PP Multifilament Yarn
Multifilament yarns are composed of a bundle of very thin, infinitely long threads. The threads are generally referred to as filaments. These yarns are generally spun on vertical machines with filaments extruded out of the spinnerets and air-cooled before getting wound onto spools.In multi filament yarn production,
each spinneret contains a plurality of holes (usually 30–100) and each hole of the spinneret creates a filament. Hence, multi filament yarns are a collection of extremely fine mono filaments (filament diameter, 10–50 μm). The Multi filament yarns are much more flexible than mono filaments at equivalent linear density and also higher covering power.
read morePP multi filament yarns ( twisted & Non twisted) with 700 to 4000 deniers has 5.5 to 6.5 GPD ( grams per denier) having good tenacity , high impact stress, water resistant , intermingled & recyclable.
PP yarns are classified into 2 types :
1) BCF stands for “bulked continuous filament” and refers to a one step process where one or multiple filament yarns are tangled by airstream. The end use for BCF yarns is usually carpets as BCF yarns are very bulky.
2) CF stands for “continuous filament” in which spin finishes yields high- and medium-tenacity yarns which contributes to stable production processes.
Why Bajaj ?
Trouble shooting guide - PP Multifilament yarns
|Filament breakages due to degradation||Moisture in the material.||Use hopper dryer.|
|Polymer dust/ powder in the material.||Use dust free material, eliminate sharp corners in conveying system particularly at hopper valves which generate polymer dust due to abrasion of granules at these sharp corners|
|High level of low molecular weight component in the material.||Use narrow molecular weight distribution material, reduce extrusion temperature.|
|Pigments / masterbatches degrading at spinning temperature||Use high temperature stability pigments / masterbatches.|
|Higher melt residence time in the extruder / manifold||Adjust melt residence time to optimum level.|
|Extrusion temperature too high||Optimise extrusion temperature profile|
|Uneven temperature distribution in manifold and spin pack||Check heating system, temperature controllers & thermocouples for its working.|
|Filament breakage at spinneret||Melt viscosity is too high or too low.||Adjust melt viscosity by optimising extrusion temperature.|
|Addition of some types of pigments drastically reduce melt viscosity.||Use high pressure & temperature stability pigments, reduce extrusion temperature.|
|Uneven melt flow or formation of channel due to damaged filter pack of spinning head.||Replace damaged filter pack, reduce the pressure between extruder & filter pack|
|Uneven melt flow due to malfunctioning of metering pump.||Check metering pump drive system, replace worn out parts of metering pump.|
|Bits of decomposed material clog spinneret holes.||Clean & replace spinneret, check for pigment degradation, reduce spin pack temperature.|
|Filament breakage at quenching zone||Melt draw down too high creating very high filament tension in spin-line zone.||Reduce take-up velocity.|
|Quench air velocity too high, filaments sticking to each other.||Reduce quench air velocity, temperature respectively.|
|Filamentation at spin finish applicator, worn out thread guides||Check thread guides for damage / serration, repair / replace spin finish applicator.|
|Filament breakage at winding zone||Jerks, vibrations & erratic drive of godets and winder||Check godet and winder drive for jerks and vibration, repair the same.|
|Worn out thread guides resulting into filamentation.||Replace worn out thread guides.|
|Non-uniformity of spun filaments||Degradation of material.||Use polymer free of moisture & dust. Use hopper dryers & feeders, reduce extrusion temperature, use narrow molecular weight distribution polymers|
|Non-uniform dispersion of pigments, degradation of pigments.||Use high temperature grade pigments, particle size of pigment could be less than 5μm size.|
|Through-put variation.||Check metering pump drive system & replace worn out metering pump parts.|
|Damaged or choked filter pack causing uneven melt flow.||Replace damaged filter pack with new pack.|
|Temperature variation between various spinning heads resulting into variation in melt viscosity.||Check temperature controller and thermo couples, maintain temperature variation between all spinning head within +/- 1degC.|
|Partial blocking of spinneret holes causing uneven melt flow.||Clean the spinnerets holes or replace spinning block with new pack.|
|Variation in quench air velocity.||Check & adjust air blower speed, clean air filters & nets.|
|Variation in take-up / winding speed.||Check AC inverters of godets and winders for their performance.|