Stainless Steel Metal Sand

Irregular Stainless Steel Filtration Powder

The media is designed to support high dirt holding capacity, stable pressure development and protection of spinneret capillaries. Applications include PET, rPET, PA6, PA66, PP and other thermoplastics in POY and FDY filament spinning, BCF, industrial yarn and staple fibre extrusion, subject to application approval.

Depth Filtration Before the Spinneret

Irregular particles form intricate flow paths through the packed bed, providing contact area for retaining contamination before the melt reaches the spinneret. Textured surfaces and a three dimensional retention path support capture and dirt holding.

Polymer melts may contain hard solids from raw materials or equipment, together with deformable gels. Contaminants reaching the spinneret can restrict capillaries and contribute to filament breaks, pressure instability and quality variation.

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. 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, rather than a bonded or sintered porous disc, candle or element.

Controlled Production

Water atomisation creates an irregular particle morphology. High velocity water jets disintegrate a controlled molten metal stream; the droplets cool and solidify before the powder is collected, dried, sieved and classified into defined size fractions.

The process starts with molten metal leaving the tundish. Water jets divide the stream into droplets, rapid heat extraction solidifies them during descent, and the collected powder is dried and graded. The resulting irregular stainless steel powder is supplied against the approved product specification.

Typical Polymer Melt Spin Pack

The loose powder bed operates within a sealed and supported assembly. The approved pack drawing governs the component sequence, sealing materials, loading and pressure limits.

Component Names and Engineering Functions

The graded bed progressively captures solids and gels while distributing melt to the spinneret. In a balanced pack, this supports consistent flow and reduces the risk of capillary contamination.

Bed Design and Filament Performance

Alloy Selection

Select the grade around polymer chemistry, pack preheating, melt temperature, differential pressure, oxidation sensitivity and resistance to compaction. Final approval requires a process review and confirmation against the current product specification and batch certificate of analysis.

Chemical Composition Limits (Mass %)

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

Particle Size Control

Build the packed bed from controlled coarse, medium and fine fractions. The final blend depends on required filtration performance, 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.

Apparent density describes a loosely filled powder volume; tap density describes the volume after a defined tapping procedure. Packed bed void fraction depends on the loading method and particle distribution. The apparent density, tap density and porosity figures above are indicative values and must be confirmed against the agreed specification.

Media Performance and Controlled Trials

High mechanical strength and particle integrity support resistance to deformation and compaction as pressure rises. Irregular surfaces and comparatively low apparent density provide contact area and useful void volume. Controlled size fractions allow the filter bed structure, required filtration performance and pressure profile to be adjusted.

Performance is established in the complete spin pack and process. Agree the baseline media, trial quantity, operating window and acceptance criteria before routine supply, then 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 state whether each value is gauge, absolute or differential.

Application Information for Selection

Provide the product and polymer type, throughput per spin pack, melt temperature, cavity dimensions, available bed depth and screen arrangement. Include spinneret and capillary diameters, hole count, current particle size blend, pack weight and loading method.

Initial pressure, maximum permitted pressure, typical pack life and the target filtration improvement are also required. Describe any yarn quality issue or contamination type so that a controlled trial specification can be prepared.

Supply Planning

Forecast based stock and call off arrangements can support smaller deliveries against actual consumption, reduce customer held inventory and working capital requirements, and improve continuity of supply. Grade approval, particle size range, forecast volumes, stock location and delivery arrangements should be agreed before a programme begins.