26 Quality Control- concept, principles, Standards and Specifications, quality assurance, care symbols, standard symbols

V. RameshBabu

epgp books

 

 

 

 

  1. INTRODUCTION TO QUALITY

 

Quality means conformity of a product to specifications and standards stipulated for the product either by the manufacturer or the consumer before going into actual production of the product. Quality is a relative term and varies from place to place and user to user for the same product perceptions of quality differ from person to person and his ability to pay.

 

1.1 Quality Control

 

1.1.1 Definitions for the Quality Control

  1. Quality Control may be defined as that “Industrial management technique or group of techniques by means of which products of uniform acceptable quality are manufactured”-Alford and Beatty.
  2. Quality Control refers to the systematic control of those variable encountered in a manufacturing process which affects the excellence of end product such variable result from the application of materials, men, machine and manufacturing condition.-Bethar and Stackman

1.2 Concept/Principles of Quality Control

 

The Quality control System Requirements are based on the principle of PDCA Cycle.

 

Process Cycle

  1. Understanding the customers’ quality requirements.
  2. Organizing & training quality control department.
  3. Ensuring proper flow of quality requirements to the QC department.
  4. Ensuring proper flow of quality requirements to the Production Department.
  5. Establishing quality plans, parameters, inspection systems, frequency, sampling techniques, etc..
  6. Inspection, testing, measurements as per plan.
  7. Record deviations
  8. Feed back to Production Department.
  9. Plan for further improvement.

1.3 Quality Assurance

 

The present open global market doesn’t allow a quality control system that concentrates only on the product and manufacturing process. Normally in apparel firm the quality control process starts with inspection of fabric and continues until inspection of finished and packed garments. But the present scenario needs stretching this quality control process at both the starting and closing ends. That is at the starting; the process of manufacturing the yam and fabric needs to be controlled and needs to be compatible with garment manufacturing process and end use of the garments. And at the closing ends it includes the marketing and after sales service.

 

Quality assurance is ensuring process from starting to end to assure quality.

  • A planned and systematic set of activities to ensure that variances in processes are clearly identified, assessed and improving defined processes for fulfilling the requirements of customers and product or service makers.
  • A planned and systematic pattern of all actions necessary to provide adequate confidence that the product optimally fulfills customer’s expectations.
  • A planned and systematic set of activities to ensure that requirements are clearly established and the defined process complies to these requirements.

“Work done to ensure that Quality is built into work products, rather than Defects.” This is by

 

(a) identifying what “quality” means in context;

(b) specifying methods by which its presence can be ensured; and

(c) specifying ways in which it can be measured to ensure conformance.

  1. QUALITY CONTROL IN APPAREL

2.1 Quality Control in Fabric

 

The four ingredients of a fabric quality control

  1. Physical characteristics

Details should be stated about fibres, yarns, material construction, finishing treatment, finished width and acceptable tolerances.

  1. Performance characteristics

All-important characteristics need to be specified, together with tolerances. Typical areas are shrinkage, colourfastness to light, washing, laundering, rubbing etc, and strength, care characteristics, flame retardants features.

  1. Visual defects

The grading system to be used should be specified, together with the level of acceptance.

Ex: 4-Point system, 10-Point system.

  1. Shade specification

The colors of the purchased materials should be specified, together with tolerances between batches and pieces and within pieces.

 

The raw material specification sheet provides an effective means of communication; it should never be made the exclusive channel of information flow. Companies who are implementing a Policy of continual improvement is seeking to promote long-term relationships with reliable suppliers, and is recognizing the need for direct communication at managerial level. This suggests the need for vendor rating and for clear policies on communication in the context of quality assurance. However, the fashion business is dynamic and every season sees new combination of cloth and trims. The selection, inspection and testing of materials has to be done very carefully.

2.2 Quality Control in Spreading

 

Various factors that can affect spreading should be checked, such as ply alignment, ply tension or slackness, bowing, and splicing.

 

Here are possible spreading defects

  1. Not enough plies to cover the quantity of garments required.
  2. Narrow fabric.
  3. Plies not all facing in the correct direction. That is, not all the plies are spread face down, face up, or face to face, as required.
  4. Mismatching of checks. Plies not spread accurately one above another ready for cutting.

The same authors also list the following possible pattern defects:

  1. Pattern parts missing. Correct number of parts for all sizes not included by the marker maker.
  2. Mixed parts. Parts not correctly labelled in marker; therefore, a marriage of wrong-sized parts.
  3. Patterns not facing in the correct direction on napped fabrics.
  4. Patterns not all facing in the same direction (either way) on a one way fabric.
  5. Patterns not aligned with respect to the fabric grain. As a result, a garment may not drape or fit properly.
  6. Line definitions poor (e.g., chalk, too thick, indistinctly printed line, perforated lay not fully powdered), leading to inaccurate cutting.
  7. Skimpy marking. Either the marker did not use the outside edge of the pattern or the pattern was moved or swung after partial marking to squeeze the pattern into a smaller space in the interest of fabric economy. Alternatively, the pattern is worn around the edges and should be replaced.
  8. Generous marking. A combination of points 7 and 8 results in components being sewn together with puckering or pleating.
  9. Marker too wide. Garment parts at the edge of the lay are cut with bits missing,
  10. Not enough knife clearance freedom.
  11. Mismatched checks and stripes.
  12. Notches and drill marks omitted, indistinct, or misplaced

2.3 Quality Control in Cutting

 

Cutting quality is a prerequisite for quality in a finished product. In addition, cut work quality affects the ease and cost with which construction is accomplished. The quality of work leaving the cutting room is determined by how true the cut fabric parts are to the pattern; how smooth or rough the cut surface is; material or fabric defects in the cut fabric parts; shade differences between cut fabric pieces within a bundle.

 

Here are some defects that may arise in cutting

  1. Frayed edges. May impede cutting time by clogging the knife action and/or mar the fabric with rips or pulled yarns. The amount of fraying depends on fabric construction and finish.Improper cutting tools or dull knives cause excessive fraying in a pattern as the section is cut.

    2.Fuzzy, ragged or serrated edges. The result of poor cutting implements. Such edges will impede sewing and/or diminish sewing quality. Such a condition is caused by faulty knife edges such as burrs, chips, or dullness.

 

3.Ply-to-ply fusion. More common and troublesome. Adjacent plies in a block are fused together, which makes it difficult for the sewing machine operator to pick up a single ply quickly. Fusion occurs due to heat created by excessively high speed of cutting or by the friction of a dull knife. To prevent fusion, check knife speed, keep knives sharp, place wax paper between fabric plies, and lubricate cutting blade.

 

4.Single-edge fusion. Consists of a single ply whose cut yarn-ends are, fused to form a hard brittle rim on the cut edge. Sometimes, this is desirable to prevent fraying; however, hardness and brittleness are undesirable if they impede sewing manipulation or may result in seams uncomfortable to the consumer.

 

5.Pattern precision. Misshape or distortion of the pattern perimeter as cut. Whether it is under or overcut is due to the poor manual control of the, cutting machine and poor lines on the marker. To assure precision in a pattern, check markers before cutting, use tensionless spreading, or allow time for the fabric to relax. After a cut, check the top, bottom, and middle plies against the pattern.

 

6.Notches. Notch size refers to the depth of a notch. If the depth is too great, the notch may show after a garment is sewn. If the notches are too small sewing operators may have difficulty locating them quickly, resulting in decreased efficiency. Misplacement of a notch may be due to an improper spread marker, poor control of a cutting machine with the cutter’s notching tool stroking diagonally instead of vertically, incorrect marker in that the notches formatting parts do not coincide. Check notch placement against mating pieces. Quality control in stitching may be a problem if notches are not aligned.

 

7. Drilling. The drill hole may be too large or too small in diameter. In addition, a drill may become too hot due to high speed or wrong size, causing the plies to fuse together at the drill hole. The drill must stroke vertically to the table for uniform placement throughout the bundle. Sometimes fabric properties are such that the slight movement of yarns in a fabric would close a drill hole. In such cases, it is necessary to drill holes with a marking fluid.

 

2.4 Quality Control Sewing

 

Sewing defects

  1. Needle damage as evidenced by holes, picked threads, ruptured threads or other damage to the fabric; caused by wrong size or type of needle, blunt needle, needle heat, or machine feeding difficulty.
  2. Feed damage, particularly on thicker or sheer fabrics, or when machining over transverse seams, from incorrect type of teeth, excessive pressure by foot, improper alignment of feed and foot, damaged throat plate, excessive machine speed.
  3. Skipped stitches, from the hook irregularly failing to pick up the loop of thread from a needle’s eye owing to a number of causes.
  4. Thread brakes, arising from too thick a thread for the needle, too thin a thread, needle heat, operator working unrhythmically, or too tight tensions.
  5. Broken stitches, arising from the wrong stitch type, too tight tensions, a badly formed joint in the seam where the second line of stitch runs over the first and cracks it, sharp feeds, and too great a pressure.
  6. Seam grin, arising from too loose a tension or too large a stitch, or the use of the wrong stitch type.
  7. Seam pucker, because of incorrect handling by the operator, misaligned notches, or tight thread tensions.
  8. Pleated seams, an extreme form of 7, where operator failed to ease in fullness evenly.
  9. Wrong stitch density. Too many give rise to jamming and rupture of fabric threads; too few to grinning or weak seams.
  10. Uneven stitch density Operator causes machine to snatch and does not allow machine to control fabric.
  11. Staggered stitch, from faulty feed motion, incorrect needle, and other machine parts.
  12. Improperly formed stitches, caused by bad tension, incorrectly adjusted timing, ill-fitting machine components.
  13. Oil spots or stains.

Seaming Defects

  1. Incorrect or uneven width of inlay, arising from bad handling by operator, incorrectly set guide, incorrectly adjusted folder. In extreme cases, the seams burst open, raw edges show, slippage of weave threads occurs, or notches are exposed.
  2. Irregular or incorrect shape of sewing line (sometimes called runoffs) in top stitching, arising from lack of or badly set guide, not following a mark, or incorrect handling.
  3. Insecure back stitching, because subsequent rows do not cover the first row of stitching.
  4. Twisted seam leading to irregular puckering or the garment parts not hanging correctly when worn; caused by improper alignment of fabric parts, mismatched notches, and allowing one ply to creep against another.
  5. Mismatched checks or stripes.
  6. Mismatched seam, where transverse seams do not match (e.g., inside lea seams at the fork of trousers).
  7. Extraneous part caught in seam unrelated piece showing through the seam.
  8. Reversed garment part, where part is sewn with face side opposite from specification perhaps when the part cut for one side of garment is sewn in the other, or when the whole garment is assembled inside out.
  9. Blind stitching showing on the face side, or not securely caught on inside arising from improperly adjusted bender.
  10. Wrong seam or stitch type used.
  11. Wrong shade of thread used.

Assembly Defects

  1. Finished components not correct to size or shape or not symmetrical.
  2. Finished garment not to size, arising from incorrect patterns, inaccurate marking or cutting, shrinking or stretching fabric, incorrect seam widths.
  3. Parts, components, closures, or features omitted, caused by bad work flow, and wrongly printed work tickets, parts omitted in cutting, careless operator.
  4. Components or features wrongly positioned or misaligned arising from incorrect marking, or sewing not following the mark (e.g., pockets, bartacks, top stitching, buttonholes, buttons, hooks and bars, hooks and eyes, zips).
  5. Interlining incorrectly positioned, twisted, too full, too tight, cockling.
  6. Lining too full, too tight, showing below the bottom of the garment, twisted, incorrectly pleated and so on.
  7. Garment parts cockling, pleated, twisted, showing bubbles and fullness; for example, collar in relation to the under collar or the neck, sleeve in relation to the armhole, pockets, tapes, zips, pads in relation to the shoulder.
  8. Garment parts shaded owing to being mixed after cutting.
  9. Parts in one-way fabrics in wrong direction, usually only small parts, such as pockets.
  10. Mismatched trimming.

2.5 Quality Control in Finishing

 

Thebasicobjectiveoffinishingmustbequalityandappearance.Appearanceisthebasisofmostconsumers‟judgmentonwhether or nottopurchasea garment.

 

Thequalityofpressingoperationcanbemeasured byevaluating thefollowing:

  1. Burned or scorchedgarments
  2. Water spots/stains
  3. Gloss and/or changeincolor (original shade)
  4. Flattenednapor surface
  5. Brokenzippers,buttons, etc.
  6. Creases notcorrectlyformed
  7. Fabricoffinishedgarmentnotsmooth,wrinkle-free,andshowingitsproper appearance
  8. Edgeswavyandstretchedor thickandcockling
  9. Garmentsnotthoroughlydried.
  10. .Pocketsnotsmooth
  11. Liningshowingpleats,creases,wrinkles,shine
  12. .Garmentsnotcorrectly molded,either indetail or total silhouette
  13. Shrinkageduetoheatandmoisture

 

  1. STANDARDSAND SPECIFICATIONS 3.1 Standards – Definition by ISO

According to ISO, standards are documented agreements containing technical specifications or other precise criteria to be used consistently as rules, guidelines, or definitions of characteristics, to ensure that materials, products, processes and services are fit for their purpose.

 

3.2 Specifications:

 

A specification or spec is a precise statement of a set of requirements to be satisfied by a material, product, system, or service that indicates the procedures for determining whether each of the requirements is satisfied.

 

Two important elements in Specifications

  • The numbers used in writing specs address two important elements in Specifications:
  • (a) MINIMUMS & (b) TOLERANCES a. Minimums
  • A minimum is the least or low acceptable value for any given parameter or dimension.
  • Establishing minimums can be very difficult task because it is these values that encompass performance, appearance, and quality of the product.
  1. Tolerances
  • A tolerance describes the range of acceptable values, or in other words, it describes allowable deviations from specified values.
  • Tolerances may be listed in several ways; as range from X to Y, as plus/minus value such as X + Y, or as a minimum with any value greater than the value listed is being acceptable.
  • A major problem with tolerances is that they can accumulate or stack up in a product. The result is an unacceptable product, even though no single specification is outside the acceptable limit. Tolerances are included when a range is acceptable. However, not all the specs include tolerances.

Each factory will need to prepare forms appropriate to their own requirements and example specifications, divided into sections are available to provide a suggested basis.

 

Yarn Specification – Example

  • Yarn type – cotton/polyester blend, for single jersey knitting
  • Yarn specification no. Date
  • Description count
  • Composition
  • Fibre quality:
  • Twist factor:
  • ASTM grading:
  • Uster levelness: cv%
  • Thins (50% setting) per 1,000m
  • Thick (setting 3) per 1,000m
  • Neps(setting 3) per 1,000m
  • Winding
  • Coefficient. of friction:
  • Tolerances: in accordance with statutory instrument 2124: 1973 – textile products (indications of fibre content) regulations 1973
  • Typical value for count delivery acceptance being +12½% of nominal count. Some trade associations give rules applicable to their members.
  • Shades:
  • Tolerances:
  • Colour fastness:
  • (Assessed On 1 X 1 Rib Fabric Sample From Yarn Supplied)
  • Change In Shade Staining
  • Washing: – Rating
  • Perspiration
  • Rubbing
  • Dry Cleaning
  • Gas Fumes
  • Light

PRODUCT SPECIFICATION – Example

 

Commercial data

  • Garment description
  • Specification no: – date:
  • Style no:
  • Design no:
  • Sizes
  • Wt. Per doz.

Technical data

  • Yarns main ground
  • Pile / inlay
  • Trims
  • Fabrics main
  • Trims (neck,cuffs,skirt)
  • Finishing main
  • Details
  • Trims
  • Laying up & cutting
  • Patterns drawings
  • Lay markers
  • Cut

Garment assembly

  • Make-Up Order And Seam Spec
  • Sewing Threads
  • Tapes Zips

Aesthetic data

  • Shade and handle
  • As sealed patterns
  • Fabrics
  • Yarns
  • Requirements
  • Appearance and hang
  • As sealed garments ref.

Customer data

  • Measurements: size chart and measuring points as in drawings
  • Labelling: type
  • Location
  • Legend

Performance

  • Stability
  • Colour Fastness – BS 1006
  • Pilling
  • Extensibility (Cuffs And Skirts Fabric Only And In Course Direction)
  • Bursting Pressure (On Main Fabric Only)
  • Seam Stretch
  • Seam Security
  • Needle Damage
  • Non-knitting yarn

Raw materials specification – examples

  • Sewing threads
  • Specification no: date:
  • Needle Thread For O/Lock, Cover Seams And L/S Tabbing And Finishing
  • Fibre
  • Structure
  • Designation
  • Shade
  • Other Requirements
  • Colour Fastness
  • Bobbin Thread For Lockstitch
  • Same As The Needle Thread

Tapes

  • Specification no date
  • Location
  • Width
  • Structure
  • Shade
  • Colour Fastness

Zips

  • Specification no
  • Location
  • Length
  • Tapes
  • Shade
  • Colour Fastness
  • Stability
  • Other Requirements

Process specification – example

  • Fabric
  • Referencesspec no
  • Fabric description
  • Product specification nos. Relating
  • Specification no date
  • Machine gauge
  • Diam feeders
  • Speed
  • Width roll length finished:
  • Min. Useable roll weight finished:

Finishing requirements

  • Processes
  • Finished fabric parameters
  • GSM
  • Width overall

Manufacturing requirement

  • Operation seamspec. Ref. Extras/seam finish Process specification – example
  • Seam specification
  • Referencesspec no
  • Specification for
  • Specification ref. No: date
  • Make-up order nos.:
  • Sewing threads

Manufacturing requirements

  • Stitch
  • Seam
  • SPI
  • Run-in
  • Needle
  • Tensionetc
  1. CARE LABELS AND SYMBOLS

Denotes the washing instructions a customer has to follow while washing the garment. Generally wash care label also provides information as to at what temperature garment Fiber content may be mentioned in different languages.

 

Ex:

 

100% COTTON

 

100%    COTON

 

100%    COTONE

 

 

The garment consists of             80% COTTON

15% POLYESTER

5%    LYCRA

It should be mentioned in descending order as mentioned above.

 

This instructions are not only to protect the consumer but also to protect the manufacturer against return made by consumers who do not care for their garment as instructed.

 

Wash/Instruction Label: Denotes the washing instructions, a customer has to follow while washing the garment. Generally wash care label also provides information as to at that temperature garment has to be pressed. Type of water (plain / Cold / Soda / Warm) to be red, dry clean / hard wash and the type for dying – Lay flat to dry, Tumble dry low etc. Different processes covered in care labelling

  1. Laundering: A process intended to remove soil or stains by washing with an aqueous detergent solution (and possibly bleach) and normally including subsequent rinsing, extracting and drying.
  2. Chlorine bleach: A process carried out in an aqueous medium before, during or after washing processes, requiring the use of chlorine based bleaching agent for the purpose of removing stains and/or improving whiteness.
  3. Non-chlorine bleach: A bleach that does not release the hypochlorite ion in solution, for example sodium perborate, sodium percarbonate, etc.
  4. Dry-cleaning: A process for cleaning textile articles by means of organic solvents (eg, petroleum, perchlorethylene, fluorocarbon). This process consists of cleaning, rinsing, spinning and drying.
  5. Tumble drying: A process carried out on a textile article after washing, with the intention of removing residual water by treatment with hot air in a rotating drum.
  6. Ironing: A method of pressing using a heated hand iron sometimes together with moisture or steam, and a gliding motion.
  7. Pressing: A process of smoothing and shaping by heat and pressure, with or without the presence of steam.

 

Symbols

At present, there is no universal symbol system. The ASTM symbols are accepted in NAFTA countries. ISO/GINETEX symbols are accepted in most of Europe and Asia, and Japan has their own symbol system. Negotiations are under way to harmonise the two major systems; ASTM and GINETEX, into a truly universal symbol system for care procedures. Among the various systems the major systems, which are followed worldwide are listed below:

  1. International Care Labelling System (GINETEX)
  2. ASTM Care Labelling System
  3. British Care Labelling System
  4. Japanese Care Labelling System
  5. Canadian Care Labelling System
  6. Indian Care Labelling System

 

  1. CONCLUSION

Apparel quality control is one of the key functions in producing a quality garments by establishing a standards and specifications, implementing quality control concepts and principles in cutting, sewing, finishing and ensuring quality by proper care label instructions to competent in the world market.

 

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REFERENCES and URLs

  1. Grover E.G. and Hamby D.S., “Hand Book of Textile Testing and Quality Control”, Wiley Eastern Pvt Ltd., New Delhi, 1969.
  2. Jacco Solinger, “Apparel Manufacturing Hand Book”, Prentice Hall, 1993.
  3. Prodip V.Mehta, “An Introduction of Quality Control for the Apparel Industry”. ASQC quality Press, Marcel Dekker Inc., Newyork, 1992.
  4. Managing Quality In Apparel Industry, S.K.Bhrdwaj & Pradip V Mehta. Quality is Free,Philip Crosby.
  5. Narayana V. and Sreenivasan N.S., “Quality Management – Concepts and Tasks”, New Age International, New Delhi, 2007.
  6. Zeiri., “Total Quality Management for Engineers”, Wood Head Publishers, 2000.
  7. Feighenbaum., A.V., “Total Quality Control”, McGraw Hill, New York, 1993.