Tamil Nadu HSE Second Year Textile Technology cheat sheet

Fibres are classified as natural (vegetable, animal, mineral) or man-made (regenerated, synthetic, inorganic); vegetable examples are cotton, flax, jute, animal examples wool and silk, mineral example asbestos.

Cotton is about 90-95% cellulose with a natural twist (convolutions); it is hydrophilic, moisture regain about 8.5%, and degrades in strong mineral acids.

Wool is a protein (keratin) with overlapping scales giving felting shrinkage; it has high elastic recovery, moisture regain about 13-16%, and is damaged by alkalis and chlorine bleach.

Silk is a protein fibroin filament; degumming removes sericin, and it loses strength in sunlight and perspiration due to amino acid breakdown.

Regenerated fibres: viscose and modal from wood pulp cellulose; acetate is a cellulose ester that is thermoplastic and soluble in acetone.

Synthetic fibres: polyester (terephthalic acid + ethylene glycol, melt spun), nylon 6 and 6,6 (polyamide, melt spun), acrylic (polyacrylonitrile, wet spun), polypropylene (olefin, lightest fibre).

Burning test identification: cotton burns with paper smell and grey ash; wool and silk smell of burnt hair with crushable bead; polyester melts and shrinks with black hard bead; nylon melts with celery-like smell.

Solubility tests: acetate dissolves in acetone; nylon dissolves in formic acid; polyester dissolves in hot meta-cresol; cotton dissolves in 70% sulphuric acid; wool dissolves in sodium hypochlorite.

Ginning separates seed from lint: saw gin for short/medium staple, roller gin for long staple cotton; ginning percentage = (weight of lint / weight of seed cotton) x 100.

Blow room objectives: opening, cleaning, blending and lap/feed formation; beating points increase with finer, dirtier cotton; cleaning efficiency is highest at the first beater.

Carding individualises fibres, removes impurities and neps, and forms a sliver; carding produces the carded sliver with fibre orientation but no parallelisation of hooks.

Card sliver irregularity is reduced by doubling at drawing; draft = (input linear density / output linear density); doubling gives no draft by itself.

Combing removes short fibres (noils) and neps and parallelises fibres; combing preparation uses a sliver lap or ribbon lap machine before the comber.

Roving (speed frame) applies draft and a small twist to form a package suitable for ring spinning; roving twist is low to allow drafting at the ring frame.

Ring spinning: draft in the drafting zone, twist inserted by the traveller on the ring, winding on the cop; spindle speed, traveller speed and balloon control determine yarn quality.

Yarn count systems: indirect count = length per unit mass (Ne = 840 yd per lb); direct count = mass per unit length (tex = g per 1000 m); resultant count of a twofold yarn = count/number of plies.

Warp preparation sequence: winding, warping, sizing (slashing) and drawing-in or tying-in; sizing adds size pick-up to protect warp yarns from abrasion.

Loom motions: primary (shedding, picking, beat-up), secondary (let-off, take-up) and auxiliary (weft stop, warp stop, temple).

Basic weaves: plain (1/1), twill (e.g. 2/1, 3/1) and satin/sateen; derived weaves include rib, basket, herringbone and diamond.

Fabric cover and sett: ends per inch (EPI) and picks per inch (PPI) define density; crimp = (yarn length in fabric - fabric length) / fabric length x 100.

Knitting: weft knitting (single jersey, rib, interlock) uses needles and loops in course and wale directions; warp knitting (tricot, raschel) uses warp beams and is faster.

Knitted fabric properties: stretch and extensibility higher than woven, edges curl in single jersey, and Wales per inch (WPI) and courses per inch (CPI) describe density.

Non-woven basics: web formation (carded, air-laid, spun-laid), bonding (needle punching, thermal, chemical, spunlace); GSM (g/m2) is the key specification.

Fabric defects: warp streak, weft bar, missing end, double pick, oil stain; a weaver's knot and loom tension affect defect rate.

Singeing burns off protruding fibres to give a smooth surface; gas singeing is most common; it is done before desizing and bleaching.

Desizing removes added size: enzymatic (amylase for starch), oxidative or acid methods; desizing efficiency is checked by iodine test.

Scouring removes natural impurities (waxes, pectins, proteins) using alkali and detergent; it improves absorbency; weight loss is a measure of scouring.

Bleaching removes natural colour using hydrogen peroxide (alkaline, with stabiliser) for cotton; sodium hypochlorite is cheaper but can damage cellulose.

Mercerising is treatment with concentrated caustic soda (about 20-30% NaOH) under tension; it increases lustre, strength and dye uptake and improves dimensional stability.

Dye classes: reactive (cotton, covalent bond, good fastness), vat (cotton, excellent fastness), direct (cotton, easy but lower wash fastness), acid (wool/silk/nylon), disperse (polyester, applied at high temperature).

Dyeing methods: exhaust (batch) and continuous (pad-dye); dye fixation and fastness depend on pH, temperature, electrolyte and time.

Printing methods: direct, discharge and resist; styles include block, screen (flat/rotary), roller and transfer; printing is localised dyeing with thickener in the paste.

Moisture regain = (weight of moisture / oven-dry weight) x 100; standard testing atmosphere is 20 +/- 2 degrees C and 65 +/- 2% RH.

Fibre length and fineness: staple length by comb sorter; fineness by micronaire (cotton) or denier (filaments); 1 tex = 9 denier.

Yarn strength: lea strength (skein) and single yarn strength; CSP = count strength product = lea strength (lb) x count (Ne).

Evenness testing uses Uster evenness tester; CV% and IPI (imperfections: thin, thick, neps) are reported; the Uster Statistics are used for comparison.

Fabric tests: tensile strength (strip/grab), tear strength (Elmendorf), bursting strength (diaphragm/ball), abrasion (Martindale), pilling (ICI pilling box).

Colour fastness tests: washing, rubbing (crock), light, perspiration; assessed against grey scales for staining and change in shade.

Dimensional stability: shrinkage after washing measured as % length and width change; relaxation and felting shrinkage differ for knit and woven goods.

Quality control tools: control charts (mean, range), frequency distribution, AQL sampling (ISO 2859) for lot acceptance.

Pattern making methods: drafting (flat pattern), draping on dress form and grading; basic blocks are bodice, sleeve, skirt and trouser.

Measurements and ease: body measurement plus wearing ease and design ease give pattern dimensions; seam allowance is added after drafting.

Marker planning minimises fabric waste; marker efficiency = (area of pattern pieces / area of marker) x 100; grain line must follow warp direction.

Cutting methods: straight knife, round knife, band knife, die cutting and computerised (CNC) cutting; fabric lay height and ply control accuracy.

Sewing: stitch types (lock stitch 301, chain stitch 401, overlock 504) and seam classes (superimposed, lapped, bound); SPI (stitches per inch) affects seam strength.

Seam strength and slippage tested by tensile testing; needle size and thread tex must match fabric GSM.

Finishing operations: pressing, fusing (interlining), trimming, checking and packing; fusing temperature, pressure and time must suit the interlining.

Garment defects: skipped stitch, seam puckering, shade variation, measurement deviation; AQL inspection uses 4-point or 10-point system for fabric faults.

Mill organisation: production, quality control, maintenance, stores, marketing and HR departments; line and staff functions must be defined.

Maintenance types: preventive (scheduled), breakdown (corrective) and predictive (condition-based); MTBF and MTTR measure reliability.

Machine maintenance schedule: carding wire and flat clothing, ring frame spindle and traveller, loom tappet and shuttle; lubrication charts reduce wear.

Productivity measures: OEE = availability x performance x quality; machine utilisation and operator efficiency are tracked per shift.

Work study: method study and work measurement; standard time = observed time x rating factor + allowances.

Safety: guarding of nip points, interlocked doors on cards and looms, dust and cotton fly control, noise limits (about 90 dBA for 8-hour exposure).

Fire safety: cotton dust is combustible; spark detection, earthing and fire extinguishers (CO2/dry powder) are required; housekeeping reduces risk.

Statutory and welfare: factory act provisions on working hours, ventilation, lighting and first aid; safety training records must be maintained.

Costing elements: direct material, direct labour, direct expenses and overheads; prime cost = direct material + direct labour + direct expenses.

Factory cost = prime cost + factory overheads; total cost = factory cost + administration and selling overheads; selling price = total cost + profit margin.

Cost per metre of fabric = (yarn cost + sizing + weaving charge + processing + overheads) / production in metres; waste and seconds must be included.

Break-even quantity = fixed cost / (selling price per unit - variable cost per unit); contribution = selling price - variable cost.

Entrepreneurship steps: idea and market survey, project report, finance (term loan, working capital), statutory registration (Udyam, GST), plant layout and manpower.

Government support for textile MSMEs includes subsidies, technology up-gradation schemes and cluster development; loan eligibility depends on project viability.

Effluent treatment: textile processing generates high BOD/COD, colour and salts; primary (screening, sedimentation), secondary (biological) and tertiary (membrane, reverse osmosis) treatment.

Environmental controls: ETP and ZLD (zero liquid discharge), restricted azo dyes, formaldehyde limits, water and energy conservation; ISO 14001 is the environmental management standard.