winding M/C Company Name : S T T Machinery Co Ltd (S T T = Shiaw Tai Tong ) Model : S T T - I E W 10272 Patent No : 187203 Serial No : 2987-2 Manufacturing Date : 2006 Origin : Taiwan
  54. 54. Quality assurance: Quality assurance is defined as all those possible planned and systematic actions necessary to provide adequate confidence than a product or service will satisfy given requirements for quality. The Quality Assurance Department is assigned to maintain consistently uniform quality of the material in process and various stages of manufacturing. Objects of Quality Control: Specification test Raw material control Process control Process development Product testing Research
  55. 55. Quality Assurance System: Quality assurance procedure may be divided into two major parts Online quality control Offline quality control Online Quality Control: Online quality control comprises with the raw material control, process control & finish fabric inspection. Raw material control: As the quality product depends upon the raw material quality, quality assurance department must ensure the best qualities of raw material (with economical consideration) are used in production. The yarn should be with a known concentration and high degree of purity The dyes and chemical should be compatible with each other The fabric must be without faults, with proper absorbency, whiteness as per requirement of the subsequent process.
  56. 56. Process Control: The method chosen for process must be provided with necessary parameters. During weaving samples should be checked at each stage of process. During finishing, temperature, speed, padder pressure, overfeed should be controlled a per requirement GSM, width, shrinkage (both length & width) should be maintaining as per buyer requirement. Finish Fabric Inspection: Purpose: To ensure that an acceptable quality fabric is used for producing garments and proper quality of shipment is received from the supplier. Scope: All produced and incoming fabrics of Sinha Denims Ltd. Procedure: •Store in charge will check the received fabric with the report length and type of fabric with the stated shipment document quantity and the actual order quantity. •The finding will be recorder in inventory report and discrepancy regarding fabric type, color and length will be notified to the GM/ASTT> Manager. •For in-house products quality control officer will guide all over inspection. •Quality inspector (fabric) shall check 100% receive fabric for quality. He will identify any defect, hole or stain in the fabric and make calculating given below-
  57. 57. Point calculation system Defect area Point 1” to 3” 1 3” to 6” 2 6” to 9” 3 Above 9” 4 For any hole in fabric 4 Calculations of points is done by- = Actual Point Grade
  58. 58. •If point grade is 40 or below then the fabric is ok. If the result is more than 40 points, then inform it to GM or respective merchandiser •The fabric is also checked for shading defect in side by side and length. Any non- conformities/ shading will be notified to asst. manager using inspected reports. Roll wise color uniformly card is maintained for identification of shade variations. •During the fabric inspection if the yardage of any roll is reported more or less by the fabric inspection machine then the one specified in the roll, the roll will be measured manually using measuring tapes. Only calibrated measuring tape should be used. •The result of fabric inspection shall be recorded in fabric inspection report. Defects found in the final inspection: Uneven shade Oil spot Neps Crease mark Machine stoppage mark Reed mark Pick missing Double end Hole
  59. 59. Offline quality control: Offline quality control generally comprises different tests of final product so that it is possible to identify whether it pass against the norms given by buyer, the following test are generally done- GSM test Shrinkage test Shade Check Wash fastness test Fastness to water Rubbing fastness test Perspiration test Durability test Dimensional stability
  60. 60. Basic Procedure of Production Planning & Control A planned work brings success. Without planning nothing is complete within the required time. So planning has its own importance which is intolerable. Planning gives a schedule task and control controls it successfully. But production planning and control is not an easy task. Its basic working procedure is as follows- Taking order form marketing division Analyzing the orders Planning for dyeing the yarn Planning for weaving the fabric Planning for finishing the fabric It is only a basic procedure. It may change according to the type of order. Sometimes the order is planned only for finishing the materials or only for weaving the goods. Then some steps are minimizing for planning.
  61. 61. a)Taking order from the marketing division: Sinha Denims Ltd. Marketing division supplied fabric orders to the planning and control division by a specific format. b) Analyzing the orders: After getting the fabric order, this section analyzes the orders according to buyers order quantity, type of orders (i.e. type of fabric) delivery date etc. This section plans for required quantity of fabric to be weaved, delivery fabric. c) Planning for weaving of the fabric: Production planning for weaving is called ‘” Beam Plan”. Weavers beam is prepared according to m/c capacity, reed count, fabric construction, width, GSM and priority of delivery etc and written in a pattern card. d) Planning for finishing of the fabric: Finishing schedule is same as weaving. After weaving, materials go to the finishing section. The fabric can be finished in the regular finishing m/c. Finishing will be selected according to the type of the fabric to be finished. Finishing data is written to the pattern card and is informed to the planning section. However this section always forces to all the departments to finish all the work within the delivery time given by the buyers. Thus, it plays a very important role in the success of the company.
  62. 62. Costing of the product Costing system mainly describe how the cost of the final product is fixed by the company top managements. As it is a fabric manufacturing factory, so according to the buyer/ customer requirements of final garments, merchandiser gives the consumption of fabric with specifications. Then it is calculated how much yarns are required for processing. After that, the final cost is fixed including some profit. Then the unit price is offered to the buyer for the approval. Costing of a product includes: Yarn cost weaving cost Dyes and chemical cost Cost of dyeing Cost of finishing Cost of cutting Labor cost (direct & indirect) Factory cost Office and administrative cost Others cost Profit,etc.
  63. 63. Comments: Costing of a unit product is the most secret matter of the industry. The company policy does not allow flashing this out. So we could not collect the price of the product.
  64. 64. Marketing Information: Sinha Denims Ltd. Is a 100% export oriented denim fabric manufacturer. So they sell their product to export market. They also take some initiative for market development through communicating with new buyer and taking part in different international garments fair Product & Customer: As it is a denim industry, its main products are 3/1, 2/1, 2/2, 1/1 L.H.T & R.H.T and 3/1 broken twill. The factory ensures faults free fabrics as per customer requirements, through practice of faults free control procedures
  65. 65. Country of Export: England USA Germany Sweden Spain Italy Denmark France
  66. 66. Maintenance: Machine, Building & facilities are subjected to deterioration due to their use & exposure to environmental condition. Process of deterioration ,if unchecked, culminates in rendering these service facilities unserviceable & brings them to a standstill .In Industry ,therefore has no choice but to attend them from time to time to repair & recondition them so as to elongate their life to extent it is economically & physically possible to do so. It is in this in the context that maintenance assumes important as an engineering function .It is made responsible for provision of a condition of these machines, buildings, & service that permit uninterrupted implementation of plans requiring their use.
  67. 67. Objectives of maintenance: •To keep the factory plants, equipments, machine, tools in an optimum working condition. •To ensure specified accuracy to product & time schedule of delivery to customer. •To keep the down time of machines to the minimum thus to have control over the production program. •To keep the production cycle within the stipulated range. •To modify the machine tools to meet the need for production Types of maintenance:
  68. 68. Break Down MaintenancePreventive Maintenance Maintenance Electrical Maintenance Mechanical Maintenance Electrical Maintenance Mechanical Maintenance Types of maintenance:
  69. 69. Preventive Maintenance: Preventive maintenance is a predetermined routine actively to ensure on time inspection/ checking of facilities to uncover conditions that may lead to production break downs or harmful description. Breakdown Maintenance: In this case, repairs are made after the equipment is out of order and it cannot perform its normal functions. Routine Maintenance: Maintenance of different machines is prepared by expert engineer of maintenance department. Normally in case of weaving machine maintenance is done after every 7 days for complete checking of different important parts are done.
  70. 70. Maintenance Procedure of Different machine: •Weaving Machine Maintenance: Mechanical Items need to be checked & Service Grease the bearing. Complete cleaning of machine. Cleaning of relay valves, replace scale if required. Checking air supply filters, regulators, and auto drain scales. Cleaning filter element and blow out. Greasing the unloading roller bearings. Checking oil level and bolts of unloading roller gearbox. Checking of unloading roller couple and packing. Checking and cleaning of main vessel level indicator. Check the oil level of pump bearing and refill if required. Check the function of heat and cool modulating valves. Check all belts and belt tension.
  71. 71. •Finishing machine: Maintenance: Mechanical Items need to be checked & service Grease padder bearing & expender device unit by Staburg NBU. Complete cleaning of m/c. Checking oil level and bolts of unloading roller gear box. Check oil level of hydraulic system. Check all belts, all chain and belt tension. Check gear box plotting and its oil. Check main line air pressure and air pressure gauge. Check pneumatic belts, brushes, if required tight them properly. Check in feed motor. Check squeeze roller hydraulic cylinder. Check turn table, belt tension, and gearing.
  72. 72. Conclusion Findings: Project is an essential part for textile education because it minimizes the gap between theoretical and practical knowledge. Undoubtedly, this Project taught us lot about textile technology, production processes, textile machineries, industrial management, and made us comfortable to industrial life. Besides it gave us the first opportunity to work in industry. Limitations: Because of secrecy act, the data of costing and marketing activities have not been supplied We did not get enough supervision form the responsible persons of different section due to their busy schedule. So there may some limitation of data of different section in this report. We had a very limited time. In spite of willingness to study in more details it was not possible to do so. Some of the points in different chapters are not include as these were not available. It is not possible to in compass the whole process in such a small frame as this report.
  73. 73. Suggestions: Due to shortage of technical persons (Textile Engineers) sometimes quality level drops which need to be minimize by employing technical person. Especially at night shift. During our project preparing period, most of the time the product were not first time right and need to be re processed, increasing the production cost this problem has to be overcome. We observe that there is lack of understanding between the top level personnel and floor level workforce, weakening the chain of command. Supervisor or floor in-charge did not properly follow the program. So sometimes operators deviate from the set procedure which may hamper the quality of the product. The machine in weaving and finishing section should be modernized to control all the parameters properly to minimize the rejection percentage. Weaving production needs to increase as well as technical persons need to employed there. The machine stoppage time should be analyzed and minimized. The maintenance should be carried out when the machine is out of action and routine maintenance should be carried out regularly. More skilled labor should be used in the project to improve productivity.
  74. 74. BIBLIOGRAPHY: Technical Solutions: Weaving from Mr. Younus Technical Solutions: Weaving from Mr Tareq Technical Solutions: Weaving from Mr Zahid Technical Solutions: Quality Assurance & Control From Mr. Taufiq Maintenance & Utilities: from Mr. Shahadath Hossain Laboratory Tests: from SDL Document
  75. 75. Yarn type of yarn for denim fabric
  76. 76. World Wide denim production
  77. 77. Jeans
  78. 78. THANKS TO ALL