Tamil Nadu HSE First Year Textile Technology cheat sheet

Textile fibres are classified as natural (cotton, jute, wool, silk) or man-made (regenerated viscose/lyocell and synthetic polyester/nylon/acrylic); textile fibres have a high length-to-diameter ratio and are flexible.

Cotton is a seed hair of cellulose; its convolutions and lumen help identification, and maturity affects dye uptake, strength and neps. Micronaire is an air-flow measure of fineness and maturity.

Wool is a protein (keratin) fibre with scales and crimp; silk is a continuous protein filament of fibroin held by sericin gum, which is removed by degumming.

Moisture regain at 65% RH and 20 °C is approximately cotton 8.5%, viscose 13%, wool 16%, silk 11%, nylon 4.5% and polyester 0.4%.

Linear density: tex = mass in g per 1,000 m; denier = mass in g per 9,000 m; cotton count Ne = (length in yd/840)/(mass in lb); Ne ≈ 590.5/tex; Nm = 1,000/tex.

Fibre identification: burning cotton smells like burnt paper and leaves grey ash; wool smells of burnt hair; polyester melts and forms a hard bead; acetone dissolves acetate but not polyester.

Tenacity = breaking load/linear density, expressed in cN/tex or gf/denier; extension at break, initial modulus and work of rupture describe stiffness and toughness.

Staple fibres are short (cotton about 10–50 mm) and require spinning; continuous filaments such as silk or polyester filament can be used directly or cut into staple.

Typical carded cotton yarn sequence: blow room → carding → draw frame (two passages) → speed frame → ring spinning; combed yarn adds combing after the breaker draw frame.

Draft = surface speed of front (delivery) roller / surface speed of back (feed) roller; total draft is the product of individual machine drafts.

In draw frame, doubling means feeding several slivers together; with no count change, draft ≈ number of doublings, and doubling improves evenness by averaging irregularities.

Combing removes short fibres, neps and trash as noil; higher noil % gives cleaner, stronger yarn but lower yarn yield.

Ring spinning twist: TPI = spindle speed (rpm) / delivery speed (in/min); twist multiplier TM = TPI / √Ne for cotton count.

Production (kg/h) = delivery speed (m/min) × 60 × tex × efficiency / 1,000,000.

Plied yarn resultant count: for indirect cotton count, 1/Ne(resultant) = 1/Ne1 + 1/Ne2; for direct tex, tex(resultant) ≈ tex1 + tex2, ignoring twist contraction.

CSP = Ne × lea strength in lb; higher CSP indicates a stronger yarn for its count. Twist direction is S or Z; alternate twist can cause snarling.

Weaving cycle: shedding separates warp ends, picking inserts weft, beat-up pushes weft to the fell, let-off releases warp and take-up winds fabric.

Plain weave has 1/1 interlacing and a 2×2 repeat; twill has diagonal floats and a repeat of at least 3×3; satin has long floats and fewer intersections, giving lustre.

Loom selection rule: tappet for simple repeats, dobby for small geometric patterns, jacquard for large or complex designs; shuttleless looms include rapier, projectile, air-jet and water-jet.

Woven cover factor = threads per cm × √tex; compare warp and weft cover factors to judge fabric tightness; higher cover factor means denser fabric.

Crimp % = (yarn length in fabric − fabric length)/fabric length × 100; crimp affects extensibility, cover and fabric weight.

Knitting: course is a horizontal row of loops, wale is a vertical column; stitch density = courses/cm × wales/cm; loop length controls GSM and extensibility.

Weft knitting uses one yarn across the width (single jersey, rib, interlock); warp knitting uses many warp yarns along the length (tricot, raschel).

Fabric GSM = sample mass (g) / sample area (m²); measure after conditioning; GSM alone does not define thickness or cover.

Cotton wet-processing sequence: singeing → desizing → scouring → bleaching → mercerizing (optional) → dyeing/printing → finishing.

Singeing removes protruding fibres; desizing removes starch/PVA size; scouring removes waxes, oils and pectins; bleaching destroys natural colour with peroxide or hypochlorite.

Mercerization uses 18–22% NaOH at controlled tension, followed by washing and neutralization; it increases lustre, strength and dye uptake of cotton.

Dye selection rule: reactive/vat/direct for cellulose; disperse for polyester; acid for wool and nylon; cationic for acrylic; sulphur for cellulosic deep shades.

Reactive dyes form covalent bonds with cellulose under alkaline conditions; unfixed dye must be soaped/washed off to achieve wash fastness.

Printing methods include block, screen, roller, transfer and inkjet; print paste contains dye/pigment, thickener and auxiliaries, followed by steaming and washing.

Finishing: mechanical processes include calendering, raising and sanforizing; chemical processes include softening, water repellency, flame retardancy and resin crease recovery.

Effluent from dyeing/printing has high BOD, COD, colour and TDS; treatment train: screening → equalization → coagulation/flocculation → biological treatment → tertiary treatment.

Condition textile samples at 20 ± 2 °C and 65 ± 2% RH before testing; report the standard atmosphere used because moisture changes strength, count and dimensions.

Yarn count: measure a known length on a wrap reel, weigh it, and calculate tex = mass(g)/length(km) or Ne = (length yd/840)/(mass lb).

Tenacity = breaking load/linear density; for yarn, CSP = Ne × lea strength (lb); for fabric, report tensile strength in N or breaking force per width.

Evenness testing gives CV%, thin places, thick places and neps; the Uster evenness tester and spectrogram help locate periodic faults.

Fabric tests: GSM, thickness, air permeability, abrasion (Martindale), pilling, tear strength, colour fastness to wash/light/rubbing/perspiration.

Moisture regain % = (wet mass − dry mass)/dry mass × 100; moisture content % = (wet mass − dry mass)/wet mass × 100.

CV% = (standard deviation/mean) × 100; control charts detect process drift; AQL sampling accepts or rejects a lot by defect class and sample size.

The 4-point fabric inspection system assigns 1–4 penalty points according to defect length; larger or longer defects receive more points.

Gear speed rule: driven speed = driver speed × (driver teeth/driven teeth); gear ratio = driven teeth/driver teeth; idler gears change direction, not overall ratio.

Belt drives transmit motion smoothly but can slip; chain drives avoid slip; cams convert rotary motion into specified follower motion in weaving and winding.

Preventive maintenance includes daily cleaning, lubrication, inspection of wire/roller/spindle tape, and scheduled replacement; records support trend analysis.

Condition monitoring uses vibration, temperature, noise and oil analysis; rising vibration often indicates unbalance, misalignment, bearing wear or loose parts.

Instrumentation chain: sensor/transducer → signal conditioning → controller/display → actuator; calibration against a traceable standard is required for reliable measurement.

A PID controller combines proportional, integral and derivative actions; integral removes offset and derivative reduces overshoot in temperature, tension or speed loops.

Availability = MTBF/(MTBF + MTTR); OEE = availability × performance × quality; both are used to judge maintenance and production effectiveness.

Before restarting after maintenance, check guards, interlocks, lubrication, tools and direction of rotation; confirm no personnel are inside the machine.

Machine safety rule: guard all nip points, belts, gears and shafts; interlocks must stop the machine when a guard is opened; never bypass an interlock.

Lockout/tagout: isolate energy, lock the isolator, attach a tag, verify zero energy, and remove locks only by the person who applied them.

Fire classes: A solids, B flammable liquids, C gases, D metals; electrical fires need CO2 or dry powder, not water; water is unsuitable for oil and live electrical equipment.

Cotton dust and fly cause respiratory risk and fire/explosion risk; use enclosure, local exhaust ventilation, grounding, housekeeping and suitable respirators.

Noise above 85 dB(A) over an 8-hour shift requires hearing conservation; reduce noise at source, enclose machines and provide hearing protection.

Textile effluent is characterised by BOD, COD, pH, TDS, colour and heavy metals; treatment includes primary, secondary and tertiary stages, with sludge management.

Waste hierarchy: reduce, reuse, recycle, recover energy, dispose; energy audits and water reuse lower operating cost and environmental load.

Break-even quantity = fixed cost/(selling price per unit − variable cost per unit); a project report should cover market, process, machinery, investment, cost and profitability.