Stainless Steel Metal Sand

Depth Filtration Before the Spinneret

Irregular particles form a network of intricate flow paths within the packed bed, increasing the contact area for retaining contamination before the melt reaches the spinneret.

Representative Irregular Particle Morphology

Polymer melts may contain hard solids from raw materials or equipment together with deformable gels.

If they reach the spinneret, contaminants can restrict capillaries and contribute to filament breaks, pressure instability and quality variation.

CAPTURE AND DIRT HOLDING: Textured particle surfaces provide a large contact area and a three dimensional retention path.

PRESSURE MANAGEMENT: A graded bed creates resistance to flow. Initial pressure and subsequent pressure rise depend on melt viscosity, throughput, bed depth, particle distribution, loading method and contamination accumulation.

PROCESS COMPATIBILITY: Alloy grade and particle blend must suit the polymer chemistry, melt temperature, preheating conditions and allowable differential pressure.

Product form: graded loose powder for a particulate filter bed - not a bonded or sintered porous disc, candle or element.

Application Scope

Suitable for validated packed bed spin pack duties in PET, rPET, PA6, PA66, polypropylene and other thermoplastic polymer processes.

POY and FDY filament spinning

BCF, IDY (industrial yarn) and staple fibre extrusion

Virgin and recycled polymer streams subject to process review

Controlled Production

High velocity water jets disintegrate a controlled molten metal stream; the droplets cool, solidify, dry and are classified into defined size fractions.

Water atomisation process - representative production sequence

Process Sequence

MELTING: A controlled molten metal stream leaves the tundish.

ATOMISATION: High velocity water jets divide the stream into droplets.

SOLIDIFICATION: Rapid heat extraction solidifies the droplets during descent.

CLASSIFICATION: Powder is collected, dried, sieved and graded to specification.

OUTPUT: Irregular water atomised stainless steel powder in controlled size fractions, supplied against the approved product specification.

ARRANGEMENT RESULT: The graded bed progressively captures solids and gels while distributing melt to the spinneret.

In a balanced pack, the spinneret produces parallel filaments with more consistent flow and reduced capillary contamination risk.

Melt flows through the metal sand bed from coarse to medium to fine. This graded arrangement delays blockage and progressively increases filtration resistance.

Retaining mesh is required above and below the loose sand, with supporting screens and a breaker plate beneath it.

Modern packs typically include the inlet cover, sealing ring, flow guide, filter layers, distribution/breaker plate, spinneret and pressure housing.

Two or three powder grades are commonly used. Their particle sizes, quantities and bed depths must be selected for the polymer, viscosity, melt cleanliness, temperature and throughput.

This is a representative configuration; individual Barmag, Neumag, TMT and other OEM packs may combine or reposition some screens and distribution plates.

A correctly engineered coarse to medium to fine metal sand bed provides progressive depth filtration and controlled melt flow resistance.

It removes gels and contaminants, protects spinneret capillaries and supports uniform melt distribution across the spinneret.

Potential Filament Quality Benefits

Improved yarn and filament linear density uniformity

Lower Decitex / Denier variation and Uster CV%

More consistent tenacity and elongation

Reduced contamination related variation; molecular orientation, shrinkage and dye uptake also depend on polymer and downstream processing

Fewer gels, slubs, broken filaments and spin breaks

Reduced fuzz, loops and downstream processing defects

More stable pack pressure and extended operating life

Average linear density and tensile properties remain primarily controlled by polymer quality, pump delivery, temperature, quenching, spinning speed and draw ratio.

Metal sand grades, quantities and bed depths must therefore be matched to the polymer and process.

Insufficient filtration allows contaminants and spinneret blockage, while excessive filtration resistance can cause high pressure, melt heating, polymer degradation and reduced pack life.

Alloy Selection

Final approval requires a process review and confirmation against the current product specification and batch certificate of analysis.

Chemical composition limits (mass %)

Grade selection considers polymer chemistry, pack preheating conditions, melt temperature, differential pressure, oxidation sensitivity and resistance to compaction.

SELECTION CONTROL: Validate initial pressure, pressure rise rate, polymer colour, filament performance and pack life under the actual operating conditions.

Particle Size Control

The final blend depends on the retention target, bed depth, melt viscosity, throughput and allowable pressure drop.

Particle size fractions are determined by dry sieving in accordance with ISO 4497:2020 - Metallic powders: determination of particle size by dry sieving

Irregular morphology supports useful void volume and multiple flow paths through the packed bed.

IMPORTANT: Apparent density, tap density and porosity values are indicative supplier data.

Particle strength, irregular morphology and controlled size fractions are designed to support stable filtration; actual results depend on the full pack architecture and operating conditions.

Recommended trial measurements

Initial pack pressure at stabilised throughput and melt temperature

Pressure rise rate during the agreed operating period

Pack life against the existing approved media

Filament breaks, yarn quality and spinneret cleanliness

Polymer colour and any evidence of oxidation or degradation

QUALIFICATION PRINCIPLE: Agree the product specification, trial quantity, operating window, measurable success criteria and review point before routine commercial supply.

Qualification links the approved media specification to measurable plant performance

Agree the baseline media, trial quantity, operating window and acceptance criteria before routine supply. Compare like for like operating conditions.

Upstream pack pressure is not necessarily the pressure drop across the powder bed. Record downstream pressure where available, and identify gauge, absolute or differential pressure.

Provide complete process, spin pack and operating data so our technical team can propose a controlled trial specification.

Information Required for Selection

Product and polymer: POY, FDY, BCF, industrial yarn, staple fibre or other extrusion duty

Throughput per spin pack and operating melt temperature

Spin pack cavity dimensions, available bed depth and screen arrangement

Spinneret diameter, capillary diameter and hole count

Current particle size blend, pack weight and loading method

Initial pressure, maximum permitted pressure and typical pack life

Target filtration improvement, yarn quality issue or contamination type

India - China Supply Partnership

Established Manufacturing and Global Reach

Established manufacturing capability in China since 2007 is supported by application expertise and commercial coordination in India. The stainless steel metal sand is accepted by major polymer spinners in China and international markets, with our wider filtration portfolio exported to more than 40 countries.

Competitive Technical Performance

Controlled particle sizing, irregular morphology and alloy options position the media as a credible alternative to established European and US products. Comparable or potentially improved performance can be confirmed through customer specific spin pack trials under agreed operating conditions.

Planned Surat – Silvassa Stock Programme

Selected approved grades and particle size ranges will be imported in consolidated quantities and stocked locally in Surat and Silvassa against agreed customer forecasts or blanket orders. Customers will be able to call off smaller quantities according to actual consumption instead of purchasing and storing a complete shipment.

Rapid Local Call Off Supply

Local dispatch from Surat and Silvassa will provide the shortest practical delivery time and a faster response to urgent or unplanned requirements. It will also reduce exposure to international freight schedules, customs clearance delays and costly emergency shipments.

Customer Inventory and Supply Benefits

The programme will reduce customer held inventory, working capital commitment and warehouse requirements. Scheduled call offs and planned stock replenishment will support reliable material availability, purchasing flexibility and continuity of production.